Blackmans Bay STP environmental noise assessment · Blackmans Bay STP environmental noise assessment Report No. 421451-01 Vipac Engineers & Scientists Ltd ... 29 July 2016 Page 3

Acoustics Vibration Air Quality Mechanical & Structural Systems Fluid Mechanics Sustainability Building Technologies

BMD and Acciona Joint Venture

Blackmans Bay STP

environmental noise assessment

Report No. 421451-01

Vipac Engineers & Scientists Ltd

PO Box 506 Kings Meadows TAS 7249

July 2016

BAJV – Blackmans Bay STP upgrade DPEMP environmental noise assessment.

421451-01 BAJV - Blackmans Bay STP upgrade DPEMP environmental noise assessment 29 July 2016 Page 2 of 19

Commercial - in - Confidence

DOCUMENT CONTROL

BLACKMANS BAY STP ENVIRONMENTAL NOISE ASSESSMENT

Report No. Library Code 421451 - 01 ACS

Prepared for Prepared by

BMD Constructions Vipac Engineers & Scientists Ltd

PO Box 197 PO Box 506 Wynnum Kings Meadows

Queensland 4178 Tasmania 7249

Contact Paul Elliott Contact Dr Alex McLeod

+61 7 3033 9421 +61 3 6343 2077

Mobile +61(0)407 409 548 Mobile +61(0)439 357 297

Email [email protected]

Email [email protected]

Author Alex McLeod Date: 28 July 2016

Senior Consultant

Reviewed by Date:

Authorised by Peter Bunker Date: 28 July 2016

Manager, Tasmania

Approved by Date:

Revision History

Revision No. Date Issued Reason/Comments

1 29 July 2016 errors

Distribution

Copy No.______ Revision No. Location

1 1 Project/Client File

2 1 Client

3 1 Vipac Library

Keywords noise, dBA, STP, OCF, SWL, sound pressure level

mailto:[email protected]

mailto:[email protected]




Table of Contents Executive Summary ................................................................................................................... 4 1 Introduction ...................................................................................................................... 5 2 Site description ................................................................................................................ 5 3 Noise assessment criteria ................................................................................................ 7 3.1 Operation ......................................................................................................................... 7 3.2 Construction .................................................................................................................... 8 4 Environmental noise modelling ........................................................................................ 8 4.1 Atmospheric conditions .................................................................................................... 8 4.2 Operation ......................................................................................................................... 9 4.2.1 Sound power data ........................................................................................................ 9 4.2.2 Model scenarios ......................................................................................................... 10 4.2.3 Model results and discussion ..................................................................................... 13 4.3 Construction .................................................................................................................. 17 4.3.1 Sound power data ...................................................................................................... 17 4.3.2 Predicted sound pressure levels ................................................................................ 18 5 Conclusions ................................................................................................................... 18 5.1 Recommendations ......................................................................................................... 19 5.1.1 Operations ................................................................................................................. 19 5.1.2 Construction ............................................................................................................... 19

List of figures

Figure 1 – Aerial view with receiver location marked. ................................................................. 6 Figure 2 – Noise source locations, Operation. .......................................................................... 11 Figure 3 – Wire frame view, Operation, view from the south-east. ............................................ 12 Figure 4 – Predicted noise emission contours, Operations model scenario under neutral weather.

.......................................................................................................................................... 14 Figure 5 – Predicted noise emission contours, Operations with temporary power generation

model scenario under neutral weather. .............................................................................. 15

List of tables

Table 1 – Receiver locations. ..................................................................................................... 6 Table 3 – Sound power levels, Operation. .................................................................................. 9 Table 4 – Sound power level spectra, Operation. ..................................................................... 10 Table 5 – Predicted received sound pressure levels, Operational scenarios. ........................... 16 Table 6 – Predicted received spectra, Operations model scenario. ......................................... 16 Table 7 – Source sound power levels, Construction. ................................................................ 17 Table 8 – Predicted sound pressure levels, Construction. ........................................................ 18 Table 9 – OCF discharge silencer insertion loss 1/1 octave band spectrum. ............................ 19

References [1] Vipac report 4854_01 CEE - BLACKMANS BAY WWT PLANT STAGE 1 – ACOUSTIC ASSESSMENT. [3] SoundPLAN Acoustic modelling software - Braunstein & Berndt GmbH. [4] CONCAWE The oil companies’ international study group for conservation of clean air and water – Europe (est. 1963) report 4/81.




Executive Summary Vipac was commissioned to undertake an environmental noise assessment of a proposed upgrade to the Blackmans Bay STP.

Ambient noise data and site specific noise emission criteria for operations post upgrade were provided in Vipac report 4854_01 and utilised here.

Predicted noise emission levels a sensitive receiver locations where below the project criteria with the following source requiring consideration of noise reduction for this to be achieved:-

Inlet works

OCF case

OCF inlet duct

OCF exhaust discharge

Prediction of construction noise indicates that Tasmanian EPP acoustic indicator levels are unlikely to be exceeded during construction.

Noise control recommendations are provided in section 5.1 of the report




1 Introduction Vipac was commissioned by BMD, on behalf of the BMD and Acciona Joint Venture (BAJV), to conduct a Development Plan and Environmental Management Plan (DPEMP) environmental noise assessment of a proposed upgrade of the Blackmans Bay sewerage treatment plant (STP). Project specific guidelines were provided by the Tasmanian EPA with the section relevant to noise provided below:-

6.4 Noise

Undertake a noise assessment that includes:

Measured or estimated ambient sound levels at nearest residences for daytime, evening and night time periods.

Sound power output levels for all major sources of noise (including both fixed and mobile equipment).

Results of noise emission modelling to predict the 30, 35, 40 and 45 dB(A) noise contours under typical and plausible worst case operating conditions.

Details of potential noise nuisance taking into account changes in noise frequencies and tonal components, increases in ambient noise levels, the time varying nature of emissions (e.g. modulation, impulsive or intermittent noise) and the temporal span of the noise emissions.

Details of noise levels likely to be generated during the construction and start-up phases must be identified and any temporary mitigation requirements specified.

Ambient noise measurements in the area surrounding the STP were conducted in November 2014 and project specific noise emission criteria for operational noise from the upgraded plant determined (see Vipac report 4854_01[1]). This forms the basis for the assessment provided here. To address the remaining guidelines Vipac proposed the following:-

Development source sound power spectra for the current major noise emitting equipment on site based near-field spectral noise measurements. Development of source sound power spectra for new sources to be installed as part of the upgrade from manufacturers data and/or Vipac library data.

Construct an environmental noise model of STP operations using SoundPLAN environmental noise modelling software.

Predict noise emission contours and detailed single point data at sensitive receiver locations.

Assessment of predicted noise emission results against project noise criteria

Prediction of potential construction phase noise levels based on Vipac library sound power data and equipment and processes details provide by BMD.

Assessment of construction phase and start-up phase noise levels

2 Site description The Blackmans Bay STP is located on the western bank of the Derwent River approx. 4.5 km south of the centre of Kingston. The local tomography rises sharply off the river to the STP and continues to rises to the west, south-west and north-west of the STP. Medium density housing is present to the north of the STP at approx. 160 m while low density housing is present to the west and south. The closest residence is approx. 100 m to the west of the STP boundary fence.




The acoustic environment was described as follows in Vipac report 4854_01[1]:-

The acoustic environment at the residential dwellings consists of light traffic noise from Tinderbox Road and Suncoast Drive, faint noise from the WWTP, bush noises (wind in trees, birds etc), noise from the wave action along the rivers edge, and noises typical of a suburban environment. The area may generally be regarded as acoustically quiet.

Table 1 provides location information for eight potentially noise sensitive residential receiver locations identified for this project. The locations form the basis for single point noise emission prediction. Figure 1 provides an aerial view with the location of the STP and receiver locations marked.

Receiver locations

Position number Coordinates (MGA) Comments

1 526573 / 5237417 Location B in Vipac report 4854_01[1]

2 526615 / 5237590

3 526739 / 5237650 Location C in Vipac report 4854_01[1]

4 526491 / 5237491

5 526442 / 5237378 Location A in Vipac report 4854_01[1]

6 526326 / 5237302

7 526397 / 5236959

8 526875 / 5236976

Table 1 – Receiver locations.

Figure 1 – Aerial view with receiver location marked.

0 200 m

N

1

8 7

6

5

4

3

2

Blackmans Bay STP




3 Noise assessment criteria

3.1 Operation

The following table from Vipac report 4854_01[1] provides noise emission criteria for three residential locations surrounding the STP. The figure below, also from the report, provides locations for the three locations referenced in the table (see Vipac report for discussion of criteria development).

For this assessment the criteria outlined in the table above are adopted as follows for the assessment of operational noise post upgrade:-

Medium density housing to the north of the STP: 37 dBA, LAeq,10min

Low density housing to the west and south of the STP: 32 dBA, LAeq,10min

Closest residence (house B or receiver 1): 35 dBA, LAeq,10min




NB: A temporary power generator for short duration use during power outages is to be considered as an operational scenario in this assessment. Given the intended use of this equipment Vipac consider it inappropriate to assess this source against the low level noise criteria presented above. Given this this source will be assessed against Tasmanian Environmental Protection Policy(Noise) 2009 (EPP) acoustic indicator values (see section 3.2 below for details).

3.2 Construction

For construction noise predicted noise levels will be assessed against acoustic indicator values provided in the Tasmanian Environmental Protection Policy(Noise) 2009 (EPP) as follows in the table below:-

Table 2 – EPP acoustic indicator levels.

4 Environmental noise modelling SoundPLAN[2] software was used for carrying out detailed noise emission spectra and contour modelling. This program allows the use of the CONCAWE[3] calculation method for modelling atmospheric attenuation of noise from industrial complexes. Parameters influencing sound propagation and attenuation include:

Source type (point, line, plane).

Relative source and receiver height.

Topography and barriers.

Industrial buildings as sources and/or barriers.

Ground absorption.

Distance attenuation.

Atmospheric conditions (pasquill stability, temperature, humidity and vector wind speed).

Reflecting surfaces.

Source directivity.

As all propagation and attenuation parameters are frequency dependent, all input source data has been based on octave band sound power spectra. All source and geodata is projected in the Map Grid of Australia (MGA) reference coordinate system.

4.1 Atmospheric conditions

SoundPLAN[3], via the CONCAWE[4] prediction algorithm, models atmospheric attenuation using Pasquill stability indices in combination with vector wind speed and direction to determine appropriate frequency dependent attenuation/amplification. In this study, the following propagation condition was modelled as follows:-

Neutral propagation: Situations where the atmospheric conditions are considered to be neutral occur with a Pasquill stability class D and no wind. These conditions can typically




occur in the hour before sunset and the hour after sunrise. Neutral conditions also occur fairly frequently during still, cloudy conditions.

NB: Other weather conditions, including ‘worst case’ weather, where not considered due to the proximity of closest sensitive receiver locations negating any significant influence from atmospheric conditions.

4.2 Operation

4.2.1 Sound power data

Table 3 provides the sound power levels (SWLs) for the equipment proposed for operations post upgrade of the STP (equipment list provided by BAJV). Details regarding the development of the SWLs presented are provided. Table 4 provides the SWL spectrum for each source.

Overall sound power Levels (dBA) Operation

Source SWL Noise data provided by BAJV

Comments

Inlet works* 85 < 75 dBA at 1 m Spectral shape from measured data in current inlet works screening room

Sludge dewatering building

78 73 dBA at 1 m inside

Building breakout noise through glazing and roll door. Spectral shape and transmission loss from measured data of current inlet works centrifuge room

Digester blowers 82 69 dBA at 1 m outside enclosure

X2 blowers. Spectral shape from measured data of existing aeration blowers

IDEA blower 92 81 dBA at 1 m outside enclosure

X2 blowers. Spectral shape from measured data of existing aeration blowers

Digester sludge pumps 91 < 80dBA at 1 m X 2 pumps. Spectral shape from Vipac library data.

General purpose pumps

81 < 70dBA at 1 m X 3 pumps. Spectral shape from Vipac library data.

Service water pumps 86 < 75dBA at 1 m X 2 pumps. Spectral shape from Vipac library data.

Thickened sludge pumps

93 < 80dBA at 1 m X 3 pumps. Spectral shape from Vipac library data.

OCF case* 90 85 dBA at 1 m Reduced to 80 dBA @ 1m. Spectral shape from measured data of existing OCF.

OCF discharge* 84 Manufacturers data SWL 109 dBA

Reduced to 84 dBA SWL. Spectral shape from manufacturers data. Stack height 12 m with vertical directivity considered in the model.

OCF inlet duct* 89 Existing OCF duct SWL 99 dBA

Existing OCF duct measured SWL of 99 dBA. Reduced to 89 dBA SWL. Spectral shape from measured data of existing OCF.

Primary tank OCF case 77 - Measured data of existing fan

Primary tank OCF inlet 88 - Measured data of existing fan

Temporary power generator exhaust

97

85 dBA at 1 m Vipac library data for equivalent unit. Temporary power generator enclosure

106

* Requires consideration of noise reduction, discussed in recommendations section (5.1).

OCF: Odour Control Fan.

Table 3 – Sound power levels, Operation.




1/1-octave band sound power spectra (dBA) Operation

Source Frequency (Hz)

Total 31.5 63 125 250 500 1k 2k 4k 8k

Inlet works 44 55 72 73 80 79 78 74 66 85

Sludge dewatering building 33 50 61 69 71 74 68 61 54 78

Digester blower 29 61 72 71 72 73 79 73 68 82

IDEA blower 39 71 82 81 82 83 89 83 78 92

Digester sludge pumps 48 55 70 78 85 87 84 80 73 91

General purpose pumps 38 45 60 68 75 77 74 70 63 81

Service water pumps 43 50 65 73 80 82 79 75 68 86

Thickened sludge pumps 50 57 72 80 87 89 86 81 75 93

OCF case 44 60 71 75 82 85 85 78 69 90

OCF fan discharge - 66 68 69 69 72 74 75 82 84

OCF fan inlet duct 41 59 71 75 81 83 86 76 65 89

Primary tank OCF case 29 45 49 62 75 68 65 62 53 77

Primary tank OCF inlet 43 59 66 72 78 81 82 82 79 88

Temporary power generator exhaust

61 87 88 89 91 89 88 85 76 97

Temporary power generator enclosure

78 89 98 101 101 99 96 93 85 106

Table 4 – Sound power level spectra, Operation.

4.2.2 Model scenarios

Two model scenarios where considered as follows:-

Operations: All sources presented in section 4.2.1 operating with the exception of the temporary power generator.

Operations with temporary power generation: All sources presented in section 4.2.1 operating

Figure 2 presents a model plan view with an aerial photographic underlay and the location of the noise sources marked. Figure 3 provides a wire-frame model view from the south-east.




Figure 2 – Noise source locations, Operation.

Digester blowers Odour control fan (Case and discharge as point sources. Inlet duct as line source)

Service water pumps

Inlet works (Line source below roof area)

Sludge dewatering building (Area sources on building facade)

General purpose pumps

Primary tank OCF (Inlet and case)

Thickened sludge pumps

IDEA blowers (Point sources X2 below roof area)

Temporary generator

Digester sludge pumps




Figure 3 – Wire frame view, Operation, view from the south-east.




4.2.3 Model results and discussion

4.2.3.1 Predicted sound pressure level contours

To assist with the visualisation of predicted noise propagation from the STP noise emission contours are provided for the two model scenarios as follows:-

Operations, under neutral weather;

Operations with temporary power generation, under neutral weather.




Figure 4 – Predicted noise emission contours, Operations model scenario under neutral weather.




Figure 5 – Predicted noise emission contours, Operations with temporary power generation model scenario under neutral weather.




4.2.3.2 Predicted sound pressure levels

Table 5 presents the predicted noise levels at receivers under the two modelling scenarios.

Predicted sound pressure levels (dBA)

Receiver No.

Model scenario

Operations Operations with power temporary generation

1 35 43

2 30 38

3 33 44

4 24 35

5 21 33

6 16 27

7 23 34

8 30 38

Noise emission criteria 35 dBA. Noise emission criteria 37 dBA.

Noise emission criteria 32 dBA.

Table 5 – Predicted received sound pressure levels, Operational scenarios.

From the above:-

All predicted noise levels are below the assessment criteria for the project under the Operations model scenario.

With the temporary power generator operating the predicted levels are above the operational assessment criteria at most locations. However, as discussed above, Vipac considers assessment against EPP acoustic indicator levels more appropriate given the intended infrequent use of the generator. The predicted levels are below indicators levels for outside bedrooms (45 dBA) and outdoor living spaces (50 dBA).

NB: Sound pressure levels at receivers 7 and 8 have the potential to be 1 to 2 dBA higher under worst case weather conditions.

4.2.3.3 Predicted received spectra

Table 6 presents predicted 1/1-octave band spectra at receiver locations under the Operations modelling scenario.

Predicted received 1/1-octave band sound pressure level spectra (dBA) Operations

Receiver Frequency (Hz)

Total 31.5 63 125 250 500 1k 2k 4k 8k

1 - 18 26 24 29 28 29 23 15 35

2 - 16 21 17 21 24 25 20 8 30

3 - 18 25 20 23 26 28 23 11 33

4 - 12 17 13 16 19 18 11 3 24

5 - 10 15 12 14 14 14 7 1 21

6 - 6 9 6 8 9 8 - - 16

7 - 7 10 5 14 19 17 7 - 23

8 - 13 18 14 21 26 26 16 - 30

Table 6 – Predicted received spectra, Operations model scenario.




From the above:-

The predicted levels at 125 Hz suggest the potential for tonality in this octave band. The dominant sources at this frequency are the IDEA blowers.

NB: Analysis of the predicted received spectra under the Operations with temporary power generation suggest the potential for relatively high levels of low frequency acoustic energy from the temporary generator.

4.3 Construction

Based on information provided by BMD the following construction stages have been identified as having the potential to produce high environmental noise emission levels. The construction activity and equipment to be used is listed for each stage:-

Stage 1

The excavation for the IDEA tanks, 30t excavator and trucks.

Stage 1A

Excavator 20t for trenching for internal pipelines.

Concrete trucks and concrete vibrators.

Compaction equipment and grader for backfill and road construction.

Stage 3

Cleaning tanks and modifications to existing structures.

Franna.

Water blaster.

Generator.

New pipework and conduits.

Excavator 20t for trenching for internal pipelines and conduits.

Small concrete works, concrete trucks and concrete vibrators.

4.3.1 Sound power data

Table 7 presents SWL levels for the sources identified in section 4.3 above. The data was sourced from Vipac library data.

Overall sound power levels (dBA) Construction

Source SWL Comments

Excavator 20t 101

Vipac library data.

Excavator 30t 102

Truck 107

Grader 109

Vibrating roller 111

Concrete vibrators 99

Water blaster 100

Generator 99

Table 7 – Source sound power levels, Construction.




NB: 1/1-octave band SWL spectra for the source in table 7 were utilised in the model to predict LAeq,10min sound pressure levels for each of the construction stages identified in section 4.3.

4.3.2 Predicted sound pressure levels

Table 8 presents predicted sound pressure levels at the eight receiver locations for the three construction stages identified.

Predicted sound pressure levels (dBA)

Receiver No. Model scenario

Stage 1 Stage 1A Stage 3

1 45 50 35

2 37 43 39

3 38 45 41

4 38 42 28

5 27 38 27

6 20 31 22

7 30 34 31

8 33 38 36

Receiver not noise sensitive during construction.

Table 8 – Predicted sound pressure levels, Construction.

From the above:-

Predicted levels are below the environmental indicator levels outlined in section 3.2.

NB: Vipac consider it unlikely that maximum noise levels from construction would typically exceed 60 dBA at any sensitive location. Impact noise generated during demolition may at times exceed this level.

5 Conclusions Vipac was commissioned to undertake an environmental noise assessment of a proposed

upgrade to the Blackmans Bay STP.

Ambient noise data and site specific noise emission criteria for operations post upgrade were provided in Vipac report 4854_01 and utilised here.

Predicted noise emission levels a sensitive receiver locations where below the project criteria with the following source requiring consideration of noise reduction for this to be achieved:-

Inlet works

OCF case

OCF inlet duct

OCF exhaust discharge

Prediction of construction noise indicates that Tasmanian EPP acoustic indicator levels are unlikely to be exceeded during construction.




5.1 Recommendations

5.1.1 Operations

5.1.1.1 Inlet works

The development of the inlet works SWL spectrum for this assessment was conservative due to a lack of acoustic data and noise emission levels may potentially be substantially less than modelled here. Predicted levels indicate that a reduction of 3 – 6 dBA may be required. This could be achieved by enclosing the works on the north and east sides with a material with an appropriate sound transmission loss and lining the internal sides with absorption.

5.1.1.2 Odour control fan

5.1.1.2.1 Case An enclosure for the OCF fan case is proposed that would provide performance of 85 dBA sound pressure level at 1m. Vipac recommends that this is upgraded to a performance criterion of 80 dBA sound pressure level at 1 m.

5.1.1.2.2 Inlet duct Development of the inlet duct sound power level spectrum for this assessment was based on measurement of the existing OCF discharge ducting, both the new and old OCF are similar capacity fans. Based on this the new OCF inlet duct is likely to require an inlet silencer providing a 10 dBA insertion loss with performance across the frequency range 250 Hz to 4 kHz 1/1-octave bands.

5.1.1.2.3 Exhaust discharge Development of the OCF exhaust discharge sound power level spectrum for this assessment was based on manufacturers SWL data. The exhaust of the OCF requires a discharge silencer with an insertion loss performance as detailed in table 9 below.

OCF discharge silencer insertion loss 1/1 octave band spectrum (dB)

Source Frequency (Hz)

Total 63 125 250 500 1k 2k 4k 8k

Manufacturers SWL (dBA) 78 88 103 103 103 100 100 92 109

Silencer insertion loss (dB) 12 20 34 34 31 26 25 10

Modelled SWL (dBA) 66 68 69 69 72 74 75 82 84

Table 9 – OCF discharge silencer insertion loss 1/1 octave band spectrum.

NB: It was commented in section 4.2.2.3 that predicted levels at 125 Hz suggest the potential for tonality in this octave band with the dominant sources at this frequency are the IDEA blowers. Vipac recommends that care is taken in the development/selection of enclosures for the IDEA blowers such that tonal noise emission breakout doesn’t generate potentially instructive noise emissions.

5.1.2 Construction

Vipac recommends that vibratory equipment, in particular vibrating rollers for road and pad works, are not utilized prior to 7 am as the low frequency noise generated by such equipment has the potential to cause excessive noise nuisance at such times.

VIPAC ENGINEERS & SCIENTISTS

Vipac Engineers & Scientists Limited A.C.N. 005 453 627 A.B.N. 33 005 453 627 PO Box 476, Rosny Park, Tasmania 7018 AUSTRALIA Telephone (+61 3) 6244 5556, Facsimile (+61 3) 6245 9200, www.vipac.com.au

Melbourne • Sydney • Adelaide • Perth • Brisbane • Hunter Valley • Tasmania • Singapore • Kuala Lumpur • Hong Kong • Bangkok

NAT A

CEE 2 December, 2014 PO Box 201 Richmond Victoria 3121 4854_01.docx

Attention: Ian Wallis BLACKMANS BAY WWT PLANT STAGE 1 – ACOUSTIC ASSESSMENT

An upgrade of the Blackmans Bay Waste Water Treatment Plant (WWTP) is proposed. To fulfil the requirements of the DP&EMP for the project a noise assessment of the upgrade is required, and this letter presents stage 1 of that assessment comprising an initial noise survey and conceptual noise mitigation for the upgrade to meet the appropriate noise criteria.

SUMMARY A noise survey of the current Blackmans Bay WWTP has been conducted that involved both site and community noise measurements. Based on this work a preliminary noise assessment of the upgraded plant has been conducted. Once the location and incorporated plant items for the upgrade are known with more certainty, a more detailed noise assessment will be conducted as a second stage of this work. Two general residential areas were identified, one to the west of the site, and another to the north off Suncoast Drive. There is a single residence close to the western boundary of the site which will be critical in determining the level of noise mitigation required for the upgraded plant. Community noise measurements showed the plant to be generally inaudible to the residents on the western side due to topographic screening by the intervening ridge, while at Suncoast drive a tone from an odour fan was the only identifiable noise source. Wave noise from the foreshore was the dominant background noise at night. The measured background noise levels were then used in conjunction with relevant state policy and planning schemes, to determine acceptable noise criteria for the plant upgrade. As the plant operates 24 / 7, night time will be the critical period, and the criteria determined for this time ranged from 32 dBA for residents to the west, to 37 dBA for Suncoast Drive. These criteria apply at the residential boundary. From the plant noise survey the main noise sources were identified and their sound power levels determined. These sound power levels have then been used to predict the community noise levels assuming no inplant noise attenuation for the upgraded plant. The predictions indicate noise mitigation beyond the current situation is required for three sources viz: the sludge building odour ID fan and trunking, and the primary tank odour fan. Concepts for the noise control have been recommended along with a not to exceed sound power level of 86 dBA for a single item that will ensure the plant emissions are acceptable.

1.0 SITE DESCRIPTION The Blackmans Bay Waste Water Treatment Plant (WWTP) is located adjacent to the foreshore of the Derwent River in Blackmans Bay. The land rises sharply from the river to the WWTP which is on a gently rising slope to residential areas to the north and west of it. Shallow gullies lead up to the houses on Suncoast Drive to the north (location C), and into recreational space to the south west. The nearest

CEE

Blackmans Bay Wwt Plant Stage 1 – Acoustic Assessment

Reference: 4854_01.docx 2-Dec-14 Page 2 of 9 Commercial-In-Confidence

residence (location B), is to the west on a slight ridge that offers some topographic screening to further residential houses behind it (location A). The land between the WWTP and the houses is predominantly open pasture with some light open bush in the gullies. Figure 1 shows the general area and surrounds. The nearest residences to the plant typical of the surrounding area are within 170 to 300 m of the plant with the closer ones having clear view of it. The acoustic environment at the residential dwellings consists of light traffic noise from Tinderbox Road and Suncoast Drive, faint noise from the WWTP, bush noises (wind in trees, birds etc), noise from the wave action along the rivers edge, and noises typical of a suburban environment. The area may generally be regarded as acoustically quiet. The WWTP comprises several settling ponds, a sludge building, some outdoor pumps / fans and two external but enclosed blowers.

Figure 1: Site and Surrounds

C

A

B

WWTP

300 m

170 m

250 m

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1.1 Site Noise Sources A site visit by Vipac to the WWTP was conducted on the 7th November, 2014 during which the equipment associated with the plant was identified and relevant noise measurements made sufficient to characterise the noise sources. Waste water arrives on site at the sludge De-watering building where initial solids are removed from the water. The building is of besser block construction with some windows, and roller doors for access. The main noise sources identified here were the centrifuge, heat exchanger and air compressor, all of which are inside the building. Odour from the Sludge building is removed by an induced draught fan located some 20m to the SW of the building, while the water is gravity fed to the Primary settlement tank. Water flow from the exit of the Primary tank, and a tone from the odour fan there, are the main noises for this tank. Water then passes to an aeration tank where a blower provides air to oxygenate the water. The blowers are the main noise source here and are in light weight enclosures on the down hill side of the tank. They are thus well screened from any residences. The water then passes to the final settlement tank. No significant noise sources were identified with this tank. The main noise sources are then listed in Table 1. In calculating the sound power levels the following is noted: § The sludge building was assumed hollow besser block with sections of glazing. § The blower power level includes the barrier effect of the aeration tank that it sits behind. The barrier

effect is considerable (15 dB), as the blower is close to it, and the barrier high (4m). The blower level is for the No.2 unit operating at 100%.

§ The ID fan typically runs at around 80% capacity, and that level is quoted in the Table. At 100% the sound power level was 4 dB higher.

The sound spectra associated with each source is shown in Figure 2, measured close to the source. Tones associated with the blower, ID fan, and tank odour fan are clear to see.

SOURCE SOUND POWER, dBA COMMENT

Sludge Building Centrifuge 73 Located Inside Building

Heat Exchanger 57 Located Inside Building Air Compressor 49 Located Inside Building, Cyclic

ID Fan 89 At 80% Fan Ducting 89 For 3m length

Primary Tank Odour Fan 89 Tonal

Aeration Tank Blowers 79 Low frequency, Tonal, Enclosed & Screened

Table 1: Current Site Noise Sources

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Figure 2: Near Field Sound Pressure Levels for Main Noise Sources 1.2 Community Noise Levels The community noise levels were measured at three residential locations considered typical of the houses surrounding the WWTP. Location B is the closest and looks down an open grass paddock at the plant which is partially screened by the land. Location C has a view of the plant down a shallow and lightly tree’d gully. Location A has some relatively dense bush beside it and has its view of the plant screened by the ridge on which location B is situated. Location B is understood by Vipac to be owned by Council and currently unoccupied. Noise levels were continuously logged at each site over the period 4th to 10th November 2014, using un-attended Type 1 sound level meters. The results of the logging are summarised in the noise trends of Figure 3 to Figure 5, and Table 2.

LOCATION SOUND PRESSURE LEVEL, dBA L10 L90 Leq

A , House , 300m SW Day 50 36 43 Evening 41 26 32 Night 47 23 35

B, House , 170m W Day 51 36 45 Evening 45 31 40 Night 43 30 39

C, House , 250m N Day 47 38 46 Evening 41 33 39 Night 44 32 42

Table 2: Summary Of Community Noise Levels

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From the measurements and observations made during them, the following is noted.

Location A § A Spa pool was located near to the logger and its pump cycles continuously. Its effect is clearly

seen in the noise trend of Figure 3. In determining the levels presented in Table 2 the Spa pump has been omitted.

§ The WWTP was inaudible. § Wave noise from the foreshore not perceived. § Bush noises (wind mainly), and birds were clear noises, birds in particular being consistently strong

at dawn and dusk.

Figure 3: Noise trends at Location A – 106 Tinderbox Rd

Figure 4: Noise trends at Location B – 116 Tinderbox Rd. Location B § Wave noise from the foreshore is audible as the main noise (level of 35 dBA). § The WWTP is audible due to the ID fan or Blower (at 29 dBA). § At 1045 there is a consistent short period of higher noise levels, assumed to be from the WWTP.

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Location C § Wave noise from the foreshore is audible (level of 34 dBA). § A tone is often clear, observed in the 630 Hz one third octave band. The tone would attract a 3 dB

penalty to the overall level measured here (making adjusted tonal level of 41 dBA). § Aside from the tone, the WWTP is generally inaudible. § Intermittent traffic noise from Suncoast drive is clear.

Figure 5: Noise trends at Location C – 93 Suncoast Drive

2.0 PROPOSED SITE UPGRADE The layout of the plant and the actual equipment to be used are yet to be determined, so prediction of the upgraded plant noise emissions is not yet possible. Once these issues have been finalised a prediction of the plant noise emissions will be conducted using the SoundPlan software. This will form Stage 2 of the noise assessment process. 2.1 Noise Criteria To assess the upgraded plant noise emissions, a noise criteria is required.

The primary state legislation for environmental noise is the Environmental Management and Pollution Control Act 1994. Under this act, the Tasmanian Environmental Protection Policy (Noise) 2009 has been developed which seeks to protect the health of an individual and their opportunity to work, study, and sleep without unreasonable interference from noise. The policy provides guideline levels, that if met, would be assumed to protect the majority of the population. Relevant guideline levels from the policy are reproduced in Table 3. The Kingborough Council Draft Interim Planning Scheme 2014 includes in its Use Standards for most zone types an acceptable solution regards noise of:

A1 Noise emissions measured at the boundary of the site must not exceed the following: (a) 55 dB(A) (LAeq) between the hours of 8.00 am to 6.00 pm; (b) 5dB(A) above the background (LA90) level or 40dB(A) (LAeq), whichever is the lower, between

the hours of 6.00 pm to 8.00 am; (c) 65dB(A) (LAmax) at any time.

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Relevant or informative criteria, and their source, are then summarised in Table 3.

Regulation / Policy Metric Value

Tasmanian EPP, 2009 Moderate Annoyance outside LAeq 16 hr 50

Outside Bedrooms (night) LAeq 8 hr 45 Kingborough Interim P. Scheme

Day time LAeq 55 Night time LAeq ≤ L90+5 or 40

Any time LAmax ≤ 65 Victoria, Regional Noise, NIRV

Lowest Base Level LAeq 32 Intrusiveness LAeq ≤ L90+5

NSW Industrial Noise Policy, 2000 Amenity, night LAeq 40

Intrusiveness LAeq ≤ L90+5

Table 3: References from which Criteria Determined

From Table 2 the night time L90 is between 23 to 32 dBA, with the quieter level due to no influence from the current WWTP or the river. The background level at night will therefore dictate the criteria for this upgrade and by combining the references of Table 3 with the background levels of Table 2 the site specific criteria for the upgrade are listed in Table 4. The criteria apply at the boundary of the noise sensitive receiver, in this case the residential houses, and not the open space directly surrounding the site.

SOUND PRESSURE LEVEL, dBA L90 Night Time L90 + 5 Min. Criteria Criteria Location A 23 28 32 32

B 30 35 32 35

C 32 37 32 37

Table 4: Noise Criteria for the WWTP Upgrade 2.2 Acoustic Issues The sound power levels presented in Section 1.1 have been used to predict the WWTP noise levels at the three locations assuming no screening of the sources by topography or in plant buildings. Whilst this may not be truly representative of the final arrangement it indicates which sources are of concern and will require attention in the upgrade. The overall plant noise at the three locations is predicted to be between 37 to 43 dBA which implies if no action is taken to mitigate noise, the plant noise emissions will most likely exceed the residential criteria. Further, using the predictions to rank the noise sources in terms of their contribution to the total at each location, the relevant noise sources are, in ranked order:

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Sludge Plant ID Fan Primary Tank Odour fan

Sludge Plant ID Fan Inlet pipe The blower is not listed here because significant in plant screening has been accounted for in its stated sound power level in Section 1.1. With regard to the plant location the following points are relevant: § The house at location B is closest to the plant and has partial view of the current plant. Any

development on the western side of the existing plant will not only be closer to this house but also in full view of it. This house will then be the most critical location with regard to the layout of the new plant.

§ The broad ridge that location B sits on the top of provides topographic screening of current plant noise emissions from residents further to the west. Should the new plant move further up the ridge this screening will be less and more residents exposed to the plant noise emissions.

§ The plant currently sits at the bottom of a shallow gully that extends up to Suncoast Drive. This provides some focussing of plant noise toward this area.

These points would indicate the best location for new plant would be to the south or south west of the existing plant, and that any noise sources that are out in the open be positioned on the eastern or southern side of buildings or large structures. 2.3 Recommended Noise Mitigation From the previous section, noise mitigation will be required for the upgraded plant, and initial concepts for that mitigation are:

§ Assuming three sources contribute to the community noise level, no single source should have a sound power level of more than 86 dBA. This sound power level includes attenuation afforded by any noise mitigation strategies. The 70 dBA criteria outside a building nominated by Tenix meets this requirement assuming the wall area is less than 40 m2.

If the new plant moves up the hill toward location B the sound power limit for an individual item reduces from 86 to 75 dBA due to the close proximity of the house at B. This would imply all major noise sources be inside masonry buildings.

§ Tonal emissions from sources should be avoided.

§ The centrifuge and air compressor will need to be inside a building.

§ The current blowers may be used provided they have attenuation equivalent to the screening their current situation affords. This would most likely be afforded by a masonry type enclosure with doors facing the Derwent river. If new blowers are used they will require an enclosure and to be located inside a building.

§ The ID fan be screened from all residents by a substantial barrier, or be placed in an enclosure.

§ The ID fan inlet pipe, if plainly visible to residents, will require noise reduction. That reduction may be achieved by externally lagging the pipe (typical thermal lagging eg. 75mm Rockwool, and aluminium outer), or dropping the internal air velocity (larger diameter pipe), or screening the pipe from residents, or a combination of these.

§ The primary settling pond odour fan should show no tones. This may be achieved with fan selection or installation of a silencer.

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MATLAB Code

§ Main access to buildings be located on the river side of the buildings.

§ The house at location B is the closest and will be critical in determining the level of noise control required. Consideration should be given to the purchase of such a close residence.

These concepts are intended to form the starting point of discussions that will develop as the design progresses to become the final noise mitigation solutions. During this process the computer model of the site will be developed using SoundPlan and help guide the noise control strategy. Should you have any queries, please do not hesitate to call this office directly. Yours faithfully VIPAC ENGINEERS & SCIENTISTS LTD

Bill Butler

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Blackmans Bay STP environmental noise assessment · Blackmans Bay STP environmental noise assessment Report No. 421451-01 Vipac Engineers & Scientists Ltd ... 29 July 2016 Page 3