Barristers and Solicitors Wellington Solicitors Acting: Paul Beverley / David Randal Email: [email protected]Tel 64-4-499 4242 Fax 64-4-499 4141 PO Box 2694 DX SP20201 Wellington 6140 BEFORE A BOARD OF INQUIRY PEKA PEKA TO NORTH ŌTAKI EXPRESSWAY PROJECT In the matter of the Resource Management Act 1991 And In the matter of a notice of requirement and resource consent applications by the NZ Transport Agency for the Peka Peka to North Ōtaki Expressway Project And In the matter of a notice of requirement by New Zealand Railways Corporation / KiwiRail Holdings Limited (trading as KiwiRail) for the realignment of a section of the North Island Main Trunk railway line through Ōtaki STATEMENT OF EVIDENCE OF SCOTT THOMAS LARNED (AQUATIC ECOLOGY) ON BEHALF OF THE APPLICANTS 12 July 2013
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Barristers and Solicitors Wellington Solicitors Acting: Paul Beverley / David Randal Email: [email protected] Tel 64-4-499 4242 Fax 64-4-499 4141 PO Box 2694 DX SP20201 Wellington 6140
BEFORE A BOARD OF INQUIRY PEKA PEKA TO NORTH ŌTAKI EXPRESSWAY PROJECT
In the matter of the Resource Management Act 1991
And
In the matter of a notice of requirement and resource consent
applications by the NZ Transport Agency for the
Peka Peka to North Ōtaki Expressway Project
And
In the matter of a notice of requirement by New Zealand
Railways Corporation / KiwiRail Holdings Limited
(trading as KiwiRail) for the realignment of a
section of the North Island Main Trunk railway line
through Ōtaki
STATEMENT OF EVIDENCE OF SCOTT THOMAS LARNED (AQUATIC ECOLOGY) ON BEHALF OF THE APPLICANTS
12 July 2013
Page 1
TABLE OF CONTENTS
QUALIFICATIONS AND EXPERIENCE.................................................................... 2
BACKGROUND AND ROLE ..................................................................................... 2
SCOPE OF EVIDENCE ............................................................................................ 3
91. Rip-rap and rock armouring can provide beneficial habitat for fish, invertebrates, algae
and bryophytes. This is especially so for the soft bottomed waterways that
predominate in the Project area. Therefore, although included within the total length
of waterway mitigation required, this is a conservative approach due to the potential
aquatic ecology benefits that hard substrate can provide.
92. As can be seen from Annexure C, the ecological values were identified using multiple
ecological criteria including:
(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) connectivity for migration between the headwaters and coast; and
(f) whether the waterway qualifies as a SIE as defined by the RPS.
93. These criteria were used without weighting to group waterways into the ecological
value categories in Table 2 and to support the proposed mitigation ratios and riparian
planting lengths. In my opinion, this approach is appropriate, transparent and robust.
As explained above, the mitigation approach I have taken utilised the total length of all
new waterway works (culverts, permanent diversions and rip-rap) rather than the
length of existing waterway affected. The evidence of Mr Bird, in response to issues
raised by the GWRC, sets out the length of existing waterways affected by the Project
as 2,552 m, which is less than the 2,834 m length of the new waterway works I used.
94. In completing my evidence two errors in the calculation of the required mitigation
lengths have been identified. These are:
(a) A 110-m diversion in the Settlement Heights catchment was inadvertently
attributed in Technical Report 12 to the moderate ecological-value Settlement
Heights Stream rather than to an unnamed, low ecological-value farm drain that
joins Settlement Heights Stream at SH1 (Table 2). I can confirm that the
unnamed drain will be permanently diverted, not Settlement Heights Stream.
This error resulted in an additional 88 m of riparian mitigation being proposed.
This is a small additional length and I have recommended that it is retained in
the present proposed mitigation length of 2,601 m (which exceeds the total
length of waterway affected by the Project). Therefore, Annexure D and Table
2 This mitigation length is 100 m longer than set out in Annexure C (2,734 m) due to an error in Appendix 10D to
the Stormwater Technical Report 10, as explained in the evidence of Mr Bird. The total disturbed length of the Racecourse stream was initially calculated at 220 m rather than 120 m.
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3 keep the same distances and mitigation requirements as in Technical Report
12 but I have footnoted the correct reference to the unnamed northern tributary.
(b) The calculation of the length of disturbed waterway in Appendix 10D of
Technical Report 10 contained an error in the length of the Racecourse Stream.
The measurement should have been 120 m rather than 220 m. This error
resulted in an additional 77 m of riparian mitigation being proposed. This also is
a small additional length and I have recommended that it is retained in the
present proposed mitigation length of 2,601 m (which exceeds the total length
of waterway affected by the Project). In my opinion this length should be
retained. Therefore, while the lengths disturbed for the Racecourse culvert in
Annexure D and Table 3 have been corrected to 120m, the proposed length of
offset mitigation in Table 3 has kept the same distance as in Technical Report
12 (154 m). The cumulative effect of the two errors listed here (for the
Settlement Heights tributary and Racecourse Stream) is the addition of 165m of
riparian planting on both banks to the mitigation proposal.
Table 3. Linear mitigation requirements based on total lengths of new waterway works (total
disturbed) in the Project area.
Waterway Ecological
value
Compensation
ratio
Total
disturbed (m)
Mitigation
required (m)
Mangaone Stream High 2 115 230
Mangapouri Stream at
Expressway Moderate 1.5 160 240
Settlement Heights Stream3 Moderate 1.5 170 255
Jewell Stream Moderate 1.5 140 210
Kumototo Stream Moderate 1.5 115 172.5
Greenwood Stream Low 0.7 55 38.5
Waitohu Tributary Stream Low 0.7 60 42
Racecourse Stream Low 0.7 120 1544
Te Roto Stream Low 0.7 65 45.5
Railway Wetland Low 0.7 95 66.5
Kennedy Wetland Low 0.7 20 14
Mangaone Overflow Low 0.7 66 46.2
School Stream at Link road Low 0.7 520 364
Gear Stream at Gear Road Low 0.7 240 168
Coolen Stream Low 0.7 44 30.8
Avatar Stream Low 0.7 64 44.8
Edwin Stream Low 0.7 200 140
3 As explained in paragraph 94(a) mitigation for the 110m diversion was calculated using the moderate-value
Settlement Heights Stream, but the diversion will actually affect a low value, intermittent, unnamed tributary. This error resulted in an additional 88 m (255 m proposed instead of 167 m) of riparian mitigation planting. 4 As explained in paragraph 94(b) this mitigation length is 77 m longer due to an error in Appendix 10D to the
Stormwater Technical Report 10, as explained in the evidence of Mr Bird. The total disturbed length of the Racecourse stream was initially calculated at 220 m rather than 120 m.
Page 22
Cavallo Stream Low 0.7 320 224
Cording Stream Low 0.7 75 52.5
Awatea Stream Low 0.7 90 63
Total 2734 2601
95. In my view it is appropriate to apply offset mitigation ratios of 2:1, 1.5:1, and 0.7:1 to
waterways in the high, moderate and low ecological-value classes, respectively (see
Table 3). The rationale for these ratios is that the uncertainty of offset mitigating
adverse effects of the Project increases with the ecological value of the waterway. For
waterways in the high and moderate ecological-value classes, mitigated lengths need
to be 50-100% greater than disturbed lengths to be certain that adverse effects are
mitigated. For waterways in the low ecological-value class, relatively smaller amounts
of mitigation will offset adverse effects of the Project. The offset mitigation
requirements are based on channel length disturbed rather than wetted area disturbed
because the proposed offset mitigation seeks to maximise the width of mitigation
areas, as noted below.
96. The Ōtaki River and Waitohu Stream were not included in the calculations, because
habitat loss is expected to be negligible in these waterways, which will be bridged
across their entire widths (albeit with bridge piles constructed in the bed of the
watercourses). The culverts to be installed at the Ōtaki Railway and Kennedy
wetlands were included in offset mitigation calculations (see Table 3).
97. The offset mitigation ratios were applied to the predicted length of altered waterway,
and the values summed to give a total offset mitigation requirement in units of channel
length (Table 3). Using this approach, a total of 2,601 m of waterway require
environmental improvements to mitigate the adverse environmental effects caused by
the Project.
Riparian buffers
98. The creation or enhancement of riparian buffers is one of the most common forms of
mitigation for potential adverse effects on waterways. Riparian planting has been
shown previously to improve aquatic ecological conditions in New Zealand streams.
99. Riparian planting is appropriate for waterways in the Project area because the original
riparian vegetation along nearly all of the waterways across the plains has been
removed by land-clearing for agriculture and urban development.
100. The widths of planted riparian buffers can influence the degree to which planting
improves ecological conditions. Planted buffer widths of approximately 10 m can
produce detectable benefits, based on a review of riparian enhancement projects on
the North Island of New Zealand. The Auckland Regional Council Riparian Zone
Management Strategy recommends a minimum planted buffer width of 10 m. In my
opinion a 20-m buffer (where possible) will substantially reduce the risk that the
planted buffers are too narrow to have significant ecological benefits. I note that the
Page 23
Kāpiti Coast District Council ("KCDC"), in its submission (at paragraph 7.1), supports
this proposed buffer width.
101. The lengths of planted riparian buffers also influence the degree to which planting
improves ecological conditions in waterways. Studies of riparian forest fragments
indicate that some benefits of riparian buffers (e.g., shading, reduction of algal cover)
are achieved within lengths of 10s of metres. Other benefits (e.g., reductions in
turbidity and fine sediment deposition, reductions in water temperature, increased
aquatic invertebrate diversity) require riparian buffer lengths of 100s or 1000s of
metres. The proposal set out below focusses on long, wide riparian buffers to ensure
that the adverse effects of the Project on waterways are mitigated, and long term
ecological benefits will be delivered. In addition to the riparian planting in the
mitigation proposal, riparian planting, and fencing will occur where appropriate at all
sites where new culverts are installed, and along all permanent diversion channels
(see paragraph 111).
Waterway offset mitigation proposal
102. The offset mitigation proposal is to mitigate the effects of the Project on ecological
conditions in existing waterways that will cross the Project, through the enhancement
of at least 2601 m of channel, as specified in Table 3.
103. The proposed offset mitigation consists of riparian retirement, planting riparian buffers,
fencing, and protection (insect and weed control, plant replacement, fence repair and
long-term protection) on both banks at the selected waterways. This proposal resulted
from assessments of numerous alternatives, including instream habitat enhancement
and smaller riparian buffer planting at all waterways in the area. Plant species to be
used for offset mitigation riparian planting are listed in Technical Report on Landscape
and Visual Assessment (Technical Report 8) and in the Draft EMP (Section 6.3).
104. To maximise the ecological benefits, the proposed offset mitigation focuses on
creating wide and long riparian buffers on a small number of waterways in the Project
area that currently have moderate to high ecological values (as shown in Table 2).
The emphasis on a few large projects in lieu of many small projects is consistent with
mitigation strategies for the MacKays to Peka Peka and Transmission Gully sections
of the Wellington Northern Corridor Road of National Significance ("RoNS").
105. Of the four waterways in the high ecological-value class in Table 2, Mangaone Stream
is, in my opinion, the most suitable for large-scale riparian enhancement. Mangaone
Stream has high potential to benefit from riparian enhancement (see paragraph 37).
The existing riparian zone is limited to grass and small exotic shrubs for most of the
length of the stream from the coast to the base of the Tararua foothills (> 10 km),
there is severe bank erosion in many areas, and there is widespread stock access to
the stream. Despite these problems, there is a diverse fish fauna with numerous
migratory species, and a diverse invertebrate fauna that is indicative of good
ecological conditions. Large-scale riparian enhancement is likely to reduce erosion
Page 24
through bank stabilisation, improve physical habitat, and possibly improve water
quality.
106. In addition to Mangaone Stream, the three waterways in the moderate ecological-
value class, Jewell, Kumototo and Settlement Heights Streams, are also suitable sites
for riparian enhancement (as discussed above). Like Mangaone Stream, these
waterways have poor physical habitat conditions in the Project area, but they also
have large areas of native forest in their upper catchments, and they are inhabited by
migratory native fish. The downstream portion of Mary Crest Stream, which lacks a
native riparian buffer, is also a candidate site for riparian enhancement. The mitigation
planting would extend the existing native-plant dominated riparian zone.
107. The offset mitigation proposal consists of riparian buffer creation at five sites,
Mangaone Stream east and west of the Project, Settlement Heights Stream east of
the Expressway, Jewell Stream east of the Project, and Mary Crest Stream
downstream of the native forest fragment. These areas are identified in Appendix 1 to
the Draft EMP and on the Landscape Concept Plans appended to Mr McKenzie's
evidence (Sheet 06). Each area will be fenced, planted and protected, as discussed
in my evidence above.
108. The widths and lengths of proposed riparian buffers at each site are listed in Table 4.
The total quantity of offset mitigation proposed is 2720 m of planted riparian buffer on
both banks of the designated waterways. The buffer width at most points will be 20 m.
There are sections of Mangaone Stream adjacent to Te Horo Beach Road where the
distance from stream bank to road will constrain the buffer width to < 20-m wide along
on the south bank. This reduction in buffer width is compensated for by extending the
total length of planted riparian buffer from 2601 m to 2720 m.
Table 4. Locations and sizes of proposed riparian buffers. Buffer widths refer to each bank.
Location Buffer length (m) Buffer width (m)
Mangaone Stream
(east of Expressway) 600 20
Mangaone Stream
(west of Expressway) 1100 5-20
Settlement Heights Stream
(east of Expressway) 520 20
Jewell Stream
(east of Expressway) 160 20
Mary Crest Stream
(west of Expressway) 340 20
Total 2720
109. The identified areas all provide continuous or near-continuous lengths of mitigation
planting. In particular, the proposed mitigation planting along Mangaone Stream will
Page 25
extend a total of approximately 1700 m (with breaks for the Expressway, railway, SH1
and local driveways).
110. The extensive riparian buffers proposed as offset mitigation should improve ecological
conditions in these waterways. With these measures in place, in my view the overall
effect of the Project on waterway habitat will be low and appropriate.
111. In addition to the wide and long riparian buffers proposed for offset mitigation, smaller
riparian plantings, and fencing to exclude stock and protect the planting, will occur
where appropriate at all sites where new culverts are installed, and along all
permanent diversion channels (Sections 4.10 and 12.1 of the Draft EMP). These
plantings are not counted towards the 2720-m of large-scale riparian buffers detailed
above. At Expressway culverts, disturbed banks on either side of the Expressway will
be planted with native species and fenced as appropriate. At the permanent diversion
channels planned for the Racecourse, School Road, Gear Road, unnamed tributary of
Settlement Heights, and Edwin and Cavallo Culverts, both banks will be planted and
fenced as appropriate. The planting width for banks adjacent to new culverts and
permanent diversion channels will be 5 m where possible (for example it will depend
on setback from the road/property boundaries, safety and flood management issues
particular to each site).
112. Riparian planting within the Project area will be provided with biannual maintenance
and inspection for five years after planting. The planted areas will be checked for
dead or diseased plants, proliferations of weeds and insect pests, and broken fences.
Maintenance will consist of plant replacement, weed cutting, fence repair and insect
and weed control. A three-year period of weed control is often needed before planted
riparian buffers consisting of New Zealand native plants are self-sustaining, and
increasing the maintenance period to five years will help to ensure that this goal is
achieved.
Waterway habitat loss and alteration monitoring
113. Planted riparian buffers will be monitored and maintained as described above and in
greater detail in the Draft EMP (Sections 8.2.3 and 10).
114. Brown mudfish (an endemic fish listed as declining) have been reported from wetlands
in the Waitohu and Mangaone catchments. These observations raise the possibility
that brown mudfish occur in waterways in the Project area, although none were
observed during field surveys. Prior to the commencement of any stream diversion
work in affected waterways, surveys of brown mudfish will be carried out by an
ecologist with prior experience in mudfish surveys. Details of the mudfish survey
designs will be set out in the Section 12.2 of the Draft EMP.
Page 26
WETLAND HABITAT LOSS AND ALTERATION EFFECTS, MITIGATION AND
MONITORING
Wetland habitat loss and alteration effects
115. The depression containing the Ōtaki Railway Wetland immediately north of Ōtaki will
be partially filled to accommodate the Project.
Wetland habitat loss and alteration mitigation
116. Plans for mitigation for the loss of the Ōtaki Railway Wetland are provided in the
evidence of Mr John Turner and in his technical report on terrestrial ecology
(Technical Report 11). The remnant Ōtaki Railway Wetland, will be restored as set
out in section 5 of the Draft EMP. Two new wetlands will be constructed, the Kennedy
Wetland adjacent to the Ōtaki Railway Wetland, and the Mary Crest Wetland on the
west side of the Expressway near Peka Peka (see section 6.1 of the Draft EMP). The
constructed wetlands are expected to have established vegetation and aquatic
organisms, and to be suitable for native birds in 2-3 years.
117. Given that the existing Ōtaki Railway Wetland is small and highly modified, the
constructed wetlands are suitable mitigation and the adverse effects of the Project on
wetland aquatic biota in the Project area will be low and appropriate.
Wetland habitat loss and alteration monitoring
118. Aquatic ecological conditions will be monitored at the remnant Ōtaki Railway Wetland
and the constructed Kennedy and Mary Crest wetlands for three years after their
completion to ensure that the wetlands achieve a level of aquatic ecological condition
equal to that of established wetlands. Aquatic invertebrates in quarterly replicate
samples will be used as the indicators of ecological condition. Hydrological conditions
and vegetation (both pre-existing and restoration plantings) at the Ōtaki Railway
Wetland and the Kennedy and Mary Crest wetlands will also be monitored for three
years. Detailed wetland monitoring procedures will be set out in the Draft EMP
(Sections 8.1.2 and 8.2.3).
RESPONSE TO COUNCIL / OTHER REPORTS
GWRC Key Issues Report of 17 May 2013
119. GWRC identifies several issues that concern potential effects of the Project on aquatic
ecology. These include issues that are identified as “key issues” and others that are
not so identified. Each of these issues are addressed below. In cases where
responses to GWRC issues have been added to the body of this evidence statement,
they are identified below. Several of the issues raised by GWRC appear in more than
one section of the GWRC Key Issues report; they are consolidated in the responses
below.
Page 27
120. GWRC Issue 1: GWRC seek further information about locations and lengths of
waterways that will be affected by reclamation (channel burial) and diversion (creation
of new channels) (GWRC report paragraphs 96 and 161).
121. Response: The information requested is provide in the evidence of Mr Bird and
discussed in my evidence above. The total length of new waterway works (culverts,
permanent diversion and rip-rap) by the Project is 2,734 m (see Annexure D). As set
out in my evidence above, due to an error in Appendix 10D to Technical Report 10
(which inadvertently added 100m to one waterway length) my offset mitigation was
based on a total length of 2,834 m. I used this distance to calculate the proposed
offset mitigation package. The actual length of existing waterway affected by the
Project is 2,552 m, which is less than the minimum length of riparian planting
proposed for offset mitigation (2,601 m in Table 3). Updates to the Draft EMP
concerning specification of diversion channels are required as set out in the proposed
consent conditions and section 12.1 of the Draft EMP.
122. GWRC Issue 2: GWRC recommends that new diversion channels provide “suitable
new instream habitat”. Post-construction monitoring of diversion channels is required
to ensure that fish passage is adequate. Riparian planting for offset mitigation is
proposed for these sections. GWRC also seeks clarity as to whether the Fish Rescue
Plan applies to the areas of waterway to be permanently diverted (GWRC report
paragraphs 23, 161, 162, 163, 165).
123. Response: Permanent diversion channels will be provided with riparian planting as
recommended by GWRC and as set out in my evidence above. The Draft EMP
(Sections 4.10 and 12.1) has been updated to include this requirement. Permanent
diversion channels will be designed to avoid any velocity or structural barriers to fish
passage (and will be monitored by an ecologist at one and four years after
construction). These requirements have been added to the proposed conditions and
the Draft EMP (sections 8.2.3 and 12.1). The fish rescue plan (section 7 of the Draft
EMP) includes fish rescue for diversions. To make it explicit, this section of the Draft
EMP has been amended to refer to permanent (as well as temporary) diversion
channels. All waterways that will be affected by diversions are intermittent, and it is
planned that where possible works occur during dry periods (section 4.6 of the Draft
EMP), so fish rescue although provided for is unlikely to be required.
124. The permanent diversion channels on Racecourse, School and Gear Streams, and
the unnamed northern tributary of Settlement Heights Stream will replace existing
channel lengths that are intermittent, straight drainage ditches through farm land.
These channels have low ecological value and lack meanders, riffles and other natural
habitat features at present. Matching existing channel complexity at these sites (as
sought by GWRC) does not require the provision of meanders, riffles and other natural
habitat features.
125. GWRC Issue 3: There is no information about Hadfield Catchment (GWRC report
paragraphs 86).
Page 28
126. Response: The applicants have confirmed5 that there are no works planned for the
Hadfield Catchment.
127. GWRC Issue 4: Restrictions on the timing and methods of instream work to minimise
negative effects on fish spawning and migration should be included in the consent
conditions (GWRC report paragraph 158).
128. Response: As discussed in my evidence above, the proposed conditions stipulate
that any work that will occur in the wetted channel outside of the period 1 March to 31
July will require a specific programme and methodology to manage migration of native
fish (prepared in consultation with GWRC).
129. The consent conditions also require the NZTA to prepare and submit to the GWRC for
certification a comprehensive EMP. Section 4.6 of the draft EMP specifies that, where
possible, instream works in intermittent waterways will be scheduled to be undertaken
in dry and drying periods when fish passage is either not possible or is likely to be
minimal. Where possible, construction schedules will consider peak migration periods
and will be contained within the CEMP and, where relevant, the SSEMPs. When
construction must be scheduled during flowing periods, block nets will be used to
exclude fish, and the fish present will be collected and relocated, as specified in the
Fish Rescue Plan, in Section 7 of the draft EMP.
130. GWRC issue 5: There is an error in Technical Report 12 (Aquatic Ecology) about one
versus two mudfish being recorded in the NZFFDB (GWRC report paragraph 159).
GWRC also raise potential effects on mudfish as a key concern (GWRC report
paragraph 160).
131. Response: Agreed. There are brown mudfish records in the NZFFDB from the
Mangaone and Waitohu catchments. As discussed in my evidence above, although
there are two mudfish records in the NZFFB, no mudfish were recorded in the surveys
undertaken for the Project. However, the proposed conditions and the Draft EMP
(section 12.2) provide for mudfish surveys prior to stream diversion work in affected
waterways. These surveys are, in my opinion, appropriate to ensure that if there are
mudfish in affected waterways they will be located and transferred.
132. GWRC Issue 6: Long culverts may preclude fish passage (GWRC report paragraph
165).
133. Response: Culvert length can be a problem if there are no resting sites in a culvert
and the culvert length exceeds the distance some fish species swim without resting.
The culverts for the Project will employ fish passage components that include baffles
and resting pools. These fish passage designs will meet the guidelines developed for
New Zealand fish species (see Technical Reports 10 and 12 for specifications and
references). The proposed culverts will appropriately provide for fish passage of
weak-swimming and poor-climbing fish such as juvenile inanga, and should therefore
be suitable for other species and juvenile stages.
5 Through a memorandum of counsel to the Board of Inquiry dated 25 June 2013.
Page 29
134. GWRC Issue 7: The compensation ratio of 0.7 for waterways of low ecological value
is not in accordance with the principle of "no net loss". Riparian planting is only
proposed for sections of four waterways, so ecological condition at remaining
waterways may decline (GWRC paragraph 167).
135. Response: In my opinion, for the reasons given in my evidence above, the offset
mitigation proposal will achieves "no net loss" of biodiversity values. In determining
the offset mitigation ratios, I started with an assessment of the ecological values of
waterways in the Project area. As my evidence explains, most of these waterways are
of low ecological value (see Tables 2 and 3). I then, as also set out in my evidence,
considered what form of offset mitigation would be most appropriate to mitigate the
effects of the Project on waterways. The strategy is to create large, long riparian
buffers on a waterways that currently have moderate to high ecological values, in lieu
of small buffers at many sites (most of which are currently in poor ecological
condition). In my opinion, for the reasons expressed in my evidence above, 20 m-
wide riparian planting over long lengths of moderate and high value waterways
provides excellent mitigation for the effects of the Project and superior mitigation to
small-scale enhancements at individual waterways, particularly those with low
ecological value. Such an outcome is consistent with that used for the MacKays to
Peka Peka project.
136. Further, I applied my professional judgement in determining the offset mitigation ratio
for the low-value waterways of 0.7. There are currently no accepted models for
scientifically determining ecological value and ecological offset mitigation ratios for
intermittent waterways, and all of the low-value waterways in the Project area are
intermittent. No such models or methodologies are supplied in the regional or district
planning documents. It is important to note that the low-value waterways will not be
removed, they will be altered (i.e., by culvert installation, rip-rap installation, and in four
cases, diversion). These waterways are clearly of low ecological value (i.e., they flow
predominantly through straightened drains in farmland, lack connectivity to upstream
habitat with higher value or to the coast, lack or have minimal riparian buffers, and
have poor-quality instream habitat conditions (see Section 5.2 of Technical Report
12). Therefore, adding 0.7 m of offset mitigation for each 1 m of disturbed channel to
the mitigation package is, in my opinion, appropriate.
137. In my opinion, even though the Project will affect a large total length of low-value
waterways (see Table 3), the proposed riparian planting offset mitigation package
(20m wide planting on either side of the selected waterways) outweighs any negative
effects on the low-value waterways. An offset mitigation ratio of higher than 0.7 for
these low value waterways would not in my view reflect their value, the effects of the
Project or the benefits of the proposed riparian offset mitigation.
138. Finally, as discussed in my evidence above, in response to GWRC's comments, all
culvert sites and all permanent diversions will be provided, where possible, with 5-m
riparian planting, in addition to the larger-scale riparian offset mitigation planting that I
have described.
Page 30
139. GWRC Issue 8: Offset mitigation areas need to be permanently protected, e.g.,
through covenanting. (GWRC report paragraph 168).
140. Response: I agree that the riparian offset mitigation areas should be provided with
long-term protection. While the NZTA holds designation on these lands, it will protect
the offset mitigation areas. If land is sold, the NZTA will provide appropriate protection
(such as a covenant) for the offset mitigation areas. The conditions of consent have
been amended to make this long term protection explicit.
141. GWRC Issue 9: More detail and clarification is required in Section 9 of the EMP
regarding the proposed trigger levels, response and remedial actions for
macroinvertebrate sampling, fish monitoring, fine sediment deposits and oil and
grease are required (GWRC report paragraph 215).
142. Response: Section 9.2 of the Draft EMP refers to Section 8.2.2 which contains more
detailed information including the proposed monitoring methods. In my opinion the
Draft EMP contains sufficient information for the stage of its development, including
reference to standard sample, measuring and assessment techniques and how the
limits should be determined for the different variables. The final EMP, which will
contain all the details reflective of detailed design, is proposed to be certified by the
GWRC.
143. GWRC Issue 10: A preconstruction monitoring plan could resolve timing issues about
methods and the EMP, which is to be submitted 20 days prior to construction (GWRC
report paragraph 216, 217, 218).
144. Response: Pre-construction turbidity monitoring will be carried out only at the Ōtaki
River and Waitohu Stream, as set out in the evidence of Mr Bird and in section 8.2.1
of the Draft EMP, to establish background variability between the upstream and
downstream monitoring sites (see paragraphs 61 and 63 above). The mudfish surveys
are to occur shortly before construction commences near each waterway. This means
that additional follow-up trapping of mudfish that may have recolonised an area
between the time of the survey and construction is not required. The intent of the
EMP is that it is provided, as a whole, to the GWRC for certification, 20 working days
prior to any works on the Project commencing. Therefore, the timing of having this
information in the EMP is suitable. However, GWRC is correct that the Draft EMP
inadvertently included two requirements for the provision of the results of the mudfish
survey. The correct approach is that the results of the surveys will be provided to the
GWRC within 10 working days of the completion of the data collection and will not be
included as part of the EMP. Section 12.2 of the EMP, and the proposed conditions of
consent, have been amended accordingly. Therefore, I do not consider that a
separate preconstruction monitoring plan is necessary given the low level of pre-
construction monitoring required.
Page 31
KCDC Key Issues Report of 17 May 2013
145. The KCDC Key Issues Report identified several issues related to aquatic ecology in
the Project area. In each case, the KCDC report referred to the GWRC report.
Therefore, no separate responses to those issues are listed here.
RESPONSE TO SUBMISSIONS
KCDC (submission 102892)
146. KCDC Issue 1: KCDC seeks that opportunities to mitigate effects of stream diversions
be extensively explored and that assurance be provided that new stream habitat
appropriately mitigates for loss or modification of habitat (paragraph 7.2). KCDC is
also concerned about the culverting of streams as a last resort.
147. Response: All permanent diversion channels and all waterway segments that are
affected by culvert installation will be stabilised to prevent erosion, planted with native
riparian plants and fenced, where appropriate, to protect the waterway and planting.
Permanent diversion channels will be planted along their entire length, on both banks,
where appropriate (section 4.10 of the Draft EMP). In my view the mitigation I have
recommended, as discussed in my evidence above, will substantially improve
ecological conditions and protect stream habitat in waterways that currently have high
and moderate ecological values.
148. The offset mitigation proposal resulted from consideration of alternative mitigation
options, including instream habitat enhancement and smaller riparian buffer planting at
all waterways in the area. The proposal to create wide and long riparian buffers at five
sites is intended to maximise ecological benefits. Distributing the offset mitigation
measures over a large number of sites would, in my opinion, dilute the ecological
benefits. In particular, focusing offset mitigation on the numerous sites that are
currently highly degraded, highly intermittent drains and swales would provide little
benefit to those sites, or to the Project area as a whole. The emphasis on a few large
projects in lieu of many small projects is consistent with the offset mitigation strategies
for the MacKays to Peka Peka and Transmission Gully sections of the Wellington
Northern Corridor RoNS. An additional benefit of the offset mitigation proposal is that
the mitigation sites can be protected in perpetuity.
149. The NZTA's approach to this Project is only to provide culverting where required. As
noted in my evidence above, the Expressway will traverse 12 large catchments and
several smaller catchments. Culverting is required to cross most of these waterways.
All culverts within waterways that are predicted to be fish migration routes will provide
for fish passage.
150. KCDC Issue 2: KCDC queries the robustness of fish sampling and the absence of
mudfish sampling (paragraph 7.3).
151. Response: The fish sampling methods are provided in Section 5.6.1 of Technical
Report 12. The KCDC submission does not elaborate on its concerns with the
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sampling methods. Single-pass electric fish surveys were used to determine whether
fish were present and the composition of fish, particularly native migratory species.
The fish surveys were non-quantitative and not intended to produce estimates of fish
density; instantaneous estimates of fish density made far before the commencement
of construction would not be useful. In my opinion, the sampling provided sufficient
information on to which to base my assessments of the need for fish-passage, which
were required to develop plans for culverts in advance of consent lodgement. While
specific mudfish surveys were not carried as part of the AEE, such surveys are
specified as pre-construction monitoring requirements.
152. Fish monitoring proposed for the Project will follow the electric-fishing protocol that
has been designed for robust assessments of fish diversity and relative abundance in
wadeable New Zealand waterways, by Bruno David and colleagues. This is an
accepted and standardised protocol, and is reflected in the Draft EMP (Section 8.2.2).
Mudfish surveys are specified in the draft conditions, and detailed methods for the
mudfish surveys are included in Draft EMP (Section 12.2).
153. As mentioned above, while no specific mudfish surveys were undertaken, numerous
fish surveys were undertaken and no mudfish were identified. I am comfortable with
the robustness of the fish sampling proposed and consider it appropriate.
154. KCDC Issue 3: KCDC raises an issue about the potential ecological effects of settled
(coarse) sediments that can affect benthic habitat near the site of entry, in addition to
suspended (fine) sediments that settle slowly and affect water clarity near the site of
entry (paragraph 7.4).
155. Response: I agree. Coarse sediments generated by out-of-stream works such as
dewatering are relatively easily controlled by retention ponds, sediment barriers, and
transport off-site. Coarse sediments that are bypass these structures will be
dominated by sand fractions; sand slugs that appear downstream of construction sites
can be a potential problem.
156. The Draft EMP specified that fine sediment deposition will be monitored downstream
of construction sites (Section 8.2.2). This section of the EMP has been updated to
provide for coarse sediment (sand) monitoring and exceedence limits will be included
(and Section 9.2). Sediment deposit monitoring will be carried out downstream of
construction sites using the sediment depth procedure set out in the Cawthron
publication on Sediment Assessment Methods (Clapcott et al. 2011). The Draft EMP
(section 4.5)also specifies that instream structures used in construction, such as fords,
are designed to minimise erosion, and the channel downstream of these structures is
to be inspected following large flows for accumulations of coarse and fine sediment.
In addition, instream works in intermittent streams, which make up the majority of
waterways in the Project area, will occur during dry periods where possible (section
4.6 of the Draft EMP).
157. KCDC Issue 4: While KCDC considers the measures intended to minimise the risk of
construction activities on fish migration appropriate, it seeks further clarification on "the
Page 33
potential effects of earthworks on diversions during the migration periods" (Paragraph
7.5).
158. Response: As discussed above, the proposed conditions stipulate that any work that
will occur in the wetted channel outside of the period 1 March to 31 July will require a
specific programme and methodology to manage migration of native fish (prepared in
consultation with GWRC).
159. Clarification is also provided in the Draft EMP which covers the potential effects of
earthworks on diversions during migration periods in Sections 4.5 and 4.6. These
measures include:
(a) areas of stream that are affected by culvert installation and temporary diversion
to be block-netted upstream and downstream to keep fish out of the affected
area;
(b) where possible, construction activities in intermittent waterways will be
scheduled to be undertaken in dry and drying periods when fish passage is
either not possible or is likely to be minimal;
(c) in perennial and near-perennial streams, in-stream construction activities that
impede flow or fish movements will be concentrated into periods outside of the
peak migration periods; and
(d) short-term in-stream works can be undertaken during migration periods, if few
migratory native fish are present upstream and downstream of the construction
site, and the fish present are collected and relocated, as specified in the Fish
Rescue Plan.
160. KCDC Issue 5: KCDC considers that the AEE confuses mitigation with risk
minimisation for sediment effects which has resulted in proposed best-management
construction practices being designed to minimise the effects of construction works on
aquatic values rather than to mitigate them (Paragraph 7.7).
161. Response: I agree that the focus in the conditions and various management plans is
on ensuring that best management practices are used to minimise (and thereby
mitigate) adverse effects of sediment input. I support this preventative mitigation
approach. As I see it, the underlying question is: with best management practices
implemented through the conditions as proposed, what are the effects of the Project
and do they require further mitigation than those already proposed in the conditions?
162. Based on the combination of erosion and sediment control measures, construction
and post-construction monitoring, timing and management of works during fish
migration, fish rescue, the low risk of elevated sediment input to waterways with high
ecological values, and the existing soft bottom predominant waterway environment, I
consider that the effects of Expressway construction on waterway ecology will be low.
163. KCDC Issue 6: KCDC queries (at paragraph 7.8) the accuracy of the assessments on
ecological value related to aquatic ecosystems (without any elaboration) and raises
Page 34
concerns about the riparian mitigation proposed (despite supporting the "substantial"
riparian planting proposed in paragraph 7.1).
164. Response: I consider that my assessments are appropriate and have provided me
with sufficient information to adequately assess the effects of the Project. I have
addressed offset mitigation issues at length in my evidence above. In summary, I am
satisfied that the offset mitigation I have proposed appropriately mitigates the effects
of the Project on waterways and, at the very least, achieves "no net loss" of
biodiversity values.
165. KCDC Issue 7: KCDC seeks justification for the proposed turbidity trigger of 50%
given that a trigger of 20% has been applied to other NZTA projects in the area.
166. Response: I have addressed this issue in my evidence above. In my opinion, for the
reasons set out in those paragraphs, the 50% trigger is appropriate for the aquatic
ecology affected by the Project.
167. KCDC Issue 8: KCDC notes that riparian planting is not planned for the Ōtaki River
where it crosses the Project area (Paragraph 7.9).
168. Response: I confirm that riparian planting along the Ōtaki River is not part of the
mitigation proposal. While I did consider such planting, the effects of riparian planting
on the banks of a wide braided river, such as the Ōtaki River, would not have
measureable benefits for water quality or aquatic ecology (as recognised by KCDC in
its submission). Even after planted trees matured (if not removed by floods), they
would have negligible effects on water quality and aquatic ecology, due to the
mismatch between relatively small planted areas and the very large river-floodplain
system. Very large areas of riparian planting along the whole river system would be
required to achieve any measurable aquatic ecology benefit which, on such a large
system, would only occur over many decades. Riparian buffer restoration is, in my
opinion, much more effective on small waterways. Riparian buffer planting as I
propose is also, in my opinion, far more closely related to the effects of the Project
which are predominantly culverting of small, intermittent, waterways and diversions at
four small, intermittent, waterways.
169. KCDC Issue 9: KCDC notes that it is unclear whether mitigation planting is proposed
on streams separate to stream realignments and that this, in turn, could result in
double dipping (Paragraph 7.10).
170. Response: There is no double-dipping in the mitigation proposal. As noted above,
riparian plantings will be made (where possible) at all sites where new culverts are
installed, and along all permanent diversion channels (section 4.10 of the Draft EMP).
These plantings have not been counted towards the 2,720 m of large-scale riparian
buffers in the mitigation proposal.
Page 35
GWRC (102880)
171. The issues raised in GWRC's submission are a brief summary of the more detailed
material contained in its key issues report, and addressed above. Therefore, my
responses to the GWRC submission are as set out above.
Sharyn Sutton (102855), Wayne Jarvis (102869)
172. These submissions raise matters relating to potential adverse ecological effects
generally, in terms of loss of stream habitat and associated riparian margins, effects
on native fish, and the release of sediment across affected catchments. For the
reasons expressed in detail in my evidence above, while the Project will have adverse
effects on aquatic ecology, I consider that those effects will be appropriately mitigated.
Caleb Royal (102883), Pātaka Moore (102888) and Rupene Waaka (102897)
173. I understand that the NZTA discussed the proposed riparian planting mitigation
approach with Nga Hapū o Ōtaki. These submissions do not comment on the
adequacy of the approach but rather all propose that Nga Hapū o Ōtaki be involved in
the development and implementation of the EMP and the mitigation proposed.
Amended conditions are proposed, as set out in the evidence of Ms Beals, providing
for a Community Liaison Group to consider iwi and wider community involvement in
implementing mitigation measures. Further, the Draft EMP (Section 1) requires that
document to be finalised in consultation with Nga Hapū o Ōtaki and I support that
approach.
Kelly Donovan and Jarrod Lill (102887)
174. This submission relates to the effects of the proposed riparian mitigation planting on
their property at 40 Te Horo Beach Road. I recognise and fully accept the owners'
strong attachment to their property and their association with the planting they have
undertaken. In terms of this planting, in my view it will be able to be incorporated into
the riparian mitigation planting proposed as part of the Project. There is no proposal
to remove existing native riparian plants. Rather, the proposed planting will be
designed to fit in with what is already present, will supplement the efforts the owners
have already made and should further enhance birdlife on their property (and in the
surrounding area).
175. The proposed riparian planting, and the Project as a whole, will not have an adverse
effect on eels at this property. Rather, I expect that, with the riparian planting
proposed, eel populations and aquatic life generally will further improve on a waterway
with high ecological value but poor physical habitat, water quality and riparian zone
composition (as discussed in my evidence above).
176. I have explained above my reasons for recommending that long lengths of the
Mangaone Stream be planted to mitigate waterway effects of the Project. I recognise
that this planting affects people's property. That is why I have been careful in my
assessment as to the nature and amount of mitigation reasonable to mitigate for the
Page 36
Project's effects. In my opinion, the proposed riparian planting, which includes 40 Te
Horo Beach Road, is necessary to mitigate the Project's effects appropriately.
John Camm and Christine Stone (102847)
177. This submission concerns weed control at sites proposed to be used for riparian
planting. It is acknowledged that where stream margins are currently regularly grazed
or mown, as is the case along the edge of the 46 Te Horo Beach Road, the risk of
weed establishment is low. Fencing such sections of stream and excluding stock for
the purpose of riparian planting will increase the risk of weed invasion in these areas,
especially during the establishment phase.
178. To address this potential problem, all sites of riparian planting within the Project area
will be provided with biannual maintenance and inspection for five years after planting
(section 8.2.3 of the Draft EMP). The planted areas will be checked for dead or
diseased plants, proliferations of weeds and insect pests and broken fences.
Maintenance will consist of plant replacement, weed cutting, fence repair and insect
and weed control. Once established, native riparian trees and shrubs should reduce
the colonisation and growth of weeds in these areas, although some weed
establishment around the margins of the riparian planting is still likely occur (though
this is likely to be less of an issue than currently exists). Where the riparian margins
proposed for planting already support native trees and shrubs, these will be left in
place and supplementary planting provided as necessary, along with 5 years of
maintenance.
Gillian and Barry Hart (102865)
179. This submission also notes that riparian planting sites may become infested with
weeds. As discussed above, weed control will be provided for riparian planting in the
Project area for 5 years. Once the riparian planting is established, weed issues are
likely to be less than currently occur.
Ōtaki Community Board (102894)
180. The Ōtaki Community Board states that the loss of streams must be accounted for
and properly mitigated and the culverting should be minimised. The Board also raises
issues about "low compensation ratios". I have addressed both of these matters in
detail above. I consider that the effect of the Project on streams has been
appropriately mitigated and that the mitigation ratios used are appropriate.
CONCLUSION
181. In my opinion:
(a) the construction effects of the Project on aquatic ecology, with the proposed
conditions (including monitoring) and the management techniques to be
developed through the Draft EMP, are low and acceptable;
Page 37
(b) the effects of the Project on fish passage, with all culverts in fish-bearing or
potentially fish-bearing streams designed to facilitate fish passage, and
appropriate monitoring conditions, will be low and appropriate;
(c) the aquatic ecology effects of contaminants in road runoff from the Project will
be low and result in a better aquatic ecology outcome than presently exists for
SH1;
(d) with the extensive riparian restoration programme proposed as mitigation, the
effects of the Project on waterway habitat will be low and appropriate; and
(e) with the proposed mitigation, the effects of the Project on the Ōtaki Railway
Wetland will be low and appropriate.
Scott Thomas Larned
12 July 2013
Page 38
ANNEXURE A: WATERWAYS IN THE PEKA PEKA TO NORTH ŌTAKI PROJECT AREA
Page 39
ANNEXURE B – OBSERVATIONS OF FISH SPECIES
Observations of fish species in waterways in and near the Project area, and classification of migratory and climbing behaviour and conservation status. Records are from the 2011-2012 field surveys and the NZFFDB. Conservation status from Allibone et al. (2010). Paranephrops planifrons (koura) is included as it is recorded in the NZFFDB. Symbols: S+N = present during surveys and recorded in NZFFDB. S = present during 2011-2012 field surveys only. N = recorded in NZFFDB only. BM = inanga reported in the Ōtaki River by Boffa-Miskell (2001). Blank = not recorded in these waterways.
Fish species Migratory Climbing ability Conservation status
Man
gao
ne
Ōta
ki
Wait
oh
u
Man
gap
ou
ri
Sett
lem
en
t H
ts
Co
ole
n
Mary
Cre
st
Jew
ell
Ku
mo
tot
Anguilla dieffenbachii (longfin eel) Yes High (juvenile) Declining S+N S+N S+N S S S
Anguilla australis (shortfin eel) Yes High (juvenile) Not threatened N N N S S S
Gobiomorphus cotidianus (common bully) Yes Moderate Not threatened N N N
Gobiomorphis breviceps (upland bully) No Low-moderate Not threatened S+N N
Galaxias brevipinnis (koaro) Yes High Declining N N N
Galaxias fasciatus (banded kokopu) Yes High (juvenile) Not threatened S+N S+N N S S S
Galaxias argenteus (giant kokopu) Yes Low Declining N N
Galaxias postvectis (shortjaw kokopu) Yes High Declining N N S+N
Galaxias maculatus (inanga) Yes Low Declining N BM N
Cheimarrichthys fosteri (torrentfish) Yes Low Declining S S+N N
Neochanna apoda (brown mudfish) No Low Declining N N
Retropinna retropinna (common smelt) Yes None Not threatened N
Geotria australis (lamprey) Yes High Declining S N
Rhombosolea retiaria (black flounder) Yes None Not threatened N
Paranephrops planifrons (koura) No Moderate Not evaluated S+N N S+N S
Salmo trutta (brown trout) Some Low (juvenile) Naturalised N N N
Oncorhynchus mykiss (rainbow trout) No Low (juvenile) Naturalised S
Scardinius erythrophthalmus (rudd) No None Naturalised N
Page 40
ANNEXURE C – ATTRIBUTES OF WATERWAYS
Attributes used to assess ecological values of waterways in the Project area. Water quality classes are from GWRC reports. Invertebrate (MCI, QMIC), fish (Fish IBI) and physical habitat (PHA) scores are from surveys in the Project area. Native fish species are from field surveys and NZFFDB; some NZFFDB records are for sites upstream or downstream of the Project area. SIE: significant indigenous ecosystem in the GWRC pRPS. Connectivity: high = continuous, semi-natural channels from headwaters to coast, moderate= downstream connections to drains, low = no connectivity upstream and/or downstream. Waterways listed from north to south.
Waterway Water
quality PHA MCI QMCI Fish IBI
Native fish
SIE Connectivity
Dominant land cover
upstream of
Project
Greenwood Stream
– Low – – – – – Low Agriculture
Waitohu Stream
Excellent upstream High Good Excellent Poor 14 Yes High
Native forest, agriculture
South
tributary of Waitohu Stream
– Low – – – – – Low Agriculture
Mangapouri Stream
Poor Moderate Poor Poor Very Poor
1 Yes High Urban
Racecourse Stream
– – – – – – – Low Agriculture
Te Roto
Stream – Low – – – – – Low Agriculture
Ōtaki River Excellent upstream – Excellent Excellent Fair 12 Yes High Native forest
Culverts for waterways in the Project area, and lengths of channel alteration for new works. Lengths of culverts, diversions and other works are from the culvert schedule in Technical Report on stormwater (AEE Chapter 18). The length of rip-rap and other works at each site was estimated as the difference between total disturbed length and the sum of the culvert and diversion lengths. Six culverts will function only for water conveyance and flood control, and no fish passage measures are planned due to the lack of upstream or downstream connectivity.
Culvert name Culvert
length (m)
Fish passage
Diversion length (m)
Rip-rap, other works
(m)
Total disturbed
(m)
Greenwood Culvert 25 Yes 0 30 55
Waitohu Tributary Culvert
40 Yes 0 20 60
Railway Wetland Culvert
75 Yes 0 20 95
Kennedy Wetland Culvert
15 Yes 0 5 20
Mangapouri Culvert at Expressway
60 Yes 0 40 100
Mangapouri Culvert at NIMT
20 Yes 0 40 60
Racecourse Culvert6 65 No 55 0 120
Te Roto Culvert 40 No 0 25 65
Mangaone Culvert at link road east
16 Yes 0 19 35
Mangaone Culvert at Expressway
50 Yes 0 30 80
Mangaone Overflow Culvert Expressway
50 No 0 0 50
Mangaone Overflow Culvert Link Rd (east)
16 No 0 0 16
School Rd Culvert at Link Rd (east)
16 No 500 4 520
Gear Culvert at Gear Road
20 Yes 120 10 150
Gear Culvert at Expressway
40 Yes 40 10 90
Settlement Heights Culvert
40 Yes 1107 20 170
Coolen Culvert 40 Yes 0 4 44
Avatar Culvert 60 No 0 4 64
Edwin Culvert 100 Yes 95 5 200
Jewell Culvert 120 Yes 0 20 140
Cavallo Culvert 80 Yes 230 10 320
Cording Culvert 70 No 0 5 75
Awatea Culvert 68 Yes 0 22 90
Kumototo Culvert 88 Yes 0 27 115
Total8 1214 1150 370 2734
66
The lengths affected for this waterway in Appendix 10D to the Stormwater Technical Report 10 were incorrect, as explained in the evidence of Mr Bird. The total disturbed length of the Racecourse stream was initially calculated at 220 m rather than 120 m. The measurements have been corrected to reflect those in Mr Bird's evidence. 7 The diversion length occurs on an low value, intermittent, unnamed northern tributary to the Settlement Heights Stream and not on
the main stem. 8 Reflecting the correct lengths for the Racecourse culvert and diversion as corrected in the evidence of Mr Bird.