BEFORE A BOARD OF INQUIRYPEKA PEKA TO NORTH ŌTAKI EXPRESSWAY PROPOSAL

UNDER the Resource Management Act 1991

IN THE MATTER OF applications for resource consents and a notice of requirement in relation to the Peka Peka to North ŌtakiExpressway Proposal

BY NZ Transport Agency and KiwiRail

STATEMENT OF EVIDENCE OF IAN KENNETH GRANT BOOTHROYDON BEHALF OF THE GREATER WELLINGTON REGIONAL COUNCIL

AND THE KAPITI COAST DISTRICT COUNCIL

Freshwater Ecology

DATE: 9 August 2013

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INTRODUCTION

1. My name is Ian Kenneth Grant Boothroyd. I am the Team Leader Ecology and

Principal Environmental Scientist at Golder Associates (NZ) Limited, Auckland. I have

over 25 years' experience in aquatic ecology and resource management issues. I hold

the qualifications of BSc (Hons) Zoology (University of Manchester, UK), MSc Applied

Hydrobiology (University of Wales, UK) and DPhil Freshwater Biology (University of

Waikato, NZ).

2. I am a chartered member of the Society of Biology, UK (CBIOL, MBS); and I am a

Certified Environmental Practioner (CEnvP) endorsed by the Environmental Institute of

Australia and New Zealand (EIANZ). I am a member of the Royal Society of New

Zealand (MRSNZ) and the Environmental Institute of Australia and New Zealand

(MEIANZ). I am a past-President of the New Zealand Limnological Society (New

Zealand Freshwater Sciences Society), and a member and former elected-Councillor of

the Royal Society of New Zealand (RSNZ).

3. Previously, I have worked for the University of Auckland (Senior Lecturer, School of

Geography, Geology and Environmental Science), the National Institute of Water and

Atmospheric Research (NIWA) (Project Director), the Hawke’s Bay Regional Council

(Manager Environmental Monitoring), Waikato Regional Council (Environmental

Scientist) and Hauraki Catchment Board (Water Quality Biologist).

4. My areas of expertise are in aquatic ecology and entomology, especially the biodiversity

of freshwaters, assessments of developments on aquatic and terrestrial resources,

assessments of the value and significance of freshwater and terrestrial habitats and

biological communities, biological monitoring of freshwaters, state of the environment

monitoring, and mitigation solutions. I have undertaken ecological surveys and site

assessments throughout New Zealand for the past 25 years.

5. I have experience in working across a range of freshwater resources from large rivers to

small streams and wetlands throughout the North and South Islands.

6. I have undertaken assessments of ecological resources and riparian management

throughout New Zealand. I have led and conducted scientific research on the benefits

of riparian planting to streams and rivers and I have published a number of scientific

papers on the subject of the benefits of riparian planting to aquatic ecosystems

(Boothroyd and Langer (1999); Rowe et al. 2002; Boothroyd et al. 2004; Quinn et al.

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2004). In addition I have co-authored several national protocols for aquatic

management and assessments including instream monitoring (Stark et al. 2000) and

instream habitat assessments (including riparian assessments) (Harding et al. 2009). I

am currently a co-author of a proposed guideline for Ecological Impact Assessments in

New Zealand.

7. I am familiar with frameworks and criteria used for the assessments of the significance

of ecological values and their application to biodiversity management and

enhancement. I have recently provided Court-mediated independent peer review to

matters associated with defining and locating areas of ecological significance in the

Auckland, Wellington, Canterbury and Bay of Plenty regions.

8. My involvement to date in the proposed Peka Peka to North Ōtaki Expressway project

(Expressway or PP2NO) has involved site visits on 17 July 2013 and 9 August 2013,

and a meeting of ecologists on 18 July 2013.

9. I confirm that I have read the code of conduct for expert witnesses contained in part 5 of

the consolidated Environment Court Practice Note 2011. I have complied with it in

preparing my evidence. I confirm that the issues addressed in this statement of

evidence are within my area of expertise. I have not omitted to consider material facts

known to me that might alter or detract from the opinions expressed.

10. I am authorised by the Wellington Regional Council (WRC) and Kāpiti Coast District

Council (District Council) to present this evidence on their behalf.

SCOPE OF EVIDENCE

11. My evidence will address the following matters relating to the potential impacts of the

Expressway on freshwater ecology:

(a) Aquatic ecological investigations;

(b) Assessment of ecological values;

(c) Loss of aquatic habitat through stream diversions, culverting or bridging;

(d) Loss and modifications to wetland habitat;

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(e) Construction effects on native fish and aquatic organisms;

(f) Proposed mitigation measures;

(g) Monitoring; and

(h) Roles and Responsibilities.

EXECUTIVE SUMMARY

12. The construction and operation of the proposed Expressway affects some 23 streams

and rivers and will also result in the loss of a freshwater wetland. In my opinion, the

level of mitigation and ratio of compensation for loss of aquatic habitat from culverts and

diversions is inadequate and does not take into account the potential value of the

waterways.

13. The construction of the proposed Expressway will result in the loss of a wetland. The

proposed mitigation for the loss of the wetland has additional functions (i.e., stormwater

storage). In my opinion the stormwater function and the ecological mitigation function of

wetlands needs to be separated in location, design and maintenance.

14. The proposed turbidity monitoring for the earthworks during construction of the

proposed Expressway is inconsistent with that planned for the MacKays to Peka Peka

Expressway.

15. I make the following recommendations:

(a) I recommend the inclusion of an additional criterion to the proposed

designation consent condition 25 and proposed resource consent condition

G.30 (WRC) as follows:

i) Details of channel formation, substrate, and aquatic habitat features for the purpose of enhancing aquatic ecological function.

(b) I recommend that temporary stream diversions should be concentrated into

periods outside of the peak fish migration period (August to January) and be

subject to the same provisions as for permanent diversions (as detailed and

anticipated in the draft Ecological Management Plan (EMP) (paragraph 12.1;

Appendix A of Mr Turner’s evidence).

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(c) I recommend that the proposed designation condition 25 and proposed

resource consent condition G.30 (WRC) should include an additional condition

referring to temporary causeways.

(d) I recommend that the following condition be added to proposed resource

consent condition G.33:

i) Minimise construction and operational effects arising from temporary causeways on matters such as fish passage, stream habitat and water quality;

(e) I recommend that the design and development of temporary and permanent

diversions and the temporary causeways include a suitably qualified and

experienced aquatic ecologist and this be specified in proposed designation

condition 25(i) and proposed resource consent condition G.30.

(f) I recommend that revised mitigation ratios are applied to the mitigation

calculations at least as:

(i) 3:1 for High aquatic ecological value streams;

(ii) 2:1 for Moderate aquatic ecological value streams; and

(iii) 1:1 for Low aquatic ecological value streams.

(g) I recommend riparian planting of at least 20m either side of the selected

locations for the mitigation of the loss of aquatic habitat.

(h) I find some inconsistency and confusion amongst evidence regarding the

proposed mitigation for the loss of the Ōtaki Railway wetland, and recommend

that mitigation for the loss of wetland is not mixed with a function of stormwater

treatment or storage. Accordingly I recommend that an at least equivalent

area (i.e., same as Kennedy Wetland) of additional wetland be constructed at

Mary Crest for the purpose of ecological mitigation.

(i) I recommend that the turbidity trigger be modified to 20% increase in turbidity

from upstream to downstream in the waterways selected for monitoring and

this should be reflected in the draft EMP and proposed resource consent

conditions.

(j) I recommend that proposed designation condition 76 (District Council) be

rephrased to include: ‘‘The LP shall be prepared by a suitably qualified and

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experienced landscape architect in conjunction with a suitably qualified and

experienced ecologist...’

AQUATIC ECOLOGICAL INVESTIGATIONS

16. The Expressway is a continuation of the Wellington Northern Corridor, which is one of

the seven roads of national significance (RoNS) that were announced as part of the

Government Policy Statement (GPS) on Land Transport Funding in May 2009. The

proposed Expressway is 13 km long and largely follows the existing State Highway 1

(existing SH1). The Expressway traverses four main river catchments (Waitohu

Stream, Mangapouri Stream, Ōtaki River and floodplain and the Mangaone Stream), in

addition to several smaller waterways.

17. Chapter 20 (Part G, Volume 2) of the Assessment of Effects on the Environment for the

Expressway covers Aquatic Ecology, and I have also looked at the chapters on

Hydrology (Chapter 17), Stormwater (Chapter 18) and Terrestrial Ecology (Chapter 19).

I have also reviewed the Aquatic Ecology Technical Report by NIWA (Technical Report

12).

18. The aquatic ecological survey aimed to map and describe the values of aquatic

ecological systems, and to describe the distribution and abundance of aquatic native

flora and fauna that occur along this route. The potential environmental effects to

aquatic systems of both the construction and ongoing operation of the Expressway are

assessed, and measures to mitigate adverse effects are all provided in Technical

Report 12.

19. The Expressway crosses some 23 natural waterways and artificial drains; sampling and

investigations were focused on the 23 waterways that may be affected by the

Expressway. All perennial streams were sampled, although it is not clear to me what

criteria were used to classify waterways as perennial or ephemeral.

20. Ecological sampling was carried out only on the portion of stream deemed affected by

the proposed Expressway. Additional fish surveys were carried out at eight sites

upstream of the existing SH1 along the Ōtaki River, Waitohu Streams and Mangaone

Streams for the purpose of ascertaining the presence of migratory fish in these upper

catchments. I concur with this approach as it provides a more comprehensive

assessment of the ecological values of the full catchments rather than just the sections

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affected by the Expressway. Further information was collated where available from

WRC records.

21. I draw attention to the fish sampling method adopted for the assessment surveys (being

a single pass electric fishing over a 30 m reach), and note that in my opinion it is

preferable to sample for fish species using a variety of methods including electric fishing

but also methods such as spotlighting and netting/trapping which can provide a more

complete assessment of the diversity of the fish communities; reliance only on electric

fishing means that some species can be missed. In addition, standard protocols

emerging1 suggest an alternative reach length (of 100-150 m) for fish surveys.

22. I also note the use of habitat scoring to reflect the habitat value. Whilst I am in general

agreement with the application of habitat scoring protocols, I am cautious of their

interpretation. Although I acknowledge the modified nature of many of the waterways,

in the absence of a suitable reference stream condition (or control site), the suggestion

that the streams impacted by the Expressway have low quality because typically

lowland soft-bottom streams retain low habitat scores needs to be treated with some

caution.

ASSESSMENT OF AQUATIC ECOLOGICAL VALUES OR SIGNIFICANCE

23. In his evidence, Dr Larned outlines the attributes he has used to establish the ecological

value of waterways by:

(a) Physical habitat;

(b) The prevalence of at-risk fish species;

(c) Condition classes for fish and invertebrate communities and water quality;

(d) The prevalence of native forest in the catchment;

(e) The connectivity for migration between the headwaters and the coast; and

(f) Whether the waterway qualifies as a significant indigenous ecosystem (SIE) as

defined in the WRC Regional Policy Statement (RPS).

1

Bruno O David, Mark P Hamer, Kevin J Collier, Mike D Lake, Graham M Surrey, Kate McArthur, Carol Nicholson, Alton Perrie & Matthew Dale (2010): A standardised sampling protocol for robust assessment of reach-scale fish community diversity in wadeable New Zealand streams, New Zealand Journal of Marine and Freshwater Research, 44:3, 177-187

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24. I acknowledge that there are no accepted methods for determining the ecological or

significance of streams but I do note that Policy 23 of the RPS requires that indigenous

ecosystems with significant biodiversity values are those that meet one or more of five

criteria:

(a) representativeness;

(b) rarity;

(c) diversity;

(d) ecological context; or

(e) tangata whenua values.

25. In my opinion, some of the attributes used by Dr Larned meet some of the WRC criteria

while others do not or are in addition to those represented by WRC. Similarly, no

threshold values are provided for condition classes or the prevalence of native bush

within the assessment of values, and clearly no specific tangata whenua values have

been considered.

26. It is important to note that these valuations are based on the sites assessed (being

those affected by the proposed Expressway), and do not necessarily reflect the value of

the respective stream systems. In my opinion it would be helpful to see also a

classification for the catchment systems.

27. Nevertheless, in my view, the attributes used by Dr Larned are acceptable for

distinguishing ecological values and in my opinion, the ecological values applied to the

waterways affected by the Expressway (as detailed in Table 2 of the evidence of

Dr Larned) represent a sensible continuum of aquatic values and reflect the significance

of these waterways in the Kāpiti Coast District. These same groupings are likely to

have occurred using any range of attributes.

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EFFECTS OF THE EXPRESSWAY ON AQUATIC ECOSYSTEMS

28. The effects of the Expressway on the aquatic ecosystems are described in Chapter 20

(Part G, Volume 2) of the application for resource consents and in the evidence of

Dr Larned as:

(a) Temporary effects of construction activities on water quality and habitat;

(b) Impaired fish and invertebrate migration due to culverts;

(c) Effects of road runoff on water quality and channel erosion;

(d) Loss and alteration of habitat in waterways; and

(e) Loss and alteration of habitat in the Railway wetland.

29. The identified effects listed above are a mix of the effects of construction and operation

of the Expressway on the aquatic ecosystems. Nevertheless I concur with the list of

effects. It is not my intention to detail all the effects that might occur but I will draw

attention to those that I consider require specific attention.

Effects of construction activities

30. In his evidence, Mr Holmes states that the construction of the Expressway involves

earthworks of some 800,000 m3. In the absence of erosion and sediment control there

will be adverse effects on the aquatic ecosystems.

31. In paragraph 33 of his evidence, Mr Bird explains that sediment generation has been

estimated using the Universal Soil Loss Equation, and goes on to state that this

technique is not designed to estimate soil loss from large earthworks projects but is a

useful comparative tool for identifying sediment hot spots where adverse effects may

arise.

32. Dr Larned then bases his assessment of the risk of generation of sediments that may

affect the ecological values of waterways on sediment yield estimated by the empirical

model used by Mr Bird. The risk is estimated as a percentage increase above

background yield estimates and range from < 0.1% to 79.8% above background. In

paragraphs 53 and 54 of his evidence Dr Larned states that for 17 out of 21 catchments

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crossed by the Expressway, sediment yield due to construction is low (<0.1% to 13.8%

above background); and in four catchments yields are expected to range from 22% to

79.8% above background).

33. Dr Larned goes on to state (paragraph 53 of his evidence) that the catchments of

waterways with high ecological value are predicted to have low construction sediment

yields.

34. Despite these assurances, I have some difficulty in relying on such a coarse filter for

assessing the risk of sediment. I am unfamiliar with the model used (the Universal Soil

Loss Equation) and I cannot ascertain what assumptions were made in predicting the

background and predicted yields; nor the limitations of the model.

35. I also note that no reference is made in evidence to the sediment type, the transport

and distribution of sediment, and the settlement characteristics of the sediment; and

how these characteristics might interact within the different types of streams. For

example, soils that contain large amounts of clay or colloidal material stay in

suspension longer and can affect the clarity of the water whereas sandy soils, being

larger particles, deposit rapidly onto the stream bed.

36. It is not clear to me how the sediment generated will behave within the respective

waterways and the likelihood of localised or downstream effects of increased turbidity or

increased deposition are not clearly stated.

Ōtaki Railway Wetland

37. In their evidence, Dr Larned and Mr Turner both reference that the 0.8 ha ‘Ōtaki

Railway wetland’ will be affected by the Expressway. Mr Turner considers that the

wetland has been modified through a range of human activities as well as a highly

modified catchment. Nevertheless, Mr Turner goes on to recognize that the wetland

has a diverse range of native vegetation.

38. Although in his evidence, Mr Turner identifies that only 0.5 ha of the wetland will be

removed, Mr Bird, in his evidence, states that due to the extent of the wetland which will

be impacted “it may not be practicable to preserve the remnant portion during

construction”. Mr Bird identifies that the hydrology of any wetland habitat remaining

after construction of the Expressway will be significantly compromised during

construction.

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39. Therefore I remain cautious of the fact that any remnant of the Ōtaki Railway wetland

will be retained. Due to this uncertainty the overall mitigation proposed for the loss of

Ōtaki Railway wetland (i.e., Kennedy Wetland and wetland at Mary Crest) should be

increased to reflect the possibility that the remnant may not occur.

40. Although in Chapter 20 (Part G, Volume 2) of the application for resource consents it is

stated that the Ōtaki Railway wetland (or parts of it) may have resulted from

excavations (perhaps to drain the surrounding wetland) it is a significant wetland within

Kāpiti Coast District and the Wellington Region. Terrestrial and aquatic plants, fish and

aquatic invertebrates were surveyed as part of the application, but I note that a

comprehensive survey of wetland birds was not undertaken. Even though it is a small

wetland, it is highly likely the wetland will provide habitat for indigenous wetland bird

species, and as part of a corridor for the movements of wetland birds within the region.

41. In my opinion the loss of the wetland is a highly significant impact resulting from the

construction of the Expressway. I discuss the mitigation for the loss of the wetland later

in my evidence.

LOSS OF AQUATIC HABITAT

42. In paragraph 85 of his evidence Dr Larned describes the type and extent of loss of

aquatic habitat through the installation of culverts, concrete aprons and rip-rap, by

channel diversions and by the loss of the Ōtaki Railway Wetland. In paragraph 88 of

his evidence, Dr Larned states that total length of waterway disturbed through these

measures is 2,734 m of stream length.

43. In paragraphs 73 and 74 of his evidence, Mr Holmes describes additional stream works:

proposed temporary causeways and temporary culverts respectively.

Culverts

44. It is my understanding that total length of 1,214 m of new culverts (24 new culverts

ranging in length from 16 to 120 m in length) will be required for the construction of the

Expressway. Six of these new culverts will be constructed to function as water and

flood conveyance only with no provision for fish passage. It is my understanding that

these culverts occur in waterways with low ecological values and comprising largely

intermittent, often channelised waterways or swales within paddocks. I note that some

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of the lengthier stretches of disturbed habitat occur in waterways with moderate

ecological values (Kumutoto, Jewel and Settlement Heights Streams).

45. In paragraph 132 of his evidence, Dr Larned indicates that the culverts will be designed

to meet the requirements for the passage of fish. The objective is to enable the

passage of both swimming (weak climbing ability) fish (e.g., inanga) as well as fish with

a strong climbing ability (e.g., eels and kokopu). I concur with this approach.

Stream diversions

46. It is my understanding that some 1,150 m of stream length will be lost to new stream

diversions (Annexure D of Dr Larned’s evidence). As stated in paragraph 79 of

Dr Larned’s evidence, all permanent diversions replace paragraphs of intermittent

waterways, drains and swales that currently have low ecological values.

47. Nevertheless, it is not clear how the stream diversions will be constructed, what aquatic

ecological values are expected to be either replicated or enhanced within the

diversions, and it is not clear what post-construction monitoring of these diversions is

planned. I note that in section 12 of the draft EMP it is stated that matching existing

channel complexity at sites of permanent stream diversions is not required as the

existing channels do not have such features. I do not agree with this statement.

48. In my experience, the addition of simple channel features such as meanders, shallow

gradients and deeper pools, along with riparian planting (which is occurring) can

substantially enhance the aquatic values of a waterway.

49. At the very least I would expect that all permanent diversions will reflect a no-net loss of

ecological condition and value but enhancements to improve stream condition are also

warranted in the planned Site-specific Environmental Management Plan (SSEMP) and

this should be required by conditions.

50. Accordingly I recommend the inclusion of an additional criterion to the proposed

designation condition 25 and proposed resource consent condition G.30 (WRC) as

follows:

ii) Details of channel formation, substrate, and aquatic habitat features for the purpose of enhancing aquatic ecological function.

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Temporary stream diversions

51. In the indicative SSEMP provided as Appendix A of Mr Holmes' evidence I note that

reference is made to temporary diversions that will be required for the installation of

new culverts. Similar reference to temporary stream diversions is made in Chapter 20

(Part G, Volume 2) where reference is made to the provision of fish passage around in-

stream works in permanent and near-permanent streams.

52. I recommend that such instream works requiring temporary stream diversions should be

concentrated into periods outside of the peak fish migration period (August to January)

and be subject to the same provisions as for permanent diversions (as detailed and

anticipated in the EMP (paragraph 12.1; Appendix A of Mr Turner’s evidence).

Temporary causeways

53. In paragraph 73 of his evidence, Mr Holmes makes reference to proposed temporary

causeways for the construction of Bridge 1 (the Waitohu Stream bridge) and Bridge 5

(the Ōtaki River bridge). I found no further reference to the structures in the application

or evidence, and sketches were not available to me at the time of the preparation of my

evidence.

54. From the evidence of Mr Holmes it appears that the expectation is that the causeway

will be constructed from one bank by end tipping river-won clean crushed rock to

provide a working platform from which the piling equipment can be driven into the river

substrate. I note that both bridges appear to be similar in design and are parallel bridge

structures.

55. Causeways constructed into and across waterways can have significant effects on

aquatic habitat and aquatic ecosystems. Although a small area, clearly some in-stream

habitat is temporarily lost to the causeway. Depending on the seasonal timing and

length of time the causeway is in place, I do not consider that the loss of temporary

habitat is a significant effect to the aquatic ecosystems. During periods of low flow

when river waters recede from the margins, the intrusion of the causeway may result in

a proportionally greater loss of instream habitat.

56. However, I am concerned about the intrusion of the causeway into and across the

waterway. The causeway will have a significant influence on the river flow which will be

diverted around the structure (either naturally or engineered as part of the temporary

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causeway). Alterations to flow may have implications to other parts of the river both

across the river and immediately downstream, particularly through scouring of the

stream bed and concentration of flood flows.

57. In addition, the causeways and the bridge construction are likely to result in additional

sediment intrusions into the waterway. This concern is in part generated by the nature

of the development of the causeway and its stability.

58. I recommend a resource consent condition that such instream works requiring

temporary stream causeways should be concentrated into periods outside of the peak

fish migration period (August to January) or appropriate temporary fish bypass diversion

channels be erected to ensure that the unimpeded passage of juvenile fish past the

causeways can occur.

59. I note that Mr Holmes suggests that the relevant SSEMPs relating to each of the

bridges will contain further details of the use and management of these causeways,

which will be submitted to the WRC prior to commencement of any work.

60. I note that proposed designation condition 25 and proposed resource consent condition

G.30 (WRC) relating to the content of SSEMPs, while referring to stream realignment

and culverting, does not make reference to the inclusion of causeways.

61. In my opinion the proposed designation condition 25 and proposed resource consent

condition G.30 (WRC) should include an additional requirement as follows:

‘In respect of temporary causeways:

iii) A suitably qualified and experienced aquatic ecologist be engaged in the design and development of the temporary causeway;

iv) Measures/methods to maintain fish passage during and following completion of construction works along the stretches of stream affected by the exercise of this consent;

v) Specific consideration to avoid periods of seasonal migration of native fish;

vi) Details of causeway design, structure and extent;

vii) Details of source, location, method of extraction, washings, and compaction of material to be used to build the causeway;

viii) Details of sediment management resulting from the extraction of source material, build and operation of the causeway;

ix) Confirmation of appropriate sizing of causeway and allowances for flow paths during high flows;

x) Detailed diversion plans and any other measures or details as appropriate to achieve compliance with all conditions of this consent and the objectives of the relevant management plans;

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xi) Confirmation that placement of material in the wetted channel will be clean-wash river source material, and the time spent by machinery in the wetted channel, including the number of vehicle crossings, will be minimised; and

xii) Confirmation that any excess material resulting from the causeway will be removed immediately on completion of the work;

62. In addition I recommend that the following condition be added to proposed resource

consent condition G.33:

ii) Minimise construction and operational effects arising from temporary causeways on matters such as fish passage, stream habitat and water quality;

Fish rescue and relocation

63. I note that the draft EMP (paragraph 7) includes reference to the development of a Fish

Rescue and Relocation Plan to be developed by a suitably qualified fish biologist to

guide all work in any permanent or intermittent water body that is to be diverted or

reclaimed, and a requirement for final approval by WRC. I concur with this approach

but note that permits are required from the Department of Conservation for the

relocation of fish and this provision should be included within paragraph 7 of the EMP

(Appendix A of Mr Turner’s evidence).

Roles and responsibilities

64. I recommend that the design and development of temporary and permanent diversions

and the temporary causeways include a suitably qualified and experienced aquatic

ecologist and this be specified in proposed designation condition 25(i) and proposed

resource consent condition G.30 (WRC).

MITIGATION

Mitigation ratios

65. The purpose of the offset mitigation proposal is to mitigate the effects of the

Expressway on aquatic ecological values. Ecological offsetting has been applied widely

in New Zealand in resource management through such measures as re-planting of

riparian vegetation or pest and weed control to enhance ecological values. The extent

of offsetting has largely been derived using expert judgement or from negotiated

settlements. To date, there has been little emphasis on generating regionally or

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nationally consistent outcomes, or even outcomes that assure full replacement of the

scale or type of ecological values lost.

66. One of the full replacement ecology approaches used in New Zealand is the Stream

Ecological Valuation method (SEV)2. The SEV results in a score that measures the

site's ecological functional value (from 16 assessed attributes) and from that calculates

the number of 'ecological units' that represent the residual, unavoidable impact of the

development (e.g., loss of habitat). The ecological units are then increased by a

multiplier to account for (usually) the time lag between loss of values at the

development site and full replacement at the offset site, which for most ecological

values takes several years to achieve.

67. It is my understanding that the WRC have ‘adopted’ the use of the SEV for stream loss

mitigation, at least in practice (as it is not required by any plan rule). The SEV approach

as used for calculating offset mitigation in applications for resource consents for both

the Transmission Gully and the MacKays to Peka Peka Expressway projects.

68. In paragraph 89 of his evidence, Dr Larned describes the approach to the mitigation for

waterway habitat loss. In this case, Dr Larned does not use the SEV approach; rather

Dr Larned uses a simple approach to evaluate the offset mitigation requirements using:

(a) The ecological value classes;

(b) The length of new waterway works (the sum of new works rather than the sum

of waterway lost); and

(c) Environmental offset mitigation ratios.

69. I note that Dr Larned utilises the total length of all new waterway works (2,834 m) rather

than the length of existing waterway affected by the new works to calculate the offset

mitigation. This is somewhat atypical but regardless I note that Mr Bird in his evidence

clarifies that some 2,552 m of waterway is actually affected by new works. As the offset

mitigation calculation is based on the longer stream length there is additional benefit to

the mitigation package.

2

Storey, R.G., Neale, M.W., Rowe, D.K., Collier, K.J., Hatton, C., Joy, M.K., Maxted, J., R., Moore, S., Parkyn, S.M., Phillips, N. and Quinn, J.M. (2011) Stream Ecological Valuation (SEV): a method for assessing the ecological function of Auckland streams. Auckland Council Technical Report 2011/009.

Page 17

70. In paragraph 91 of his evidence, Dr Larned states that rip-rap and rock can provide

beneficial habitat especially in the soft-bottom waterways that dominate in the area. I

am not convinced that this is a significant benefit to the streams in this region and I note

that Dr Larned includes these areas as part of the stream modification. I agree that rip-

rap and rock are modifications to waterways and for the purposes of calculating

mitigation is a loss of stream habitat.

71. In paragraph 95 of his evidence Dr Larned has suggested offset mitigation ratios as

follows:

(a) 2:1 for High aquatic ecological value streams;

(b) 1.5:1 for Moderate aquatic ecological value streams; and

(c) 0.7:1 for Low aquatic ecological value streams.

72. Dr Larned goes on to describe the rationale for these ratios is that the uncertainty of

offset mitigation increases with the ecological value of the waterway (i.e., a greater

length of stream mitigation is required on a lower quality waterway to achieve a higher

ecological value).

73. I also note that Dr Larned has excluded the Ōtaki River and Waitohu Stream from any

mitigation calculations because habitat loss is expected to be negligible in these

waterways. I note that for the Mackays to Peka Peka Expressway application, bridge

crossings were included due to the effects of bank armouring required to stabilise the

channel beneath the bridge span. My understanding is that this is not occurring for the

Ōtaki River and Waitohu Stream bridges and I concur with Dr Larned’s view that habitat

loss will be negligible and therefore excluded from mitigation calculations.

74. In paragraph 136 of his evidence, Dr Larned describes how he has applied professional

judgement in determining the mitigation offset ratios, and goes on to say that there are

no currently accepted models for scientifically determining ecological value and offset

mitigation ratios for intermittent waterways. Whilst this is true, it is worth noting that a

number of principles have been incorporated into the SEV approach (for permanent

streams):

(a) Any ratio <1 defaults to a ratio of 1;

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(b) A minimum replacement length equal to stream length lost; and

(c) Inclusion of potential value of the waterways in calculating mitigation.

75. In keeping with these principles, I support a mitigation ratio of 1:1 as a minimum

especially as applied to intermittent streams; Dr Larned has set a mitigation ratio of

0.7:1. Furthermore, it is my understanding that for the Mackays to Peka Peka

Expressway significantly greater ratios were applied to loss of stream habitat: ratios

ranged from 0.92 to 3.6. For the loss of wetland a mitigation of 3:1 was proposed. The

final mitigation package varied following expert conferencing amongst the ecologists.

76. I also consider that in the absence of other features to discount it, the potential future

value or condition of a waterway is an important component of the offset mitigation

calculations that I do not see clearly in the ratios established by Dr Larned.

77. For these reasons I remain unconvinced that the appropriate mitigation ratios have

been applied to the offset mitigation. In my opinion, taking into account the principles of

the SEV application (as was applied to the Mackays to Peka Peka Expressway) the

mitigation ratios could be greater than those suggested.

78. My experience of calculating mitigation ratios for the loss of stream habitat suggest that

ratios of 3:1 are commonly calculated using SEVs for the loss waterways of good

ecological value, and greater if the stream to be mitigated is of poorer value.

79. In my opinion, and from my experience of mitigation for loss of stream habitat, the

mitigation ratios for the loss of stream habitat resulting from the construction of the

Expressway (aligned as presented by Dr Larned) should be at least:

(a) 3:1 for High aquatic ecological value streams;

(b) 2:1 for Moderate aquatic ecological value streams; and

(c) 1:1 for Low aquatic ecological value streams.

Mitigation by Riparian Planting

80. As Dr Larned states in paragraph 98 of his evidence, the creation or enhancement of

riparian buffers or margins alongside waterways is one of the most common and

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practical forms of offset mitigation for the loss of stream habitat. This is because in

most circumstances the planting of riparian margins generally provides value to the

instream habitat and quality such that instream ecological values improve.

Width of riparian planting (environmental enhancement, protection or restoration)

81. One of the most frequently asked questions about riparian areas is ‘How wide should a

riparian area be?’ It is well recognised that there is an economic cost to assigning a

width to a riparian area and I understand the difficulties in establishing an appropriate

area for riparian planting. There is no single answer to this question, and in most cases

it will depend on the expected purpose or objectives of the riparian area and what the

expectations are for the waterway and/or associated terrestrial environment.

82. In paragraph 100 of his evidence Dr Larned supports a 20 m width of riparian planting

(20m on each side of the waterway) in order to deliver significant ecological benefits to

the aquatic environment. I concur with this statement and recommend riparian planting

of at least 20m either side of the selected locations for the mitigation of the loss of

aquatic habitat.

Longitudinal length of riparian planting (environmental enhancement, protection or

restoration)

83. A much less frequently asked question about ecological corridors or riparian areas is

‘How long should a riparian area be?’ As discussed above in relation to the width of

riparian management areas, it is well recognised that there is an economic cost to

assigning a length to a riparian area.

84. Again, as for the question of width of riparian planting, there is no single answer to this

question, and in most cases it will depend on such matters as the expected purpose or

objectives of the riparian area, the topography of the land, the availability of land

upstream or downstream and what the expectations are for the waterway and/or

associated terrestrial environment.

85. In my opinion, research suggests that something in the order of 250 m to

350 m is an appropriate minimum length to achieve environmental benefit to

ecosystems.

86. I note that in Table 4 of his evidence, Dr Larned recommends riparian buffer lengths

that are for the most part quite substantive in length and I concur with this approach to

riparian planting.

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Connectivity of riparian planting (environmental enhancement, protection or restoration)

87. Connectivity in ecosystems is a multidimensional phenomenon and occurs laterally

(terrestrial environments alongside streams), vertically (root area to vegetation canopy),

and longitudinally (riparian and terrestrial environments up and down streams).

88. As I have stated in my evidence above, one of the benefits from mitigating for the loss

of stream habitat by riparian planting is extending the longitudinal length of riparian

enhancement along the stream length.

89. Similarly, in my opinion, greater mitigation benefit is achieved through encouraging a

greater mitigation effort at fewer locations. The purpose of such a strategy is to prevent

fragmentation of the mitigation effort into small pockets scattered across the landscape.

90. In paragraph 104 of his evidence, Dr Larned states that the offset mitigation focuses on

creating wide and long riparian buffers in a small number of waterways. I concur with

this approach and note that it is consistent with mitigation strategies agreed for the

Transmission Gully Project and the proposed Mackays to Peka Peka Expressway.

Mitigation for the loss of the Ōtaki Railway Wetland

91. It is my understanding that the proposed mitigation for loss of Ōtaki Railway wetland is

the creation of two wetland areas, one at Ōtaki (Kennedy Wetland) and one at Mary

Crest.

92. I have noticed some inconsistency and confusion amongst evidence regarding the

proposed mitigation for the loss of the Ōtaki Railway wetland.

93. In paragraph 82 of his evidence, Dr Webby confirms that the existing Ōtaki Railway

Wetland will be partially reduced in area (from 0.8ha to 0.3ha). However, Dr Webby

goes on to say: ‘to compensate for this loss of wetland storage area for attenuating

stormwater runoff from the Te Manuao Catchment, it is proposed to construct a second

wetland area in the series using the vacant space between the existing railway

embankment and the proposed expressway embankment to the north of Mangapouri

Stream....The two wetlands will be connected by a long pipe while the primary outlet

from the second wetland to the Mangapouri Stream will be a shorter pipe’. Dr Webby

goes on to refer to this wetland as ‘the wetland storage pond’.

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94. The sequence of proposed wetlands is shown as Figure 9b in Annexure C of

Dr Webby’s evidence, where it refers clearly to the ‘Rail Wetland Remnant’ and

‘Kennedy Wet Land’ respectively.

95. In paragraph 106 of his evidence, Mr Bird states that the remnant Ōtaki Railway

Wetland will indeed receive runoff from the Expressway, although mostly treated in

swales prior to discharge to the proposed remnant area.

96. I note that Mr Bird also states that runoff from a small length of Expressway is currently

proposed to discharge direct to the proposed remnant Ōtaki Railway Wetland but could

be directed to the drainage system on the opposite side of the Expressway. I suggest

that neither of these is desirable if the discharge of stormwater is prior to any form of

treatment.

97. Although in paragraph 107 of his evidence, Mr Bird states that Kennedy Wetland is

proposed as mitigation for the loss of the Ōtaki Railway Wetland, and states that no

direct Expressway runoff will enter Kennedy Wetland, I note that nevertheless, Kennedy

Wetland does form part of the sequence of stormwater storage ponds alongside the

Expressway.

98. My interpretation of the evidence of Dr Webby is that these wetlands provide for the

storage of stormwater, and the enhancement of storage of stormwater as a

consequence of the modifications from the construction of the Expressway.

99. On the other hand, in paragraph 49 of his evidence, Mr Bird discusses the need for

‘clean’ water from the Te Manuao catchment to be piped around the works (and

whether this is permanent or temporary). I am uncertain what clean water this entails,

and whether that is non-construction water (i.e., free of sediments) or non-stormwater-

derived water (from some other part of the catchment). If the latter is applicable then I

am uncertain where stormwater from the urbanised part of the Te Manuao catchment

will be discharged and/or stored.

100. I raise this issue because whereas the proposed Kennedy Wetland (second wetland in

the sequence) is proposed as part mitigation for the loss of a large area of the Ōtaki

Railway Wetland, it appears that the proposed wetland may have a primary stormwater

storage function. In my opinion, and as much as is possible, any mitigation for the loss

of aquatic ecosystems must have a primary ecological purpose; this is consistent with

approaches taken for the Transmission Gully and the Mackays to Peka Peka

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Expressway, as well as a no net loss policy. Even though a stormwater wetland can

provide ecological function, its design, function and maintenance will always take

another priority other than ecological.

101. I recommend that the resource consent conditions reflect the primary ecological

purpose of ‘Kennedy wetland’ with stated objectives and monitoring accordingly. I am

cautious of accepting that stormwater treatment wetlands and their connections to

waterways form part of mitigation. Whilst I acknowledge that some treatment from

swales has been afforded to stormwater runoff, my understanding is that these storage

wetlands are requirements as best practice for the minimisation of potential stormwater

quality impacts of the waterways and in my opinion do not form part of mitigation for

loss of ecological values.

102. I also note that, in my opinion, and in that of Ms Myers, there is sufficient opportunity to

create additional wetland area for the mitigation of the loss of Ōtaki Railway Wetland at

Mary Crest. The benefit of additional wetland creation in this area is that it has no

connection to stormwater management or storage and in that case is true primary

purpose mitigation for ecological function.

103. I also note that in the reference to the outlet pipe from proposed Kennedy Wetland to

the Mangapouri Stream, no reference is made to passage for fish. Eels occur in the

existing Ōtaki Railway Wetland and I recommend that appropriate provision for fish

passage (at least for fish with climbing ability) be included in the resource consent

conditions.

MONITORING

104. In paragraphs 60 to 70 his evidence, Dr Larned proposes a monitoring programme to

assess the effects of the construction of the Expressway on waterways. Proposed

monitoring is also set out in paragraph 8 of the proposed EMP (Appendix A of

Mr Turner’s evidence).

105. I agree that monitoring of the effects and the mitigation is necessary and should be

detailed in consent conditions and respective plans.

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Turbidity trigger levels

106. I note that Dr Larned has suggested a 50% difference in turbidity between upstream

and downstream monitoring sites as the trigger level for turbidity monitoring as part of

the monitoring programme (when the downstream turbidity exceeds 5 NTU). In the

EMP (paragraph 8.2.2) the 50% is regarded as an ‘indicative’ trigger until the pre-

construction monitoring is complete. I note that proposed resource consent condition

G.42 (WRC) reflects this provisional trigger level for the Ōtaki River and Waitohu

Stream. I also note that 50% trigger is accepted for the Mangapouri and Mangaone

Streams and chosen intermittent waterway (proposed resource consent G.42 (WRC).

107. In paragraph 64 of his evidence, Dr Larned acknowledges that the proposed 50%

trigger level differs from monitoring trigger levels established for the Mackays to Peka

Peka Expressway (where a 20% increase from upstream to downstream turbidity levels

was agreed and established). Dr Larned sets out his reasons for recommending a 50%

trigger in his evidence.

108. Although I acknowledge Dr Larned’s comments about ‘false alarms’ of turbidity being

triggered, I remain of the opinion that the lower 20% trigger level should be retained for

the PP2NO Expressway, and that proposed resource consent condition G.42 (WRC)

should be modified to reflect a 20% trigger level and replace the 50% trigger level.

109. My reasons for recommending this change are that:

(a) the sediment generation is based on the USLE model (the assumptions and

limitations of which are not clearly stated); and

(b) there is a lack of information of the likely sediment types that may enter the

waterways and their likely behaviour within the waterways and the current

level of details of the management of sediments.

110. I note that in paragraph 65 of his evidence, Dr Larned acknowledges that by using a

higher trigger level (i.e., 50%) there is a higher risk of undetected suspended sediment

entering the rivers. In my opinion, in the higher and moderate ecological value

waterways, this risk is unacceptable, especially given the extent of earthworks required

for the construction of the Expressway, and the importance of the waterway features

within the region and district.

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111. Furthermore, I also note that following a trigger event the level of response commences

at a low level (i.e., visual audit), escalating only as the breach of the trigger level

continues. I consider that this slow escalation of response to be appropriate to a lower

trigger level (i.e., 20%); and a higher entry level of response will be required for a higher

trigger level (i.e., 50%).

112. Accordingly, in my opinion, the proposed resource consent condition G.42 (WRC)

should be modified to replace the 50% trigger level with a 20% trigger level consistent

with the proposed Mackays to Peka Peka Expressway and the draft EMP will need to

be updated to reflect this change.

Settled sediment

113. In paragraph 8.2.2 of the draft EMP (Appendix A of Mr Turner’s evidence), reference is

made to the monitoring of ‘settled sediment’. Settled sediment refers to the deposition

of fine and coarse grained sediments on the substrate or benthos of waterways. As

outlined above in my evidence, settled sediment can have significant effects on aquatic

ecosystems.

114. Monitoring of settled sediment is included in proposed resource consent condition

G.41 b). I endorse the inclusion of settled sediment monitoring in condition G.41.

115. I also endorse the proposed methods for monitoring fine and coarse sediments as set

out in paragraph 8.2.2 of the EMP.

ROLES AND RESPONSIBILITIES

116. My understanding of the proposed resource consent conditions is that the

implementation of the mitigation and monitoring is expected be detailed via a series of

management plans (e.g., EMP, Landscape Plan) and reference is made to preparation

with inputs from suitably qualified specialists (proposed designation condition 23b(i) and

proposed resource consent condition G.28(i). I concur with this approach.

117. However, I am concerned that there is insufficient input from a suitably qualified and

experienced ecologist at the design and implementation stage(s) as well as the

response to any contingencies that may be required should mitigation not reach its

required objectives.

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118. For example, proposed designation condition 76 refers to ‘The LP shall be prepared by

a suitably qualified and experienced landscape architect...’ I note that no reference is

made to working with a suitably qualified and experienced ecologist (nor other

disciplines) in implementing the landscape planting.

119. In my opinion it is very important to clearly distinguish the ecological mitigation (which is

typically specific vegetation planting to achieve specific ecological outcomes) from

landscape planting (which is typically specific vegetation planting to achieve specific

landscape outcomes). This may seem obvious and readily apparent but in my view the

separation can get ‘confused’ or even ‘lost’ as the detail within respective management

and design plans emerges.

120. I have seen how areas identified for ecological mitigation can become multipurpose and

the vegetation planting plan may change with the result that the planned ecological

objectives are not met or are diluted. This especially often occurs where landscape,

stormwater/flood management and ecological mitigation interconnect. I do understand

that such juxtapositions are unavoidable and are likely to emerge during detailed design

stages of the proposed Expressway.

121. Therefore, I recommend that proposed designation condition 76 be rephrased to include

"The LP shall be prepared by suitably qualified and experienced landscape architect in

conjunction with a suitably qualified and experienced ecologist..."

CONCLUSIONS AND RECOMMENDATIONS

122. My conclusions and recommendations are set out above in my Executive Summary.

Ian Kenneth Grant Boothroyd9 August 2013