APPENDIX C Pond Performance Review Effects

APPENDIX C - Pond Performance Review andEnvironmental Effects

Status: Draft Project number: Page 1 Our ref: Document3

REPORT

Takaka WWTP Upgrades Pond Performance Review and Environmental Effects

Prepared for Tasman District Council March 2012

@ rvrwn" Takaka WWTP Upgrades

This document has been prepared for the benefit of Tasman District Council. No liability is accepted bythis company or any employee or sub-consultant of this company with respect to its use by any otherperson.

This disclaimer shall apply notwithstanding that the report may be made available to other persons foran application for permission or approval to fulfil a legal requirement.

QUALITY STATEMENT

Stephen Sinclair Jon Krause

Annika Hesse

/4(ry l-Peter Loughran 19t03t12

19103112Rainer Hoffmann

Don Young

NELSON2nd Floor, 281 Queen Street, Richmond, Nelson 7020PO Box 3455, Richmond, Nelson 7050TEL +64 3 546 8728, FAX +64 3 548 201 6

REVISION SCHEDULE

PROJECT MANAGER PROJECT TECHNICAL LEAD

PREPARED BY

CHECKED BY

APPROVED FOR ISSUE BY

RevNo

Signature or Typed Name (documentation on file).

Prepared by Checked by Reviewed by Approved byDate Description

Status: FinalPoect number: z,2404161

Ma¡ch2O12Our ref: r Pond in Series Performance FNL.docx

Takaka WWTP Upgrades

Status: Final March 2012 Project number: Z2404161 Our ref: r_Pond in Series Performance_FNL

This document has been prepared for the benefit of Tasman District Council. No liability is accepted by this company or any employee or sub-consultant of this company with respect to its use by any other person.

This disclaimer shall apply notwithstanding that the report may be made available to other persons for an application for permission or approval to fulfil a legal requirement.

QUALITY STATEMENT

PROJECT MANAGER PROJECT TECHNICAL LEAD

Stephen Sinclair Jon Krause

PREPARED BY

Annika Hesse

CHECKED BY

19/03/12 Peter Loughran

REVIEWED BY

19/03/12 Rainer Hoffmann

APPROVED FOR ISSUE BY

………………………………............... ……/……/…… Don Young

NELSON 2nd Floor, 281 Queen Street, Richmond, Nelson 7020 PO Box 3455, Richmond, Nelson 7050 TEL +64 3 546 8728, FAX +64 3 548 2016


Status Final March 2012 Project number: Z2404161 i Our ref: r_Pond in Series Performance_FNL

Executive Summary This report presents a review of the upgrade of the Takaka wastewater treatment plant (WWTP) as proposed in the assessment of environmental effects and as adopted in the draft resource consent conditions. The proposed upgrade included the following. Installation of two aerated lagoons prior to the existing oxidation ponds. Minor modifications to the existing oxidation ponds. Construction of a new wetland. Construction of rapid infiltration basins as means for land disposal of the treated effluent. Provisions for the installation of a UV disinfection system within 12 months if the faecal coliform

trigger value is breached due to wastewater discharges during continuous monitoring.

An assessment of the performance of the Takaka WWTP oxidation ponds in series has been carried out to determine the expected effluent quality. In addition to the pond performance assessment, an assessment of the environmental effects of the pond effluent discharge into the receiving environment, namely the groundwater and the Takaka River, has been carried out. The pond performance assessment has been carried out under the assumption that the following modifications are carried out as part of the Takaka WWTP upgrade. Desludging of oxidation Pond 1. Installation of baffles in oxidation Pond 1 to create a clarification zone in the first third of the first

oxidation pond for settlement of septage solids. Recirculation of oxygen rich Pond 2 effluent to clarification zone or installation of brush type

aerators on clarification zone to ensure aerobic conditions in the top liquid layer in the clarification zone.

Installation of aerators to provide up to 9 kW of aeration on the remaining two thirds of the oxidation pond 1. No aerators required on Pond 2.

Installation of baffles in oxidation Pond 2. Installation of a septage receiving facility and balancing tank prior to the discharge into the

clarification zone in the first oxidation pond. Management of septage discharges to achieve consistent discharge volumes across the entire

year. For the assessment of the environmental effects on the receiving environment it has been conservatively assumed that. No changes to the pond effluent quality will occur as effluent passes through the upgraded

wetland system. No further treatment occurs in the rapid infiltration basins, i.e. in the soil matrix between the

infiltration surface and the groundwater. No reduction of contaminants, apart from faecal coliforms (95% reduction), occurs in the

groundwater. To assess the impact on the receiving environment, groundwater dilution and river mixing has been taken into account. The conclusion from the pond performance and environmental effects assessment is as follows. 1. The predicted pond effluent quality does not meet the proposed draft consent conditions with respect

to pond effluent concentrations of total nitrogen (TN), total ammoniacal nitrogen, total phosphorous (TP) and faecal coliforms (FC).

2. The annual mean dissolved reactive phosphorous (DRP) concentrations is the only contaminant parameter that exceeds the ANZECC guideline values in the 50m mixing zone in the Takaka River for all assessed scenarios. The soluble inorganic nitrogen (SIN) concentration in the 50m mixing zone in the Takaka River exceeds the ANZECC guideline values in 2050. All other annual mean contaminant concentrations comply with the ANZECC guideline values. It is noted that a single sample of a given contaminant may exceed the ANZECC guideline values.


Status Final March 2012 Project number: Z2404161 ii Our ref: r_Pond in Series Performance_FNL

3. The six months winter/off-peak period rolling mean groundwater FC concentration exceeds 100 cfu/100ml during all assessed scenarios but the six month peak/shoulder period rolling mean groundwater FC concentration remains well below 100 cfu/100ml.

It is recommended that: Aerated lagoons prior to the oxidation ponds are not required as part of the WWTP upgrade. A UV disinfection system is not required as part of the WWTP upgrade to protect the Takaka

River. (Note that the current draft consent conditions may require UV disinfection if certain triggers are breached)

The WWTP has the ability to accept septage loads. However, septage discharges should be managed to achieve consistent discharge volumes across the entire year.

Septage is discharged from a septage receiving facility with balancing tank into a new clarification zone in Pond 1.

The following modifications to the oxidation pond system have been taken into account when assessing the treatment performance and are recommended to be included in the Takaka WWTP upgrade. 1. Sludge survey of Pond 1 and desludging if required (prior to upgrades). 2. Installation of baffles in oxidation Pond 1 to create a clarification zone in the first third of the first

oxidation pond for settlement of septage solids including recirculation of oxygen rich Pond 2 effluent or brush type aerators on clarification zone to ensure aerobic conditions in the top liquid layer in the clarification zone.

3. Installation of aerators to provide up to 9 kW of aeration on the remaining two thirds of the first oxidation pond. No aerators are required on Pond 2.

4. Installation of baffles in oxidation Pond 2.

Council notes that the predicted pond effluent quality does not meet the proposed draft consent conditions with respect to pond effluent concentrations of total nitrogen (TN), total ammoniacal nitrogen, total phosphorous (TP) and faecal coliforms (FC).

Council accepts the modelling results which indicate that dissolved reactive phosphorous levels in the Takaka River may be elevated above the ANZECC guideline values as a result of the discharge from the RIBs.

Council accepts the modelling results with respect to faecal coliform concentrations in the groundwater at the edge of the river that indicate that during the winter period faecal coliform concentrations may be above the 100cfu/100ml UV disinfection trigger value previously approved in the draft consent conditions.

A discussion paper which assesses the differences between the recommendations stated in the draft consent conditions compared to what is now expected be prepared based on the findings from this document. The discussion paper should also include suggested revised consent conditions and justification for the changes.


Status: Final March 2012 Project number: Z2404161 Our ref r_Pond in Series Performance_FNL

Tasman District Council Takaka WWTP Upgrades

CONTENTS Executive Summary ................................................................................................................................ i

1 Introduction ...................................................................................................................................... 1

2 Flow and Load Periods and Scenario ............................................................................................... 1

3 Flows and Loads .............................................................................................................................. 2

3.1 Flows and Loads Excluding Septage ........................................................................................... 2

3.2 Septage ...................................................................................................................................... 3

4 Pond Performance Review............................................................................................................... 6

4.1 BOD Removal ............................................................................................................................. 6

4.1.1 Pond Areal Loading .............................................................................................................. 6

4.1.2 Current Pond Performance ................................................................................................... 7

4.1.3 Future Flows and Loads ....................................................................................................... 7

4.1.4 Treatment Model for Carbonaceous Removal ....................................................................... 8

4.1.5 Model Output ........................................................................................................................ 9

4.1.6 Comparison of Actual Pond Performance Against Model Output ........................................ 10

4.2 Removal of Nitrogen ................................................................................................................. 11

4.2.1 Treatment Model for Nitrogen Removal .............................................................................. 11

4.2.2 Model Output ...................................................................................................................... 12

4.2.2.1 TN Removal using Reed’s Approach ........................................................................... 12

4.2.2.2 TN Removal using Middlebrooks’ Approach ................................................................ 12

4.2.2.3 Total Ammoniacal Nitrogen Removal using Pano and Middlebrooks’ Approach .......... 13

4.2.2.4 Total Ammoniacal Nitrogen Removal using Reed’s Approach ..................................... 13


4.3 Phosphorous Removal .............................................................................................................. 15

4.3.1 Treatment Model for Phosphorous Removal ....................................................................... 15


4.4 Faecal Coliforms Removal ........................................................................................................ 16

4.4.1 Treatment Model for Faecal Coliforms Removal ................................................................. 16

4.4.2 Model Output ...................................................................................................................... 17


5 Aeration Requirements in Pond 1 .................................................................................................. 18

5.1 Aeration Requirements Including Septage ................................................................................ 18

6 Environmental Effects in the Takaka River ..................................................................................... 20

6.1 Site Description ......................................................................................................................... 20

6.2 Receiving Environment Guideline Values .................................................................................. 21



6.3 Groundwater and River Dilution Model ...................................................................................... 22

6.3.1 Model Assumptions and Inputs ........................................................................................... 22

6.4 Model Outputs ........................................................................................................................... 25

6.4.1 BOD River Concentration ................................................................................................... 25

6.4.2 TN River Concentration according to Reed ......................................................................... 26

6.4.3 Total Ammoniacal Nitrogen River Concentration according to Reed ................................... 27

6.4.4 Soluble Inorganic Nitrogen River Concentration ................................................................. 28

6.4.5 Dissolved Reactive Phosphorous River Concentration ....................................................... 30

6.4.6 Faecal Coliform River Concentration .................................................................................. 32

7 Conclusion ..................................................................................................................................... 33

7.1 Wastewater Treatment System ................................................................................................. 33

7.1.1 BOD ................................................................................................................................... 33

7.1.2 Nutrients ............................................................................................................................. 34

7.1.3 Faecal Coliforms ................................................................................................................ 34

7.2 Environmental Effects in the Takaka River from Treated Wastewater Discharge ....................... 35

7.3 Summary .................................................................................................................................. 37

8 Recommendations ......................................................................................................................... 38

LIST OF TABLES Table 3-1: Population Equivalents (Excluding Septage) .......................................................................... 2

Table 3-2: Average Dry Weather Flows (Excluding Septage) .................................................................. 2

Table 3-3: Influent Characteristics (Excluding Septage) .......................................................................... 3

Table 3-4: Influent BOD Load .................................................................................................................. 3

Table 3-5: Reported Septage Volumes (per MWH Correspondence with John Osmos, March 2011) ...... 4

Table 3-6: Projected Septage Volumes ................................................................................................... 4

Table 3-7: Per Capita Septage Contribution During Peak Period ............................................................. 5

Table 3-8: Per Capita Septage Contribution During Shoulder Period ....................................................... 5

Table 3-9: Per Capita Septage Contribution During Off-Peak Period ....................................................... 5

Table 3-10: Per Capita Septage Contribution During Winter Period ........................................................ 5

Table 4-1: Recommended Design Pond BOD Loading Rates .................................................................. 6

Table 4-2: Takaka WWTP Pond 1 BOD Loading Including sBOD Load from Septage ............................. 6

Table 4-3: Takaka WWTP Pond 1 BOD Loading ..................................................................................... 8

Table 4-4: Predicted Pond 1 BOD Effluent Concentration ....................................................................... 9

Table 4-5: Takaka WWTP Pond 2 BOD Loading ..................................................................................... 9

Table 4-6: Predicted Pond 2 BOD Effluent Concentration ..................................................................... 10

Table 4-7: Predicted Pond 1 TN Effluent Concentrations Using Reed ................................................... 12

Table 4-8: Predicted Pond 2 TN Effluent Concentrations Using Reed ................................................... 12

Table 4-9: Predicted Pond 1 TN Effluent Concentrations Using Middlebrooks ....................................... 12

Table 4-10: Predicted Pond 2 TN Effluent Concentrations Using Middlebrooks ..................................... 12



Table 4-11: Predicted Pond 1 Total Ammoniacal Nitrogen Effluent Concentrations Using Pano and Middlebrooks ........................................................................................................................ 13

Table 4-12: Predicted Pond 2 Total Ammoniacal Nitrogen Effluent Concentrations Using Pano and Middlebrooks ........................................................................................................................ 13

Table 4-13: Predicted Pond 2 Total Ammoniacal Nitrogen Effluent Concentrations Using Reed ............ 13

Table 4-14: Comparison between Observed and Predicted TN Pond 2 Effluent Concentrations ............ 14

Table 4-15: Comparison between Observed and Predicted Total Ammoniacal Nitrogen Pond 2 Effluent Concentrations ..................................................................................................................... 14

Table 4-16: BOD Removal Across Pond 1 and Pond 2 .......................................................................... 16

Table 4-17: Predicted Pond 2 TP Effluent Concentrations ..................................................................... 16

Table 4-18: Predicted Pond 1 FC Effluent Concentrations ..................................................................... 17

Table 4-19: Predicted Pond 2 FC Effluent Concentrations ..................................................................... 17

Table 5-1: Aeration Requirements in Pond 1 including Septage ............................................................ 19

Table 6-1: ANZECC Guideline Values ................................................................................................... 22

Table 6-2: Groundwater Dilution and Reduction Factors ....................................................................... 23

Table 6-3: Takaka River Dilution Factors for 2011 ................................................................................. 23




Table 6-7: River Background Concentrations at Kotianga ..................................................................... 24

Table 6-8: Peak Period BOD River Concentration ................................................................................. 25

Table 6-9: Shoulder Period BOD River Concentration ........................................................................... 25

Table 6-10: Off-Peak Period BOD River Concentration ......................................................................... 25

Table 6-11: Winter Period BOD River Concentration ............................................................................. 26

Table 6-12: Peak Period TN River Concentration according to Reed .................................................... 26

Table 6-13: Shoulder Period TN River Concentration according to Reed .............................................. 26

Table 6-14: Off-Peak Period TN River Concentration according to Reed ............................................... 26

Table 6-15: Winter Period TN River Concentration according to Reed .................................................. 27

Table 6-16: Peak Period Total Ammoniacal Nitrogen River Concentration according to Reed ............... 27

Table 6-17: Shoulder Period Total Ammoniacal Nitrogen River Concentration according to Reed ......... 27

Table 6-18: Off-Peak Period Total Ammoniacal Nitrogen River Concentration according to Reed ......... 28

Table 6-19: Winter Period Total Ammoniacal Nitrogen River Concentration according to Reed ............. 28

Table 6-20: Peak Period SIN River Concentration ................................................................................. 29

Table 6-21: Shoulder Period SIN River Concentration ........................................................................... 29

Table 6-22: Off-Peak Period SIN River Concentration ........................................................................... 29

Table 6-23: Winter Period SIN River Concentration ............................................................................... 29

Table 6-24: Peak Period DRP River Concentration without River Background Concentration ............... 30

Table 6-25: Shoulder Period DRP River Concentration without River Background Concentration ......... 30

Table 6-26: Off-Peak Period DRP River Concentration without River Background Concentration.......... 30

Table 6-27: Winter Period DRP River Concentration without River Background Concentration ............. 31

Table 6-28: DRP River Concentration Sensitivity Analysis Peak Period and 50m Mixing Zone .............. 31



Table 6-29: DRP River Concentration Sensitivity Analysis Peak Period and 200m Mixing Zone ............ 31

Table 6-30: Peak Period FC River Concentration .................................................................................. 32

Table 6-31: Shoulder Period FC River Concentration ............................................................................ 32

Table 6-32: Off-Peak Period FC River Concentration ............................................................................ 32

Table 6-33: Winter Period FC River Concentration ................................................................................ 32

Table 6-34: FC Groundwater Concentration .......................................................................................... 33

Table 7-1: Predicted TN and Total Ammoniacal Nitrogen Pond 2 Effluent Concentrations in 2050 ........ 34

Table 7-2: Predicted FC Pond 2 Effluent Concentrations in 2050 .......................................................... 34

Table 7-3: Predicted Annual Mean Contaminant Concentration in Takaka River, 50m Mixing Zone ...... 35

Table 7-4: Predicted Annual 95 Percentile Contaminant Concentration in Takaka River, 50m Mixing Zone ..................................................................................................................................... 35

Table 7-5: Predicted Six Months Rolling Mean FC Groundwater Concentrations .................................. 36

LIST OF FIGURES Figure 3-1: Average Annual Temperature Profile (OP = oxidation pond) ................................................. 3

Figure 4-1: Average Annual Dissolved Oxygen Profile (OP – oxidation pond) ......................................... 7

Figure 4-2: Observed Pond 2 BOD Effluent Concentration 2009 to 2011 .............................................. 10

Figure 4-3: Observed Pond 2 TN and Total Ammoniacal Nitrogen Effluent Concentration 2009 to 2011 15

Figure 4-4: Observed Pond 2 Faecal Coliform Effluent Concentration 2009 to 2011 ............................. 18

Figure 6-1: Relevant Locations for the Assessment of Environmental Effects ....................................... 20

APPENDICES Appendix A - Mitigation of Potential Nuisance Periphyton Growth in the Takaka River


Status: Final March 2012 Project number: Z2404161 Page 1 Our ref: r_Pond in Series Performance_FNL

1 Introduction Continuous on-line influent monitoring at the Takaka wastewater treatment plant (WWTP) was carried out from 18 November 2010 to 17 February 2011 using the SCAN UV/Vis spectrolyser and ammolyser and from 25 August to 6 October 2011 using an ammolyser. The results of the influent monitoring are presented in the Flows and Loads Report prepared by MWH for Tasman District Council in November 2011. The results showed that the flows and carbonaceous loads into the treatment plant are lower than initially assumed. Nutrient loads during the summer months however are greater than assumed in the initial design (conducted prior to the Assessment of Environmental Effects (AEE), November 2008). Moreover, a review of the AEE and further investigations of the Takaka River has shown that the AEE assumptions in terms of river flow volumes (1-d Mean Annual Low Flow (MALF)), the river dilution values and the extent of the mixing zone (50m) within the Takaka River were overly onerous to the Council. An ecological study of the river carried out in September 2010 by MWH recommended that higher river flow volumes (14-d MALF), greater dilution factors and a greater mixing zone (200m) would be appropriate to use for the assessment of environmental effects of the WWTP discharge without compromising the health of the receiving environment (i.e., the Takaka River). This initial design assumed the following treatment units would be associated with the upgrade of the WWTP: Aerated lagoons (two lagoons with staged construction) primary facultative pond (existing) (Pond 1 – 0.9025 ha) maturation pond (existing) (Pond 2 – 0.675 ha) wetland (to replace the existing marsh cells) rapid infiltration basins.

Due to the lower than assumed carbonaceous load to the Takaka WWTP, now and in future, a review of the oxidation pond performance has been undertaken to assess the need for the aerated lagoons prior to the oxidation ponds. Based on the recommendations of the September 2010 investigation, an assessment of the environmental effects was carried out using the updated flows and loads to the Takaka WWTP and the pond performance review. These reviews are the focus of this report.

2 Flow and Load Periods and Scenario

The influent monitoring showed that there were distinct changes in the influent characteristics and the flows over the monitoring period with a significant increase in flows and loads over the Christmas period and an even further increase during January. The following periods during the year have been evaluated for the Takaka WWTP: Peak – 1-20 January (approximately three weeks) Shoulder – 1-31 December and 21 January to 17 February (approximately one month on either

side of the peak period) Off-Peak - ~ October/November and March/April (approximately two months on either side of the

shoulder period) Winter – beginning of June to end of August (approximately three months). For each of the four periods, the performance of the treatment plant has been assessed for the following future scenarios: 2011 2018 2028 2050.



3 Flows and Loads

3.1 Flows and Loads Excluding Septage This section presents the flows and loads entering the plant which have been utilised for the assessment of the pond performance and the environmental effects excluding septage. The flows and loads are based on the online monitoring that has been carried out between November 2010 and February 2011. The monitoring results and the methodology for obtaining the future flows and load are presented in more detail in the Flows and Loads Report prepared by MWH in November 2011. The tables presented in this section (3.1) have been taken from this Flows and Loads Report. It is noted that the flows and loads presented below do not include the additional load that is delivered into the pond through the septage, which is discharged directly into Pond 1. The population equivalents that have been assumed for the flow and load predication for each scenario in each period are presented in Table 3-1.

Table 3-1: Population Equivalents (Excluding Septage)

Year Peak Population

(PE)

Shoulder Population (PE)

Winter & Off-Peak Population

(PE)

2011 4086 2700 2261

2018 4150 2736 2291

2028 4286 2847 2384

2050 4507 2983 2498

The average dry weather flow (ADWF) calculated for each scenario and period are presented in Table 3-2. Table 3-2: Average Dry Weather Flows (Excluding Septage)

Year Peak Average Dry Weather

Flow (m3/d)

Shoulder Average Dry Weather Flow (m3/d)

Winter & Off-Peak Average Dry Weather

Flow (m3/d)

2011 630 415 375

2018 640 420 380

2028 660 440 395

2050 695 460 410

Per capita flow factor (l/per.d)

154 154 164

The influent characteristics used in the model to assess pond performance at the Takaka WWTP are presented in Table 3-3.



Table 3-3: Influent Characteristics (Excluding Septage)

Influent Characteristics Unit Peak Shoulder Off-Peak Winter

Temperature °C 23 20 18 10

BOD concentration mg/l 382 375 335 335

TN concentration mg/l 172 196 77 77

FC concentration cfu/100ml 2.00E+07 2.00E+07 2.00E+07 2.00E+07

TP Concentration mg/l 22 23 18 18

Flow per capita l/person.day 154 154 164 164

BOD per capita g/person.day 58 61 55 55

TN per capita g/person.day 25 30 13 13

It has been assumed that the per capita load factors and the influent concentrations remain constant over the design horizon of the WWTP upgrade. The annual temperature profile of the ponds at the Takaka WWTP has been recorded over the past 10 years. The average monthly temperatures for both ponds at the Takaka WWTP are presented in Figure 3-1. The periods assessed for pond performance in this memo are shaded in different colours.

Figure 3-1: Average Annual Temperature Profile (OP = oxidation pond) Based on the per capita loads observed during the monitoring period and the assumed population equivalents, biological oxygen demand (BOD) influent loads to the Takaka WWTP have been calculated. These loads are presented in Table 3-4.

Table 3-4: Influent BOD Load

Influent BOD Load (kg/d)

Peak Shoulder Off-Peak Winter

2011 236 164 125 125

2018 240 166 126 126

2028 248 173 131 131

2050 261 181 138 138

3.2 Septage Septage is discharged directly into the first pond and was not captured by the influent monitoring. Twelve septage samples have been collected between July and September 2011. Technical Memorandum No.7 – Review of Septage Handling Options presents the results of this analysis. On the basis of these samples the following composition has been assumed in order to assess the impact of septage on the contaminant load of the Takaka WWTP:



47 kg/m3 chemical oxygen demand (COD) (estimated) 26 kg/m3 total suspended solids (TSS) 5.9 kg/m3 biological oxygen demand (BOD) 1.0 kg/m3 total nitrogen (TN) 0.2 kg/m3 total ammoniacal nitrogen. The septage volumes reported by John Osmos, the local septabe tank operator, in March 2011 are presented in Table 3-5.

Table 3-5: Reported Septage Volumes (per MWH Correspondence with John Osmos, March 2011)

Time Period Total Septage Volume

(m3) Working Days in Period

(No.) Average Daily Septage

(m3/day)

15 Nov to 23 Dec 2009 140 27 5.2

24 Dec 2009 to 20 Jan 2010 65 17 3.8

1 Jun to 30 Aug 2010 118 65 1.8

The current management of septage discharges results in peak discharges during the weeks leading up to the Christmas period. Little septage discharges occur during the winter period. In future, it is anticipated that septage discharges will be managed to achieve a more balanced discharge throughout the entire year (see Section 4.1.3). For the purpose of the pond performance assessment, seasonal septage discharges during the year 2011 have been assumed. However, for the future scenarios, the total annual volume has been averaged throughout the entire year to calculate the daily average based on the assumption of 5 working days per week. The projected annual and daily average septage volumes adopted for this assessment are presented in Table 3-6. Table 3-6: Projected Septage Volumes

Year Septage Volumes (m3/year) Daily Average Volume (m3/day)

2011 854 Peak and Shoulder: 5.0

Off-peak: 3.0 Winter: 2.0

2018 917 3.5

2028 999 4.0

2050 1,184 5.0

Based on the population equivalents presented in Table 3-1, the per capita septage volume, BOD and TN contribution has been calculated for each period and scenario (Table 3-7 through Table 3-10). Most of the BOD load in the septage is inert and bound to solids. The BOD load associated with the solids will settle out quickly in the first oxidation pond and will remain captured in the sludge. Therefore, only the soluble BOD fraction of the BOD load is required to be treated in the oxidation ponds. The Takaka septage samples showed that approximately 80% of the total BOD load is associated with solids. For the assessment of the pond performance and to determine aeration requirements, it was assumed that 20% of the total BOD is soluble BOD (sBOD) and requires treatment which is in line with typical industry practice. Table 3-7 to Table 3-10 also present the sBOD load to Pond 1.



Table 3-7: Per Capita Septage Contribution During Peak Period

Year

Per Capita Septage Contribution Peak Period sBOD Load to Pond 1

(kg/day) Volume (l/per.day) BOD

(g/per.day) TN (g/per.day)

2011 1.22 7.22 1.22 5.9

2018 0.84 4.98 0.84 4.1

2028 0.93 5.51 0.93 4.7

2050 1.11 6.55 1.11 5.9

Table 3-8: Per Capita Septage Contribution During Shoulder Period

Year

Per Capita Septage Contribution Shoulder Period sBOD Load to Pond 1



2011 1.85 10.93 1.85 5.9

2018 1.28 7.55 1.28 4.1

2028 1.41 8.29 1.41 4.7

2050 1.68 9.89 1.68 5.9

Table 3-9: Per Capita Septage Contribution During Off-Peak Period

Year

Per Capita Septage Contribution Off-Peak Period sBOD Load to Pond 1



2011 1.33 7.83 1.33 3.5

2018 1.53 9.01 1.53 4.1

2028 1.68 9.90 1.68 4.7

2050 2.00 11.81 2.00 5.9

Table 3-10: Per Capita Septage Contribution During Winter Period

Year

Per Capita Septage Contribution Winter Period sBOD Load to Pond 1



2011 0.88 5.22 0.88 2.4

2018 1.53 9.01 1.53 4.1

2028 1.68 9.90 1.68 4.7

2050 2.00 11.81 2.00 5.9



4 Pond Performance Review

4.1 BOD Removal

4.1.1 Pond Areal Loading

Facultative ponds are designed on the basis of surface BOD loading (kg BOD/ha.d). Equations to calculate the design BOD pond loading rate (s) are as follows:

s = 350 (1.107 – 0.002T)T-25 Mara (1987) s = 20T-120 Mara (1976)

Where:

T = mean air temperature (°C) The maximum acceptable organic loading rate (OLR) before the facultative pond turns anaerobic can be calculated using the following equation: s,max = 60 (1.099)T McGarry and Pescod (1970)

Where:

T = mean air temperature (°C) These equations are based on the assumption that no aeration is provided on the facultative pond. Using the temperatures presented in Table 3-3, the recommended design BOD loading rates for the Takaka WWTP have been calculated (Table 4-1) using the above presented formulas.

Table 4-1: Recommended Design Pond BOD Loading Rates

Recommended Design BOD Loading Rates Unit Peak Shoulder Off-Peak Winter

Design OLR (Mara 1987) kg BOD/ha.day 311 253 217 100

Design OLR (Mara 1976) kg BOD/ha.day 340 280 240 80

Max OLR (McGarry & Pescod) kg BOD/ha.day 526 396 328 154

Pond 1 at the Takaka WWTP has a surface area of 0.9025 ha. The BOD load to pond 1 at the Takaka WWTP is presented in Table 4-2 below.

Table 4-2: Takaka WWTP Pond 1 BOD Loading Including sBOD Load from Septage

Pond 1 BOD Loading Rate Unit Peak Shoulder Off-Peak Winter

2011 kg BOD/ha.day 268 192 165 164 Note: Bold values indicate the BOD loading rates to Pond 1 that exceed the recommended design loading rates presented in Table 4-1. Table 4-2 shows that, during winter, the BOD load to Pond 1 at the Takaka WWTP exceeds the recommended design loading rate and supplemental aeration is required to ensure process performance. During the shoulder, peak periods and off-peak periods, the BOD load to Pond 1 remains below the design BOD loading rate calculated using both of Mara’s approaches (1987 and 1976).



4.1.2 Current Pond Performance

The analysis above in Section 4.1.1 is suggesting that Pond 1 at the Takaka WWTP is currently operating within recommended loading rates during most of the year, but with the pond being slightly overloaded during the winter period. The dissolved oxygen (DO) concentration can be used to further assess the pond health. Oxygen plays two critical roles in pond systems: the control of odour by facilitating the oxidation of sulphides and other odorous compounds

produced in the pond sediments disinfection (sunlight disinfection) is directly dependent on DO concentrations. The annual DO concentration pattern has been monitored at the Takaka WWTP over the last 10 years. The average monthly DO concentrations for both ponds at the Takaka WWTP are presented in Figure 4-1. The periods assessed for pond performance in this memo are shaded in different colours.

Figure 4-1: Average Annual Dissolved Oxygen Profile (OP – oxidation pond)

Figure 4-1 shows that the DO concentration in Pond 1 is above 5 mg/l during the warmer months of the year (September to March). During the colder months of the year (April to August), the dissolved oxygen concentration drops down to an average over the last 10 years of 3 mg/l. It is noted that the DO concentration dropped below 1 mg/l during the winter months (June/July/August) in more recent years (2007 to 2010). The draft consent conditions require a minimum DO concentration of 1.4 mg/l in Pond 2 once the WWTP upgrade is completed. The DO profile presented in Figure 4-1 indicates that, during the summer months, the ponds at the Takaka WWTP are currently in good health and not overloaded, i.e. DO concentration above 1.4 mg/l. During the colder winter months, the ponds may be slightly overloaded. However, the DO monitoring of the ponds has not shown anaerobic conditions in the ponds. The assessment of the pond health indicates that the ponds, at their current configuration, are capable of treating the received load including the septage. Odour complaints received may be contributed to either septicity in sewerage system or temporary overloading due to shock loading of trade waste over short periods of time.

4.1.3 Future Flows and Loads

Table 3-6 predicts septage volumes to increase by 28% between 2011 and 2050, an increase from 854 m3/year to 1,184 m3 year. John Osmos indicated that his business would move to a more structured septage collection regime which would see the customers enter an agreement with John Osmos to pump out the septic tanks on a regular basis (every three to five years). This would allow John Osmos to stagger septage collection



throughout the year rather than experiencing a peak work load for the duration of the summer holidays, as currently occurring. Following the preparation of Technical Memorandum No.7, titled “Review of Septage Handling Options”, the Council has indicated that the preferred septage handling option is the discharge of screened septage into the first oxidation pond (Option 2). Option 2 includes a septage receiving facility and a buffer tank with mechanical mixing for buffering of septage and trade waste flows prior to discharge into the existing oxidation ponds. Compartmentalisation of the first oxidation pond is required to allow for the creation of a clarification zone where the sludge settles out. Both septage and wastewater are discharged to the inlet of the clarification zone. It is proposed to compartmentalise the first third of the first oxidation pond (~3,000m2) with a baffle curtain. For the purpose of this analysis, it has been assumed that the clarification zone does not contribute to the treatment capacity of the first oxidation pond for nutrient and BOD removal. Hence, the treatment capacity of the first pond is reduced and areal BOD loading rate is increased. It is required to either recirculate algae rich effluent from Pond 2 to the clarification zone or install aerators on the clarification zone to ensure an aerobic top liquid layer in order to minimise any odour nuisance. Additional aerators are also required on the remaining area of the first oxidation pond to compensate for the reduced pond area and the additional soluble BOD load from the septage. The BOD loading into the first oxidation pond with a reduced surface area for treatment (0.5985 ha) including the additional septage soluble BOD load (20% of the total septage BOD load) is presented in Table 4-3. It is noted that the performance assessment for 2011 is based on the current oxidation pond configuration without the clarification zone. Hence, the pond loading rate increases significantly between 2011 and 2018.

Table 4-3: Takaka WWTP Pond 1 BOD Loading

Pond 1 BOD Load (kg/ha.d)


2018 437 292 252 252

2028 451 305 262 262

2050 475 320 275 275

Note: Bold values indicate the BOD loading rates to Pond 1 that exceed the recommended design loading rates presented in Table 4-1. Table 4-3 shows that the BOD load to Pond 1 exceeds the recommended design loading rate during all periods and scenarios. During all winter scenarios, the BOD loading of Pond 1 exceeds the maximum loading rate calculated using the McGarry and Pescod approach. This indicates that additional aerators on Pond 1 are required to deal with septage discharges in future.

4.1.4 Treatment Model for Carbonaceous Removal

The expected pond effluent concentrations have been calculated using a treatment model. BOD removal across the pond is based on first order rate removal. The following formula has been used to calculate the BOD removal across the ponds:

1

Where: Ce = effluent concentration (mg/l) C0 = influent concentration (mg/l) k = first order reaction rate constant (d-1) D = hydraulic retention time (d)



The first order reaction rate constant is calculated as follows:

Where:

k = first order reaction rate constant (d-1) at a given temperature k20 = first order reaction rate constant (d-1) at 20°C = 0.3 d-1 for primary facultative ponds and = 0.1 d-1 for secondary facultative ponds θ = temperature coefficient = 1.035 T = temperature (°C)

The following assumptions have been made while assessing the performance of the ponds at the Takaka WWTP. 1. The aerated lagoon previously included in the upgrade of the Takaka WWTP is no longer required due

to the existing capacity of the pond system.

2. In the cases when the Pond 1 BOD loading rate exceeds the recommended design loading rate, aeration will be provided in form of surface aspirators to overcome the overloading of the natural pond system. Calculations of the aeration requirements are further addressed in Section 5.

4.1.5 Model Output

Taking into account the additional soluble BOD load associated with the septage discharge, the predicted BOD effluent concentrations from Pond 1 are presented in Table 4-4. It is noted that a reduced Pond 1 area of 0.5985 ha has been used to calculate the removal efficiency. This is a conservative approach to estimate the Pond 1 effluent concentration because both septage and raw wastewater will be discharged into the inlet of the clarification zone and it is expected that some removal other than the settling of septage solids takes place within the clarification zone.

Table 4-4: Predicted Pond 1 BOD Effluent Concentration

Pond 1 Effluent Concentration (mg/l)


2011 59 45 43 57

2018 85 66 63 82

2028 87 68 65 85

2050 91 71 68 88

Based on the Pond 1 effluent concentrations and a Pond 2 surface area of 0.675 ha, the Pond 2 BOD load has been calculated. The Pond 2 BOD load is presented in Table 4-5.

Table 4-5: Takaka WWTP Pond 2 BOD Loading



2011 55 28 24 31

2018 80 41 35 46

2028 86 45 38 50

2050 94 49 42 54

Table 4-5 shows that the Pond 2 BOD load is well below the design loading rates for all periods and scenarios. Therefore, no aeration is required on Pond 2. The Pond 2 BOD effluent concentrations have been calculated using the first order removal formula. The predicted BOD effluent concentrations from Pond 2 are presented in Table 4-6.



Approximately 70-90% of the effluent BOD from a facultative pond is contributed to the algae it contains. The filtered BOD can be conservatively estimated at 30% of the effluent BOD. Filtered BOD concentrations are presented in brackets in Table 4-6.

Table 4-6: Predicted Pond 2 BOD Effluent Concentration

Pond 2 Effluent Concentration (mg/l)


2011 24 (7.3) 15 (4.6) 15 (4.4) 23 (7.0)

2018 35 (10.6) 22 (6.8) 21 (6.4) 34 (10.1)

2028 37 (11.1) 24 (7.2) 23 (6.8) 36 (10.7)

2050 40 (12.0) 26 (7.8) 25 (7.4) 38 (11.5)

4.1.6 Comparison of Actual Pond Performance Against Model Output

Figure 4-2 presents the actual BOD concentration in the effluent of Pond 2. The periods assessed for Pond performance in this memo are shaded in different colours. The model predictions of the Pond 2 BOD effluent concentrations for the year 2011 (including septage) are included in Figure 4-2 as solid lines inside the shaded areas.

Figure 4-2: Observed Pond 2 BOD Effluent Concentration 2009 to 2011

Figure 4-2 shows that, in most instances, the model predicts lower Pond 2 effluent concentrations than actually observed. This indicates that short-circuiting occurs in the oxidation ponds under current conditions reducing the retention time of the wastewater in the system or that sludge accumulation in the pond system reduces the retention time. It is noted that a sludge survey of the oxidation ponds will be carried out in August 2012 which will confirm the extent of sludge accumulation. An assessment of the Pond 2 BOD effluent concentration with a reduced retention time showed that the Pond 2 BOD effluent concentrations would increase by approximately 5-10 mg/l depending on the wastewater temperatures in the pond.

Winter



Subsequent to the upgrade to the Takaka WWTP, including the installation of baffles and desludging of oxidation Pond 1, the problem of reduced retention times will be remediated and the retention times assumed in the model will be applicable. Baffling of oxidation Pond 2 is recommended as part of the upgrade and this will maximise the hydraulic retention time in Pond 2.

4.2 Removal of Nitrogen

4.2.1 Treatment Model for Nitrogen Removal

TN effluent concentrations from Pond 1 and Pond 2 have been calculated using the Reed and Middlebrooks formulas. Total ammoniacal nitrogen effluent concentrations from Pond 1 and Pond 2 have been calculated using the Pano and Middlebrooks formula. TN Reduction as per Reed:

. .

Where: Ce = effluent concentration (g/m3) C0 = influent concentration (g/m3) k = first order reaction rate constant (d-1) D = hydraulic retention time (d)


Where:

k = first order reaction rate constant (d-1) at a given temperature k20 = first order reaction rate constant (d-1) at 20°C = 0.0064 θ = temperature coefficient = 1.039 T = temperature (°C)

TN reduction as per Middlebrooks:

1 0.000576 0.00028 . . .

Where: Ce = effluent concentration (g/m3) C0 = influent concentration (g/m3) D = pond retention time (d) T = temperature (°C)

Total ammoniacal nitrogen reduction as per Pano and Middlebrooks: For temperatures below 20 °C,

1 0.0038 0.000134 . . .

For temperatures above 20 °C,

1 0.005035 . .



Where: Ce = effluent concentration (g/m3) C0 = influent concentration (g/m3) A = pond area (m2) Q = wastewater flow (m3/d) T = temperature (°C)

4.2.2 Model Output

4.2.2.1 TN Removal using Reed’s Approach

The Pond 1 and Pond 2 TN effluent concentrations are presented in Table 4-7 and Table 4-8.

Table 4-7: Predicted Pond 1 TN Effluent Concentrations Using Reed

Pond 1 TN Effluent Concentration (mg/l)


2011 99 109 65 82

2018 103 116 70 86

2028 104 117 70 86

2050 104 118 70 86

Table 4-8: Predicted Pond 2 TN Effluent Concentrations Using Reed



2011 49 54 34 56

2018 51 58 36 59

2028 52 58 36 59

2050 52 59 37 60

4.2.2.2 TN Removal using Middlebrooks’ Approach

The Pond 1 and Pond 2 TN effluent concentrations are presented in Table 4-9 and Table 4-10.

Table 4-9: Predicted Pond 1 TN Effluent Concentrations Using Middlebrooks



2011 159 167 87 95

2018 171 185 98 103

2028 171 187 98 104

2050 172 189 99 105

Table 4-10: Predicted Pond 2 TN Effluent Concentrations Using Middlebrooks



2011 134 130 66 77

2018 145 144 74 84

2028 146 147 75 86

2050 148 150 77 87



4.2.2.3 Total Ammoniacal Nitrogen Removal using Pano and Middlebrooks’ Approach

The Pond 1 and Pond 2 total ammoniacal nitrogen effluent concentrations are presented in Table 4-11 and Table 4-12.

Table 4-11: Predicted Pond 1 Total Ammoniacal Nitrogen Effluent Concentrations Using Pano and Middlebrooks

Pond 1 Total Ammoniacal Nitrogen Effluent Concentration (mg/l)


2011 110 95 40 65

2018 125 115 51 75

2028 126 117 52 76

2050 127 120 54 77

Table 4-12: Predicted Pond 2 Total Ammoniacal Nitrogen Effluent Concentrations Using Pano and Middlebrooks



2011 75 52 15 44

2018 86 64 19 51

2028 87 66 20 52

2050 90 69 21 54

4.2.2.4 Total Ammoniacal Nitrogen Removal using Reed’s Approach

The Pond 2 total ammoniacal nitrogen effluent concentrations have also been calculated based on Reed’s approach to calculate TN assuming that the total ammoniacal nitrogen concentration is a percentage of the TN. Based on observations of the ratio between TN and total ammoniacal nitrogen concentration in the effluent of Pond 2, it has been assumed that 85% of the TN is total ammoniacal nitrogen. Table 4-13 presents the Pond 2 total ammoniacal nitrogen effluent concentrations using Reed’s approach.

Table 4-13: Predicted Pond 2 Total Ammoniacal Nitrogen Effluent Concentrations Using Reed



2011 42 46 29 48

2018 43 49 31 50

2028 44 49 31 50

2050 44 50 31 51


Two different models have been used to predict the TN and total ammoniacal nitrogen concentrations in the effluent of Pond 2. Table 4-14 and Table 4-15 present the average TN and total ammoniacal nitrogen concentrations observed in the Pond 2 effluent at the Takaka WWTP between 2009 and 2011 and compares these values to the TN and total ammoniacal nitrogen concentrations predicted using Middlebrooks’, Reed’s and Pano and Middlebrooks’ models.



Table 4-14: Comparison between Observed and Predicted TN Pond 2 Effluent Concentrations

Period

2011 Pond 2 TN Effluent Concentration (mg/l)

TN Observed TN according to

Middlebrooks TN according to Reed

Peak No data 134 49

Shoulder 50 130 54

Off-Peak 60 66 34

Winter 52 77 56

Table 4-15: Comparison between Observed and Predicted Total Ammoniacal Nitrogen Pond 2 Effluent Concentrations

Period

2011 Pond 2 Total Ammoniacal Nitrogen Effluent Concentration (mg/l)

Total Ammoniacal Nitrogen Observed

Total Ammoniacal Nitrogen according to Pano and

Middlebrooks

Total Ammoniacal Nitrogen according to Reed

Peak No data 75 42

Shoulder No data 52 46

Off-Peak No data 15 29

Winter 43 44 48

Table 4-14 shows that the predicted TN effluent concentrations using Middlebrooks’ approach are much higher than the observed concentrations. Apart from the off-peak period, the TN concentrations predicted using Reed’s approach correlate with the observed data. The total ammoniacal nitrogen data available from the Takaka WWTP is limited to the five samples which have all been taken during the winter period. However, if a ratio between TN and total ammoniacal nitrogen of 1.21 (as calculated from the observed winter data) is applied to determine the total ammoniacal nitrogen concentrations from the observed TN data during the shoulder and off-peak periods, the total ammoniacal nitrogen concentration during the shoulder and off-peak periods can be calculated to 41 mg/l and 50 mg/l, respectively. Comparing these values with the predicted values presented in Table 4-15, it is apparent that the Pano and Middlebrooks model over-estimates the total ammoniacal nitrogen concentrations in the Pond 2 effluent for the shoulder period and under-estimates the concentration during the off-peak period. As for the TN concentrations, the total ammoniacal nitrogen concentration predicted using Reed’s approach correlate with the observed data, apart from during the off-peak period where the Reed’s approach under-estimates the total ammoniacal nitrogen concentration compared to the concentration calculated from the observed TN data.

Figure 4-3 illustrates the comparison between the observed TN and total ammoniacal nitrogen concentrations in the effluent of Pond 2 and the concentrations predicted using Reed’s model. The periods assessed for pond performance in this report are shaded in different colours. The model predictions of the Pond 2 TN effluent concentrations using Reed’s approach for the year 2011 (including septage) are included in

Figure 4-3 as solid lines inside the shaded areas. It is noted that data for Pond 2 total ammoniacal nitrogen effluent concentrations is only available for the winter periods in 2010 and 2011.



Figure 4-3: Observed Pond 2 TN and Total Ammoniacal Nitrogen Effluent Concentration

2009 to 2011

Figure 4-3 shows that the observed TN concentrations in the effluent of Pond 2 are below the predicted concentrations during the winter period. Limited data is available outside the winter period. Actual TN concentrations during the off-peak period appear to be higher than the predicted concentrations whereas during the shoulder period, the actual observed TN concentrations are below the predicted concentrations. Reed’s approach is considered more appropriate to predict TN and total ammoniacal nitrogen effluent concentrations. Reed’s approach to predict TN and total ammoniacal nitrogen Pond 2 effluent concentrations has been used in Section 6 to assess the environmental effects of the discharge on the Takaka River. The prediceted TN and total ammoniacal nitrogen Pond 2 effluent concentration presented in Figure 4-3 are calculated based on the assumption that the entire Pond 1 volume is available for treatment, i.e. the clarification zone is not existent at the time of the monitoring. An assessment of the TN and total ammoniacal nitrogen Pond 2 effluent concentrations with a reduced retention time (in case short-circuiting exists or settled sludge takes up treatment volume within Pond 1) showed only a small increase in Pond 2 effluent concentrations between 2-4 mg/l.

4.3 Phosphorous Removal

4.3.1 Treatment Model for Phosphorous Removal

Phosphorous removal in pond based treatment systems is usually crudely estimated using the model developed by Houng and Gloyna (1984) which predicts that 45% P will be removed when BOD removal is above 90%. The TP concentration in the septage has not been measured in the septage samples that have been analysed between July and September 2011. However, it has been assumed that the TP contained in the septage is mainly associated with solids which will readily settle out in the clarification zone of the first oxidation pond. Therefore, there is no increase in the TP influent concentration between the scenario including septage and the scenario excluding septage.



Table 4-16 presents the BOD removal percentage across the pond system at the Takaka WWTP including the soluble BOD load from the septage.

Table 4-16: BOD Removal Across Pond 1 and Pond 2

BOD Removal Across Pond 1 & Pond 2 (%)


2011 94% 96% 96% 94%

2018 91% 95% 95% 91%

2028 91% 94% 94% 91%

2050 90% 94% 94% 90%

Table 4-16 shows that BOD removal across the ponds is always greater than 90%. Therefore, a 45% TP removal efficiency has been assumed for all periods and scenarios to calculate the TP effluent concentrations from Pond 2. The predicted concentration of TP for Pond 2 is shown in Table 4-17.

Table 4-17: Predicted Pond 2 TP Effluent Concentrations

Pond 2 TP Effluent Concentration (mg/l)


2011-2050 12.1 12.7 9.9 9.9


Only three samples for TP in the Pond 2 effluent were measured. All three samples fall within the winter period 2010 and range from 7.9 to 10 mg/l. Table 4-17 states a predicted Pond 2 TP effluent concentration of 9.9 mg/l during the 2011 winter period. The model is therefore considered appropriate to calculate TP effluent concentrations.

4.4 Faecal Coliforms Removal

4.4.1 Treatment Model for Faecal Coliforms Removal

Faecal Coliforms (FC) removal across the pond is based on first order rate removal (Marais). The following formula has been used to calculate the removal:

1

Where:

Ce = effluent concentration (mg/l) Ci = influent concentration (mg/l) k = first order reaction rate constant (d-1) D = hydraulic retention time (d)




Where:

k = first order reaction rate constant (d-1) at a given temperature k20 = first order reaction rate constant (d-1) at 20°C = 2.6 θ = temperature coefficient = 1.19 T = temperature (°C)

4.4.2 Model Output

FC concentrations from Pond 1 and Pond 2 have been calculated using the first order removal formula. Table 4-18 and Table 4-19 present the predicted FC effluent concentrations from Pond 1 and Pond 2.

Table 4-18: Predicted Pond 1 FC Effluent Concentrations

Pond 1 FC Effluent Concentration

(cfu/100ml) Peak Shoulder Off-Peak Winter

2011 4.24E+05 2.80E+05 3.64E+05 1.45E+06

2018 6.50E+05 4.29E+05 5.60E+05 2.16E+05

2028 6.73E+05 4.48E+05 5.84E+05 2.24E+06

2050 7.10E+05 4.72E+05 6.14E+05 2.34E+06

Table 4-19: Predicted Pond 2 FC Effluent Concentrations

Pond 2 FC Effluent Concentration

(cfu/100ml) Peak Shoulder Off-Peak Winter

2011 1.20E+04 5.00E+03 9.00E+03 1.40E+05

2018 1.90E+04 8.00E+03 1.40E+04 2.12E+05

2028 2.10E+04 9.00E+03 1.50E+04 2.28E+05

2050 2.30E+04 1.00E+04 1.70E+04 2.49E+05


Figure 4-4 presents the actual faecal coliform concentrations in the effluent of Pond 2. The periods assessed for pond performance in this memo are shaded in different colours. The model predictions of the Pond 2 faecal coliform effluent concentrations for the year 2011 are included in Figure 4-4 as solid lines inside the shaded areas.



Figure 4-4: Observed Pond 2 Faecal Coliform Effluent Concentration 2009 to 2011 Figure 4-4 shows that the observed faecal coliform concentrations are variable within the periods over the last three years. A comparison between the observed and predicted data is therefore difficult. For the year 2011, the predicted peak period faecal coliform concentration is slightly lower than the average of the three samples taken during this period. No samples were taken during the 2011 shoulder period, however, the samples from December 2010 indicate that the predicted faecal coliform concentration represents the average of the three samples. The predicted faecal coliform concentration during the off-peak period is higher than the observed sample. It is noted that only one sample has been collected during this period. The predicted faecal coliform concentration during the 2011 winter period is lower than the one sample that has been collected. However, the samples collected during the 2010 winter period show lower faecal coliform concentrations than predicted.

5 Aeration Requirements in Pond 1

5.1 Aeration Requirements Including Septage Table 5-1 presents the aeration requirements for Pond 1 including the additional load from septage to ensure that Pond 1 is operated within the recommended design loading rates at any point in time.



Table 5-1: Aeration Requirements in Pond 1 including Septage



2018 437 292 252 252

2028 451 305 262 262

2050 475 320 275 275

Recommended Design Loading Rate (kg/ha.d)

Organic Loading Rate 311 253 217 80

Pond 1 BOD Load (kg/day)1

2018 248 162 138 138

2028 257 169 144 144

2050 271 178 151 151

Natural Pond BOD Removal Capacity (kg/day)2

Removal Capacity 186 151 130 48

BOD Removal Required via Aeration (kg/d)

2018 62 11 8 90

2028 71 18 14 96

2050 85 27 21 103

Oxygen Requirement (kg O2/d)

2018 75 13 9 108

2028 85 21 16 115

2050 102 32 26 124

Aeration Requirement (kWhr/d)

2018 124 21 15 179

2028 141 35 27 191

2050 170 53 43 207

Aeration Power Requirement (kW)

2018 5 1 1 7

2028 6 1 1 8

2050 7 2 2 9

Note 1: Pond 1 BOD load includes sBOD load from septage Note 2: Based on an effective pond area of 0.5985 ha, i.e. pond area without clarification zone. Table 5-1 shows that Pond 1 requires continuous aeration for each period from the year 2018 onwards. It is noted that the aeration requirement during winter is the highest (9kW in 2050), closely followed by the aeration requirement over the peak period (7kW in 2050). There is some potential to minimize the aeration requirements throughout the year by limiting septage discharges to the shoulder and off-peak period. However, this has not been considered further in this assessment since the overall aeration requirement is low and operation savings from septage discharge controls are small. It is noted that the presented number of aerators does not include the aerators that may be required on the clarification zone.



6 Environmental Effects in the Takaka River

6.1 Site Description The Takaka WWTP is located in the vicinity of the Takaka River. The discharge of the treated effluent via rapid infiltration basins mixes with the groundwater and is then discharged via the groundwater into the Takaka River. For the purpose of establishing dilution factors in the river, a theoretical point discharge into the river has been assumed. In practice, the groundwater will discharge into the Takaka River over a dispersed area along the embankment of the river. The assumed discharge point is located approximately 600m upstream of the confluence of the Waikoropupu River with the Takaka River and approximately 4km upstream of the river mouth. Figure 6-1 below shows the relevant locations for the assessment of the environmental effects.

Figure 6-1: Relevant Locations for the Assessment of Environmental Effects

An investigation into the dispersion and dilution characteristics of the lower Takaka River (MWH 2005) indicated that discharge of treated wastewater via the groundwater seepage zone enters the river from the true right bank at the beginning of a long sweeping outside bend. The discharge plume hugs the true right bank for the first 400m with minimal lateral mixing. The outside of the bend is armed with heavy rip-rap due to the relatively high water velocities which occur along this reach and which maintain deep water (up to 3m deep) against the bank. Beyond 400m the river straightens and the plume begins to



mix transversely across the river. It becomes fully mixed across the full width of the river some 800 to 900m downstream of the groundwater discharge zone (downstream of the Waikoropupu River confluence). Key characteristics of the mixing zone include the following. The discharge plume occupies a narrow band of relatively deep water against the true right bank

for the first 400m downstream of the groundwater discharge zone. Little transverse mixing occurs over the first 400m. Full mixing across the entire width of the river occurs at approximately 800m to 900m downstream

of the groundwater discharge plume zone, downstream of the Waikoropupu River confluence. In a worst case scenario the projected average dry weather wastewater flow of ~700 m3/day

(8.1 L/s, during the 2050 peak period) discharged into the river at a 14-day MALF would receive 1663 fold dilution after full mixing (downstream of the Waikoropupu and Takaka River confluence).

It is noted that the assessment of the environmental effects is directed at the effects in the Takaka River upstream of the confluence with the Waikoropupu River (indicated by the yellow shape in Figure 6-1). The confluence with the Waikoropupu River is located approximately 600m downstream of the assumed treated wastewater discharge point. Past the point of the confluence, the environmental effects will be significantly reduced due to the increased dilution within the River. The inflow from the Waikoropupu River approximately doubles the flow in the Takaka River.

6.2 Receiving Environment Guideline Values The fresh water guideline values presented in the Australian and New Zealand Environment Conservation Council (ANZECC) water quality guidelines1 (ANZECC guidelines) have been used to assess the environmental effects of the treated wastewater discharge via groundwater into the Takaka River. The ANZECC guidelines provide a summary of the water quality guidelines proposed to protect and manage the environmental values supported by the water resources and to maintain a designated water use. For some environmental values the ANZECC guideline value may be an adequate guide to quality (e.g. for contact recreation or drinking). For other specific environmental values the guideline can be just a starting point to trigger an investigation to develop more appropriate guideline based on the type if water resource and inherent differences in water quality across regions. For water whose environmental value is aquatic ecosystem protection, for example, the investigation should aim to develop and adapt these guidelines to suit the local area or region. Therefore, the aquatic ecosystem guideline values such as total nitrogen (TN), total ammoniacal nitrogen, soluble inorganic nitrogen (SIN) and total phosphorous (TP) can be used as trigger levels for further investigation of the environmental impacts of the treated wastewater discharge on the Takaka River. The ANZECC guideline values considered relevant to the assessment of the environmental effects of the treated wastewater discharge via groundwater into the Takaka River are presented in Table 6-1. The guideline values for TN, ionised ammoniacal nitrogen (ionised NH4-N), oxidised nitrogen (NOx), SIN, TP and dissolved reactive phosphorous (DRP) apply to slightly disturbed lowland ecosystems2.

1 Australian and New Zealand Environment and Conservation Council (ANZECC) (2000) Guidelines for Fresh and Marine Water Quality. 2 These values have been derived from sampling in the Haast River.



Table 6-1: ANZECC Guideline Values

Parameter ANZECC Freshwater Protection Guidelein Value for New

Zealand3

TN 0.614 mg/l

Total ammoniacal nitrogen Toxicity 99% protection of species Toxicity 95% protection of species

At pH = 8 0.32 mg/l 0.9 mg/l

Ionised NH4-N nutrient guideline value 0.021 mg/l

NOx 0.444 mg/l

SIN4 0.465 mg/l

TP 0.033 mg/l

DRP 0.01 mg/l

Faecal Coliforms 150 cfu/100ml (for primary contact recreation5)

1,000 cfu/100ml (for secondary contact recreation6)

The assessment of the background levels (Takaka Wastewater Treatment Plant – Mitigation of Potential Nuisance Periphyton Growth in the Takaka River, prepared by MWH, September 2010) showed that SIN may exceed the ANZECC trigger level from time to time, even without the impact of treated wastewater discharges.

6.3 Groundwater and River Dilution Model The following formula has been used to determine the contaminant concentrations within the Takaka River.

1

Where: Ce = effluent concentration (mg/l) R = Groundwater reduction factor DGW = Groundwater dilution factor DR = River dilution factor

6.3.1 Model Assumptions and Inputs

Table 6-2 to Table 6-7 present the model input values required to solve the above presented equation.

Groundwater In 2007, a groundwater investigation was undertaken at the WWTP site to determine the influence of the discharge of treated wastewater from the existing ground disposal system7. The investigation monitored contaminant concentrations up and down gradient of the discharge to determine the influence of the effluent on groundwater quality. The investigations found E. coli concentrations in the treated wastewater discharged to the ground quickly reduced from approximately 2500 cfu/100mL to less than 100cfu/100mL within 50 metres of groundwater travel and to around 10 cfu/100mL within 200 metres of groundwater travel.

3 For lowland rivers at <150m altitude 4 Soluble inorganic nitrogen = NH3-N + NH4-N + NO3-N + NO2-N 5 Water used for primary contact activities such as swimming, bathing and other direct water-contact sports. 6 Water used for secondary contact activities such as boating and fishing. 7 MWH, 2007, Takaka WWTP Upgrade – Groundwater Study, prepared for Tasman District Council, April 2007.



A further groundwater observation was undertaken as part of the RIB trial during August 20118. The distances observed during 2007 are greater than those used during the 2011 RIB trial, but the results confirm that bacteria are rapidly attenuated in the receiving environment. The investigation concluded that with the Takaka River being greater than 350 metres down gradient of the discharge location, additional groundwater mixing and natural die of would further reduce the faecal coliforms concentration to levels equivalent to the background and up-gradient groundwater. The distance from the proposed RIB location to the Takaka River in a northwest direction is approximately 600 metres. Similar long distance trends can be expected from the proposed RIB site as observed in the 2007 study. Table 6-2 presents the groundwater dilution and reduction factors determined in the 2007 MWH groundwater study report. Based on the work carried out during 2011, these values are considered conservative.

Table 6-2: Groundwater Dilution and Reduction Factors

Contaminant Groundwater Dilution Factor Groundwater Reduction Factor

BOD 10 0

TN 10 0

Total ammoniacal nitrogen 10 0

DRP 10 0

FC 10 0.98

Takaka River An assessment of the ecology of the Takaka River9 (Appendix A) has shown that the 14-day Mean Annual Low Flow (14d-MALF) and a 200m mixing zone is the most appropriate scenario to assess the environmental effects of the treated WWTP effluent on the Takaka River. The assessment of the effects on the Takaka River presented below is based on the 14-d MALF and presents the contaminant concentrations in the Takaka River for four different mixing zones (50m, 100, 200m and 400m). The river dilution factors presented in Table 6-3 to Table 6-6 have been based on dilution factor determined in a dye study in the Takaka River which was carried out in 200510. The dilution factors presented in the 2005 study were based on the 1-d MALF and superseded wastewater discharge volumes. The dilution factors presented in Table 6-3 to Table 6-6 have been recalculated using the 14-d MALF and current wastewater discharge volumes as presented in Table 3-2.

Table 6-3: Takaka River Dilution Factors for 2011

River Flow & Dilution Peak Shoulder Off-Peak Winter

50m Dilution Factor 14 21 24 24




8 MWH, 2011, Takaka WWTP RIB Trial Results and Hydrogeological Assessment, prepared for Tasman District Council, October 2011 9 Letter to Gavin Hutchison (TDC), dated 14 September 2010: Takaka Wastewater Treatment Plant – Mitigation of Potential Nuisance Periphyton Growth in the Takaka River, prepared by MWH 10 Dye Mixing and Water Quality Study of the Takaka River, prepared by MWH, 2005





















Background contaminant concentrations in the Takaka River upstream of the wastewater discharge have been analysed by Council. The results of Council’s water quality monitoring (nutrients) in the Takaka River at Kotianga over the period 1999 to 2007 are summarised in Table 6-7. The Kotianga site is located 2-3 km upstream of the Takaka WWTP.

Table 6-7: River Background Concentrations at Kotianga

Contaminant (Median Concentration) River Background Concentration at Kotianga

Bridge in Takaka River

BOD (mg/l) 0

TN (mg/l) 0.24

Total ammoniacal nitrogen (mg/l) 0.003

NO3-N (mg/l) 0.15

DRP (mg/l) 0.003

FC (cfu/100ml) 15



6.4 Model Outputs This section presents the predicted river contaminant concentrations on the edge of the mixing zone within the Takaka River based on the performance of the pond system including the additional load from septage discharges to the WWTP, the reduction in the groundwater and the dilution in groundwater and river.

6.4.1 BOD River Concentration

Table 6-8 to Table 6-11 present the BOD concentrations in the river 50m, 100m, 200m and 400m downstream of the assumed discharge point for each of the time periods throughout the year.

It is noted that the model used to predict the BOD river concentration does not take any BOD removal in the rapid infiltration basins into account. The effluent BOD from a facultative pond is contributed to the algae it contains. The algae will be removed in the wetland and the rapid infiltration basins and therefore only the filtered BOD concentration as presented in Table 4-6 in brackets is the actual BOD contribution to the river. The predicted BOD concentrations in the river as presented Table 6-8 to Table 6-11 are therefore conservative.

Table 6-8: Peak Period BOD River Concentration

Year Peak Period BOD River Concentration (mg/l)

50m Mixing Zone 100m Mixing Zone 200m Mixing Zone 400m Mixing Zone

2011 0.25 0.12 0.06 0.03

2018 0.27 0.13 0.06 0.03

2028 0.29 0.14 0.07 0.04

2050 0.34 0.16 0.08 0.04

Table 6-9: Shoulder Period BOD River Concentration

Year Shoulder Period BOD River Concentration (mg/l)


2011 0.11 0.05 0.03 0.01

2018 0.11 0.05 0.03 0.01

2028 0.13 0.06 0.03 0.02

2050 0.15 0.07 0.03 0.02

Table 6-10: Off-Peak Period BOD River Concentration

Year Off-Peak Period BOD River Concentration (mg/l)


2011 0.08 0.04 0.02 0.01

2018 0.09 0.04 0.02 0.01

2028 0.09 0.04 0.02 0.01

2050 0.10 0.05 0.02 0.01



Table 6-11: Winter Period BOD River Concentration

Year Winter Period BOD River Concentration (mg/l)


2011 0.12 0.06 0.03 0.01

2018 0.13 0.06 0.03 0.02

2028 0.14 0.07 0.03 0.02

2050 0.16 0.08 0.04 0.02

6.4.2 TN River Concentration according to Reed

Table 6-12 to Table 6-15 present the TN concentrations in the river 50m, 100m, 200m and 400m downstream of the assumed discharge point for each of the time periods throughout the year using Reeds approach for the prediction of the TN effluent concentrations from the pond system. The ANZECC TN guideline value to ensure river health is 0.614 mg/l. Bold values in Table 6-12 to Table 6-15 highlight values which exceed the ANZECC TN guideline value.

Table 6-12: Peak Period TN River Concentration according to Reed

Year Peak Period TN River Concentration according to Reed (mg/l)


2011 0.61 0.42 0.33 0.29

2018 0.63 0.42 0.33 0.29

2028 0.65 0.44 0.34 0.29

2050 0.68 0.45 0.35 0.29

Table 6-13: Shoulder Period TN River Concentration according to Reed

Year Shoulder Period TN River Concentration according to Reed (mg/l)


2011 0.52 0.37 0.31 0.27

2018 0.53 0.38 0.31 0.27

2028 0.54 0.39 0.31 0.28

2050 0.57 0.40 0.32 0.28

Table 6-14: Off-Peak Period TN River Concentration according to Reed

Year Off-Peak Period TN River Concentration according to Reed (mg/l)


2011 0.37 0.30 0.27 0.26

2018 0.38 0.31 0.27 0.26

2028 0.38 0.31 0.27 0.26

2050 0.40 0.32 0.28 0.26



Table 6-15: Winter Period TN River Concentration according to Reed

Year Winter Period TN River Concentration according to Reed (mg/l)


2011 0.46 0.34 0.29 0.26

2018 0.46 0.35 0.29 0.26

2028 0.47 0.35 0.30 0.26

2050 0.49 0.36 0.30 0.26

Table 6-12 to Table 6-15 show that the ANZECC TN guideline value of 0.614 mg/l is exceeded in the 50m mixing zone during the peak period in all scenarios. The TN river concentrations are below the ANZECC TN guideline value for all other periods and scenarios.

6.4.3 Total Ammoniacal Nitrogen River Concentration according to Reed

Table 6-16 to Table 6-19 present the total ammoniacal nitrogen concentrations in the river 50m, 100m, 200m and 400m downstream of the assumed discharge point for each of the time periods throughout the year using Reed’s approach for the prediction of the total ammoniacal nitrogen effluent concentrations from the pond system. Bold values exceed the ANZECC total ammoniacal nitrogen guideline value (toxicity 95% protection) of 0.9 mg/l and red values exceed the ANZECC total ammoniacal nitrogen guideline value (toxicity 99% protection) of 0.32 mg/l.

Table 6-16: Peak Period Total Ammoniacal Nitrogen River Concentration according to Reed

Year

Peak Period Total Ammoniacal Nitrogen River Concentration according to Reed (mg/l)


2011 0.32 0.16 0.08 0.04

2018 0.33 0.16 0.08 0.04

2028 0.35 0.17 0.09 0.05

2050 0.38 0.18 0.09 0.05

Table 6-17: Shoulder Period Total Ammoniacal Nitrogen River Concentration according to Reed

Year

Shoulder Period Total Ammoniacal Nitrogen River Concentration according to Reed (mg/l)


2011 0.24 0.12 0.06 0.03

2018 0.25 0.12 0.06 0.03

2028 0.26 0.13 0.06 0.03

2050 0.28 0.14 0.07 0.04



Table 6-18: Off-Peak Period Total Ammoniacal Nitrogen River Concentration according to Reed

Year

Off-Peak Period Total Ammoniacal Nitrogen River Concentration according to Reed (mg/l)


2011 0.12 0.06 0.03 0.02

2018 0.12 0.06 0.03 0.02

2028 0.12 0.06 0.03 0.02

2050 0.14 0.07 0.03 0.02

Table 6-19: Winter Period Total Ammoniacal Nitrogen River Concentration according to Reed

Year

Winter Period Total Ammoniacal Nitrogen River Concentration according to Reed (mg/l)


2011 0.19 0.09 0.05 0.03

2018 0.19 0.09 0.05 0.03

2028 0.20 0.10 0.05 0.03

2050 0.22 0.11 0.05 0.03

Table 6-16 to Table 6-19 show that the ANZECC total ammoniacal nitrogen guideline value for 95% protection of species is not exceeded during any period or scenario. The ANZECC total ammoniacal nitrogen guideline value for 99% protection of species is exceeded during the peak period during all scenarios but below the guideline value during all other periods and scenarios. To comply with the ANZECC ionised NH4-N nutrient guideline value of 0.021 mg/l, the total ammoniacal nitrogen concentration in the river is required to be below 2.1 mg/l. Table 6-16 to Table 6-19 show that the river concentrations are well below this value.

6.4.4 Soluble Inorganic Nitrogen River Concentration

Table 6-20 to Table 6-23 present the soluble inorganic nitrogen (SIN) concentrations in the river 50m, 100m, 200m and 400m downstream of the assumed discharge point for each of the time periods throughout the year. The SIN is the total concentration of dissolved total ammoniacal nitrogen, NO3-N and NO2-N in the river. It has been assumed that the NO2-N concentration in the river and the WWTP effluent is zero. It has further been assumed that the NO3-N concentration in the WWTP effluent is zero due to the lack of nitrification processes in the pond system. Therefore, SIN can be calculated using the predicted total ammoniacal nitrogen concentration in the river (Table 6-16 to Table 6-19) plus the background nitrate concentration in the river (0.15 mg/l; refer to Table 6-7). Bold values in Table 6-20 to Table 6-23 exceed the ANZECC SIN guideline value of 0.465 mg/l.



Table 6-20: Peak Period SIN River Concentration

Year Peak Period SIN River Concentration (mg/l)


2011 0.47 0.31 0.23 0.19

2018 0.48 0.31 0.23 0.19

2028 0.50 0.32 0.24 0.20

2050 0.53 0.33 0.24 0.20

Table 6-21: Shoulder Period SIN River Concentration

Year Shoulder Period SIN River Concentration (mg/l)


2011 0.39 0.27 0.21 0.18

2018 0.40 0.27 0.21 0.18

2028 0.41 0.28 0.21 0.18

2050 0.43 0.29 0.22 0.19

Table 6-22: Off-Peak Period SIN River Concentration

Year Off- Peak Period SIN River Concentration (mg/l)


2011 0.27 0.21 0.18 0.17

2018 0.27 0.21 0.18 0.17

2028 0.27 0.21 0.18 0.17

2050 0.29 0.22 0.18 0.17

Table 6-23: Winter Period SIN River Concentration

Year Winter Period SIN River Concentration (mg/l)


2011 0.34 0.24 0.20 0.18

2018 0.34 0.24 0.20 0.18

2028 0.35 0.25 0.20 0.18

2050 0.37 0.26 0.20 0.18

Table 6-20 to Table 6-23 show that the ANZECC SIN guideline value is exceeded in the 50m mixing zone for all scenarios during the peak period. All other assessed periods and scenarios meet the ANZECC SIN guideline value.



6.4.5 Dissolved Reactive Phosphorous River Concentration

Table 6-24 to Table 6-27 present the dissolved reactive phosphorous (DRP) concentrations in the river 50m, 100m, 200m and 400m downstream of the assumed discharge point for each of the time periods throughout the year. The presented DRP river concentrations do not include the background river DRP concentration. The background concentration has been stated as 0.003 mg/l in Table 6-7. However, the number of samples which the background concentration is based on is unknown and there is some uncertainty around the exact DRP background river concentration. The DRP concentration in the Pond 2 effluent has not been measured. For the purpose of this memo it has been assumed that 75% of the effluent TP concentration is DRP which is a typical ratio for oxidation pond effluent. Bold values exceed the ANZECC DRP guideline value of 0.01 mg/l for lowland rivers.

Table 6-24: Peak Period DRP River Concentration without River Background Concentration

Year Peak Period DRP River Concentration (mg/l)


2011 0.065 0.031 0.016 0.008

2018 0.066 0.032 0.016 0.008

2028 0.068 0.033 0.016 0.008

2050 0.072 0.034 0.017 0.009

Table 6-25: Shoulder Period DRP River Concentration without River Background Concentration

Year Shoulder Period DRP River Concentration (mg/l)


2011 0.045 0.022 0.011 0.005

2018 0.046 0.022 0.011 0.006

2028 0.048 0.023 0.011 0.006

2050 0.050 0.024 0.012 0.006

Table 6-26: Off-Peak Period DRP River Concentration without River Background Concentration

Year Off-Peak Period DRP River Concentration (mg/l)


2011 0.031 0.015 0.008 0.004

2018 0.032 0.015 0.008 0.004

2028 0.033 0.016 0.008 0.004

2050 0.035 0.017 0.008 0.004



Table 6-27: Winter Period DRP River Concentration without River Background Concentration

Year Winter Period DRP River Concentration (mg/l)


2011 0.031 0.015 0.008 0.004

2018 0.032 0.015 0.008 0.004

2028 0.033 0.016 0.008 0.004

2050 0.035 0.017 0.008 0.004

The above tables show that the ANZECC DRP guideline value is exceeded in all assessed periods and scenarios in the 50m and 100m mixing zones. Within the 200m mixing zone, the DRP river concentrations during the peak and shoulder periods exceed the ANZECC DRP guideline value in all assessed scenarios (2011 to 2050). Within the 400m mixing zone, the DRP river concentrations meet the ANZECC DRP guideline value for all assessed periods and scenarios. A sensitivity analysis has been carried out to indentify the influence of the groundwater dilution factor in the river DRP concentrations. The peak period with a 50m and 200m mixing zone has been used for the purpose of the presentation of the sensitivity analysis. The results are presented in Table 6-28 and Table 6-29.

Table 6-28: DRP River Concentration Sensitivity Analysis Peak Period and 50m Mixing Zone

Year

Peak Period DRP River Concentration (mg/l)

Groundwater Dilution of 10




2011 0.065 0.033 0.022 0.016

2018 0.066 0.033 0.022 0.017

2028 0.068 0.034 0.023 0.017

2050 0.072 0.036 0.024 0.018

Table 6-29: DRP River Concentration Sensitivity Analysis Peak Period and 200m Mixing Zone

Year

Peak Period DRP River Concentration (mg/l)





2011 0.016 0.008 0.005 0.004

2018 0.016 0.008 0.005 0.004

2028 0.016 0.008 0.005 0.004

2050 0.017 0.009 0.006 0.004

Table 6-28 and Table 6-29 show that the DRP river concentration is sensitive to the groundwater dilution factor. The assumed groundwater dilution factors and the fact that no additional phosphorous reduction in the wetland and the RIBs has been assumed adds a level of conservatism to this assessment that may oppose more stringent effluent quality standards than necessary to minimise adverse effects on the receiving environment. Insufficient research has been carried out in the river to prove that the current situation has a negative impact on the receiving environment.



6.4.6 Faecal Coliform River Concentration

Table 6-30 to Table 6-33 present the FC concentrations in the river 50m, 100m, 200m and 400m downstream of the assumed discharge point for each of the time periods throughout the year.

Table 6-30: Peak Period FC River Concentration

Year Peak Period FC River Concentration (cfu/100ml)


2011 18 16 16 15

2018 18 16 16 15

2028 18 17 16 15

2050 19 17 16 15

Table 6-31: Shoulder Period FC River Concentration

Year Shoulder Period FC River Concentration (cfu/100ml)


2011 16 15 15 15

2018 16 15 15 15

2028 16 15 15 15

2050 16 16 15 15

Table 6-32: Off-Peak Period FC River Concentration

Year Off-Peak Period FC River Concentration (cfu/100ml)


2011 16 15 15 15

2018 16 16 15 15

2028 17 16 15 15

2050 17 16 15 15

Table 6-33: Winter Period FC River Concentration

Year Winter Period FC River Concentration (cfu/100ml)


2011 30 22 19 17

2018 31 23 19 17

2028 33 24 19 17

2050 36 25 20 18

Table 6-30 to Table 6-33 show that the FC concentration in the river is only slightly elevated above the background concentration of 15 cfu/100ml for most assessed scenarios and periods. Winter is the only period in which the FC river concentration is noticeably higher than the background concentration. All river FC concentrations in the tables above are below the ANZECC contact recreation trigger value of 150cfu/100ml.



Table 6-34 presents the FC groundwater concentration for assessment against the trigger value presented in the AEE. Bold values in Table 6-34 exceed the UV trigger level of 100cfu/100ml in the groundwater that prompts further investigations for the need for a UV disinfection system.

Table 6-34: FC Groundwater Concentration

Year FC Groundwater Concentration (cfu/100ml)


2011 38 16 28 410

2018 38 16 28 424

2028 42 18 30 456

2050 46 20 34 498

Table 6-34 shows that the UV trigger value is only exceeded during the winter period. It is noted that comparison of groundwater monitoring data from groundwater monitoring bores within the existing wastewater discharge plume have not exceeded the UV trigger value of 100cfu/100ml since December 2008. FC reduction in the wetland and in the soil matrix have not been taken into account in this assessment and are likely to further reduce FC concentrations in the groundwater.

7 Conclusion

7.1 Wastewater Treatment System For the assessment of the wastewater treatment system performance, the performance of the two oxidation ponds in series has been assessed. No treatment in the wetland subsequent to the oxidation ponds has been taken into account when assessing the environmental effects from the treated wastewater discharge. The wetland is constructed for the purpose of TSS removal (mainly algae solids) and to satisfy cultural requirements. The summary below assumes that septage is discharged to the plant into Pond 1.

7.1.1 BOD

The assessment of the oxidation pond system showed that the existing ponds provide sufficient treatment capacity to treat the total BOD load in the wastewater influent including septage. Therefore, no aerated lagoons are required prior to the oxidation ponds to remove BOD. The following modifications to the oxidation pond system have been taken into account when assessing the treatment performance. Desludging of oxidation Pond 1. Installation of baffles in oxidation Pond 1 to create a clarification zone in the first third of the pond

for settlement of septage solids. Recirculation of oxygen rich Pond 2 effluent to clarification zone or installation of brush type


Installation of aerators to provide up to 9 kW of aeration on the remaining two thirds of the first oxidation pond, no aerators required on Pond 2.

Installation of baffles in oxidation Pond 2.



Moreover, it has been assumed, that after the year 2018, septage discharges are managed to achieve consistent discharge volumes across the entire year and a septage receiving facility and balancing tank are installed prior to the discharge into the first oxidation pond. The pond performance assessment showed that the BOD effluent concentrations included in the draft resource consent conditions of 25 mg/l mean and 50 mg/l 95%tile can be achieved in the wetland effluent up to the year 2050 if septage is discharged into the first oxidation pond11.

7.1.2 Nutrients

Oxidation pond systems have a limited ability to remove nutrients. Reed’s model has been used to predict the TN and total ammoniacal nitrogen effluent concentrations from Pond 2 based on the pond configuration stated above, i.e. including a clarification zone in Pond 1. The predicted TN and total ammoniacal nitrogen mean and 95%tile effluent concentrations from Pond 2 are presented in Table 7-1 (refer to footnote 11). The draft consent conditions have been included for comparison.

Table 7-1: Predicted TN and Total Ammoniacal Nitrogen Pond 2 Effluent Concentrations in 2050

Parameter

Draft Consent Conditions

Existing 2011 Predicted 2050

Mean 95%tile Mean 95%ile Mean 95%tile

TN (mg/l) 30 50 47 55 51 60

Total Ammoniacal Nitrogen (mg/l) 15 30 40 48 43 51

Table 7-1 shows that the existing treated wastewater quality and that predicted in the future for nitrogen related compounds exceed the proposed limits of the draft consent conditions. The predicted (2050) TP Pond 2 treated wastewater concentrations are 11.2 mg/l and 12.7 mg/l for the mean and 95 percentile criteria, respectively. These values exceed the proposed mean limit of the draft consent conditions (mean: 7 mg/l) but are within the proposed 95 percentile limit (15 mg/L). The pond based treatment system as proposed for the upgrade of the Takaka WWTP is not able to meet the proposed draft consent conditions in respect to TN, total ammoniacal nitrogen and TP.

7.1.3 Faecal Coliforms

The predicted concentrations of faecal coliforms for the year 2050 are presented in Table 7-2. The draft consent conditions have been included for comparison as has the predicted existing treated water quality12.

Table 7-2: Predicted FC Pond 2 Effluent Concentrations in 2050

Parameter Draft Consent Conditions Existing 2011 Predicted 2050

Median 95%tile Mean 95%ile Median 95%tile

FC (cfu/100ml) 5,000 50,000 9,000 110,000 17,000 195,000

11 For this assessment, it has been assumed that each year, two samples are taken during the shoulder and off-peak periods and one sample is taken from the peak and winter periods, respectively. 12 For this assessment, it has been assumed that each year, 2 samples are taken during the shoulder and off-peak periods and one sample is taken from the peak and winter periods, respectively.



Table 7-2 shows that the predicted median and 95 percentile concentrations exceed the respective draft consent limits for both assessed scenarios. It is anticipated that further FC reduction will occur within the wetland (up to 2-log) but this reduction has not been taken into account when assessing the environmental effects from the treated wastewater discharge.

7.2 Environmental Effects in the Takaka River from Treated Wastewater Discharge

The assessment of environmental effects in the Takaka River from treated wastewater discharges from the Takaka WWTP has been based on the contaminant effluent concentrations from the oxidation ponds. Treatment in the wetland, the rapid infiltration basins or the soil matrix has not been taken into account in this assessment. The assessment is therefore considered conservative in this regard. Table 7-3 presents the predicted annual mean contaminant concentrations in a 50m mixing zone in the Takaka River. The annual mean has been calculated on the assumption that sampling is carried out in the months of January, March, May, July, September and November (refer to footnote 12), The ANZECC guideline values have been included in Table 7-3 for comparison. Values in bold exceed the ANZECC guideline values.

Table 7-3: Predicted Annual Mean Contaminant Concentration in Takaka River, 50m Mixing Zone

Parameter ANZECC Guideline

Values

Annual Mean River Concentration

2011 2018 2028 2050

BOD (mg/l) N/A 0.09 0.13 0.11 0.17

TN (mg/l) 0.614 0.46 0.49 0.50 0.52

Total Ammoniacal Nitrogen (mg/l)

0.320 0.19 0.21 0.22 0.24

SIN (mg/l) 0.465 0.375 0.425 0.443 0.476

DRP (mg/l) 0.01 0.043 0.045 0.046 0.049

FC (cfu/100ml) 150 17 19 19 20

Table 7-3 shows that only the DRP concentrations in the Takaka River and SIN concentration in 2050 exceed the ANZECC guideline values in the 50m mixing zone. All other annual mean contaminant concentrations comply with the ANZECC guideline values. It is noted that a single sample of a given contaminant may exceed the ANZECC guideline values (refer to Section 6 for the predicted concentrations during each period). For the purpose of assessing the frequency of exceeding the ANZECC guideline values, the annual 95 percentile contaminant concentrations in the Takaka River at the 50m mixing zone are presented in Table 7-4.

Table 7-4: Predicted Annual 95 Percentile Contaminant Concentration in Takaka River, 50m Mixing Zone

Parameter ANZECC Guideline

Values

Annual 95%tile River Concentration

2011 2018 2028 2050

BOD (mg/l) N/A 0.16 0.23 0.26 0.29

TN (mg/l) 0.614 0.58 0.60 0.62 0.65

Total Ammoniacal Nitrogen (mg/l) 0.320 0.29 0.31 0.33 0.35

SIN (mg/l) 0.465 0.438 0.460 0.479 0.503

DRP (mg/l) 0.01 0.064 0.066 0.069 0.074

FC (cfu/100ml) 150 23 28 29 32



Table 7-5 presents the predicted six months rolling mean FC groundwater concentration taking into account a groundwater contaminant reduction factor of 98% and a groundwater dilution factor of 10. The river dilution has not been taken into account when calculating the values presented in Table 7-5. Two six months rolling mean values have been presented, one which represents sampling from June to November (six months winter/off-peak period rolling mean) and one which represents sampling from December to May (six months peak/shoulder/off-peak period rolling mean). The six months winter/off-peak period rolling mean considers three samples each from the winter and off-peak period whereas the six months peak/shoulder/off-peak period rolling mean takes one peak period sample, two shoulder period samples and three off-peak period samples into account. This assessment is considered conservative since FC reduction in the wetland and the soil matrix has not been taken into account.

Table 7-5: Predicted Six Months Rolling Mean FC Groundwater Concentrations

Year

Groundwater FC Concentration (cfu/100ml) including Septage

6-months winter/off-peak period rolling mean 6-months peak/shoulder/off-peak period rolling mean

2011 149 16

2018 226 26

2028 243 28

2050 266 31

Table 7-5 shows that the six-months winter/off-peak period rolling mean exceeds 100 cfu/100ml during all scenarios. The value of 100 cfu/100ml in the groundwater is included in the draft consent conditions as a trigger value for a weekly monitoring programme. It states that if this trigger value is exceeded the weekly monitoring programme shall be implemented, for up to four weeks, to determine whether this trigger value is exceeded consistently. If the results of the more frequent monitoring programme confirm that the faecal coliform trigger value is being exceeded and the exceedance can be attributed to the wastewater treatment plant (the stock on the farm may cause exceedances) then an UV disinfectant stage shall be added to the treatment system within 12 months of the initial exceedance. Based on the model predictions, weekly monitoring carried out during the winter period would have the highest chance of consistently exceeding the trigger value of 100 cfu/100ml. However, the model has conservatively assumed that there is not any FC reduction in the wetland or in the RIB sub-surface and it is likely that the dilution factor of 10 in the groundwater is also conservative. Moreover, the impact of the exceedance of the trigger value on the Takaka River is minor due to the dilution in the Takaka River. The FC concentration in the Takaka River remains well below the ANZECC guideline value for primary contact recreation of 150 cfu/100ml at any point in time. Based on this analysis, it can therefore be concluded that a UV disinfection system is not required as part of the upgrades to protect the Takaka River.



7.3 Summary The above conclusions are summarised as follows.

1. The aeration lagoons, which were included in the AEE and draft consent conditions, are no longer required as part of the Takaka WWTP upgrade.

2. This assessment assume that the following improvements are included in the Takaka WWTP upgrade.

a. Installation of a septage receiving facility including a balancing tank. b. Septage flow management to achieve even distribution throughout the entire year, i.e.

avoid shock loading during the peak period. c. Desludging of Pond 1 if required as outcome of sludge survey. d. Installation of baffles in oxidation Pond 1 to create a clarification zone in the first third of the

first oxidation pond for settlement of septage solids. e. Recirculation of oxygen rich Pond 2 effluent to clarification zone or installation of brush type


f. Installation of aerators to provide up to 9 kW of aeration on the remaining two thirds of the first oxidation pond.

g. Installation of baffles in oxidation Pond 2.

3. According to this assessment, the existing draft consent conditions for the upgraded wetland effluent concentrations can not be met in the Pond 2 effluent for the following contaminants.

a. TN. b. total ammoniacal nitrogen. c. Faecal Coliforms.

4. The following annual mean contaminant concentrations are below the ANZECC guideline values in the 50m mixing zone of the Takaka River although some of the Pond 2 effluent concentrations exceed the draft consent conditions.

a. BOD. b. TN. c. Total ammoniacal nitrogen. d. SIN (only exceeded between 2028 and 2050). e. Faecal coliforms.



8 Recommendations It is recommended that. Aerated lagoons prior to the oxidation ponds are not required as part of the WWTP upgrade. A UV disinfection system is not required as part of the WWTP upgrade to protect the Takaka

River. (Note that the current draft conditions may require UV disinfection if certain trigger values are exceeded).

The WWTP has the ability to accept septage loads. However, septage discharges should be managed to achieve consistent discharge volumes across the entire year.

Septage is discharged from a septage receiving facility with balancing tank into a new clarification zone in Pond 1.

The following modifications to the oxidation pond system have been taken into account when assessing the treatment performance and are recommended to be included in the Takaka WWTP upgrade.

1. Sludge survey of Pond 1 and desludging if required (prior to upgrades). 2. Installation of baffles in oxidation Pond 1 to create a clarification zone in the first third of the first

oxidation pond for settlement of septage solids. 3. Recirculation of oxygen rich Pond 2 effluent to clarification zone or installation of brush type


4. Installation of aerators to provide up to 9 kW of aeration on the remaining two thirds of the first oxidation pond. No aerators are required on Pond 2

5. Installation of baffles in oxidation Pond 2. Council notes that the predicted pond effluent quality does not meet the proposed draft consent

conditions with respect to pond effluent concentrations of total nitrogen (TN), total ammoniacal nitrogen, total phosphorous (TP) and faecal coliforms (FC).

Council accepts the modelling results which indicate that dissolved reactive phosphorous levels in the Takaka River may be elevated above the ANZECC level as a result of the discharge from the RIBs.

Council accepts the modelling results with respect to faecal coliform concentrations in the groundwater at the edge of the river that indicate that during the winter period faecal coliform concentrations may be above the 100cfu/100ml UV disinfection trigger value previously approved in the draft consent conditions.

A discussion paper which assesses the differences between the recommendations stated in the draft consent conditions compared to what is now expected be prepared based on the findings from this document. The discussion paper should also include suggested revised consent conditions and justification for the changes.


Appendix A Mitigation of Potential Nuisance Periphyton Growth in the Takaka River

APPENDIX D - Wetland Design Statement

Status – Final Page 1 February 2012 Project Number – Z2404161 Tm11 Wetland Design Statement Final

PROJECT TECHNICAL MEMORANDUM FOR TASMAN DISTRICT COUNCIL

Date: 24 February 2012 Correspondence Out No.: 22466

To: Tasman District Council Project Technical Memo No.: 11

For the Attention of: Jeff Cuthbertson Project Stage: Preliminary Design

Project: Takaka WWTP Upgrades Project Number: Z2404161

Subject: Wetland Design Statement – Surface Flow Wetland

Prepared by: David Stewart, Jonathan Krause Checked by: Zoe Burkitt

Reviewed by: Rainer Hoffmann Authorised by: Don Young

1 Introduction

The purpose of this Technical Memorandum is to present key design parameters associated with the proposed surface flow wetland and the basis of these parameters. Also included in this memo is a discussion of the feasibility of a floating wetland, as distributed by Kauri Park Nurseries as an alternative to a surface flow wetland. Wastewater delivered to the Takaka Wastewater Treatment Plant (WWTP) is currently treated by two oxidation ponds connected in series (with mechanical aerators) after which the effluent passes through rudimentary wetland cells before being discharged into soakage trenches. Part of the proposed upgrade is the construction of new surface flow wetland cells to improve treatment of the wastewater, particularly to reduce suspended solids prior to dosing effluent to the new rapid infiltration basins (RIBs) for disposal. The treatment provided by the wetlands is therefore critical for maximizing the life of the RIBs. For effective and sustainable operation of the RIBs it is necessary to dose effluent into them, preferably quickly enough to flood the surface of the basins so that the effluent soaks downwards in a ‘plug flow’ pulse that sucks air in behind it. It is proposed to pump effluent from the wetland cells to the RIBs approximately every eight hours. The wetland cells will then operate at a variable water depth, with the water level increasing between dosing events. This Technical Memorandum supersedes the MWH letter titled, “Takaka WWTP Wetland – Review and Assessment of Alternatives”, to Gavin Hutchison, dated 10 June 2010.

2 Background of Wetland Design

In 2006, NIWA were commissioned by the Council on behalf of Manawhenua Ki Mohua to carry out a review of the proposed wastewater treatment plant upgrade that was largely focused on the requirement to remove bacterial contamination from the wastewater. In this review, NIWA suggested the installation of open water wetland cells, ie. shallow-lined pond with wetland fringe (known as a “hybrid” wetland). The driver for this “hybrid” approach proposed by NIWA was that the open water areas would provide greater opportunity for natural UV to penetrate into the wastewater leading to increased bacterial die off. As stated in the Cultural Impact Assessment (CIA) 19 September 2005, iwi support the creation of a wetland as part of the upgrades as it is seen to improve the quality of the discharge to land. Iwi requested that they be involved in sourcing the plants and that the wetland is lined to prevent water from short-circuiting from the wetland to the river.


The wetland scheme proposed and described in the resource consent application is a lined, free water surface flow hybrid-type wetland system with planted areas and approximately 30% open water zones designed in accordance with the USEPA wetland guidelines

1. It was proposed that the water depth would be maintained

between 150mm and 450mm in the planted areas. A hydraulic retention time (HRT) through the wetlands of three to five days was targeted, although this was dependant on space constraints at the site and peak summer flow rates.

3 Purpose of the Wetland

The purpose of the wetland is to:

• reduce the suspended solids in the pond effluent prior to dosing the RIBs to minimise the rate of clogging of the RIB infiltration surface

• promote faecal coliform (FC) reduction through settlement and natural UV (sunlight) exposure

• satisfy cultural requirements. This is consistent with the approach taken in the Assessment of Environmental Effects (AEE). The Working Party has also indicated through discussions that they are in favour of a wetland as part of the plant upgrade, although this has not yet been formally confirmed. In addition to the above stated treatment objectives for the wetland, a variety of biological and physical treatment processes take place within the system. These processes have not been taken into account in the updated treatment process model when assessing the plant performance and therefore the model takes a conservative approach in this regard. However, a well designed and functioning wetland should include the following additional benefits:

• biological (microbial) degradation of BOD and nutrients by bio-films attached to the plant stems and the wetland soils

• plant uptake of carbon and nutrients

• physical filtration and settlement / precipitation.

4 Wastewater Design Parameters

Takaka is a popular summer destination and experiences a considerable increase in population over the peak summer holiday period. This results in a significant seasonal increase in wastewater volumes. Takaka can also experience heavy rainfall events, which greatly increase wastewater flows as a result of infiltration of surface water into the sewer system. The flow and load parameters used in this design statement are based on revised plant influent levels contained in the Flow and Loads report, dated November 2011. These design parameters are different than presented in the November 2009 AEE. The use of these revised parameters is based on the assumption that the Council will prefer to seek an amendment of the AEE to adopt these changes instead of modifying the plant design to include additional treatment steps that would ensure compliance with the draft consent conditions. Projected wastewater flows taken from the Flows and Loads report is summarised in Table 1.

1 USEPA Manual – Constructed Wetlands Treatment of Municipal Wastewaters, (2000)


Table 1: Projected Wastewater Flows for 2028 and 2050 Derived from Measured Data

Parameter Unit Summer Peak Period

Shoulder Period

Winter/Off-Peak Period

2028 2050 2028 2050 2028 2050

Average Dry Weather Flow (ADF)

m3/day 660 700 440 460 395 410

Peak Hourly Flow m3/hour 71 75 47 50 39 41

Wet Weather Flow m3/day 2640 2775 1755 1840 1800 1890

Peak Hourly Wet Weather Flow

m3/hour 187 196 124 130 128 134

By 2050, the new wetland system will need to treat a peak summer average wastewater flow of about 700m

3/day.

A disadvantage of wastewater treatment systems that include oxidation ponds is that the large surfaces of the ponds collect rainfall increasing the total flow to a subsequent treatment stage such as the proposed wetland. For example, if the peak wet weather wastewater flow is caused by a rainfall event of 200mm over 24 hours, rainfall on the Takaka ponds (area 15,775m

2) could increase the flow to the wetlands by a further 3,155m

3.

5 Proposed Wetland Design

5.1 Design Principles

This design document is for a conventional surface flow wetland based on other wetland systems designed by MWH and in operation for some years at sites including St Arnaud in Tasman district; Winton in Southland district; Milton, Waihola and Clinton in Clutha district; and Mataura in Gore district. The design principles follow the original design concepts set out in the original USEPA design manuals, but the specific design does not strictly follow the NIWA proposed “hybrid” type design with respect to maintaining open zones within the wetland comprising of approximately 30 % of the total area. The primary purpose of the wetland is to remove suspended solids, and MWH has concerns, based on experience at other sites, that large open water zones will promote algal growth and increase overall suspended solids levels exiting the wetland. Open areas within the wetland will still be provided in the wetland to promote bacterial (FC and E.coli) removal through natural UV exposure, but they will be dispersed within the entire wetland in order to prevent significant rates of algae re-growth. The sizing of the wetland is primarily based on ensuring suspended solids in the effluent are removed to appropriate levels prior to discharging to the RIBs. A properly functioning wetland with respect to suspended solid removal is therefore critical for maximizing the lifespan of the RIBs and minimizing maintenance requirements. The design is based on that of the wetland at St Arnaud in Tasman district which was designed by MWH and constructed in 2001. At St Arnaud the wastewater treatment scheme includes an aerated pond followed by two wetland cells with the effluent discharged into rapid infiltration trenches, which is very similar to the scheme proposed for Takaka. The wetland cells at St Arnaud are operated at a water depth of 0.45m and a retention time at peak summer wastewater inflows of five to six days. They are planted with mainly Carex secta, Phormium tenax (NZ flax), and Juncus species.

5.2 Wetland Sizing and Planting

It is proposed to size the wetland to have sufficient volume to provide a retention time within each wetland cell of approximately 5.5 days at the projected peak holiday flow in dry weather of 700m

3/d. This will require a total

wetland water volume of 700m3/d x 5.5d = 3,850m

3.


At an operating depth of 0.45m a total wetland area of approximately 8400m2 (0.84ha) will be required. This

could be provided by, for example, six wetland cells, each 100m long and 15m wide. At the projected peak holiday flow in dry weather of 700m

3/d each cell would receive a wastewater volume of 117m

3/d by using a

flow divider to distribute one sixth of the total flow to each cell. Peak wet weather wastewater flows of up to 1,000m

3/d should be maintained so as to retain a retention time

of at least three days. Wetland plants will be planted in a growing media with the stalks and leaves of the plants providing the bio-surface and baffling of the flow that together achieve BOD reduction and TSS removal from the wastewater. The wetland plants will be placed at 1m centres to allow room for growth whilst still retaining open areas between plants where sunlight can penetrate the shallow water depth and kill off pathogenic bacteria. It is proposed to plant the wetland with mainly Carex secta, which would allow the wetland to operate at a normal water depth of 0.45m due to the ability of Carex secta to grow in greater water depths than many other wetland plant species. Another species that can withstand water depth variation is Phormium tenax, which is planted along with Carex secta at the St Arnaud wetland. To provide diversity, Juncus pallidus and Eleocharis sphacelata plants will also be included.

5.3 Management of Stormwater Flows

In order to maintain treatment through the wetland during the wet weather periods and thus maintain a good effluent quality, it is more cost effective to control the flow out of the ponds under such wet weather conditions rather than increase the size of the wetlands to cope with it. This can be done by utilising the storage within the ponds and limiting the outflow from the pond system into the wetland to a maximum of 1,000m

3/d (42m

3/h)

by installing a means of controlling the flow at the discharge from the second pond such as a flow control valve or notched weir. The available storage in the oxidation ponds during wet weather events is further described in Technical Memorandum 9, titled “Alternative RIB Design Assessment”, dated 17 November 2011. The final design of the treatment plant will include provisions for dealing with emergency overflow events when the water level in the ponds exceed the pond bunding height. This is however expected to be a rare occurrence. It is proposed that the wetland cells will have an outlet that allows them to overflow into the RIB dosing chamber. This arrangement will maintain the design operating level of 0.45m in the wetland cells unless the inflow in wet weather increases (to a regulated maximum of 1000m

3/d) and causes a temporary increase in

water level. In extreme wet weather, the groundwater level may rise to above the water level in the wetland cells. To allow for this and prevent potential damage to the wetland lining membrane, the wetland cells will have pressure relief valves fitted and 0.5m high standpipes that will allow groundwater to discharge into the wetland cells and balance the water level against the groundwater level. The bund height around the wetland will be approximately 8.0mRL, whereas the likely ground level of the wetland will be approximately 6.5mRL.

5.4 Cost Estimate

The capital cost for the surface flow wetland concept design as described above is approximately $820,000 (+/- 20%) (refer to Attachment 1 for details). This figure excludes Preliminary and General items, design and contingency costs. This figure can be directly compared to the estimate provided in the 2012 Annual Management Plan of $725,000. The estimated cost for the wetland is therefore within the project budget.


6 Expected Wetland Performance

Constructed wetlands are natural systems and their performance in reducing contaminant concentrations in wastewater varies with season and climate. The general mechanisms for contaminant removal are as follows.

• BOD is reduced by uptake by the plants and breakdown by the biofilm on the surfaces of plants as well as sedimentation and anaerobic decomposition in the sludge layer on the floor of the wetland.

• Total suspended solids (TSS) is reduced by adhesion to the biofilm on the surfaces of plants as well as sedimentation and anaerobic decomposition of organic solids (such as algae) in the sludge layer on the floor of the wetland. Removal of TSS is increased by a slow flow velocity through the wetland (high retention time) and a greater depth for settlement of solids. Operating the Takaka wetland at 0.5m water depth rather than 0.3m water depth should improve TSS reduction.

• Total Nitrogen (TN) can be removed by plant uptake but once a steady state is reached return of TN through plant decomposition ultimately balances removal by uptake. TN removal is only sustainable if the influent to the wetland is nitrified and TN can be removed by denitrification by carbon in the wetland.

• Bacteria (faecal coliform and E.coli) are killed by the action of ultraviolet light in sunlight penetrating the shallow water depth in open areas. Adhesion of solids containing bacteria on the plant surfaces, and other settling solids can also reduce bacteria concentrations. Bacteria reduction is increased by high water clarity (good TSS removal) and shallow water depth. Operating the Takaka wetland at 0.5m water depth rather than 0.3m water depth is likely to adversely affect bacteria reduction, although this should be offset by improved TSS removal and hence improved water clarity. The USEPA manual for design of constructed wetlands predicts that in general there should be a reduction of approximately 2-log in FC concentration across the wetland and this is in accordance with general experience in New Zealand.

Tanner et al surveyed the performance of constructed wetlands in New Zealand

2 and found that their

performance was generally similar to that of constructed wetlands in the USA. However, they found there was a wide variation in the performance of the wetlands surveyed due to factors such as differences in design approaches, success of plant establishment and operational maintenance. Consequently, removal of contaminants ranged from 37-85% for TSS, 23-87% for BOD and 66-98% for faecal coliforms. Based on the TSS concentrations in the Takaka pond effluent given in Tables 2 and 3, 37-85% TSS removal in the wetland would result in effluent concentrations in the range 20-95mg/L in the peak summer period and 9-38mg/L in winter. Due to the variability in design parameters and outcomes in the review sited above, MWH have based the proposal for Takaka on that of the well performing and local wetland at St Arnaud. The recorded performance of the wetland system at St Arnaud in Tasman district, designed by MWH and constructed in 2001, is similar to what is required at Takaka and as such forms a good basis for the design approach. Based on the expected effluent quality from the Takaka pond system and monitoring data from the pond/wetland system at St Arnaud (see Attachment 2), the expected quality of the effluent from the proposed wetland for Takaka under typical peak summer and winter operating conditions is as summarized in Tables 2 and 3. These concentrations are not intended for consenting purposes, but represent conditions appropriate for design purposes.

2 Tanner, C.C., Sukias, J.P.S., Dall, C., (2000). Constructed Wetland in New Zealand – Evaluation of an emerging

“natural” wastewater technology, Water 2000 Conference, March 2000, NZWWA, Auckland, NZ.


Table 2: Expected Final Effluent Quality after the Proposed Wetland for Takaka in the Peak Summer Period

Parameter Concentration in Pond Effluent

Mean

Concentration in Wetland Effluent

Median(90%ile)

TSS (mg/L) 150 30 (50) BOD (mg/L) 44 15 (30) NH3-N (mg/L) 32 25 (30) TP (mg/L) 10 10 Faecal coliform (cfu/100ml) 16,000 250 (1000)

Table 3: Expected Final Effluent Quality After the Proposed Wetland for Takaka in Winter

Parameter Concentration in Pond Effluent

Mean

Concentration in Wetland Effluent

Median(90%ile)

TSS (mg/L) 60 20 (50) BOD (mg/L) 29 10 (25) NH3-N (mg/L) 70 45 (60) TP (mg/L) 10 10 Faecal coliform (cfu/100ml) 133,000 250 (1000)

The effluent quality that can be produced by wetlands under storm conditions is less easy to predict. While the increased flow rate through a wetland will reduce its ability to reduce the concentrations of contaminants, this will be partly offset by the influent from the ponds having lower concentrations of contaminants due to dilution by rainwater. The wastewater entering the pond system will also be dilute due to the stormwater infiltration that causes the increased flow, but unfortunately it takes some time for the dilute wastewater to reach the outlet of the pond system so that this does not help the wetlands.

7 Construction and Operation of the Wetland

In order to fit within the constraints of the available site, it is proposed that the wetland will be constructed as six individual cells, operated in parallel, each approximately 100m long and 15m wide, with a normal operating depth of 0.45m. Wastewater from the second pond will discharge into a flow-splitting chamber from where it will be distributed evenly to each wetland cell. The wetland cells will be lined with either an HDPE membrane or clay, with plants anchored into gravel mounds on top of the membrane as done at other wetlands designed by MWH. To eliminate the risk of the membrane being lifted if the groundwater table rises above the water level in the wetland cells, the membrane lining will be fitted with groundwater vent pipes with non-return valves at approximately 20m centres (spacing to be confirmed) to allow groundwater to rise and overflow into the wetland cells and balance the water level with the groundwater (or floodwater) level. The wetland plants selected, once established, are capable of surviving a temporarily increased water level as high as 1.2m, so that the temporary increase in water level during extreme wet weather events will not affect the wetland. Each wetland cell will be fitted with a rock media filter as part of the discharge chamber (as used at St Arnaud and other wetlands designed by MWH) to prevent pieces of plant matter being carried out and into the RIBs. In normal operation, treated wastewater will overflow through the discharge chamber from each wetland cell and into a single dosing chamber from which the effluent will be pumped to the duty RIB. This arrangement will allow the wetland cells to always operate at their design water level of 0.45m, during dry weather conditions. The dosing chamber will likely be constructed from two 30m

3 pre-cast concrete water tanks set into the

ground and inter-connected to provide a holding capacity of 60m3. One tank will contain the dosing pump and

a standby dosing pump, each with a pumping capacity of approximately 100m3/h. During the peak holiday

period in 2050, when the wastewater flow is expected to be as high as 700m3/d, this will result in up to seven

dosing events each day, although it is more likely that during the daytime when the peak inflow of wastewater to the treatment facility is expected to be 75m

3/h, dosing will be almost continuous.


8 Floating Wetlands as an Alternative Treatment Option

An alternative to surface flow wet wetlands has come onto the market in New Zealand in the form of floating treatment wetlands. At present there is one supplier of this technology in New Zealand – Kauri Park Ltd, based in the North Island. MWH have undertaken several reviews of their work where floating wetlands have been proposed as alternatives to constructed wetlands or land based secondary / tertiary treatment. The key benefits of floating wetlands for the Takaka project are.

• Maintaining a relatively high water level, which prevents flotation of the wetland pond liner during flood events to a relatively high storm event.

• Ability to handle fluctuating water levels (due to RIB dosing or during storm events) without affecting the performance of the wetland. A separate storage cell for the RIB dosing pump(s) would not be required.

• In principal, the hydroponic nature of the system potentially leads to an improved interaction between plant roots and wastewater flow leading to multiple benefits including bio-film development and increased contact opportunities with the suspended biofilm, higher rates of plant absorption and greater filtration potential. This has not been proven through actual performance data though.

• The planted rafts are ideally planted in 1.2m to 1.5m of water greatly decreasing the footprint (area) requirement for the system when compared to traditional constructed wetlands.

• Can be allowed to flood without causing harm to the plants since the plants stay on the water surface. Allowing the wetlands to flood will eliminate uplift forces on the impermeable liner.

• Solids will settle to the bottom of pond and will not affect wetland performance. MWH have obtained a proposal from Kauri Park for a floating wetland based option to assess the feasibility of this option against a surface flow wetland (refer to Attachment 3 for draft proposal). Their proposal is based on an installation in the second oxidation pond, but the figures can be applied to a stand-alone system between the second oxidation pond and the RIBs. Their proposal should be considered preliminary at this time since further work would be required to refine their design if required. The size of the floating wetland design quoted above was driven by the level of treatment required for TSS. A TSS level of 50mg/l was initially selected as an appropriate target for RIB dosing, but seasonal variations in TSS concentrations and plant flows should be investigated further to determine if this level is appropriate for the Takaka plant. NIWA have been assisting Kauri Park with research and development. A few photographs (supplied by Kauri Park) are included below. Not visible in the photos are curtains that drape across the downstream edge perpendicular to the flow that assist with TSS removal. These curtains provide the primary means for TSS removal. As Kauri Park have developed their product they have added these curtains, and have now begun to add a floating permeable membrane as a final stage for shading to remove algae. Both of these developments are likely to add treatment potential, but it has made it difficult for MWH to be able to determine the design basis for the system and therefore the likelihood that the system will provide long term, cost effective treatment. As the system is relatively new to the market, and as this approach has resulted in the development of these additions and with little truly comparative data available, a scientific assessment of performance cannot be conducted. Kauri Park have suggested to MWH the floating membrane be added at the Takaka plant as it is included on the sketch that forms part of their proposal.


Photograph 1: Helensville installation – launch day and after five months

Photograph 2: Floating wetlands at McLeans Pit Landfill

Photograph 3: Floating wetlands at Kerepehi ponds showing covers


A capital cost estimate of the floating wetlands was prepared based on the Kauri Park proposal (Attachment 1). The estimated capital cost for a floating wetland based on the concept design is $685,000, which excludes Preliminary and General items, design and contingency costs. This design is based on 2050 design flow rates for the shoulder period, not the peak summer period as used for the surface flow wetland design. Designing the floating wetland based on peak summer flow rates would increase the overall size and associated costs. Therefore, while this cost cannot be directly compared to the costs for the surface flow wetland ($820,000), it is likely that a floating wetland design that is based on peak summer periods would still offer some cost advantages compared to a surface flow wetland. As mentioned above, the wetlands at the Takaka WWTP are critical for removing suspended solids in the water that is dosed to the RIBs. The major disadvantage of the floating wetland system is that there is a lack of any long-term full scale operational data available at the moment. Kauri Park do offer performance guarantees, but they cannot be backed up by actual data. The systems have been installed for stormwater treatment and also to investigate their use for assisting with nutrient reduction in the central lakes, but the first full scale installations for wastewater have only recently been installed. A further issue relating to a change in technology from a surface flow wetland to a floating wetland system is that this will require consultation with the Consenting Authority since it is a change in the draft consent conditions and further consultation with iwi. MWH have asked for comment from Kauri Park, who have been involved with consultation with iwi for other similar situations where more conventional systems had been proposed. Their experience so far has been that the floating system is acceptable as a form of land based treatment. They have not had specific involvement with the iwi consulted with in Golden Bay.

9 Summary

This design statement provides the basis of the design of the surface flow wetland. A detail design is still required to be completed in the Detail Design phase of the project. The surface flow wetland is a key treatment step in that it improves the quality of the wastewater (particularly with respect to TSS) prior to dosing to new rapid infiltration basins (RIBs) for disposal. The treatment provided by the wetlands is therefore critical for maximizing the life of the RIBs. Exposure to natural UV light will be provided between plants to promote bacteria (FC and E.coli) removal. Open water zones (30% of total wetland area) proposed by NIWA are not to be provided as a result of concerns of algal growth and a corresponding increase suspended solids levels in these areas. Literature suggests that a 2-log reduction of bacteria can be expected with a proper functioning wetland.

The wetland is designed for a hydraulic retention time of 5.5 days for 2050 peak summer dry weather flows. This ensures a sufficient level of suspended solid removal. At an operating depth of 0.45m, a total wetland area of approximately 8400m

2 (0.84ha) will be required. This could be provided by, for example, six wetland

cells, each 100m long and 15m wide. Preliminary layouts have confirmed that sufficient space is available at the site, although the exact dimensions are to be confirmed during the detailed design phase. With a typical operating depth of 0.45m, the plants proposed for the wetland are Carex secta, Phormium tenax Juncus pallidus and Eleocharis sphacelata. These species can grow in greater water depths than many other wetland plant species. During wet weather periods, the storage within the ponds should be utilised as much as possible to limit the flow and loading of contaminants into the wetlands. Flow into the wetlands from the second pond should be limited to a maximum of 1,000m

3/day by installing a flow control valve or a v-notched weir.

A dosing chamber containing the RIB dosing pumps at the end of the wetlands is required to provide sufficient storage volume for bulk dosing the RIBs. Floating wetlands were assessed as an alternative to a surface flow wetland. Floating wetlands are a relatively new technology. While the concept of the floating wetlands is promising, there is a lack of long-term performance data, which adds risk to the project as a result of the uncertainty of the level of treatment that can actually be attained.


There appear to be some capital cost advantages associated with floating wetlands compared to a surface flow wetland.

10 Recommendation

The following items are recommended.

• That Council review and adopt the design parameters described in this memo.

• That the design of the wetlands is based on a surface flow system.

• That Council understand and acknowledge the difference between the wetland design proposed in the AEE and those contained in this memo. The wetland is not to be designed as a “hybrid-type” wetland with open areas proposed by NIWA, but as a continuously planted wetland. The purpose of this is to maximise the removal potential of suspended solids. With this design, faecal coliform removal still will be achieved in the open areas between the plants.

• That the Council note the potential shortfall of approximately $100,000 between the estimated cost for the surface flow wetland compared to the 2012 AMP budget. MWH will prepare a revised cost estimate upon the completion of the preliminary design phase and will advise of any implications of this cost differential.

• That floating wetlands are not considered feasible until long-term performance data is available, particularly for total suspended solids.

This Project Technical Memorandum has been prepared for the benefit of Tasman District Council. No liability is accepted by this company or any employee or sub-consultant of this company with respect to its use by any other person. This disclaimer shall apply notwithstanding that the Project Technical Memorandum may be made available to Tasman District Council and other persons for an application for permission or approval or to fulfil a legal requirement.

Status – Final February 2012 Project Number – Z2404161 Tm11 Wetland Design Statement Final

Attachment 1 Capital Cost Estimates – Surface Flow and Floating Wetlands


Attachment 2 Operating Data for TSS in the St Arnaud Pond/Wetland System 2009-2011

Date TSS in pond effluent

(mg/L) TSS from wetland cell 1

(mg/L) TSS from wetland cell 2

(mg/L) 2009

January 5 130 1500 360 January 15 230 180 190 January 21 180 140 58 February 20 - 14 14 April 1 140 7 4 July 7 45 20 18 October 28 160 37 70 December 17 35 24 39 December 17 110 16 27 December 22 140 21 33 December 23 120 39 38

2010 January 7 100 32 56 January 14 140 110 190 January 20 88 26 40 January 28 100 31 370 March 28 - 20 28 April 28 82 110 20 July 14 13 26 33 October 4 90 60 160 December 8 120 39 43 December 16 86 36 36 December 22 140 28 26 December 30 110 36 20

2011 January 6 120 38 11 January 12 140 45 53 January 19 160 32 38 January 28 120 30 24 February 2 130 22 12 February 17 130 33 16 March 3 90 28 30 March 18 110 18 72 March 31 93 7 14 April 28 72 8 9 July 26 63 21 23 October 12 110 58 68 Median TSS in effluent (after excluding unsatisfactory data points as highlighted yellow) is 28mg/L, 90%ile 45mg/L


Attachment 3 Kauri Park’s Floating Wetland Proposal (Draft)

APPENDIX E - Takaka Wastewater Treatment PlantNotice of Requirement to Alter theExisting Designation - lncorporatingAmendments

Status: Draft Project number: Page 1 Our ref: Document3

REPORT

Takaka Wastewater Treatment Plant – Alteration to a Designation Amendment

Prepared for Tasman District Council

MAY 2010 OCTOBER 2012

TASMAN DISTRICT COUNCILTakaka Wastewater Treatment Plant - Alteration to a Designation

Status: Final May 2010Project number: Z2404121 Our ref: Takaka WWTP Designation Amendment October 2012

This document has been prepared for the benefit of Tasman District Council. No liability is accepted by this company or any employee or sub-consultant of this company with respect to its use by any other person. This disclaimer shall apply notwithstanding that the report may be made available to other persons for an application for permission or approval to fulfil a legal requirement.

QUALITY ASSURANCE STATEMENT

PROJECT MANAGER REVIEWED BY Jonathan Krause Frances Lojkine

PREPARED BY APPROVED FOR ISSUE BY Janan Dunning Jonathan Krause

CHRISTCHURCH Hazeldean Business Park, 6 Hazeldean Road, Addington, Christchurch 8024 PO Box 13-249, Armagh, Christchurch 8141 TEL +64 3 366 7449, FAX +64 3 366 7780

REVISION SCHEDULE Rev No Date Description Prepared By Reviewed By Approved By



TASMAN DISTRICT COUNCIL Takaka Wastewater Treatment Plant - Alteration to a Designation Amendment

CONTENTS

PART I – Application Form ............................................................................................................................ 1

PART II – Description and Assessment of Effects ........................................................................................ 1

1 Introduction .......................................................................................................................................... 1

2 Background ......................................................................................................................................... 1

2.1 History of Takaka WWTP .................................................................................................... 1

2.2 The Existing Designation ..................................................................................................... 2

2.3 Resource Consents ............................................................................................................. 2

2.4 The Requirement for a Designation ..................................................................................... 2

3 Why the Alteration is Necessary ......................................................................................................... 3

3.1 Existing Treatment Plant and Operation .............................................................................. 3

3.2 The Proposed WWTP Upgrade ........................................................................................... 3

4 Site Details .......................................................................................................................................... 4

4.1 Physical Description............................................................................................................. 4 4.1.1 Existing WWTP Site and Physical Setting ........................................................... 4 4.1.2 Proposed Designation Site ................................................................................... 5 4.1.3 Land Ownership ................................................................................................... 5 4.1.4 Terrestrial Ecology................................................................................................ 5 4.1.5 Geology and Groundwater ................................................................................... 5 4.1.6 Cultural and Heritage Values ............................................................................... 6

5 Description of Proposed Works ........................................................................................................... 6

5.1 Site Layout ........................................................................................................................... 6

5.2 Proposed Treatment and Disposal Facilities ....................................................................... 6

5.3 Flood Protection ................................................................................................................... 7

5.4 Proposed Site Works ........................................................................................................... 7

6 Statutory Assessment ......................................................................................................................... 7

6.1 Resource Management Act 1991 ........................................................................................ 7 6.1.1 Part II RMA ........................................................................................................... 8 6.1.2 Part 8 RMA – Designations and Heritage Orders ................................................ 9 6.1.3 Tasman Regional Policy Statement ................................................................... 10 6.1.4 Proposed Tasman Resource Management Plan ............................................... 10

6.2 Other Documents – LTCCP ............................................................................................... 11



7 Assessment of Environmental Effects ............................................................................................... 12

7.1 Baseline ............................................................................................................................. 12

7.2 Positive Effects .................................................................................................................. 12

7.3 Construction Effects ........................................................................................................... 12 7.3.1 Construction Traffic and Noise ........................................................................... 13 7.3.2 Erosion, Dust and Sediment Control .................................................................. 13 7.3.3 Effects on Groundwater ...................................................................................... 13

7.4 Operational Effects ............................................................................................................ 13 7.4.1 Visual Amenity Effects ........................................................................................ 13 7.4.2 Effects on Rural Amenity .................................................................................... 14 7.4.3 Social, Cultural and Economic Effects ............................................................... 15 7.4.4 Natural Hazards.................................................................................................. 15 7.4.5 Effects on Groundwater and Surface Water ...................................................... 16

8 Alternatives ........................................................................................................................................ 16

8.1 WWTP Location ................................................................................................................. 16

9 Consultation ...................................................................................................................................... 17

9.1 Manawhenua ki Mohua ...................................................................................................... 17

9.2 Neighbours ......................................................................................................................... 17

9.3 Other Stakeholders ............................................................................................................ 18

10 Outline Plan Waiver........................................................................................................................... 18

11 Conclusion ......................................................................................................................................... 18

LIST OF TABLES Table 2-1: Designation D180 ......................................................................................................................... 2 Table 6-1: TRMP Rules Assessment .......................................................................................................... 11

LIST OF FIGURES Figure 4-1: Location of the Takaka WWTP ................................................................................................... 4

APPENDICES

Appendix A: Land Requirement Plan

Appendix B: Indicative Site Development Plan

Appendix C: Landscape and Visual Impact Assessment

Appendix D: Objectives and Polices

Appendix E: Cultural Impact Assessment



PART I – Application Form



Resource Management Act – Form 18 – Tasman District Council

Notice of Requirement served under Section 181 of the Resource Management Act 1991.

To: Tasman District Council (Regulatory Authority) Private Bag 4 Richmond Nelson 7050

From: Tasman District Council (Engineering Services) Private Bag 4 Richmond Nelson 7050

(Please note different address for service at the end of this form)

Tasman District Council gives notice of a requirement for an alteration to a designation for a public work:

1. The site to which the notice of requirement applies is described in the following table:

Site Owner Certificate of Title

Legal Description Address

Takaka Wastewater Treatment Plant

Tasman District Council

101/72 Part of Pt Sec 19 Takaka District

Haldane Road, Takaka.

2. The nature of the proposed public work is:

The Tasman District Council (TDC) serves notice of an alteration to designation D180 by altering the boundary to incorporate approximately 1.8ha of land for wastewater treatment and disposal purposes. The alteration is necessary to provide adequate land to upgrade and expand the Takaka Waste Water Treatment Plant (WWTP).

The Tasman District Council proposes to upgrade the Takaka WWTP by constructing a new aerated lagoon and a series of rapid infiltration basins on land immediately adjacent to the existing WWTP. This land would become part of D180 in the Tasman Resource Management Plan and be designated for “wastewater treatment and disposal purposes”.

3. The effects of the proposal on the environment, and the ways in which the adverse effects would be mitigated are discussed in the attached document.

4. Alternatives are considered in the attached document.

5. The proposal and the designation are reasonably necessary to achieve the objectives of the requiring authority for the reasons discussed in the attached document.



6. The following resource consents are necessary and applications have been lodged with Tasman District Council:

Consent to discharge treated wastewater to land from the Takaka Wastewater Treatment Plant;

Consent to discharge contaminants (odour) to air from the Takaka Wastewater Treatment Plant;

Consents to establish several Geotechnical Investigation bores on the proposed treatment plant site.

These consents are sought for a term of 25 years.

7. Consultation was undertaken as detailed in the attached document.

8. Tasman District Council (Engineering Services) has attached the information required to be included in this notice by the Tasman Resource Management Plan, or any regulations made under the Resource Management Act 1991 in the attached document.

........................................................ Signature of person giving notice or person authorised to sign on behalf of person giving notice

............................

Date: May 2010

Address for service of applicant: MWH New Zealand Limited PO Box 3455 Richmond, Nelson 7050 Attention: Rob Lieffering Telephone: (03) 543 7053 Email: [email protected] MWH New Zealand Ltd Hazeldean Business Park P O Box 13 249 CHRISTCHURCH Attention: Janan Dunning Telephone: (03) 366 4790 Fax: (03) 366 5345 Email: [email protected]


Status: Final Page 1 May 2012Project number: Z2404121 Our ref: Takaka WWTP Designation Amendment October 2012

PART II – Description and Assessment of Effects

1 Introduction The Takaka township and several nearby coastal settlements in Golden Bay have undergone significant growth since the 1980’s. This growth and the recognition of the sensitivity of the coastal environment have put significant pressure on the Takaka Wastewater Treatment Plant (WWTP) to receive, treat and discharge wastewater. This pressure is particularly evident during summer months when visitor numbers to the Takaka and coastal Golden Bay settlements peak. To manage, treat and dispose of the increased wastewater the Tasman District Council (TDC) proposes to upgrade the existing Takaka WWTP both in respect of capacity and the standard of wastewater discharge.

2 Background

2.1 History of Takaka WWTP The Takaka WWTP was established in the mid 1980’s with the construction of an inlet screen and one oxidation pond. A major upgrade carried out in the mid 1990’s involved the addition of a second oxidation pond, a series of eight longitudinal marsh cells and an infiltration drain. The current WWTP site is designated in the Tasman Resource Management Plan (TRMP) for “sewage disposal purposes” with the designation covering an area of approximately 8ha. The designation includes old sections of the Takaka River bed that regularly flood, though to date the operational areas of the WWTP have avoided being overtopped by floodwaters. Currently, the existing treatment pond system is operating close to full capacity. During peak summer months the loads entering the system exceed the treatment capacity of the facultative ponds. The treatment capacity was reduced further by a substantial deposit of sludge on the base of the primary pond that built up over 20+ years of operation. This build up of sludge was removed from the pond during 2008, but only temporarily improves capacity. The 2007 design population (summer peak) is approximately 4000 persons. Since the Takaka WWTP was established, significant residential development has occurred in Takaka, and in the Golden Bay settlements of Pohara, Tata Beach and Ligar Bay which are also served by the Takaka WWTP. The upgrade of the WWTP is now necessary to provide for the additional treatment and disposal facilities adequate to accommodate increases in wastewater volumes anticipated to grow to 9000 4500 by 2050.



2.2 The Existing Designation Table 2-1 contains the details of the existing Takaka WWTP designation D180 in the TRMP.

Table 2-1: Designation D180

TRMP Designation Details Takaka WWTP

TRMP Designation Site ID D180

Site Location Haldane Road, Takaka

TRMP Planning Map AM50

Site Name and Function Takaka Sewage Treatment Pond

Purpose Sewage disposal purposes

Area 7.9677 ha

Duration 5 years

The existing site currently has little capacity for additional infrastructure, and is not favoured due to its vulnerability to flooding.

2.3 Resource Consents The Tasman District Council operates the plant under permit NN960204 which authorises the discharge of contaminants to land via an old channel of the Takaka River. While this permit expired on 31 August 2008, the Tasman District Council lodged an application in February 2008 for a new effluent discharge permit, allowing the WWTP to continue operating until the consenting process is complete. The consent application is referenced by Tasman District Council regulatory as RM080146. The Tasman District Council has also applied for consent to discharge odour to air from the wastewater plant as a new consent. The application is referenced by Tasman District Council regulatory as RM080166. The applications were publically notified, attracting seven submissions, all in opposition. The applicant has placed the application on hold at this time while it consults with submitters. A 25 year term of consent is sought for both discharge permits. The applicant has also applied for resource consent to install geotechnical investigation bores within and near the site to establish ground and groundwater conditions. No other resource consents will be required in relation to the proposal as activities aligned with the purpose of the designation will be authorised in accordance with and upon the confirmation of the designation.

2.4 The Requirement for a Designation Section 166 of the Resource Management Act 1991 (RMA) identifies the Tasman District Council as a Requiring Authority. Application to designate land in a District Plan can only be made by a Requiring Authority. By this document the Tasman District Council is serving notice of a requirement to alter the existing Takaka WWTP designation to provide for the expansion and upgrade of the plant. The additional area would be incorporated into the existing designation through a boundary adjustment and would be designated for wastewater treatment and disposal purposes. The inclusion of this land in the existing designation would enable the Tasman District Council to increase the capacity and efficiency of the WWTP, to provide for future growth, and to enable the quality of the wastewater discharge to be improved.



The alteration would add approximately 1.8ha to the existing designation identified in the TRMP as D180, which contains the existing Takaka WWTP site. Upon the inclusion of the additional land, the total area designated for the Takaka WWTP would increase from approximately 7.97ha to 9.77ha. The location and extent of the designation sought is shown on Plan LP01 attached in Appendix A, and is part of land legally described as Pt Sec 19 Takaka District. The land was recently purchased by the Tasman District Council. An Indicative Site Development Plan is provided in Appendix B.

3 Why the Alteration is Necessary

3.1 Existing Treatment Plant and Operation The increased load on the treatment plant over the summer months has caused the facultative ponds to overload on several occasions. The flow through the ponds has also been of shorter duration than designed for, due to the build-up of sludge reducing the holding capacity. As a consequence objectionable odour has been discharged from the plant, primarily over the peak summer months, resulting in complaints from nearby residents. De-sludging of the primary pond however has been completed and is expected to resolve the capacity issue in the short term. The wetland cells are unlined and during low flows dry out causing the wetland plants to die and allowing weeds to proliferate. Much of the wastewater discharged to the cells is infiltrating before reaching the end of the cells. Conversely, during wet weather when the groundwater levels are high, wastewater cannot infiltrate efficiently, and can overflow directly to an adjacent old river channel, bypassing the infiltration trenches. These operational deficiencies coupled with the inability of the plant to receive additional wastewater resulting from projected growth in Takaka and the surrounding settlements necessitate the proposed upgrade and expansion of the plant. The expansion of the WWTP within the existing site is constrained by the size of the designation, the land available, and the vulnerability of the site to flooding. The alteration of the designation to include the new site as proposed is necessary for the Tasman District Council to achieve its objectives of providing for the effective treatment and disposal of wastewater into the future.

3.2 The Proposed WWTP Upgrade The proposed upgrade to the Takaka WWTP would provide sufficient treatment capacity for the predicted increases in wastewater volumes up to 2050. The upgrade design is a result of planning work associated with an application to the Government for Sanitary Works Subsidy funding, and consultation with iwi and other key stakeholders. The proposed upgrade would include new screening headworks, a new septage receiving facility, partitioning of the first oxidation pond, installation of new aerators within the oxidation ponds, new wetlands an additional aeration lagoon, improvements to the existing wetland, and the construction of a series of Rapid Infiltration Basins (RIB’s) to discharge treated wastewater to ground. These RIB’s would replace the infiltration drains that are currently used. The Tasman District Council proposes to build the new aeration lagoon, RIBs and associated infrastructure on land to the east of the current WWTP designation site. The proposed location would provide adequate area for the upgrade and expansion of the WWTP’s capacity and reduce vulnerability to flooding from the Takaka River. Locating the RIBs on the proposed site would also provide a longer groundwater path between the discharged wastewater and the Takaka River, reducing the potential effect of the discharge on the quality of the Takaka River compared with the current disposal arrangement.



The Takaka WWTP does not have sufficient capacity to receive, treat and dispose of wastewater from its design catchment through to 2050, and currently struggles to appropriately manage wastewater during peak summer periods. If the upgrade does not take place the capacity of the WWTP will continue to be exceeded, and the environmental effects would likely become significant. In order to achieve the necessary upgrade, additional land is required, and it is appropriate that, as an important public utility, the establishment, operation and maintenance of the treatment plant overall is provided for by designating the land.

4 Site Details

4.1 Physical Description The Takaka WWTP is located beside Haldane Road, approximately 400 metres west of Takaka township, and approximately 300 metres east of the Takaka River. The general area is indicated in Figure 4-1:

Figure 4-1: Location of the Takaka WWTP

4.1.1 Existing WWTP Site and Physical Setting

The existing plant consists of: inlet works; facultative and maturation ponds; wetland marsh cells; infiltration and overland discharge channels.

Takaka WWTP Site

Golden Bay



The existing WWTP is located near the end of Haldane Road on undulating land consisting of low alluvial terraces and old Takaka River channels. The surrounding land is used primarily for pastoral productive purposes, and includes shelter and amenity trees. A low stop bank lies between the site and the Takaka River to the west. The site is elevated above the surrounding land on a low river terrace, with drainage channels either side. The topography generally climbs to the east toward Takaka in a series of low terraces. The site lies approximately 300m east of the Takaka River, and approximately 500m southwest of the nearest residential activity. The site is screened from Haldane Road by established willows and poplar trees though it is understood many of the willows are shortly to will be removed as part of the upgrades to minimise the management of flood risk to the site. There are no water supplies or stock water schemes in the vicinity of the site.

4.1.2 Proposed Designation Site

The proposed designation site is shown on the Land Requirement Plan attached in Appendix A. It is immediately adjacent to and east of the existing WWTP, and abuts the southwest corner of the existing designation (D180). It is bounded to the northeast by Haldane Road, to the southwest by an old section of the Takaka riverbed, and to the southeast and northeast by land currently in pasture and being used for stock grazing. The site is zoned Rural 1 under the TRMP, and is subject to the general and zone rules of the Plan. The nearest dwellings are more than 600m northeast of the proposed designation. The area of the proposed designation and the WWTP is susceptible to regular flooding from the Takaka River. The flood hazard extends over the rural land to the east, and consequently it is unlikely to be developed for residential activity. A full description of the physical setting is included in the Landscape and Visual Impact Assessment (LVIA) report attached in Appendix C.

4.1.3 Land Ownership

Tasman District Council owns the land underlying the existing treatment ponds, and has recently purchased the additional 1.8 ha underlying the proposed designation site.

4.1.4 Terrestrial Ecology

The site is located on highly modified land historically used for rural productive purposes. There is no obvious presence of indigenous vegetation or habitat, and vegetation primarily consists of exotic pasture grasses with some intermittent woody weed species such as gorse and broom. The site does not contain any wetland areas. Consequently, the site does not hold significant terrestrial ecology values.

4.1.5 Geology and Groundwater

The area is underlain by well sorted river gravels with variable sand components of fluvial origins. The deposits are made up of light brown to grey sandy gravel with slightly weathered greywacke, sandstone, granite and quartz. The gravels are loose to medium dense and slightly weathered at depth. The deposits were formed during the deposition of the Takaka River floodplain. Groundwater investigations carried out in relation to the discharge application indicate that groundwater is relatively shallow, and flows through permeable river gravels in a northwest direction toward the Takaka River. There are no groundwater users between the proposed designation site and the Takaka River.



4.1.6 Cultural and Heritage Values

The TRMP does not indicate that the site contains any known heritage or cultural values. A review of the New Zealand Historic Places Trust (NZHPT) and New Zealand Archaeological Association (NZAA) databases do not reveal any known heritage or archaeological sites or values.

5 Description of Proposed Works

5.1 Site Layout The proposed site layout is shown on the Indicative Site Plan attached in Appendix B. The activity on the area to be included in the designation site would include the addition of a new aerated lagoon, eleven consist of at least eight bunded RIBs and associated support buildings and infrastructure. It would also involve earthworks necessary to provide flood protection to the site. Bunding is required to provide flood protection to the infiltration surface.

5.2 Proposed Treatment and Disposal Facilities The upgrade to the WWTP would involve refurbishing the existing wastewater treatment ponds and wetland cells to bring the level of treatment in line with current international wastewater treatment standards. The WWTP components proposed for the area to be included in the designation are: Aerated Lagoon: A 2.5m deep aerated lagoon to provide primary wastewater

treatment and replace the existing role of the facultative pond. The fully lined lagoon will hold up to 6,400m3 of wastewater, providing a hydraulic retention time of up to 3.5 days, adequate to manage peak summer inflows. The aeration of the lagoon throughout its depth will ensure that adequate oxygen levels are achieved to avoid aerobic conditions that could result in the release of objectionable odours.

Rapid infiltration Basins (RIBs): up to 11 at least eight RIBs would be formed to provide a new

ground disposal system and replace the existing infiltration trenches. The RIBs would be formed on exposed alluvial gravels, with treated wastewater dosed into each basin in turn. The treated wastewater would then discharge to ground through the basin floor. The RIBs have been designed to accommodate wastewater volumes calculated on population projections to peak flows in 2050.

UV Disinfection: UV treatment is a provisional component of the WWTP upgrade,

providing a contingency in the event that the upgraded system does not achieve the expected environmental effects standard of treatment.

The site would also contain a raised platform that would hold a control building, a screening compactor, inlet works, and a small storage shed. The site would be fully fenced with a standard stock-proof farm fence or similar around the perimeter. A 2m high chain-link security fence would may be installed around the pre-treatment facilities to provide additional security around the most exposed and hazardous area of the site.



5.3 Flood Protection The existing WWTP site is located on the Takaka River flood plain. An old river channel bounds the site to the northeast, separating it from Haldane Road. A flood review carried out by Tasman District Council estimates this channel regularly routes flood waters from the Takaka River between the existing oxidation ponds and adjacent landward terraces with a two year Average Recurrence Interval (ARI). The site is subject to inundation in a 50 year flood event and has a history of frequent partial inundation during smaller flood events. The Tasman District Council however has no record of the oxidation ponds being overtopped by flood waters. The area to be included in the designation is also subject to flooding, albeit to a lesser degree than the existing site. Located on a higher river terrace landward of the WWTP, the new site would also be inundated in a 50 year event. To safeguard the proposed wastewater treatment infrastructure from this flood risk, flood protection would be achieved by creating a bund around the RIBs forming a raised platform to contain the access, parking areas and plant buildings. Flood protection berms would be formed around the remainder of the site, to protect the aeration lagoon and RIBs. The level of the land would be raised a maximum of 1.5m above the existing contour to achieve the necessary level of flood protection. This would ensure that the WWTP could continue to operate during small but frequent flood events, and would also ensure Tasman District Council staff could gain access to the site during a flood. The height of the flood platform and berms would provide approximately 0.3m freeboard above a 1 in 50 year flood event.

5.4 Proposed Site Works Earthworks of approximately 3000m3 5000m3 would be required in order to form the WWTP infrastructure proposed for the new site. This would include excavating the lagoon and RIBs, and forming the platform and flood protection bunds berms. The earthworks would likely commence with stripping and stockpiling of topsoil, followed by the excavation and contouring of the underlying material. It is anticipated that the site would be formed using material excavated from the Lagoon and RIBs and imported material where necessary. The stockpiled topsoil would then be replaced on the top of the platform and the external faces of the flood protection bunds berms, stabilised and re-vegetated. The works would be provided for by the designation as they are in accordance with the purpose of the designation. The effects of the site works are assessed in Part 7 of this document.

6 Statutory Assessment

6.1 Resource Management Act 1991 The RMA provides the framework for all resource utilisation in New Zealand. The amendments to the RMA as a result of the Resource Management (Simplifying and Streamlining) Amendment Act 2009 came into effect in October 2009, and apply to the consideration and determination of this notice. Section 9(3) RMA restricts the use of land where that use would contravene a rule in a District Plan or proposed Plan, or in relation to matters that would normally fall within the authority of a District Council. To carry out an activity that contravenes a rule requires resource consent from the relevant authority. The designation process removes the need for a requiring authority to obtain resource consent for most land use activities that are undertaken in accordance with the purpose of the designation. Under s.176(1) the provisions of s.9(3) do not apply to public works undertaken by a requiring authority under a designation.



Section 15 RMA places restrictions on the discharge of contaminants into the environment. This proposal requires consent in respect of the discharge of treated wastewater to land, and odour to air. Consent for these activities is being sought concurrently.

6.1.1 Part II RMA

Part II RMA contains sections 5 to 8. The purpose of the RMA is contained in s.5, with all resource use, development and protection under the RMA to be consistent with that purpose. Section 5 promotes the sustainable management of natural and physical resources in a manner that achieves social, cultural, economic and environmental wellbeing (the four wellbeings). As an effects-based statute, the RMA provides a framework for activities to be permitted or authorised through resource consent or the designation of land for a given purpose where an activity does not result in significant adverse affect effect on the life supporting capacity of soil, air or water. Sections 6 to 8 are subordinate to s.5, and therefore to the purpose of the RMA. Section 6 identifies matters of national importance to be recognised and provided for in exercising duties and functions under the RMA. Section 7 lists matters to which decision makers should have particular regard. The relevant section 6 matters are:

(a) the preservation of the natural character of the coastal environment (including the coastal marine area), wetlands, and lakes and rivers and their margins, and the protection of them from inappropriate subdivision, use, and development:

(e) the relationship of Maori and their culture and traditions with their ancestral lands, water, sites, waahi tapu, and other taonga:

The WWTP upgrade will preserve the natural character of the Takaka River and maintain the relationship between Maori and their ancestral waters (Takaka River) by discharging treated wastewater to ground rather than directly to the river. This is aligned with the iwi preferences as discussed under the consultation section of this document. The relevant section 7 matters are:

(b) the efficient use and development of natural and physical resources: (c) the maintenance and enhancement of amenity values: (d) intrinsic values of ecosystems: (f) maintenance and enhancement of the quality of the environment: (g) any finite characteristics of natural and physical resources:

Clauses (b) and (g) are inter-related in that the proposal represents the efficient use and development of finite resources (land). Increasing the area of the designation to provide for increased treatment plant capacity also presents the opportunity to improve the efficiency of the plant with new systems. In particular, the increased area would provide the opportunity to install the RIB’s that would provide a more compact and efficient method of discharging treated wastewater to land. The assessment of effects on the visual and amenity values of the site and surrounding area (as assessed later in this document) demonstrates that the use of the land in accordance with the designation would not result in significant adverse environmental effects. This is supported by the conclusions contained in the LVIA attached in Appendix C. The use of the proposed designation to enhance wastewater treatment and the standard of the discharge will better safeguard the intrinsic values of downstream ecosystems and better maintain the quality of the environment following mixing of the discharge in groundwater. The proposal therefore has appropriate regard for the intrinsic values of the land and resources affected by the discharge that would occur as a result of the designation sought. The RMA anticipates and enables activities with adverse effects that are less than minor, as determined in the following assessment.



The consultation undertaken by the Tasman District Council has provided insight into the values and expectations of local iwi. The process of seeking the designation has taken appropriate account of the principles of the Treaty of Waitangi (section 8 RMA) through involving iwi early in the process, and through consultation and the preparation of a Cultural Impact Assessment report (Appendix E), as considered in the consultation section later in this document.

6.1.2 Part 8 RMA – Designations and Heritage Orders

Part 8 of the RMA contains the provisions relating to designations. Section 168A sets out the process to be followed when a territorial authority (in this case the Tasman District Council) lodges a notice of requirement (NoR) for a designation within its own district. Clause (2) sets out the NoR process, which follows a similar path to a resource consent process. Clause (3) requires the territorial authority to consider the effects on the environment, subject to Part II RMA, and directs that particular regard be had to the following:

(a) any relevant provisions of — (i) a national policy statement: (ii) a New Zealand coastal policy statement: (iii)a regional policy statement or proposed regional policy statement: (iv) a plan or proposed plan; and

(b) whether adequate consideration has been given to alternative sites, routes, or methods of undertaking the work if — (i) the requiring authority does not have an interest in the land sufficient for undertaking the

work; or (ii) it is likely that the work will have a significant adverse effect on the environment; and

(c) whether the work and designation are reasonably necessary for achieving the objectives of the requiring authority for which the designation is sought; and

(d) any other matter the territorial authority considers reasonably necessary in order to make a decision on the requirement.

Section 176 sets out the effect of a designation, and states that:

(1) If a designation is included in a district plan, then — (a) section 9(3) does not apply to a public work or project or work undertaken by a requiring

authority under the designation; and (b) no person may, without the prior written consent of that requiring authority, do anything in

relation to the land that is subject to the designation that would prevent or hinder a public work or project or work to which the designation relates, including — (i) undertaking any use of the land; and (ii) subdividing the land; and (iii) changing the character, intensity, or scale of the use of the land.

(2) The provisions of a district plan or proposed district plan shall apply in relation to any land that is subject to a designation only to the extent that the land is used for a purpose other than the designated purpose.

As a unitary authority, the Tasman District Council combines regional and district council functions and duties into one consent authority. The Tasman Resource Management Plan therefore contains both regional and district plan provisions. Resource consent for a land use activity that would normally need consent and falls under the authority of a district council is not required if that activity is consistent with the purpose of the designation. If any other activity that would normally need consent is undertaken on the site, and is not consistent with the reason for the designation, the activity will still need consent. The exemption given under s.176(1) only applies to land use activities under s.9(3) RMA. Discharge activities for example require consent regardless of whether there is a designation in place, hence the parallel applications lodged for the discharge consents.



Section 181 addresses alterations to designations. Clause (3) allows minor alterations to be made by the territorial authority at any time if:

(a) the alteration— (i) involves no more than a minor change to the effects on the environment associated with

the use or proposed use of land or any water concerned; or (ii) involves only minor changes or adjustments to the boundaries of the designation or

requirement; and (b) written notice of the proposed alteration has been given to every owner or occupier of the

land directly affected and those owners or occupiers agree with the alteration; and (c) both the territorial authority and the requiring authority agree with the alteration—

In this case, altering the boundary of the existing designation to include the proposed site could not be considered minor, as the proposal would add 1.8ha to the existing 7.9ha area. The test in clause 181(a)(i) therefore must be passed for this NoR to be considered an alteration rather than a new designation. That is, if the use of the proposed site does not result in environmental effects that are more than minor (as concluded in part 7 of this document), then the NoR may be assessed and determined as an alteration to the existing designation rather than a new designation. This is particularly important in this case as the purpose of designating the land proposed would be wholly aligned with the purpose of the existing designation.

6.1.3 Tasman Regional Policy Statement

The Tasman Regional Policy Statement (RPS) became operative on 1 July 2001. The purpose of the RPS is to integrate the management of natural and physical resources of the region by providing an overview of the issues, policies and methods relevant to the whole region. The provisions of the TRMP must be consistent with the RPS. The RPS establishes sustainable resource management policies relating to tangata whenua interests; urban development, land resources, fresh water resources, river and lake resources, coastal environment, contamination and waste, environmental hazards, and other significant resource management issues associated with energy use and transportation. Objectives and policies in the RPS that are of particular relevance to this resource consent application are attached in Appendix D. The assessment finds that the WWTP expansion that would be provided for by the designation would be consistent with the relevant provisions of the RPS.

6.1.4 Proposed Tasman Resource Management Plan

The TRMP was prepared in accordance with the RMA and is required to be consistent with the RPS. The TRMP is written in five main sections, addressing both the Regional and District Council obligations of the Tasman District Council as a unitary authority. The TRMP became partially operative in November 2008, with the remaining proposed sections of the Plan at various stages to becoming operative. Regardless, the Tasman District Council affords full weight to the TRMP provisions. Part II: Land, contains the provisions relevant to this proposal in terms of s.9(3) RMA. The TRMP contains a number of objectives and policies that guide decision making in the Tasman District. The relevant matters are contained within Chapter 5: Site Amenity Effects, Chapter 7: Rural Environment Effects, Chapter 9: Landscape, Chapter 12: Land Disturbance Effects and Chapter 13: Natural Hazards. The relevant objectives and policies from these sections are attached and assessed in Appendix D. The assessment of the TRMP finds that the WWTP expansion to be provided for by the alteration to the designation sought is consistent with the relevant provisions. Chapters 16 and 17 of Part II: Land contain the relevant rules that apply under s.9(3) RMA. The following table identifies the rules that would apply to the activity in the absence of the site being designated. It is important to note that regardless of the presence of the designation of the site, any activity that falls outside the scope of s.9(3) RMA or the purpose of the designation is subject to the rules contained in Chapter 16 of the TRMP, and in particular the Rural 1 Zone rules in Chapter 17.



Table 6-1: TRMP Rules Assessment

TRMP Rule Activity Status

16.6.2.1 Network Utilities and Public Works: the proposal would not comply with the following clauses: (e) Landscape planting adequate to screen all buildings and

structures from roads and public places. While landscape planting is proposed as part of the visual mitigation of the extended plant, it is unlikely to be adequate to completely screen the activity from Haldane Road.

(f) Land-based effluent disposal areas or oxidation ponds are specifically excluded as permitted activities.

(g) The structures will exceed 50m2 in floor area.

Discretionary activity under Rule 16.6.2.4.

18.5.2.1 Land Disturbance: The disturbance of land to form and re-contour the site would not comply with the following clause: (u) Flood Hazard: the site would be raised by constructing a

fill platform to provide protection from flooding and ensure that wastewater treatment and disposal can continue during flood events. In a large flood event (>Q50 or greater) the platform and flood protection measures are likely to cause flood waters from the Takaka River to divert to some extent.

Discretionary Activity under Rule 18.5.2.5.

Unless the site is designated for the expansion of the WWTP therefore, the applicant would need resource consent to establish and operate the expanded WWTP on the new site. While the applicant could seek consent for this activity, it is not favoured for activities of this nature. Consents present significant constraints in that the conditions under which they are granted apply to the activity at the time of application, and constrain the consent holder to undertake the activity as perceived at that time. Consents generally do not allow for activities to change over time, as would happen as techniques in wastewater treatment and disposal advance and improve over the 50 – 70 year lifespan of such infrastructure. A designation however allows the activity to evolve without undue constraint provided that the purpose of the activity is not compromised and the effects on the environment are no greater than anticipated at the time of designation. Designations also protect the activity by restricting or excluding land uses from the site that may prevent or hinder it. This is particularly important in the case of public utilities such as wastewater treatment plants which are vital to the health and wellbeing of the community and the environment. Designations also advise the community through the TRMP that land has been set aside for a specific purpose.

6.2 Other Documents – LTCCP The LTCCP requires the Tasman District Council to maintain adequate wastewater network services to safeguard community health and promote community wellbeing. Wastewater treatment results in significant positive effects on the economic, environmental and social wellbeing of the community. Treatment and disposal will protect the health of the community and the environment from adverse effects of untreated or uncontrolled wastewater disposal. The upgrade and expansion of the Takaka WWTP is therefore consistent with the stated objectives in the LTCCP.



7 Assessment of Environmental Effects The Fourth Schedule of the RMA directs the matters that should be included in an assessment of environmental effects, and the level of detail that corresponds to the scale, nature and significance of the proposal and the sensitivity of the receiving environment. The presence of the established WWTP provides context for the assessment of the effects of the additional designated area, and for allowing the designation of the additional land sought. The effects on groundwater, soil quality, surface water and air quality are considered in detail in the application for discharge consents submitted to the Tasman District Council and are referred to in this document.

7.1 Baseline The existing Takaka WWTP provides useful context when considering the NoR and the potential effects of the alteration to the designation. The presence of the existing WWTP forms part of the existing and anticipated environment and to an extent, the expectations of the community in respect of land use activities in this location. The alteration to the designation would represent an increase in WWTP area of 18% of the final designated area, but the effects are considered to be no more than minor, as discussed in the following sections.

7.2 Positive Effects The alteration to the designation of the site proposed would give rise to a number of positive effects, including: providing adequate land area to expand and enhance the WWTP necessary to treat and dispose of

treated wastewater from present and future populations with minor adverse effects on the physical environment. This would enable the sustainable disposal of wastewater to land, supporting the health, safety and wellbeing of the community and environment;

improving the quality and efficiency of wastewater discharged to land, and prolonging the life of the infrastructure already established, providing a suitable return on the community’s capital investment. This is particularly important when considering the investment required to relocate the WWTP entirely;

increased ability of the treatment system to accommodate growth; providing the community with certainty regarding the long term use of that site, which in turn allows

long term planning to take the designated land use into account.

7.3 Construction Effects The construction of the WWTP facilities on the new area of land will involve moderate earthworks. Earthworks can result in adverse visual effects from stockpiling material and tracking or spilling of earth onto roads and public space, exposure of soils to erosion or instability, ground and surface water contamination, dust generation and removal or destruction of terrestrial habitat. While the detailed design of the facilities on the proposed site has not adequately progressed to define the works, it is estimated that up to 3000m3 5000m3 of earthworks would be needed to complete site works and flood protection. The TRMP does not restrict the extent of earthworks in this location. Stockpiling excavated material or construction material brought onto the site may be necessary as part of the works. Any stockpiling undertaken would be temporary and would be fully removed following the completion of works. Similarly any visual effect of the works would be temporary, and would be mitigated to some extent by the separation from the nearest residential activity. The site will be raised above the surrounding land to provide protection from flooding, but shallow external batter angles and appropriate landscape treatment would mitigate the long-term visual effect of the earthworks.



All earthworks on the site are expected to complete within approximately 12 weeks, with all works expected to be completed within 40 weeks.

7.3.1 Construction Traffic and Noise

Construction activities on the new site are not expected to generate significant traffic. It is important to note that while Haldane Road is a narrow metal road, it provides landowner access to adjacent farmland, access to the existing WWTP, and truck access to a quarry where the road terminates near the Takaka River. Construction traffic is likely to be limited. Initial traffic will transport construction plant to the site at the start of the construction period, and will then remove it upon completion. Some truck traffic can be expected, particularly where construction material needs to be brought onto the site. The construction works are not otherwise expected to generate significant amounts of additional traffic along Haldane Road. The activity does not qualify as a high traffic generating activity under the TRMP and is not subject to controls on a public road as it will not have an adverse effect on traffic safety or the efficiency of the local road network. Construction noise would be similar in effect to many agricultural activities, such as ploughing, hay cutting and baling, crop harvesting and the like. Construction noise could also be expected from the construction of the buildings on the site, but this would be no different from that of a dwelling or farm building. Construction activities are expected to remain well within the noise standards specified in the TRMP for the Rural 1 zone.

7.3.2 Erosion, Dust and Sediment Control

Earthworks can generate off-site effects from sediment runoff, and through the generation of dust nuisance. Sediment would be contained within the site through the application of standard erosion and sediment control measures such as silt fencing, hay bale walls, cut-off drains or similar. The low relief of the site does not present a particular runoff risk. The site is surrounded by flat land in pasture, and it not near any watercourse or other sensitive receiving environment. Dust generation can be controlled through a variety of measures such as compaction, mulching, re-vegetating and dampening, and these will be undertaken as necessary. Construction activities are not expected to result in objectionable or offensive dust beyond the site boundary. Dust generation from the site however should be considered in the context of Haldane Road, which as an unsealed road and is a significant source of dust during normal traffic use. The landscaping proposed as part of the mitigation of visual effects may also assist with dust mitigation through re-vegetation. The distance between the site and the nearest residential activities will also assist in avoiding adverse dust effects.

7.3.3 Effects on Groundwater

Earthworks are estimated to extend to a maximum depth of approximately 1.0m below ground level during construction of the RIBs 1.5m during the construction of the aerated lagoon. Groundwater is understood to be approximately 2 – 3m deep during dry weather conditions. It is unlikely therefore that the earthworks will encounter groundwater, or result in groundwater contamination.

7.4 Operational Effects

7.4.1 Visual Amenity Effects

The landscape and visual impact assessment report attached in Appendix C concludes that the proposal would have very little effect on the visual amenity of the landscape setting. While it is acknowledged that the development of the new site could change the visual amenity of the setting, the effect would be less than minor in the context of the recommended mitigation planting.



The report also assesses the effect of the development on the natural character of the landscape. The visual separation of the site from the Takaka River provided by existing riparian vegetation, and the mitigation planting proposed is considered adequate to ensure the effect of the new development on natural character would be negligible. The assessment concludes that once the proposed landscape planting is established, the development would have very little effect on the quality of the setting.

7.4.2 Effects on Rural Amenity

The operation of the treatment plant could potentially affect rural amenity (other than visual amenity) as a result of noise generation, traffic generation, industrial fencing, lighting, or even the presence of a utility and associated “non-rural” buildings and structures in the rural environment. Other adverse effects on rural amenity can result from the discharge of odour. Once operational, the WWTP operation on the new area of land would be relatively unobtrusive. The plant will largely operate automatically, or through telemetry connections to Tasman District Council Engineers. Consequently the activity will not generate significant traffic to the site, other than during periods of maintenance or repair. Traffic movements could be expected to reach approximately one return trip per week during normal operation, which would be substantially superseded by existing traffic activity on Haldane Road. The Rural 1 Zone noise standards are set in Rule 17.5.2.1 of the TRMP. The most stringent standard is the night time limit, measured at the notional boundary (20m from the external wall of a dwelling) of a residential activity: 40 dBA L10 70 dBA Lmax The operation of the plant is generally very quiet, with little by way of mechanical plant. Noise is most likely to be generated by the mechanical inlet screen, but this is contained inside one of the plant buildings, and would not exceed the Rural 1 zone noise standards set in the TRMP at the boundary of the nearest residential dwelling. It is important to note that in the event of a flood or other emergency where power has been cut to the site, an emergency generator would be used to power the plant until power could be restored. The generator would be located within the control building which would help mitigate noise emitted during use. Any use would be limited to emergency situations, and would be limited in duration as much as possible. It is likely that in such circumstances rural amenity would be affected by, for instance, widespread flooding, and in this context the effect of the noise generation is likely to be considered minor. Boundary fencing is proposed for the perimeter of the designation, but is likely to consist of a standard stock-proof fence as anticipated in the rural setting. Similarly, external lighting would be restricted to a single security light on the control building. The light would be directed downward and into the site, and would not cause excessive light spill beyond the site boundary. The presence of buildings, structures and plant that are not related to rural productive activities that could be expected in a rural setting can affect the amenity of the rural zone. The scale of the buildings however are within the permitted activity parameters of Rural 1 Zone buildings, and if appropriately constructed and treated / painted, could appear similar to rural farm buildings. The treatment facilities such as the aeration lagoon and the RIBs would not be significant structures in the setting, and would be difficult to see from an off-site location. The presence therefore of the utility as non-rural activity in a rural setting would not result in significant adverse effects on rural amenity. The treatment of wastewater is designed to be aerobic and consequently would generate minimal odour. Proper operation and maintenance of the treatment plant will ensure that objectionable or offensive odour is not generated from the plant that is discernable beyond the site boundary, or by residents in the Takaka residential zone.



As long as the WWTP processes are operating as planned, the discharge of odour and its effect on amenity would be minor, even within the site. Regardless however, a resource consent authorising the discharge of contaminants and odour to air has been sought from the Tasman District Council concurrent with this NoR. The effects of the operation are therefore considered to be no more than minor.

7.4.3 Social, Cultural and Economic Effects

Once operational, the WWTP on the site is unlikely to result in significant adverse effects on nearby residential activities in Takaka. Most of the dwellings along Waitapu Road (State Highway 60) primarily face away from the site to the north and east, or are substantially screened from the site by established vegetation. There is approximately 500m between the site and the nearest residential dwelling. The effect therefore of the use of the site for this activity on the nearby residents would be minor. The risk to public health and safety will be minor as the community would need to come into direct contact with untreated wastewater or contaminated groundwater to be at risk. This is unlikely other than in the event of unauthorised access to the site. The treatment process, including post-discharge treatment in groundwater, will be adequate to reduce contaminants to safe contact levels. Regardless, consent is sought in relation to the discharge of treated wastewater to ground. The site would be lost to rural productive activities as a result of the purchase and designation of the land. However, the site is a small part of a larger area owned by the present landowner, and the effect of losing 1.8ha of grazing land will be minor in that context. There are no known sites or items of cultural significance to iwi on the site. The Tasman District Council has engaged in consultation with local iwi and have their support for the proposal as it meets cultural preferences to discharge human sewage effluent to ground.

7.4.4 Natural Hazards

The site is subject to flooding from the Takaka River, though the preparation of the site would raise and recontour the land to provide protection to plant and infrastructure and reduce the likelihood of the aeration lagoon and RIBs being overtopped. Flood mitigation works would provide adequate protection to all critical infrastructure to a minimum flood event of a 50 year ARI. In the event that the site is overtopped, the existing WWTP on an adjacent lower terrace would have been inundated already, and the WWTP likely shut down in the interim. The Takaka River would be at significant flow, and would be likely to be carrying significant loads of contaminants and sediment. In addition, the high river flows would likely rapidly dilute and disperse any contaminants remaining in the ponds. The risk of the public contacting contaminated water in these circumstances is minimal as the river conditions would not be conducive to recreation. Raising the height of land in a flood plain can cause flood waters to be diverted or deflected into adjacent properties or infrastructure, exacerbating damage or inundation. The designation site is located in an area surrounded by open paddocks with few structures in the vicinity or downstream of the site. Any flood waters deflected by the raised platform or flood protection berms would be directed into the surrounding open paddocks. The proposal therefore is unlikely to result in significant adverse effects as a result of deflection. Haldane Road lies to the immediate north of the site (downstream in the event of a flood) and would present a minor barrier to flood water as it is marginally higher than the surrounding land. Regardless however, neither the road nor the proposed WWTP site would result in significant adverse effects as a result of deflecting or diverting flood waters.



7.4.5 Effects on Groundwater and Surface Water

For context, the discharge of treated effluent from the Takaka WWTP to ground would form a contaminant plume in groundwater between the RIBs and the Takaka River. The plume however would have a reasonable groundwater mixing zone within which additional contaminant reduction (i.e. coliform decay, dilution etc) occurs. It is also important to note that there are no other downstream groundwater users between the discharge location and the Takaka River. The discharge is expected to result in low levels of contaminants reaching the surface water of the Takaka River via groundwater during times of high loadings. The contaminant levels are expected to be well within water quality guidelines following the additional treatment it receives by passing through ground between the RIBs and the Takaka River. A full assessment of the environmental effects of the discharge from the site is included in the application document for the discharge consents lodged with Tasman District Council. As the WWTP has been in existence for over 20 years, the proposed upgrade should not affect amenity values in terms of discharge effects, particularly for the neighbours. The proposed upgrade design provides an acceptable solution to improving the wastewater treatment system which, because of the low levels of residual contaminants remaining after the discharge of treated effluent passes through the groundwater mixing zone, would not adversely affect the amenity values of the Takaka River and river banks.

8 Alternatives

8.1 WWTP Location There was a strong desire from Manawhenua ki Mohua for the Takaka WWTP to be moved away from the Takaka River in respect of their cultural and spiritual ties with the river. Since the WWTP is already established and is performing appropriately, the TDC does not consider it it was agreed that it was economically viable to disestablish it and relocate it away from the Takaka River. The Tasman District Council and community would incur significant costs not only from moving the plant, but also in the infrastructure arrangements necessary to operate the WWTP at an alternative site. The consideration of alternatives was based around the existing site, and no other locations were considered. This was agreed by the Takaka Wastewater Treatment Plant Upgrade Working Group, which is made up of members of the Council (including the Mayor), representatives of the Golden Bay Community Board, and two local residents. The Applicant and staff from MWH (consultants engaged by the Applicant) were also present at all meetings, but were not official members. Manawhenua ki Mohua were invited into the Working Group, but wished not to be included. The land subject to this notice of requirement was selected because of its proximity to the existing WWTP, and the suitability of the site in respect of topography, existing land use, accessibility and underlying geology. The Tasman District Council has since purchased the site, and therefore now has sufficient interest in the land to enable the work to proceed. Accordingly, the Tasman District Council need not consider alternatives to any further degree as it has satisfied the provisions of s.168A(3)(b).



9 Consultation Consultation with Iwi and other key stakeholders regarding the WWTP upgrade commenced with the circulation of a discussion document in August 2004 that considered consent and environmental requirements. A Cultural Impact Assessment report was issued in September 2005 (Appendix E) in which tangata whenua recognise that to move the WWTP, or to establish part of it on a new separate site would be prohibitively expensive, and offer conditional support for the current proposal, including: provision of a wetland; additional aerators; baffled secondary ponds; discharge to ground; provision of UV disinfection. Subsequent studies (MWH 20071) confirmed that an ultra-violet disinfection system would not provide significant additional benefit, and this option is therefore not intended at this time.

9.1 Manawhenua ki Mohua The three tangata whenua iwi holding manawhenua in the Golden Bay area are Ngati Tama, Ngati Rarua and Te Atiawa, who cooperate together as Manawhenua Ki Mohua. Consultation with Manawhenua Ki Mohua regarding the Takaka WWTP upgrade proposals has been continuing since 2004. The outcomes of this consultation are: the cultural impact assessment; the groundwater study in respect of the need for UV disinfection of wastewater treatment; a Memorandum of Agreement between iwi and Tasman District Council regarding on-going liaison

on matters concerning the operation of WWTPs. Iwi have accepted that the Takaka WWTP should be upgraded at its existing site near the Takaka River, because of economic constraints on shifting the plant to a new site. A consent term of 25 years was supported for the discharge consents currently sought. Effluent quality standards proposed for the upgraded treatment system meet national standards, and are acceptable to tangata whenua in combination with the discharge of the treated wastewater to ground rather than the Takaka River.

9.2 Neighbours Neighbouring landowners have been consulted on various aspects of the proposed upgrade and were directly notified as part of the discharge consent application process. They are aware that the Tasman District Council intends to undertake upgrades to the existing WWTP and develop the new site as part of those works. As a consequence of the submissions received following the notification of the discharge consents, the Tasman District Council held a pre-hearing meeting with submitters and discussed the proposal as a whole at that time. The Tasman District Council has since followed up with letters to the submitters and adjacent landowners inviting further discussion or clarification. Responses had not been received at the time of writing this document.

1 MWH (2007) Takaka WWTP Upgrade – Groundwater Study



9.3 Other Stakeholders Other stakeholders consulted with regarding the upgrade design concepts are Public Health South, the Nelson-Marlborough Fish & Game Council and the Department of Conservation. It is understood that these agencies are generally supportive of the proposals.

10 Outline Plan Waiver As part of this NoR, Tasman District Council requests an outline plan waiver pursuant to section 176A(2)(a) of the RMA. This is requested because the information provided in this application satisfies the requirements of section 176A(3).

Section 176A(3) - An outline plan must show— (a) the height, shape, and bulk of the public work, project, or work; and (b) the location on the site of the public work, project, or work; and (c) the likely finished contour of the site; and (d) the vehicular access, circulation, and the provision for parking; and (e) the landscaping proposed; and (f) any other matters to avoid, remedy, or mitigate any adverse effects on the environment.

The information included in the land requirement plans attached is indicative, with the final site layout and extent of works to be determined following detailed design. However, information in respect of clauses (a), (b), (d) and (f) are shown on the plan attached in Appendix B, and in respect of (e) is attached in Appendix C, and the height and location of the works will be within the provisions of the TRMP, and in general accordance with the plans attached. Consequently it is appropriate that the need to provide an outline plan is waived in this instance as the consent authority has adequate information through these plans and this application to determine the effects of the proposal.

11 Conclusion The Tasman District Council has served this notice of a requirement to alter an existing designation by incorporating additional land adjacent to the existing Takaka WWTP. The notice is served in respect of the Tasman District Council’s intention to undertake works on that site that will increase the treatment capacity and efficiency of the WWTP and improve the quality of the discharge to land. The operation of the existing plant is not optimal, and the capacity of the plant is currently reached during peak summer populations. There is no capacity therefore for the plant to receive more wastewater to accommodate predicted growth in Takaka and the Golden Bay settlements through to 2050. The expansion of the WWTP into adjacent land will enable a much needed upgrade to take place, and will increase the ability of the WWTP to receive, treat and dispose of wastewater from Takaka and the Golden Bay settlements through to 2050. The alteration of the designation as proposed will provide for the proposed works, protect the land from potentially incompatible land uses, and enable the community to plan for growth in anticipation that the plant will expand onto this site. The assessment of effects contained in this notice demonstrate that the activity can be undertaken on the site as proposed without resulting in significant adverse environmental effects. The assessment also demonstrates that designating the site as sought would be consistent with the principles and purpose of the RMA, by providing for the sustainable management of the treatment and disposal of wastewater in a manner that safeguards the community and the environment, and provides for the likely future needs of the community.


Appendix A: Land Requirement Plan


Appendix B: Indicative Site Development Plan


Appendix C: Landscape and Visual Impact Assessment

REPORT

Takaka Wastewater Treatment Plant - Landscape and Visual Impact Assessment

Prepared for Tasman District Council

17 MAY 2010

TASMAN DISTRICT COUNCILTakaka Wastewater Treatment Plant - Landscape and Visual Impact Assessment

Status: Final 17 May 2010Project number: Z2404126 Our ref: TDC_Takaka WWTP_LVIA(final).docx

This document has been prepared for the benefit of Tasman District Council. No liability is accepted by this company or any employee or sub-consultant of this company with respect to its use by any other person. This disclaimer shall apply notwithstanding that the report may be made available to other persons for an application for permission or approval to fulfil a legal requirement.

QUALITY ASSURANCE STATEMENT

PROJECT MANAGER REVIEWED BY

Jonathon Krause Janan Dunning

PREPARED BY APPROVED FOR ISSUE BY

David Compton-Moen Jonathon Krause

CHRISTCHURCH Hazeldean Business Park, 6 Hazeldean Road, Addington, Christchurch 8024 PO Box 13-249, Armagh, Christchurch 8141 TEL +64 3 366 7449, FAX +64 3 366 7780

REVISION SCHEDULE

Rev No Date Description Prepared By Reviewed By Approved By


Status: Final 17 May 2010Project number: Z2404126 Page 1 Our ref: TDC_Takaka WWTP_LVIA(final).docx

TASMAN DISTRICT COUNCIL Takaka Wastewater Treatment Plant - Landscape and Visual Impact Assessment

CONTENTS

1 Introduction .......................................................................................................................................... 2

1.1 Purpose of the Assessment ................................................................................................. 2

1.2 The Project ........................................................................................................................... 2

1.3 Receiving Environment ........................................................................................................ 2

1.4 Scope of Landscape and Visual Impact Assessment .......................................................... 3

1.4.1 Landscape Assessment Methodology.................................................................. 3

1.4.2 Visual Assessment Methodology ......................................................................... 5

1.5 Relevant Statutory Documents and Studies ........................................................................ 6

1.5.1 Resource Management Act 1991 ......................................................................... 6

1.5.2 Tasman Resource Management Plan .................................................................. 7

2 Landscape Assessment ...................................................................................................................... 7

2.1 Landscape Character .......................................................................................................... 7

2.1.1 Topography .......................................................................................................... 7

2.1.2 Landcover ............................................................................................................. 7

2.1.3 Built form / Structures / Human Elements ............................................................ 8

2.1.4 Natural Character ................................................................................................. 8

2.2 Landscape Value / Significance ........................................................................................... 8

2.3 Landscape Amenity ............................................................................................................. 8

2.4 Landscape Effects ............................................................................................................... 9

2.4.1 Effects on Landscape Character (including Natural Character) ........................... 9

2.4.2 Effects on landscape values ................................................................................. 9

2.4.3 Effects on Landscape Amenity ........................................................................... 10

3 Visual Assessment ............................................................................................................................ 11

3.1 Existing Visual Character ................................................................................................... 11

3.2 Potential Sources of Visual Impacts .................................................................................. 11

3.3 Identification of Viewpoints ................................................................................................ 11

3.4 Visual Effects ..................................................................................................................... 11

4 Mitigation Measures .......................................................................................................................... 14

5 Conclusions ....................................................................................................................................... 14



1 Introduction

1.1 Purpose of the Assessment

This report provides a landscape and visual impact assessment for the proposed extension to the Takaka Wastewater Treatment Plant (WWTP) designation, located on a river terrace of the Takaka River at the end of Haldane Road, approximately 700m west of Takaka. This report addresses the likely impacts of the proposal on the local environment with particular regard to the visual effects which will be experienced. Opportunities to avoid, remedy or mitigate adverse effects of the proposal will be considered. The landscape issues addressed relate to potential changes in the fabric, character and quality of the biophysical landscape, including landform, soils and vegetation. Visual impacts related to changes in appearance and the perception of these changes. The objectives of this report are to:

• Undertake an assessment of the character of the receiving environment, and an assessment of

local landscape values within the area of the proposed development;

• Identify the nature, extent and significance of the potential impacts of the proposal in the context

and quality of the existing landscape setting;

• Variations to the design of the scheme for the purpose of minimising potential adverse effects on

the landscape and amenity are also considered.

1.2 The Project

Tasman District Council (TDC) wishes to extend the designation area under the Tasman Resource Management Plan (TRMP) Designation D180 – Takaka Sewage Treatment Pond to the east of the current site, on the south-eastern side of Haldane Road. The designation will increase in size by approximately 1.8Ha, occupying an area approximately 180m x100m. It is likely the site will contain a number of single storey buildings including a control building, emergency generator, and a screening compactor. Other facilities will include an aeration lagoon and a number of Rapid Infiltration Beds (RIBs). Potentially the ponds and buildings will sit 1-1.5m above the existing ground level to provide protection during flooding events up to a 1 in 50 year event. Perimeter fencing may consist of a 2m high chain link fence to prevent access into the treatment area. Extensive vegetation clearance will also be undertaken as part of the extension, including the removal of large poplar trees to the south of the existing site, and large willow trees located between Haldane Road and the existing site.

1.3 Receiving Environment

The receiving environment, given the nature of the project, is separated into two distinct types, one for landscape character (including natural character) and values and the other for the zone of visual influence. The receiving environment for landscape character is shown in Figure 2.1 attached to this report. The proposed extension to the WWTP is located on a river terrace of the Takaka River, southeast of Haldane Road, and west and adjacent to the existing WWTP. The surrounding landscape is generally open pasture with pockets of mature, mostly exotic, vegetation along old river banks, former river channels and along the banks of the Takaka River itself. While the majority of this area will not be affected by the proposal, it is necessary to include the wider area in terms of landscape character, natural character and landscape values to assess the proposal in terms of context. For the purposes of this assessment, the



landscape character area is considered to be a 300m radius from the edge of the WWTP site, both existing and proposed. A full description of the landscape character is outlined in Section 2.1. For visual effects, the receiving environment is shown on figure 3.1. While the visual character of the area is generally open, the flat nature and low profile of the proposal means that there are few views of and into the site. For this reason and the relatively small scale of the proposal, a number of close range viewpoints (less than 1km) have been selected to be assessed. A full description of the visual impact is outlined in Section 3.

1.4 Scope of Landscape and Visual Impact Assessment

The landscape and visual impact assessment considers the likely effects and impacts of the proposal in a holistic sense. There are two broad components to the assessment:

1. The landscape assessment addresses whole-of-landscape issues, particularly those identified by

sections 6 and 7 of the Resource Management Act 1991 (RMA). The landscape assessment

consists of two components: a descriptive component that describes landscape character, natural

character (s.6(a)) and landscape amenity (s.7(c)), and an evaluative component that addresses

landscape values in terms of the requirements of s.6(b).

2. The visual impact assessment is primarily concerned with the effects and impacts of the proposal

on the visual experience of the landscape by the principle groups of landscape users: residents,

workers, travellers and recreationists.

1.4.1 Landscape Assessment Methodology

The landscape assessment described in this document draws upon landscape assessment theory, professional best practice, the requirements of the RMA (particularly with regard to matters of national importance identified in Part II Section 6), and procedures and principles established through case law in the Environment Court. Landscape Character The general methodology applied is that described by Peart (2005)1, whereby the landscape unit of analysis is first described in terms of its landscape character. The framework for describing landscape character is divided into the categories of topography; land cover; built form / structures / human elements; and natural character. Section 6(a) of the RMA requires that a sub-set of landscape character – natural character – be subject to specific analysis. Natural landscape character is a narrowly defined aspect of landscape character. In simple terms it is an assessment of the degree to which a given landscape is the product of nature, as opposed to cultural intervention. It can be assessed along a continuum of states from pristine wilderness, where no evidence of human intervention is apparent, to wholly developed, where scant evidence of natural elements, patterns, and processes remains. It is important to emphasise that natural character is not an absolute quality that either exists or doesn’t, but rather occurs across a continuum in matters of degree. Human interventions may diminish natural character, but do not necessarily eliminate it altogether. Natural character is generally understood to be determined by the extent to which the natural elements, patterns and processes occur in the landscape, and the extent to which they are modified by human interventions. The highest degree of natural character (greatest naturalness) occurs where there is least modification.

1 Peart, R. (2005).Landscape planning guide for peri-urban and rural areas. Environmental Defence Society, Auckland



• Natural elements: these are the products of ecological, erosional and depositional processes; the

biophysical characteristics of the landscape, such as landforms, rock outcrops, hydrological

features and vegetation communities.

• Natural patterns: patterns are formed through the interactions between landscape elements and

the processes operating on them. Patterns are apparent through the interactions of plants, soils,

aspect and slope, or through the erosion of the coastline through wave action. The regimented

character of a forestry plantation or apple orchard compared with the apparently random patterns

of trees in an indigenous forest, illustrates how natural and unnatural patterns might be

understood.

• Natural processes: Natural processes are the dynamic processes at work on the biophysical

landscape, shaping landform and vegetation communities through processes of erosion and

deposition, soil forming processes, colonisation and succession, regeneration and energy and

nutrient flows.

Table 1: Continuum of Natural Character

Natural Near- Natural

Semi-Natural (Inc pastoral agriculture &

exotic forests)

Agricultural (arable and intensive cropping)

Near- Cultural

Cultural

I I I I I I I

Very High-Pristine High Moderate-High Moderate Moderate-Low Low Very Low-Nil Landscape Value / Significance Following the descriptive phase of landscape assessment, an evaluative phase is undertaken whereby values or significance is ascribed to the landscape. The accepted approach, where the TRMP has not identified Outstanding Natural Features or Landscapes under Section 6(b) of the RMA, is to use criteria identified in Wakatipu Environmental Society Inc & Ors v QLDC [2000] NZRMA 59 (generally referred to as the modified Pigeon Bay criteria). The Pigeon Bay criteria include natural science factors, aesthetic value, an aspect of landscape values over which there is considerable debate regarding the theoretical basis for assessing visual or scenic quality, and the methods and techniques to be used. A professionally-based evaluation has been applied to the task of assessing aesthetic value, drawing upon the theoretical work of Kaplan and Kaplan (1989)2. The technique used to assess aesthetic quality includes reference to several of the factors which form the framework for the assessment of landscape character. Where the TRMP has identified Outstanding Natural Features or Landscapes, the objectives, policies and rules contained within the plan are used as the basis for landscape significance or value, and it is these values which the proposal is assessed against. Where there is some uncertainty of the landscape value, such as when the TRMP has a broad description of an Outstanding Natural Landscape (ONL), but it is not site specific, or the site neighbours an ONL, it is often necessary to complete an assessment against the values of the TRMP for completeness sake.

2 Kaplan, R., & Kaplan, S. (1989). The Experience of Nature: A Psychological Perspective. Cambridge: Cambridge University Press



Landscape Amenity In response to Section 7(c) of the RMA, a further evaluation is undertaken to define and describe amenity values. As with aesthetic values, with which amenity values share considerable overlap, this evaluation was professionally-based rather than community-based. Amenity values are defined in the RMA as “those natural or physical qualities and characteristics of an area that contribute to people’s appreciation of its pleasantness, aesthetic coherence, and cultural and recreational attributes.” In a rural context, amenity values can be understood as including such aspects as:

• a sense of spaciousness (wide open spaces)

• privacy, quietness and absence of traffic and bustle’

• an environment relatively uncluttered by structures and artificial features

• a clean environment, characterised by fresh air, clean water, etc.3

A consideration of amenity values may give rise to a second tier of valued landscapes, beneath outstanding natural landscapes identified in accordance with s.6 (b) of the Act. These are termed visual amenity landscapes (VAL). Mitigation measures to avoid, reduce or remedy any potential landscape effects are outlined in Section 4.

1.4.2 Visual Assessment Methodology

The visual assessment looks at the visual sensitivity of the landscape and its ability to absorb the

proposal. It identifies the potential sources for visual impact resulting from the project and describes the

existing visual character of the area in terms of openness, prominence, compatibility of the project with

the existing visual context, viewing distances and the potential for obstruction of views.

The visual impact assessment involves the following procedures:

• Identification of the Zone of Theoretical Visual Influence (ZTVI), i.e. the area where the proposal

will be visible from. This is done using a combination of topographic data, site visits, photographs

and GIS to accurately determine visibility of the proposal from various locations. It must be noted

that the ZTVI does not take account of existing vegetation or buildings.

• Identification of key viewpoints within the ZTVI. A selection of key viewpoints is identified during

the site visit, representative of views in the area. The viewpoints are considered representative of

the various viewing audiences and distances, being taken from public locations where views of

the proposal were possible, some of which would be very similar to views from nearby houses.

• Assessment of the degree of sensitivity of the viewpoint to changes resulting from the proposal.

Factors affecting the sensitivity of receivers for evaluation of visual impacts include the value and

quality of existing views, the type of receiver, duration or frequency of view, distance from the

proposal and the degree of visibility. For example, those who view the impact from their homes

are considered to be highly sensitive as the attractiveness or otherwise of the outlook from their

home will have a substantial effect on their perception of the quality and acceptability of their

home environment and their general quality of life. Those who view the impact from their

workplace are considered to be only moderately sensitive as the attractiveness or otherwise of

3 Goodman, de Lambert, Dawson, McMahon & Rackham (2000). Impact of development on rural landscape values. Ministry for the Environment. Available at http://www.qualityplanning.org.nz/pubs/3991.pdf Accessed 26 March 2007



the outlook will have a less important, although still material, effect on their perception of their

quality of life. The degree to which this applies depends on whether the workplace is industrial,

retail or commercial. Those who view the impact whilst taking part in an outdoor leisure activity

may display varying sensitivity depending on the type of leisure activity. Those who view the

impact whilst travelling on a public thoroughfare will also display varying sensitivity depending on

the speed of travel and whether the view is continuous or occasionally glimpsed.

• Identification of potential mitigation measures. These may take the form of revisions/refinements

to the engineering and architectural design to minimise potential impacts, and/or the

implementation of landscape design measures (e.g. screen tree planting, colour design of hard

landscape features etc.) to alleviate adverse visual impacts and generate potentially beneficial

long term visual impacts.

• Prediction of the visual impacts after the implementation of the mitigation measures.

Photomontages are often prepared for key Visually Sensitive Receivers as a tool for impact assessment, providing photorealistic impressions of the proposal. To assist with the assessment of likely visual impacts the following matrix has been prepared:

Table 2: Visual Impact Matrix

MAGNITUDE OF CHANGE (EFFECT/IMPACT)

NEGLIGIBLE SMALL MODERATE LARGE

SENSITIVITY OF

RECEIVER

LOW DE MINIMIS NEGLIGIBLE MINOR MODERATE

MEDIUM NEGLIGIBLE MINOR MODERATE MODERATE – SUBSTANTIAL

HIGH MINOR MODERATE MODERATE -

SUBSTANTIAL SUBSTANTIAL

1.5 Relevant Statutory Documents and Studies

Relevant statutory documents referred to include (1) the RMA and (2) the TRMP.

1.5.1 Resource Management Act 1991

Part II, Section 6 of the RMA identifies matters of national importance: In achieving the purpose of this Act, all persons exercising functions and powers under it, it relation to managing the use, development, and protection of natural and physical resources, shall recognise and provide for the following matters of national importance: s.6 (a) The preservation of the natural character of the coastal environment (including the coastal marine area), wetlands, and lakes and rivers and their margins, and the protection of them from inappropriate subdivision, use and development: s.6 (b) The protection of outstanding natural features and landscapes from inappropriate subdivision, use, and development:



s.6(c) The protection of areas of significant indigenous vegetation and significant habitats of indigenous fauna.

Other matters are included under Section 7:

In achieving the purpose of this Act, all persons exercising functions and powers under it, in relation to managing the use, development, and protection of natural and physical resources, shall have particular regard to- (c) The maintenance and enhancement of amenity values:

1.5.2 Tasman Resource Management Plan

Outstanding Natural Landscapes have been identified in Chapter 9: Landscape of the TRMP. Tasman District is renowned for its diversity and quality of landscape and spectacular views. Mountain landscapes are protected in the Nelson Lakes and Kahurangi national parks. Coastal landscape is partly protected in the Abel Tasman National Park. A Council study (Works Consultancy Services Ltd 1995) identified landscapes and natural features outside the conservation estate that are outstanding or of regional significance on the basis of their character, quality and visibility. The study assessed the likely development pressures and recommended future management options. Significant Natural Areas and Landscape Priority Areas have been identified in the planning maps and are listed in Chapter 18. The proposed site is not located in either of these areas. The site is located within the Rural 1 Zone of the TRMP which covers land identified as having generally the highest existing and potential productive values. In the area of this zone, rules for subdivision and development have been developed primarily to protect these qualities on a long-term basis, while allowing for reasonable use and development of the land resource. The rules for the Rural 1 Zone are outlined in Section 17.5.

An assessment of Landscape Value is undertaken in Section 2.2.

2 Landscape Assessment

Following the methodology described in detail in Section 1.4.1 above, this section describes the landscape character of the receiving environment

2.1 Landscape Character

2.1.1 Topography

The topography of the study area is undulating river terrace on the eastern side of the Takaka River. Old river banks and channels can be readily identified, with the ground gradually rising in small increments from the river’s edge. The area is largely unmodified in terms of topography with the exception of the embankments which have been constructed around the existing WWTP site. These embankments are typically 1-1.5m above the surrounding ground. The town of Takaka sits above the river, on another river terrace, approximately 500m from the current river course.

2.1.2 Landcover

Vegetation cover in the study area is predominantly exotic pasture grasses for dairy farming, typical of rural areas in Golden Bay. Large poplar trees, both Lombardy and grey (see Photo 11, Fig 2.5), exist to the south and west of the site, and form comprehensive, linear, shelter belts in places. The trees are



mature with a number of specimens over 30m in height and create a sense of containment in some locations. Along the banks of the Takaka River and old river channels, willows trees up to 12m in height are present (see Photo 9, Fig 2.5). Weed species such as gorse, broom and blackberry are also common along the river margins, screening the river from the adjoining farm land or WWTP site. There are few native species in the area with the exception of some mature Cordyline australis (see Photo 10, Figure 2.5).

2.1.3 Built Form / Structures / Human Elements

The area is typical of rural farm land with few buildings or structures of note. The extension site currently has a single storey corrugated iron shed immediately adjacent to the east. The existing WWTP site has a small single Versatile Garage as well as a number of pipes and pumps associated with the operation of the WWTP. Wooden power poles, approximately 6m in height, run parallel to Haldane Road connecting to the WWTP and typical farm fences are present. Haldane Road is a gravel single lane road with no kerb and channel. To the west of the site, between the existing WWTP and Takaka River is a quarry site containing large scale machinery (up to 5m in height) and piles of raw and quarried material up to 3m in height.

2.1.4 Natural Character

The proposed extension to the WWTP is in close proximity to Takaka River, with its closest point being approximately 600m to the east. The existing WWTP site is approximately 300m from the river. While the site is in close proximity to the river, the river has only a small influence over the natural character of the area due to thick vegetation screening views into the river. Vegetation, as described above, consists predominantly of weed species which are of little landscape value. The WWTP extension is located on river terrace with old water channels and banks clearly visible. The embankments surrounding the existing site have to a small degree disrupted the continuity of the natural river patterns and processes, but the change in elevation is barely noticeable given the small level change and consistency in vegetation cover. The growth of species such as willow along old water channels highlight natural patterns and processes. Natural elements such as native vegetation are limited, mainly to the reserve area, with rural farming activities dominating the natural character of the area. The natural character of the study area is considered to be moderate.

2.2 Landscape Value / Significance

The proposed site is not located in or near an Outstanding Natural Landscape or feature. It is considered that a robust assessment has been undertaken in the development of the TRMP, and given the character of the landscape as described above, that further assessment of the site’s value or significance is not required. The site, while having close proximity to the Takaka River, the site would fail to meet the modified Pigeon Bay criteria on the majority of factors, most notably ecological value, memorability or aesthetic value. The sense of spaciousness, quietness and absence of traffic or built structures does mean that the site exhibits a moderate degree of landscape amenity which is discussed further below.

2.3 Landscape Amenity

Landscape amenity within a rural area may be understood to include such factors as:

• a sense of spaciousness (wide open spaces)

• privacy, quietness and absence of traffic and bustle

• an environment relatively uncluttered by structures and artificial features

• a clean environment, characterised by fresh air, clean water, etc



In respect of the above factors, the site and receiving environment has a medium degree of landscape amenity as all of the above factors contribute strongly to the local character. Human elements are relatively few and there is a sense of spaciousness and openness given the site’s rural character and close proximity to the Takaka River and smaller water channels. The public reserve running parallel to Waitapu Road, approximately 300m from the proposed site provides a linear, recreational facility for local residents. At present there is no formal, developed, pathway through the reserve, but the reserve’s linear nature provide a good facility for informal and passive recreational facilities. Glimpses are available through native vegetation across the rural river terrace. Native plantings provide a high degree of amenity to the reserve and overtime will become a highly valued recreational facility, especially given the lack of well-established native plantings in the immediate area.

2.4 Landscape Effects

2.4.1 Effects on Landscape Character (including Natural Character)

In terms of effects on Landscape Character, the construction and operation of the extension to the WWTP will have a minor to negligible impact. The greatest impact on the current character will be the loss of large and mature poplar and willow trees on the southern and western boundaries of the existing site. These trees provide a degree of enclosure to views as well as screening views into areas such as the existing WWTP. The trees are distinctive, large elements in the local landscape providing amenity to the area’s amenity and character. Their value, however, is limited especially in the case of willows trees which are often viewed as weed species along river corridors or old water channels. The presence of the willows lowers the level of stewardship given to this typically rural landscape and as a result lowers the overall quality of the landscape. The removal of the willow trees, and replacement with native species on the edge of both the existing and extension site is considered a positive attribute, with the native plantings overtime improving the sense of stewardship as well as improving ecological and natural character values. The proposed embankments surrounding the extension site will assimilate into the existing landscape, appearing as minor changes in the underlying topography similar in scale to a number of old river banks/channels which run through the area, albeit in a more regular linear fashion. The existing WWTP is surrounded by similar sized embankments which have a negligible effect on the character of the area. The existing treatment ponds and RIBs are difficult to view from outside of the site due to their low profile and existing screening. The removal of the surrounding vegetation will open up views of the ponds until mitigation planting came become established surrounding the site. It is for this reason also that planting is proposed around the extension site. The proposed buildings are of a scale similar to those of typical farm sheds. While there will potentially be more buildings clustered around a small area, with associated security fencing and lighting, the scale of the buildings is such that it is possible to mitigate any potential effects on the existing rural landscape character. In terms of natural character, the proposal will have a minor to negligible effect on the current natural character. While the site is situated on a river terrace, the dense plantings along the river banks mean the site has little association with the river with the exception that recreation users have to pass the existing site to access the river, along Haldane Road. Proposed native planting along this boundary will screen any views into the site as well as improving the natural character of the area by establishing plants that would have once originally grown adjacent to the river. Following the construction of the site and the implementation of the proposed mitigation measures it is considered that the quality of natural character will remain as moderate.



2.4.2 Effects on landscape values

No effects on landscape values are envisaged as the site is not located in or near to an Outstanding Natural Landscape or Landscape Priority Area. While the proposal is located close to the Takaka River it is not of a scale that will adversely affect existing landscape values noted in the TRMP.

2.4.3 Effects on Landscape Amenity

In terms of amenity, the construction and operation of the extension to the WWTP will have a negligible effect on landscape amenity. The sense of spaciousness and openness will be unaffected and the proposal will not result in an increase of traffic or noise. If left unmitigated, the proposal could change the amenity due to the presence of buildings in a largely uncluttered landscape and from potential glare at night if security lights are included in the design. It is considered that mitigation planting can successfully mitigate any potential effects on amenity, reducing the residual effects to negligible.



3 Visual Assessment

3.1 Existing Visual Character

The existing visual character is characterised by a mix of open and partial views across old river terraces of the Takaka River. Vegetation, both native and exotic, screen views into the area which is particularly noticeable around the existing site where willows and poplars screen the majority of the site. Views from neighbouring residential properties are mixed in quality often being blocked by intervening vegetation.

3.2 Potential Sources of Visual Impacts

The potential sources of visual impact from this project are as follows:

• New earth embankments, up to 2m in height;

• Vegetation clearance including the loss of large poplar and willow species;

• Buildings associated with the WWTP;

• Fencing;

• Security lighting.

3.3 Identification of Viewpoints

A selection of key viewpoints was identified during the site visit, representative of views in the area. The viewpoints are located where the effects are either at their worst, or a recognised public viewing spot, private residence or where a large number of people will be potentially affected. Photos from these viewpoints have been included in the attached figures. The key views are as follows:

Viewpoint 1 From Haldane Road

Viewpoint 2 From Waitapu Road

Viewpoint 3 From the reserve running parallel to Waitapu Road

Viewpoint 4 From Edinburgh Road

Viewpoint 5 From Rose Road

3.4 Visual Effects

Viewpoint 1 From Haldane Road (refer to Figure 3.2, page 13)

The existing view from Haldane Road is a close, open view across grass dairy paddocks to the proposed

site. There is an old farm shed, constructed of corrugated iron and other human elements typical of a

rural area including farm fences, gates and power poles. Views into the existing WWTP site are generally

blocked by existing Willow and poplar trees (refer to figure 2.2, page 7) or the grass embankment

surrounding the ponds. The trees are located on the southern boundary of the existing site and along an

old river channel which runs between the road and the site. During construction, the most noticeable

visual effect will be the loss of large poplar trees along the southern edge of the site. Views of the

existing site will be opened up with the removal of the willows trees allowing the buildings to be visible.

The ponds will largely still not be visible due to the surrounding grass embankment. The existing and

proposed buildings are of a low stature which can be easily screened using landscape planting.

Mitigation measures proposing to replace plant native species along the boundary with Haldane Road will



reduce any potential visual effects, both of the existing site with the removal of vegetation and the

proposed extension area, significantly. Prior to planting it is considered that the visual impacts will be

minor, with the residual visual effects reducing to negligible, once planting has established.

Viewpoint 2 From Waitapu Road (refer to Figure 3.3, page 14) The view from Waitapu Road to the proposed site is largely screened by residential dwellings and associated landscape plantings. A view of the site is possible from an undeveloped section, adjacent to 58 Waitapu Road, where the site is approximately 400m away to the west. Partial and open views are also available from residential properties along this road, although some views are screened either partially or fully by intervening vegetation. From this location, the removal of vegetation will be visible along with earthworks, RIB beds, ponds, buildings and any proposed fencing. Due to the elevated position of the houses and road in comparison to the extension, views will be possible into the ponds and RIB beds. With landscape planting along the western boundary of the extension, these views will be blocked. Prior to planting it is considered that the visual impacts will be minor-moderate given the sensitivity of residential receivers, with the residual visual effects reducing to negligible, once planting has established. The planting using indigenous species will completely screen the extension to the wastewater treatment plant over a relatively short period.

Viewpoint 3 From the reserve running parallel to Waitapu Road (refer to Figure 3.4, page 15)

Partial views through gaps in the existing vegetation are available of the proposed extension site from the

public reserve which runs parallel to Waitapu Road, behind a row of residential dwellings. The reserve is

approximately 300m from the site at its closest point. The most noticeable impact from the extension to

the WWTP will be the loss of existing vegetation. The majority of the other works are low profile, and with

the ponds being elevated slightly higher than the reserve, it is unlikely views will be possible into the

ponds. Given the current levels of screening provided by existing vegetation, the visual impacts are

considered to be minor, reducing to negligible once planting has established around the proposed site.

Viewpoint 4 From Edinburgh Road (refer to Figure 3.5, page 16)

Views of the extension site from Edinburgh Road and surrounding houses are generally screened by

existing vegetation. In this location existing trees in the area are large, between 10-20m in height, and

form a substantial buffer between residential properties and the adjoining rural land. Due to the lack of

visibility from this location, the residual visual effects are considered de minimis.

Viewpoint 5 From Rose Road (refer to Figure 3.6, page 17)

The existing view to the north is open with expansive views available across the river terrace. From this

location the site is approximately 700m away to the north with the only visual impacts likely to be the loss

of existing vegetation, notably the large poplar and willow trees. Impacts resulting from earthworks,

construction of the ponds and RIBs, and associated buildings are unlikely to create any noticeable impact

given the intervening distance and low profile of the majority of the works. Residual visual effects are

considered de minimis.



4 Mitigation Measures

The following mitigation measures have been prepared to minimise any potential landscape and visual effects which may result from the extension to the Wastewater Treatment Plant and loss of existing vegetation:

1. Native landscape planting is proposed on the western and southern embankments of the

proposed extension as well as along the road boundary adjoining Haldane Road for both the

existing and proposed sites. Plant material is to be locally sourced, ideally from the Tasman /

Golden Bay area, to ensure specimens are suitable to local conditions. The plant schedule is to

be comprised of the following species, all being RX90 seedlings planted at 700mm centres, to

form a 3m wide buffer strip:

Botanical Name Common Name

i. Cortaderia richardii Toetoe

ii. Dacrycarpus dacrydioides Kahikatea

iii. Griselinia littoralis Broadleaf

iv. Hebe salicifolia Koromiko

v. Kunzea ericoides Kanuka

vi. Melicytis ramiflorus Mahoe, Whiteywood

vii. Pittosporum eugenioides Lemonwood

viii. Phormium tenax Flax

ix. Poa cita Silver Tussock

x. Cordyline australis Ti koua, Cabbage Tree

xi. Dodonaea viscose Akeake

2. Rabbit and stock proof fencing is to be provided around all landscape plantings.

5 Conclusion

Overall, I consider that the proposal will have no more than minor effects on the receiving environment for the following reasons:

• In terms of landscape character and amenity, the impact is minor to negligible. The proposal to

extend the WWTP will not overtly change the character of the area as little earthworks or

modification is required. The proposal is low profile and of a scale which can be absorbed into

the existing landscape. The existing landscape has a strong rural character, and while close to

the Takaka River, the river plays a minor role in the area’s character due to the strong presence

of weed species along its banks. The largest impact on the existing character will come from the

removal of mature poplar and willow species which will open up the character. With the proposed



landscape planting, it is possible to mitigate for the loss of these trees, replacing them with

species more suitable to the local area.

• No effects on landscape values are envisaged as the site is not located in or near to an

Outstanding Natural Landscape or Landscape Priority Area.

• The visual effect of the proposal be negligible at most once landscape planting has become

established to screen the ponds and any other associated works from nearby sensitive receivers.

tak ak a wastewater treatment pl ant - notice of requirementlanDscape anD Visual impact assessment - associateD DrawinGs

FOR CONSENTPROJECT No. Z2404126

MAY 2010

\\nzchc2s01\projects\0 E1 PROJECTS\Z24000+\Z24041\Z2404126 Takaka WWTP Upgrade\Landscape\Takaka WWTP - LVIA Figures (20100504) .indd


Notice Of Requirement

Landscape and Visual Impact Assessment - Page 2Contents

Contents

Figure 1.1 - Location Plan 3

Figure 1.2 - Preferred Option 4

Figure 1.3 - Alternative Option 5

Figure 2.1 - Landscape Character 6

Figure 2.2 - Site Photos - Landscape Character 7





Figure 3.1 - Viewpoints 12

Figure 3.2 - Viewpoint 1 - From Haldane Road 13

Figure 3.3 - Viewpoint 2 - From Waitapu Road 14

Figure 3.4 - Viewpoint 3 - From Public Reserve parallel to Waitapu Road 15

Figure 3.5 - Viewpoint 4 - From Edinburgh Road 16

Figure 3.6 - Viewpoint 5 - From Rose Road 17



Landscape and Visual Impact Assessment - Page 3Figure 1.1 - Location Plan

PROPOSED WASTEWATER TREATMENT PLANT EXTENSION



Landscape and Visual Impact Assessment - Page 4Figure 1.2 - Preferred Option



Landscape and Visual Impact Assessment - Page 5Figure 1.3 - Alternative Option



Landscape and Visual Impact Assessment - Page 6Figure 2.1 - Landscape Character

Proposed Wastewater Treatment Plant Extension

ROSE ROAD

HALDANE R

OAD



Landscape and Visual Impact Assessment - Page 7Figure 2.2 - Site Photos - Landscape Character

Photo 1. View from Haldane Road

looking west across to the existing

WWTP

Photo 2. View south looking towards

the existing WWTP




Photo 3. View of the existing quarry

west of the existing WWTP

Photo 4. View of River Takaka from

adjacent to the existing quarry




Photo 5. View looking west over the

existing oxidation ponds

Photo 6. View looking northwest

over the existing Rapid Infiltration Beds (RIB)




Photo 7. View south

from Haldane Road

lookiing at the proposal

extension area

Photo 9. Exotic weed

species such as Willow

were present in large

numbers adjacent to

water courses

Photo 10. Few native

species were identified in the immediate area

(within 200m) surround-

ing the site. This Cor-

dyline australis was an

exception rather than

the norm.




Photo 11. Tall poplar

species as Lombardy

(narrow, column-like)

and Grey (spreading)

are common in the area,

growing to heights in ex-

cess of 30m

Photo 12. A linear bank

of native species has

been planted along the

edge of the reserve, pro-

viding some screening

between the site and the

closest residential prop-

erties.



Landscape and Visual Impact Assessment - Page 12Figure 3.1 - Viewpoints

The above plan shows the viewpoints from where the proposal has been assessed

VIEWPOINTS

From Haldane Road

From Waitapu Road

From Reserve

From Edinburgh Road

From Rose Road

PROPOSED EXTENSION

TO WWTP

VP2

VP1

VP5

VP4

VP3

VP5

VP4

VP3VP1

VP2



Landscape and Visual Impact Assessment - Page 13Figure 3.2 - Viewpoint 1 - From Haldane Road

a. Viewpoint 1 - Existing view from Haldane Road looking towards

the site

Proposed extension

to WWTP site



Landscape and Visual Impact Assessment - Page 14Figure 3.3 - Viewpoint 2 - From Waitapu Road

a. Viewpoint 2 - Existing view from Waitapu Road, Takaka (SH60).

Proposed extension

to WWTP site

58 Waitapu Road



Landscape and Visual Impact Assessment - Page 15Figure 3.4 - Viewpoint 3 - From Public Reserve parallel to Waitapu Road

a. Viewpoint 3 - Existing view from the public reserve running parallel

to Waitapu Road

Proposed extension

to WWTP site



Landscape and Visual Impact Assessment - Page 16Figure 3.5 - Viewpoint 4 - From Edinburgh Road

a. Viewpoint 4 - Existing view from Edinburgh Road



Landscape and Visual Impact Assessment - Page 17Figure 3.6 - Viewpoint 5 - From Rose Road

a. Viewpoint 5 - Existing view from Rose Road

Proposed extension

to WWTP site


Appendix D: Objectives and Polices

Tasman Regional Policy Statement The following provisions are the relevant matters from the Tasman Regional Policy Statement (RPS): Chapter 5 Tangata Whenua Interests Policy 4.1 – The Council will pursue a process of consultation and participation in resource management between itself and the tangata whenua of the District Policy 4.2 – Council will seek protection of wahi tapu, water, ancestral lands, sites, coastal resources and other taonga from disturbance or contamination in a manner consistent with tangata whenua kaupapa and tikanga while acknowledging the significant private interests in land and other resource users. The Tasman District Council has undertaken substantial consultation with tangata whenua in preparing the proposal, and designing the WWTP upgrades. The disposal of treated wastewater to land is aligned with the preferences of iwi and acknowledges the values iwi place on elements of the natural and physical environment. The designation of the site as proposed is consistent with these provisions in that it will allow improvements to the quality of the wastewater discharged to land, will reduce any downstream effects on surface water quality, and will reduce the risk of the WWTP being overtopped in significant flood events where untreated wastewater would be discharged into surface water. Chapter 10 Contamination and Waste Objective 10.1 – Maintenance and enhancement of the quality of soils, water, and air for a range of uses and values where particulate, chemical, or biological contamination pose risks to this quality. Objective 10.2 – Avoidance, remedying or mitigation of adverse effects of all contaminants of soils, water, and air. Objective 10.4 – Minimised risks of contamination of the environment arising from the storage, treatment or disposal of all forms of waste. Policy 10.2 – Council will require that the adverse effects of any discharge of contaminants on existing water quality are avoided, remedied or mitigated where there is no water classification. Policy 10.3 – The Council will seek to avoid, remedy, or mitigate adverse effects of the discharge of contaminants to air. Policy 10.4 – Council will avoid, remedy or mitigate adverse effects of the disposal of solid or liquid waste contaminants, by seeking land disposal of such wastes where it is the best practicable option. Policy 10.9 – The Council will ensure that environmental contamination from the storage, treatment or disposal of wastes, particularly hazardous wastes, is avoided, remedied or mitigated. The expected effluent and odour discharges associated with continued operation of the Takaka WWTP with the upgraded treatment system proposed will be consistent with these objectives and policies of the RPS. Similarly therefore the designation of the site for its use for the treatment and disposal of treated wastewater is also consistent with the provisions of Chapter 10 of the RPS.


Tasman Resource Management Plan The following provisions are the relevant matters from the Tasman Resource Management Plan: Chapter 5 – Site Amenity Effects Objective 5.1.2 Avoidance, remedying or mitigation of adverse effects from the use of land on the use and enjoyment of other land and on the qualities of natural and physical resources. Policy 5.1.3.1 To ensure that any adverse effects of subdivision and development on site amenity, natural and built heritage and landscape values, and contamination and natural hazard risks are avoided, remedied, or mitigated. Policy 5.1.3.2 To protect the quality of groundwater and surface water from the adverse effects of urban development and rural activities. Policy 5.1.3.8 Development must ensure that the effects of land use or subdivision activities on stormwater flows and contamination risks are appropriately managed so that the adverse environmental effects are no more than minor. Policy 5.1.3.11 To avoid, remedy, or mitigate the likelihood and adverse effects of the discharge of any contaminant beyond the property on which it is generated, stored, or used. Assessment:

The assessment of effects contained in this document demonstrates that the use of the land provided for by altering the designation of the site would be consistent with the above objective and policies. In particular, the visual effects of the development of the site can be appropriately managed, and the improvements to the treatment of wastewater will reduce the scale and intensity of the existing environmental effects. Chapter 7 – Rural Environmental Effects Objective 7.4.2 Avoidance, remedying or mitigation of the adverse effects of a wide range of existing and potential future activities, including effects on rural character and amenity values. Policy 7.4.3.4 To exclude from rural areas, uses or activities (including rural-residential) which would have adverse effects on rural activities, health or amenity values, where those effects cannot be avoided, remedied or mitigated. Assessment:

For the reasons outlined in the assessment of effects, and in particular as discussed in the LVIA report appended, the use of the site in the manner proposed would not result in significant adverse effects on rural amenity. Chapter 9 – Landscape Objective 9.2.2 Retention of the contribution rural landscapes make to the amenity values and rural character of the District, and protection of those values from inappropriate subdivision and development.


Policy 9.2.3.3 To retain the rural characteristics of the landscape within rural areas. Policy 9.2.3.4 To encourage landscape enhancement and mitigation of changes through landscape analysis, subdivision design, planting proposals, careful siting of structures and other methods, throughout rural areas. Assessment:

For the reasons outlined in the assessment of effects, and in particular as discussed in the LVIA report appended, the use of the site in the manner proposed would not result in significant adverse effects on rural amenity. In particular, this is achieved by the use of natural materials in constructing the services platform and flood control bunds (soil bunds grassed and planted in native species) and the proposed mitigation planting. Chapter 12 – Land Disturbance Effects Objective 12.1.2 The avoidance, remedying, or mitigation of adverse effects of land disturbance, including:

(a) damage to soil; (d) damage to river beds, karst features, land, fisheries or wildlife habitats, or structures

through deposition, erosion or inundation; (e) adverse visual effects; (g) adverse effects on indigenous biodiversity or other intrinsic values of ecosystems.

Policy 12.1.3.1 To promote land use practices that avoid, remedy, or mitigate the adverse effects of land disturbance on the environment, including avoidance of sediment movement through sinkholes into karst systems. Assessment:

The adverse effects from land disturbance would be minor and would be confined to the construction period. Adequate mitigation measures would be applied to avoid off-site effects from the land disturbance. Chapter 13 – Natural Hazards Objective 13.1.2 Management of areas subject to natural hazard, particularly flooding, instability, coastal and river erosion, inundation and earthquake hazard, to ensure that development is avoided or mitigated, depending on the degree of risk. Policy 13.1.3.1 To avoid the effects of natural hazards on land use activities in areas or on sites that have a significant risk of instability, earthquake shaking, flooding, erosion or inundation, or in areas with high groundwater levels. Policy 13.1.3.4 To avoid or mitigate adverse effects of the interactions between natural hazards and the subdivision, use and development of land. Policy 13.1.3.5 To avoid, unless there is effective mitigation, the expansion of flood-prone settlements onto those parts of the surrounding flood plains where they might be subject to flood hazard.


Policy 13.1.3.7 To maintain or consider the need for protection works to mitigate natural hazard risk where:

(a) there are substantial capital works or infrastructure at risk; or (b) It is impracticable to relocate assets; or (c) it is an inefficient use of resources to allow natural processes to take their course; or (d) protection works will be effective and economic; or (e) protection works will not generate further adverse effects on the environment, or

transfer effects to another location. Assessment:

Due to the impracticalities involved in siting the expansion to the existing WWTP away from the Takaka River flood risk, and the substantial capital investment required, it is appropriate to provide adequate flood protection measures for the proposal. It is impractical to avoid the use of flood-prone land therefore in this case, and effective mitigation is necessary to protect the expansion necessary due to urban growth in the Takaka area. Due to its location, the separation of the site from nearby activities, and its proximity to old river channels, any effects on flood water as a result of the flood protection works proposed will be minor. Conclusion: The proposal is consistent with the intent of the relevant objectives and policies of the TRMP as the adverse effects of the activity to be provided for through the designation sought will be suitably avoided or mitigated.


Appendix E: Cultural Impact Assessment

APPENDIX F - Effects of Bunds on Flood Levels

Status – Final Page 1 March 2012 Project Number – Z2404161 Tech Memo 12 - Flood Maps_Final


Date: 22 March 2012 Correspondence Out No.: 22828



Project: Takaka Wastewater Treatment Plan Upgrade

Project Number: Z2404161

Subject: Effects of Bunds on Flood Levels

Prepared by: Rob Lieffering Checked by: Jonathan Krause

Reviewed by: Dugall Wilson Authorised by: Don Young

1 Introduction

The purpose of this technical memorandum is to present results of hydraulic modelling with respect to the changes in flooding water levels caused by the construction of bunds at the Takaka Wastewater Treatment Plant (WWTP). As proposed, the upgrades to the WWTP would include additional bunding around the new wetland area and a separate bund around the rapid infiltration basins (RIBs). The WWTP is located on the floodplain of the Takaka River and during large storm events floodwaters can inundate the WWTP as well as parts of Takaka township. Section 18 of the Tasman Resource Management Plan (TRMP) contains rules relating to land disturbance. The WWTP is located in an area called Land Disturbance Area 1 under the TRMP and rule 18.5.2.1, which states that earthworks, including construction of earth bunds, is a permitted activity provided, inter alia, “The activity does not raise the level of any land to a point where it results or may result in the damming or diversion of floodwaters (except for the maintenance of any stopbank)”. Discussions between MWH and Tasman District Council (Council) staff1 confirmed that, if taken to extremes, any earthworks which raises the level of land within the floodplain of any river is likely to result in some degree of damming or diversion. Council staff requested that data and information be provided to determine the extent of these effects for the proposed bunds around the WWTP and then a decision would be made on whether the effects were significant enough to warrant a separate land use consent to be needed for the construction of the bunds. Concerns regarding these possible effects were raised by the Takaka WWTP Working Group and the effects were therefore investigated further. In response, an assessment using an existing hydraulic model of the Takaka River and associated floodplain was undertaken to determine the extent to which the proposed bunding around the WWTP would alter the depth of floodwaters in the vicinity of the WWTP. This memo presents the results of that modelling assessment. The draft conditions of consent for the WWTP require it to be protected from inundation of floodwaters up to a 1 in 50 year flood event; however, for the purpose of the modelling analysis, a 1 in 100 year flood event was used.

1 R Lieffering (MWH) and Leif Pigott (Tasman District Council)


2 Investigations

Aurecon had previously developed a hydraulic model of the river and floodplain for the Council, primarily for the purposes of flood bank analysis (reference “Takaka Inundation Study – Hydraulic Modelling Report, dated 7 July 2010). The model of the area was developed using existing Council GIS LiDAR and aerial photographic information and survey data from the WWTP site. The model was established using a six-metre grid with predefined input hydrographs applied for the Takaka, Anatoki, and Waikoropupu Rivers. Localised runoff contributions, inflows from the Motupipi River and the influence of the reticulated stormwater networks were excluded from the model. Using this model, the Council engaged the services of Aurecon to further model the impact of floodwaters of the Takaka River as a result of the proposed additional bunding at the WWTP upgrades.

3 Assessment/Analysis

3.1 Introduction

Several scenarios were modelled, however the three which are of particular interest are: a) Modelled water depths during a 1 in 100 year flood of the Takaka River under the existing situation

(ie. no new bunds at the WWTP including the proposed RIB site).

b) Modelled changes in water depths during a 1 in 100 year flood of the Takaka River following construction of additional bunds around the new wetland and RIB site.

c) Modelled changes in water depths – expressed as a percentage of the depth of water that would normally occur – during a 1 in 100 year flood of the Takaka River following construction of bunds around the Takaka WWTP and RIB site.

These are discussed in turn in Sections 3.2-3.4 below.

3.2 Current Situation – No bunding

Figure 1 shows the maximum water depth on the Takaka River floodplain during a 1 in 100 year return flood with no new bunding (ie. the current situation). Results indicate that during such floods the WWTP area experiences water depths up to 2.8 metres.


Figure 1: Predicted water depths during a 1 in 100 year flood of the Takaka River –

Present situation at the Takaka WWTP The model predicts that large parts of Takaka township also flood during such an event, including the residential area around Feary Crescent/Edinburgh Street and also the area to the north of the Waitapu and Rototai Road intersection, these areas being located to the east of the WWTP. Water depths in these areas are generally modelled to be <0.4 metres and in some of the lower lying areas (which coincide with old river channels) water depths are modelled to be between 0.4-0.8 metres.

3.3 Bunding to Protect WWTP and RIB Areas – 1 in 100 Year Flood

3.3.1 Introduction

The model was rerun with additional bunding above the 1 in 100 year flood level. Two bunded areas were used for this scenario, one around the area proposed for the wetland located downstream of the existing bunded area of the ponds, and the second bund around the RIBs.

3.3.2 Difference in Water Level – Actual Depths

Figure 2 shows the effects of constructing bunds around the WWTP areas as the difference in water depth, in metres, compared to the depths of water that would be expected if the bunds were not present.


Figure 2: Modelled increase in water depth, expressed absolute water depth (m) that would otherwise

occur, as a result of bunds being constructed around the Takaka WWTP For the vast majority of the area there is no discernible difference (±0.01 metre) in water level (shown as light grey in Figure 2). The red and orange coloured areas in Figure 2 represent the greatest increases in water depth and occur within the farmland adjacent to the WWTP. Areas immediately to the south of the WWTP and RIBs area experience the greatest increase in water depth (up to 0.20 metres) and this is likely to be as a result of the ‘damming’ effect on the leading edge of the bunds. Conversely, areas to the north, or downstream, of the bunds experience a decrease in water depth (shown as green in Figure 2). The presence of the bunds is shown to increase the water depth both to the east and west of the WWTP – shown in yellow in Figure 2. The increases in water depth in these yellow areas are less than 0.05 metres (5 centimetres), some of which is occupied by the residential area around Feary Crescent/Edinburgh Street and also the area to the north of the Waitapu and Rototai Road intersection.

3.3.3 Difference in Water Level – Percentage Change

Figure 3 presents the changes in water level as a result of the bunds being constructed as a percentage of the water depth that would normally be expected at any particular site without the bunds in place.


Figure 3: Modelled increase in water depth, expressed as a percentage of the water depth that would

otherwise occur, as a result of bunds being constructed around the Takaka WWTP For most of the areas where there is a modelled increase in absolute water depth (i.e. the yellow, orange and red areas in Figure 2) the increase represents a water level increase of less than 10% (shown as dark blue in Figure 3). The green area in Figure 3 represents a nominal decrease in water level – corresponding to part of the grey area shown in Figure 2 where the absolute water depth change modelled is -0.01 metre. Areas which experience higher percentage increases (shown as light blue, yellow, orange, and red in Figure 3) occur at the edges of the water extent. This is to be expected because even a small increase in absolute water depth in areas where very little water would normally occur equates to a large percentage increase. At the extreme edges any amount of water compared with no water without bunds represents an increase, in terms of percentage, of infinity. However, in these extreme edge areas it is more important to consider the absolute increase in water depth, which will be less than 5 centimetres (0.05 metres).

4 Takaka WWTP Upgrade Working Group

Figures 1 and 2 were presented to the Takaka WWTP Upgrade Working Group in February 2012. The Working Group members include the Mayor, several councillors, Golden Bay Community Board members and two local residents. While the Takaka WWTP Upgrade Working Group recognised that the modelling indicated that the additional bunding would increase flood levels in Takaka, it acknowledged that such an increase is likely to be immeasurable in practical terms and these effects would therefore be acceptable to its members.


5 Summary and Conclusion

During a 1 in 100 year flood event the Takaka River inundates large areas of its floodplain, including parts of Takaka township. Hydraulic modelling of the Takaka River suggests that water depths in residential areas of Feary Crescent/Edinburgh Street and also the area to the north of the Waitapu and Rototai Road intersection would typically have <0.4 metres of water during such a flood event. Modelling predicts that the construction of bunds around the Takaka WWTP and RIB sites will have some minor effects on water levels in the area around Feary Crescent/Edinburgh Street and also the area to the north of the Waitapu and Rototai Road intersection. Increases in water depth in these residential areas are modelled to be between 0.01-0.05 metres (1 to 5 centimetres) and this generally constitutes less than a 10% increase in water depth. Furthermore, the modelling indicates that the bunds will result in some areas, which would otherwise not have any floodwaters during a 1 in 100 year flood, to have water on them, however the depth of this water will be shallow (ie. up to a maximum of 5 centimetres). When assessing the difference between the existing and the future bunded scenarios it is important to consider both the changes in absolute water depth as well as what that change in water depth is expressed as a percentage of the overall depth of water at any particular site. Based on the results of the hydraulic modelling and the recommendation by the Working Group, from a planning perspective it is concluded that the changes in water depth as a result of constructing the bunds around the WWTP are insignificant (de minimis). This Project Technical Memorandum has been prepared for the benefit of Tasman District Council. No liability is accepted by this company or any employee or sub-consultant of this company with respect to its use by any other person. This disclaimer shall apply notwithstanding that the Project Technical Memorandum may be made available to Tasman District Council and other persons for an application for permission or approval or to fulfil a legal requirement.

APPENDIX G - Microbiological Risk Assessment

Status – Final Page 1 September 2012 Project Number – Z2404161 Takaka Virus Risk Assessment_Final_RL


Date: 19 September 2012 Correspondence Out No.: 24153



Project: Takaka WWTP Upgrades Project Number: Z2404161

Subject: Takaka WWTP Viral Risk Assessment

Prepared by: Rob Lieffering Checked by: Kirsten Norquay

Reviewed by: Peter Loughran Authorised by: Don Young

1 Purpose

This microbial public health risk assessment has been undertaken in recognition of the requirements of the microbiological guidelines for freshwaters inherent in the “Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas” (the Guidelines) published by the Ministry for the Environment and the Ministry of Health (2003). The guidelines specifically state that they “cannot be directly used to determine water quality criteria for wastewater discharges” and that they “should not be directly applied to assess the microbiological quality of water that is impacted by a nearby point source discharge of treated effluent without first confirming that they are appropriate”. This microbial risk assessment addresses potential public health impacts in comparison to acceptable levels of perceived risk.

2 Scope

This microbial public health risk assessment determines the potential risk of infection relating to impacts associated with the treated wastewater discharged from the Takaka Wastewater Treatment Plant (WWTP). The probabilities of infection were determined for primary and secondary contact recreation activities in the Takaka River. The probabilities of infection from eating raw shellfish at the Takaka River mouth were also determined. It is common for an individual to be infected with a microorganism but the individual does not experience any symptoms or show signs of a particular illness. This is termed infection, whereas if the individual develops clinical symptoms, it is termed illness. The difference between infection and illness is accounted for using a morbidity rate associated with each particular pathogen. This risk assessment assesses risk of infection, rather than illness, which is a conservative approach. The assessment is based on infection associated with enteric viruses and so all WWTP log removals (and associated concentrations) in this report are for viruses. The relationship to WWTP log removals for faecal coliforms, commonly used as indicators for human disease, is dependent on the individual treatment process.


3 Guidelines

It is recognised that the definition of an acceptable level of risk of symptomatic infection is a difficult choice. In considering the calculated risk of infection, it is important to recognise the risk levels inherent in the Guidelines. The Guidelines use a combination of qualitative risk grading of the catchment, supported by the direct measurement of appropriate faecal indicators to assess the suitability of a site for recreation. In addition, alert and action guideline levels are used for surveillance throughout the bathing season. The two components to providing a grading for an individual beach are.

The Sanitary Inspection Category (SIC), which generates a qualitative measure of the susceptibility of a water body to faecal contamination.

Historical microbiological results, which generate a Microbiological Assessment Category (MAC) and provides a measure of the actual water quality over time.

The two criteria provide an overall Suitability for Recreation Grade (SFRG), which describes the general condition of a site at any given time, based on both risk and indicator bacteria counts. This grade provides the basis for telling people whether or not the water is suitable for recreational use from a public health perspective. The Microbiological Assessment Category (MAC) system for freshwater comprise a four tiered scale with three risk cut-offs, which for the Guidelines are 0.1%, 1% and 5%. These are lower than those used for the marine water guidelines and are based on the calculated level of risk of Campylobacter infections as determined from a quantitative risk assessment based on a nationwide study. The four tiers represent:

A. a no calculable risk level (NCRL) for infection – taken to be less than one infection in every 1000 exposures (ie. less than 0.1%). This risk level is equivalent to a Grade A beach

B. an increase in risk level above the threshold for infection – up to one infection in every 100 exposures (ie. between 0.1% and 1%). This risk level is equivalent to a Grade B beach

C. a substantial elevation in the probability of infection compared to the New Zealand background level – up to one infection in every 20 exposures (ie. between 1% and 5%). This risk level is equivalent to a Grade C beach

D. a significant risk of high levels of infection, ie. greater than a 1 in 20 chance of infection. (ie. > 5%). This risk level is equivalent to a Grade D beach.

The risk cut-offs were purposely set lower than those derived for marine waters as a precautionary measure and the fact that the upper level (5%) represented a doubling of the background infection level. Grades A and B are associated with suitability for recreation grades of Very Good and Good which are beaches that are satisfactory for swimming at all times and most of the time respectively. The Guidelines provide a three-tier management framework for freshwater based on bacteriological indicator values. This framework provides trigger levels for frequency of monitoring and actions to take, depending on the results of routine monitoring throughout the bathing season. The three tiers are.

Acceptable/Green Mode: No single sample greater than 260 E.coli/100 mL. Action is to continue routine monitoring. This is equivalent to a Grade B beach, or equivalent to a Grade A beach if less than 130 E.coli/100 mL (This is similar to the ANZECC Primary Recreation Guideline of 150 faecal coliforms /100mL).

Alert/Amber Mode. Single sample is greater than 260 E.coli/100 mL. Action is to increase sampling frequency and to try to identify possible location of sources of faecal contamination. This is equivalent to the demarcation between a Grade B and Grade C beach.


Action/Red Mode. Single sample is greater than 550 E.coli/100 mL. Action is to increase sampling frequency, to try to identify possible location of sources of faecal contamination, and to inform the public. This is equivalent to the demarcation between a Grade C and Grade D beach.

For the purposes of this assessment the ‘acceptable’ risk for both contact recreation and shellfish gathering is considered to be where the calculated risk is <1%. For freshwater contact recreation this equates to the Acceptable/Green Mode described above and a Grade B beach. Taking a ‘no calculable risk’ approach (ie. <0.1% risk) is not considered appropriate.

4 Microbial Risk Assessment Methodology

This quantitative risk assessment determines the potential risks of infection that could result from the discharge of wastewater. The assessment takes account of:

pathogen concentration in the raw wastewater

the efficacy of the various unit processes of the wastewater treatment plant with respect to the removal of pathogens

dilution within the environment

rates of ingestion or inhalation of water the fact that shellfish are filter-feeders and can therefore accumulate contaminants, including viruses

infectivity of the virus. This microbial risk assessment evaluated the potential public health risks associated with enteric viruses only and did not consider the risk of infection associated with other viruses, microorganisms, such as protozoa (oocysts of Cryptosporidium spp. and cysts of Giardia spp.) and bacterial pathogens (such as Salmonella spp. and thermophilic Campylobacter spp.). The risks associated with these other pathogens are generally lower than those associated with enteric viruses. This assessment has been performed by deriving the concentration of viruses that would result in calculated risks of infection that are equivalent to those inherent in the Guidelines (ie. 0.1%, 1%, and 5%). These concentrations are termed the “Risk Concentration”. Different Risk Concentrations were calculated for primary contact recreation, secondary contact recreation, and shellfish gathering. The expected concentrations of viruses that would be discharged to the Takaka River at the groundwater discharge zone as a result of the discharge of treated wastewater from the Takaka WWTP during summer peak periods and shoulder periods were then calculated. This concentration is termed the “Predicted Concentration”. The amount of dilution required to reduce the Predicted Concentration to equal the Risk Concentration was determined and these dilution rates were compared to the available dilution in the Takaka River downstream of the groundwater discharge zone. The amount of available dilution was based on previous dye testing undertaken within the Takaka River and flow records.


5 Determination of Predicted Concentration

The quality of groundwater at the point of discharge to the Takaka River has been determined by considering the expected influent virus concentration, viral removal through the treatment plant, viral removal that occurs during its passage through the RIBs and within the groundwater aquifer, and groundwater dilution that the wastewater receives between the RIBs and the point where the groundwater discharges into the Takaka River as follows.

The influent virus concentration was defined for raw wastewater based upon a review of data collected from the Mangere WWTP (Auckland) over the period 2004 to 2008, and using the 95 percentile of the data set over this period of 10,000 plaque forming units per litre (pfu/L). The virus concentrations would be expected to be more variable in smaller communities as compared to Auckland. However, using the upper part of the Auckland data provides a probable “worst case” high concentration for that from Takaka.

Removal rates for viruses within the oxidation ponds and the wetland were selected. It was assumed that the oxidation ponds would remove 90% (1-log) of all incoming viruses and the wetland would remove 80% (0.7-log) of the viruses that enter it from the oxidation pond.

Removal rates for viruses as the wastewater passes through the RIBs and moves through groundwater between the RIBs and the Takaka River. Some treatment occurs within the RIBs and viruses are removed by passage through the aquifer material. In addition, the wastewater is diluted by groundwater that flows beneath the RIBs. The rate of viral removal is dependent on the nature of the aquifer and dilution is dependent on the aquifer’s hydraulic characteristics. For the purposes of this assessment a 0.3-log removal rate (50%) has been assumed for viruses through the RIBs and groundwater and a 10 times groundwater dilution factor was applied between the RIBs and the discharge zone into the Takaka River. This dilution figure is based on the results of the RIB trial undertaken in 2011 (MWH, 2011)1.

The Predicted Concentration was calculated as follows: Raw sewage virus concentration = 1,000,000 pfu/100 L (equivalent to 10,000 pfu/L) Virus concentration after treatment in oxidation ponds (90% reduction) = 100,000 pfu/100 L Virus concentration after treatment in wetland (80% reduction) = 20,000 pfu/100 L Virus concentration after RIBs and groundwater (50% reduction, not including dilution) = 10,000 pfu/100 L Predicted Concentration of viruses at edge of groundwater discharge zone (10× dilution) = 1,000 pfu/100 L The actual concentration of viruses that are discharged into the Takaka River is dependent on the volume of wastewater discharged from the WWTP and the resultant concentration downstream of the discharge zone is dependent on the river’s flow. The various scenarios modelled are discussed in Section 7.2 below.

6 Determination of Risk Concentration

6.1 Infectivity

The dose of viruses for each exposure that would be required to result in the risks of infection inherent in the Guidelines is determined from models of the infectivity of the virus. A number of models have been presented in the literature that provide an estimate of the risk of infection given ingestion of a certain volume of known concentration of pathogen in contaminated water. These models have been predominantly determined by clinical trials and are specific to particular virus groups. The beta-Poisson model (for bacterial pathogens and viral gastrointestinal illness) is used to calculate infectivity in this scenario as being representative of gastro-intestinal infection. This has been adopted in previous assessments.

1 Takaka WWTP RIB Trial Results and Hydrogeological Assessment – October 2011, Report prepared for Tasman District Council by MWH New Zealand Limited.


The beta-Poisson model takes the form of:

N

Pi 11

Where:

Pi = the probability of infection N = dose and are parameters that define the dose-response relationship2

The characteristics of the infectivity model used in the risk assessment to assess infection are summarised in Table 1. Table 1: Characteristics of Infectivity Models3

Organism Type of Model r N50

Viruses – Gastro Model Beta-Poisson 0.2531 0.4265 - 6.2 Note: 1. The infectivity model used to assess gastro-intestinal infections derived from viruses is based on the

rotavirus model 2. N50 is the median infectious dose, ie. the dose required to provide an infection in 50 percent of the

individuals This model was used to determine the dose of virus that would need to be ingested in each exposure to result in the risks of infection inherent in the Guidelines. Table 2 presents the different viral doses which equate to the three levels of risk used in the Guidelines. Table 2: Viral Dose for Different Levels of Risk

Risk Dose of Virus for Given Risk

No Calculable Risk Level, NCRL (<0.1%)

0.0017 pfu

Risk Level Above Threshold for Infection (<1%)

0.017 pfu

Substantial Elevation in Risk Above NZ Background (<5%)

0.096 pfu

No allowance for morbidity (ie development of symptomatic illness as a result of infection) has been included in the risk assessment. This is consistent with a general precautionary approach adopted with the assessment.

2 The exponential model is derived from three assumptions: (i) that pathogens are randomly distributed in water (and hence follow a Poisson distribution); (ii) that all individuals have the same probability (r) of being infected by a single pathogen; (iii) that one pathogen reaching an "infection site" in any individual is sufficient to cause infection (so it is a "single-hit model"). The beta-Poisson model is derived by relaxing assumption (ii), replacing r by a two-parameter beta distribution (with parameters � and ��. This relaxation is necessitated by dose-response data for some pathogens in which some people are much more resistant to disease than others. The beta-Poisson equation is actually an approximation to the correct result (a hypergeometric function), but it is sufficient for most purposes. 3 Haas CN, Rose JB and Gerba CP (1999), Quantitative Microbial Risk Analysis, John Wiley.


6.2 Exposure

Contact Recreation The concentration of viruses in the water column was determined based upon the dosage of viruses associated with contact recreation. The following assumptions were made regarding the potential exposure whilst undertaking contact recreation.

Primary contact recreation: Swimmers are assumed to ingest 30 mL of water in a day4,5

Secondary contact recreation:

o canoeists are assumed to canoe for two hours and ingest water at a rate of 3.52 mL/hour in a day

o fishers are assumed to fish for three hours and ingest water at a rate of 1.79 mL/hour in a day

o persons in boats are assumed to boat for four hours and ingest water at a rate of 0.90 mL/hour in a day6.

The risks of infection with exposure through fishing and boating are similar to but less than those for canoeing due to the lower exposure rates. Accordingly only the results for canoeing have been presented in this report (using an ingested volume of slightly over 7 mL). Table 3 presents the concentration of viruses in the water column which equates to the three levels of risk used in the Guidelines for primary and secondary contact recreation. These figures are those presented in Table 2 divided by the volume of water ingested (presented in the bullet points above, however the figures in Table 3 have been converted to pfu/100 L). Table 3: Risk Concentrations for Viruses for Primary and Secondary Contact Recreation

Risk

Concentration of viruses in the water column which equates to level of risk of infection

Primary Contact Recreation

Secondary Contact Recreation - Canoeing


5.6 pfu/100 L 24 pfu/100 L


58 pfu/100 L 245 pfu/100 L


320 pfu/100 L 1,361 pfu/100 L

Shellfish Gathering Shellfish, being filter feeders, have a tendency to accumulate material (termed bioaccumulation). An assessment was made of the concentration of viruses within shellfish flesh using the application of a bioaccumulation factor that relates the concentration of virus present in the surrounding waters to the concentration of pathogen within the flesh of shellfish.

4 Crabtree KD, Gerba CP, Rose JB and Haas CN (1997), Waterborne Adenovirus: A Risk Assessment, Water Science & Technology. 35 (11/12), 1-6. 5 Payment P (1984) Viruses and Bathing Water Quality, Can J Pub Health, 75, 43-48. 6 Rijal et al et. al. (2009), Microbial Risk Assessment of Chicago Area Waterways, Proceedings of 2009 USEPA National Beach Conference


This factor can be highly variable and is dependent upon conditions around the shellfish and also the shellfish itself. A range of bioaccumulation factors are presented in the literature and a factor of 307 was used for this assessment. The typical mass of uncooked shellfish was assumed to be 60 grams per meal. The mass of uncooked shellfish upon which the risk assessment has been based is consistent with a large meal of cockles (or pipi or tuatua) or a small meal of pacific oysters.

7 Results

7.1 Introduction

The reduction in pathogen concentration within the environment is dependent upon (a) the dilution that would be expected between the point of exposure and the point of discharge and (b) the decay or inactivation within the environment. No inactivation of viruses after they emerge from the groundwater discharge zone has been assumed in this risk analysis, which is considered to be conservative.

7.2 Available Dilutions

7.2.1 Contact Recreation

Dilution increases with distance downstream of the discharge zone and is dependent on the flow in the river and the rate of discharge of wastewater from the treatment plant. A zone of reasonable mixing of 50 metres has been used for the ecological assessments and this mixing zone was used for the contact recreation microbiological risk assessment for consistency. For this assessment two rates of discharge from the WWTP have been considered, one being the predicted summer peak average dry weather flow (ADWF) daily discharge expected to occur in 2050 (700 cubic metres per day) and the second being the predicted ADWF daily discharge either side of the summer peak in 2050, referred to as the ‘shoulder period’ (460 cubic metres per day). Two different approaches were taken in respect of river flow rates, and hence dilution rates. The first is based on the median flow during the months of December, January, and February, and the second being the median flow over the entire summer period (December-February inclusive). For the purposes of this assessment it has been assumed that the peak summer discharge would occur over the entire month of January and the shoulder discharges occur for all of December and February – this differs slightly from the AEE but is more conservative in that the AEE only assumes a three week peak period between 1-21 January. It should also be noted that while the peak summer discharge does not occur in February, there is a lag time between the peak load entering the WWTP and it emerging in the Takaka River. This lag time could be a few weeks so it is appropriate to assess the risks of the peak summer ADWF during the month of February. The available dilutions at the edge of the 50 metres mixing zone under the various scenarios (river flow rates and WWTP discharge rates) are given in Table 4. Calculation of the available dilution rates was based on the results of the earlier dye testing undertaken in 2005 (MWH, 2005)8.

7 Based on the average of all the figures presented in Table 9.1 of Using Statistical Methods for Water Quality Management: Issues, Problems and Solutions. Wiley, New York. McBride G. B. (2005) 8 Investigations of the Dispersion and Dilution of Discharges into the Lower Takaka River – April 2005. Report prepared for Tasman District Council by MWH New Zealand Limited.


Table 4: Available dilution at within Takaka River at 50 metres downstream of discharge zone

River Flow

Available dilution (times dilution) within Takaka River as 50 metres downstream of discharge zone

2050 peak summer ADWF discharge (700 m3/day)

2050 shoulder period ADWF discharge (460

m3/day)

December median flow of 18.3 m3/s (29)* 44

January median flow of 12.9 m3/s 23 36

February median flow of 9.4 m3/s 19 29

Median summer (Dec–Feb) flow of 13.2 m3/s 24 36 * Figure presented for information only. The peak summer loading to the WWTP does not occur in December. 7.2.2 Shellfish Gathering

Shellfish beds exist in the vicinity of the mouth of the Takaka River, which is located well downstream of the discharge zone and full mixing has been assumed for the purposes of this assessment, including the additional dilution provided by the Waikoropupu River that enters the Takaka River approximately 600 metres downstream of the discharge zone. During summer peak periods there is ~2,500 times dilution at full mixing using February median river flows and during shoulder periods there is ~3,900 times dilution using the median February river flows. The shellfish risk assessment was only undertaken for the February median river flow (20.8 m3/s) and peak summer WWTP discharge scenario (700 cubic metres per day).

7.3 Required Dilutions

The rate of dilution required within the Takaka River to reduce the Predicted Concentration of viruses (as measured at the point where the affected by the WWTP discharge enters the Takaka River – refer Section 5) to achieve the various Risk Concentrations for primary and secondary contact recreation activities (presented in Table 3) were calculated. These are presented in Table 5. Table 5: Dilution rates required within Takaka River to achieve various risk levels

Risk Required Dilution (× dilution) to Achieve Risk Level

Primary Contact Recreation

Secondary Contact Recreation - Canoeing


178 42


18 5


4 <1


8 Risk Assessment

8.1 Contact Recreation

The available dilution (refer Table 4) for discharges during peak summer and shoulder periods results in risks of <1% for all median flows. As discussed in Section 3, this level of risk is considered to be acceptable for contact recreation in freshwater and is equivalent to a Grade B beach and is associated with a suitability for recreation grade of ‘Good’ which means the beach is satisfactory for swimming most of the time.

8.2 Shellfish Gathering

Based on a full mixing dilution rate of 2,500 times (refer Section 7.2.2) the risks associated with gathering and eating raw shellfish during peak summer loads at the WWTP and February median river flows are less than 1%. This is considered to be an acceptable risk.

9 Conclusions

For the Takaka WWTP, the predicted risks of infection resulting from the wastewater discharge associated with contact recreation at and beyond a 50 metre mixing zone are less than 1% for the period when the risks are considered to be the greatest (ie. summer peak loadings and summer river flows). The risks associated with gathering and eating raw shellfish are also less than 1%. It is noted that this assessment has been performed on a worst case basis and does not incorporate the inherent variability of the various processes involved. It is considered to provide a conservative assessment of the potential risks of infection that could result from the discharge of the wastewater. It is expected that the actual risks of infection would be less than those predicted for the majority of the time. It should also be noted that the flows within the Takaka River are heavily influenced by the operation of the Cobb Valley power station. Should the power station change its operating regime the flows may change which will affect the available dilution in the Takaka River.

This Project Technical Memorandum has been prepared for the benefit of Tasman District Council. No liability is accepted by this company or any employee or sub-consultant of this company with respect to its use by any other person. This disclaimer shall apply notwithstanding that the Project Technical Memorandum may be made available to Tasman District Council and other persons for an application for permission or approval or to fulfil a legal requirement.