Assessment of Ecological Effects for a Proposed Cleanfill Site at Nikau Palm Road, Paraparaumu

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ASSESSMENT OF ECOLOGICAL EFFECTS FOR A PROPOSED CLEANFILL SITE AT NIKAU PALM ROAD, PARAPARAUMU

NOVEMBER 2012

Report No. 2745

Prepared for:

CUTRISS CONSULTANTS LTD P.O. BOX 386 PARAPARAUMU 5254

WILDLAND CONSULTANTS LTD, 7A SUNLIGHT GROVE, PORIRUA Ph 04 237 7341, Fax 04 237 7496

99 SALA STREET, P.O. BOX 7137, TE NGAE, ROTORUA Ph 07-343-9017, Fax 07-343-9018, email [email protected], www.wildlands.co.nz

CONTENTS

1. INTRODUCTION 1

2. METHODS 1

3. SITE DESCRIPTION 1

4. VEGETATION 3 4.1 Overview 3 4.2 Indigenous shrubland 4 4.3 Wetland 4 4.4 Pasture grassland 4 4.5 Vegetation summary 4

5. FLORA 4

6. FAUNA 5 6.1 Fish 5 6.2 Birds 7

NOT THREATENED 7 6.3 Lizards 7

7. ECOLOGICAL SIGNIFICANCE 8

8. POTENTIAL CONSTRUCTION AND OPERATIONAL EFFECTS 9 8.1 Potential effects 9

9. MITIGATION OPTIONS 9

10. CONCLUSIONS 10

REFERENCES 10

APPENDIX ONE Site Photographs 12

PROJECT TEAM

Frances Forsyth - Field work, report author. Matt Todd - Field work, report author

Reviewed and approved for release by:

______W.B. Shaw Director Wildland Consultants

 Wildland Consultants Ltd 2012

This report has been produced by Wildland Consultants Ltd for Cuttriss Consultants Ltd. All copyright in this report is the property of Wildland Consultants Ltd and any unauthorised publication, reproduction, or adaptation of this report is a breach of that copyright.

1. INTRODUCTION

Cuttriss Consultants Ltd are acting for Higgins Aggregates Ltd and Goodman Contractors Ltd, to manage applications to Kāpiti Coast District Council (KCDC) and Greater Wellington Regional Council (GWRC) for resource consents to create a new clean-fill site between Paraparaumu Quarry and Nikau Palm Road, at Paraparaumu. Wildlands Consultants was commissioned to carry out an assessment of ecological effects at the site.

The proposed clean-fill site would cover an area of approximately 3.5 ha in a valley south of Nikau Palm Road and east of the Paraparaumu Quarry. The land is currently in pasture with very small pockets of indigenous regrowth and a tributary of Mazengarb Drain flows along the valley floor. The valley is approximately 80 m deep and it is proposed that the finished fill area would be about 100 × 450 m and about 60 m deep.

This report addresses the following:

 Vegetation and habitats present at the site;

 Relative ecological significance of any indigenous vegetation;

 Effects of the proposed works (including earthworks construction effects) on terrestrial and aquatic wildlife;

 Potential effects on the waterway and wetland.

2. METHODS

The proposed clean-fill site was visited on 17 July and again on 10-11 August 2011. During these visits vegetation and habitats were described, and the general abundance of all vascular plant species observed was recorded. All bird species observed during the assessment were also recorded and a fish survey was undertaken.

A further site visit was undertaken on 29 October 2012 to undertake a survey for brown mudfish (Neochana apoda) using dip netting and spotlighting as described in Ling et al. (2009).

3. SITE DESCRIPTION

The proposed clean-fill site is located in a fault-defined valley (Ohariu Fault) adjacent to Nikau Palm Road, Paraparaumu, and lies on the boundary of the Tararua and Foxton Ecological Districts. The valley runs roughly north-south, is steep-sided, and the predominant vegetation cover is exotic pasture. Refer to Figures 1 and 2 and also Appendix 1.

Figure 1: Proposed clean-fill site showing the access route through the pine plantation, existing contours, and the transmission lines. The proposed extent of fill is shown by the red line.

The valley shows some evidence of erosion, with several small landslide scars of varying ages. Bedrock is visible in a number of places, scattered throughout the site.

At the time of the 2011 site visits a dozen or more large seeps were contributing water to the first order stream present in the valley floor. This stream is a tributary of the Mazengarb Drain which is monitored by Greater Wellington for flood flows and Kapiti Coast District Council for water quality, and has been identified in the Regional Freshwater Plan as an aquatic ecosystem in need of enhancement. Downstream from the site the Mazengarb Drain is the receiving environment for a municipal wastewater discharge from an estimated serviced population of 30,000 people.

In October 2012 the seep and wetland areas were much drier with water only in tiny pools where cattle had trampled. This was despite rainfall on the day previous to the survey.

Figure 2: Proposed clean-fill site and stream to an old sediment retention pond on Nikau Palm Road.

Below the clean-fill site the stream flows through pines and blackberry to an old sediment retention pond near the bottom of Nikau Palm Road (Figure 2 and photographs in Appendix 1). There are a number of ephemeral tributaries to this stream on steep slopes within the pine forest. All of these were surveyed in October 2012 but none had flowing water.

4. VEGETATION

4.1 Overview

Vegetation at the site is predominantly pasture but small isolated pockets of indigenous shrubland (commonly Coprosma rhamnoides and tauhinu (Ozothamnus leptophyllus)) are present, particularly in valley folds. A narrow, degraded wetland occupies the bottom of the valley, dominated by marsh clubrush (Isolepis prolifera) and pukio (Carex secta).

Adjacent land to the west has a cover of plantation pines (Pinus radiata) interspersed with regenerating manuka scrub (Leptospermum scoparium), otherwise the surrounding land is also pasture.

4.2 Indigenous shrubland

Small pockets of indigenous shrubs, ranging from single plants to patches of 30 × 15 m (450 m2), were present throughout the site, but particularly in the folds of the valley slopes. Tauhinu is most common on the eastern slopes, while Coprosma rhamnoides is the major species on the western side of the valley. Other species associated with these pockets of shrubs include manuka, mahoe (Melicytus ramiflorus), hangehange (Geniostoma ligustrifolium), and various ground ferns (e.g. kiwikiwi (Blechnum fluviatile), swamp umbrella fern (Gleichenia microphylla), and thousand-leaved fern (Hypolepis millefolium)). Single, large specimens of kamahi (Weinmannia racemosa), wheki (Dicksonia squarrosa), and mamaku (Cyathea medularis) were noted. All palatable plant species had been browsed heavily by cattle.

The pest plants gorse (Ulex europaeus) and blackberry (Rubus fruiticosus) were also present.

4.3 Wetland

This small site (0.5 ha) comprises a narrow strip (300 m × 20 m maximum) in the valley floor. Thick swathes of marsh clubrush, with scattered tussocks of pukio and patches of wi (Juncus edgariae and J. pallidus), are the main species in the swamp in the valley floor. Giant umbrella sedge (Cyperus ustulatus) was also noted. The exotics tall fescue (Schedonorus arundinaceus) and creeping buttercup (Ranunculus repens) are common along the wetland margins.

4.4 Pasture grassland

The remainder of the site is covered with rough pasture, dominated by tall fescue and cocksfoot (Dactylis glomerata), although a variety of other common pasture grasses (e.g. browntop (Agrostis capillaris), sweet vernal (Anthoxanthum odoratum), and Yorkshire fog (Holcus lanatus)) are also present. Perennial herbs noted include white clover (Trifolium repens), foxglove (Digitalis purpurea), selfheal (Prunella vulgaris), and pennyroyal (Mentha pulegium).

4.5 Vegetation summary

Degraded pasture is the main vegetation cover. Three small patches of indigenous vegetation at the site each cover an area more than 100 m 2; one of these contains a tree (kamahi) greater than 4 m tall. A small degraded swampy area is present on the valley floor.

5. FLORA

Vascular plants recorded at the site are all common species, typical of the vegetation and habitat types present. No nationally threatened or uncommon plant species (as per de Lange et al. 2009) were observed at the site.

Two exotic species - gorse and blackberry - present in the site are listed in the Regional Pest Management Plan (RPMS) (Greater Wellington 2009) as site-led management species for boundary control purposes.

6. FAUNA

6.1 Fish

There are no records in the NIWA Freshwater Fish Database of any indigenous fish species at the site or in the Mazengarb Drain. There is a record for brown mudfish in an adjacent part of the Waikanae River catchment, several kilometres from the clean- fill site (Figure 3). Habitat in the wetland on the proposed clean-fill site may be suitable for mudfish, and there is habitat in the stream and pond suitable for banded kokopu (Galaxias fasciatus) and shortfin eel (Anguilla australis). Banded kokopu have been seen in the stream below the site by Department of Conservation staff (Richard Gill pers comm. 30/05/2012).

Brown mudfish are not often found with other fish species and are considered poor competitors (Petrove 2009). Historical reports and habitat analysis (Petrove 2009, O’Brien and Dunn 2007) suggest that brown mudfish tend to occupy hollows, ponds, pools, puddles and drains but rarely creeks. Forest puddles with permanent water have been found to contain the highest fish densities. This suggests that they are poor swimmers and unlikely to be found in a reach of stream with a moderate gradient and a steady water flow, for example in the pine forest reach below the wetland.

Figure 3: The route of the Mazengarb Drain from the clean-fill site to the Waikanae River and the nearest record of mudfish (NZFFD).

Fish surveys The wetland within the proposed clean-fill site and the stream and pond below the site were surveyed for fish on two occasions, 10 and 11 August 2011 and 29 October 2012.

In winter 2011 no spotlighting was done due to cold weather conditions. Few indigenous fish can be seen by spotlighting at this time of year due to low water temperatures and low availability of food. Baited Gee minnow traps were set in the pond and in the lower stream channel but no fish (including eels) or koura (freshwater crayfish) were caught.

During the October 2012 survey the wetland within clean-fill site was surveyed for mudfish as well as the stream and pond below the site. Ponding of water was much reduced at the site compared with August 2011 and it was not possible to see fish there by spotlighting due to poor water clarity. Neither was it possible to deploy traps because the ponded water areas were so small (usually 0.20 by 0.20 m wide and 0.10 to 0.20 m deep).

The stream emanating from the wetland is very small, with a wetted channel width of between 0.20 to 0.25 m and a water depth of 0.005 to 0.01 m reaching 0.10 m in the rare pools (Plate 3, Appendix 1). It has a gravel bottom with shoals of deep soft mud

and is excellent habitat for banded kokopu. However, no fish were observed in the stream during the October 2012 survey.

It was not possible to survey the entire stream as the blackberry was in leaf and this and other vegetation blocked much of the stream between the proposed clean-fill site and the pond. However, it would be reasonable to expect that banded kokopu continue to occupy the stream even though they were not observed during the survey. Late winter until late spring is considered the optimal period for surveying for brown mudfish (Ling et al. 2009). At this time of year heavy rain has charged ponds and pools and fry (young fish) are more likely to be encountered. Minnow trapping is the preferred sampling technique. However, the stream in this instance was not large enough to contain traps while maintaining the entrance cones below water. No mudfish were seen. The presence of banded kokopu along this reach would also be likely to affect mudfish presence.

The reach of stream immediately above the pond has a slow flow, a low gradient, and is overgrown with vegetation (Plates 4 and 5, Appendix 1). This reach does not quite meet the optimum water depth for brown mudfish of 0.15 0.30 m as it is a little shallower than that. It was surveyed using the method described in Ling et al. (2009). A small dip net was passed quickly through water and vegetation, and the contents carefully rinsed of mud before checking for fish. This was done along the entire accessible reach above the pond and amongst vegetation around the perimeter of the pond where water depth was optimal. A spotlight survey was conducted beforehand. No fish were observed.

6.2 Birds

Four bird species were observed during the site visit, three of which were indigenous species (Table 1). Of these species one, red-billed gull has a national threat classification of Threatened-Nationally Vulnerable (Miskelly et al. 2009), but this species will not be breeding at the site.

Table 1: Bird species observed during the site visit to the proposed Nikau Palm Road clean-fill site.

Species Common Name Threat Classification* Corvus frugilegus Rook Introduced and naturalised Larus novaehollandiae Red-billed gull Threatened-Nationally Vulnerable Rhipidura fulginosa Fantail Not Threatened Tadorna variegata** Paradise shelduck Not Threatened * Miskelly et al. 2009 ** One pair observed adjacent to proposed clean-fill site boundary.

6.3 Lizards

No lizards were observed during the site visit. Six species of indigenous skinks and geckos (Table 2) are known to occur in the general vicinity, four of which are commonly found in pasture and rough grassland. These are: common skink, brown skink, copper skink, and spotted skink. Wellington green geckos may be found in

indigenous scrub/shrubland, while common geckos are generally found in crevices in rock outcrops. Potentially, most of these species could occur within the clean-fill site, except for common gecko which lack suitable habitat. However, the site is quite degraded and any lizards present are only likely to be present in very low numbers.

Table 2: Lizard species known to occur in the general vicinity of the proposed clean- fill site.

Species Common Name Threat Classification* Oligosoma polychroma Common gecko Not threatened Oligosoma aeneum Copper skink Not threatened Naultinus punctatus Wellington green gecko Declining Woodworthia maculatus Common gecko Not threatened Oligosoma lineoocellatum Spotted skink Relict Oligosoma zelandicum Brown skink Not threatened * Hitchmough et al. 2010

7. ECOLOGICAL SIGNIFICANCE

Vegetation, Habitats, and Species

There are no significant vegetation or habitat types or species at the site, including in the wetland area. Should the site be retired from grazing, blackberry and gorse will rapidly colonise and become dominant.

Despite its degraded state the wetland nevertheless has all the characteristics required for it to be defined as a wetland: wetland hydrology, wetland soils, and a number of wetland plant species. It provides a stormwater retention service but little else in the way of ecosystem services such as water cleansing or nutrient cycling. These services would easily be reinstated by fencing off the area to exclude stock, but are difficult to recreate from scratch.

The only bird species present during the site visit that is likely to roost and breed at the site is fantail which was present in very low numbers (one) and is not a threatened species. Any lizard population is likely to comprise a common, non-threatened species and, if present, will only be in very limited numbers.

Relevant Rules and Regulations

Vegetation at the proposed clean-fill site does not meet the criteria for listing as being significant or as an ecological site as described in the District Plan sections C.8.3 (a) and (c). It does, however, trigger the District Plan rules regarding patch size and tree height (D2.2.1 (i) and (i (a))) Rural Zone Permitted Activity Standards (disturbance, removal, damage or destruction, of naturally occurring indigenous vegetation greater than 4 m in height or which forms a contiguous area of more than 100 m2).

 The Regional Pest Management Plan requires blackberry and gorse to be controlled in rural areas within 10m of a boundary.

 The alteration or modification of a wetland is a discretionary activity under the District Plan (D2.1.3B (iv)).  Water quality must be maintained to support a healthy aquatic life.  KCDC will promote the restoration of degraded or piped channelled streams (C.7.4 Policy 2).

8. POTENTIAL CONSTRUCTION AND OPERATIONAL EFFECTS

8.1 Potential effects

Potential ecological effects resulting from construction and operation of the proposed clean-fill are:

 Changes to local hydrology  Clearance of indigenous vegetation  Removal of soil  Loss of habitat for indigenous fauna  Sediment and/or flocculant release to the receiving environment  Loss of small degraded wetland and associated flora and fauna  Weed invasion

It is also possible that the small population of banded kokopu downstream from the proposed clean-fill site will be compromised. This will depend on whether water, containing flocculants toxic to fish, discharges into the stream from onsite sediment detention ponds

The proposed works will result in most of the existing vegetation and soil, and associated fauna, being cleared from the site. This will happen in stages, beginning with the formation of an access road from the neighbouring quarry via the top of the valley and running to the bottom of the valley. Soil and vegetation will be removed at the beginning of each stage, starting from the bottom of the valley. When grazing stops, weeds will invade, especially where soil disturbance occurs.

All of the small wetland areas on the site will be destroyed. Wetland currently outside the footprint of the proposed clean-fill will be used for a sediment retention pond. During the construction period, water flows will be redirected to sediment retention ponds, as set out in the sediment and erosion control plan. Water from seeps in the side gullies will be re-directed across the site using Novacoil. As filling progresses, surface water flow across completed stages will be directed to the eastern side of the site, alongside the access road. It is proposed that this water should flow in a natural channel.

9. MITIGATION OPTIONS

Proposed planting of indigenous forest species alongside Nikau Palm Road and on both sides of the valley above the fill will partly mitigate biodiversity loss and reduce

colonisation of the site by weeds. Planting should consist predominantly of manuka, and other indigenous colonising species already present on the site, e.g. mahoe, tauhinu, and hangehange. If possible, existing indigenous vegetation along the western boundary of the site should be retained. Stripped topsoil should be stored, for reinstatement to cover completed stages. Any rehabilitation strategy should include control of weeds, including wilding pines.

The proposed reinstatement of overland flow as a natural water course will require riparian planting with indigenous riparian plant species. These strips should be at least 5 m wide on each side of the stream channel. This will attract the adult flying forms of various aquatic insects to re-populate this headwater stream (c.f. Collier & Smith 1998) and encourage vegetation sustainability through natural establishment of seedlings (c.f. Reeves et al. 2006). Fencing will ensure protection from stock and enable the restoration of what is, currently, a degraded stream.

Care will need to be taken that flocculant overdosing does not occur so that banded kokopu in the receiving environment are protected.

Following disestablishment of the sediment retention pond in the lower valley of the clean-fill site, wetland hydrology should be re-established there and this area should be planted with indigenous wetland species. This should be contiguous with, and merge with, any wetland outside of the site boundary.

10. CONCLUSIONS

The proposed clean-fill development will have some minor adverse ecological effects. These effects can be mitigated by the indigenous planting proposed elsewhere on the site, weed control, reinstatement of the stream and wetland, and the establishment of a fenced and planted riparian vegetation zone.

Overall, taking mitigation suggestions into account, the net ecological effect of the proposed development will be neutral.

REFERENCES

Collier K.J. and Smith B.J. 1998: Dispersal of adult caddis flies (Trichoptera) into forests alongside three New Zealand streams. Hydrobiologia 361:53-65

Greater Wellington 1999: Regional Freshwater Plan for the Wellington Region accessed online at http://www.gw.govt.nz/assets/Plans--Publications/Regional-Freshwater- Plan/3866_RFPFreshwaterPla_s7744.pdf

Hitchmough R.A. 2009: Conservation status of New Zealand reptiles (2009). Journal of Zoology Journal of Zoology 37:203-224

Kapiti Coast District Council District Plan accessed online at http://www.kapiticoast.govt.nz/Planning/District-Planning/District-Plan1/District- Plan---Volumes-1-and-2/

Ling N., O’Brien L.K., Miller R. and Lake M. 2009: Methodology to survey and monitor New Zealand mudfish species. CBER University of Waikato contract report 104 for the Department of Conservation.

LRIS portal http://lris.scinfo.org.nz accessed 19/09/2011.

Miskelly C.M., Dowding J.E., Elliot G.P., Hitchmough R.A., Powlesland R.G., Robertson H.A., Sagar P.M., Scofield R.P. and Taylor G.A. 2009: Conservation status of New Zealand birds 2008. Nortonis 55: 117-135.

O’Brien L.K. and Dunn N.R. 2007: Mudfish (Neochanna Galaxiidae) literature review. Science for Conservation 277. Department of Conservation. Wellington.

Petrove N.K. 2009: Habitat preferences of brown mudfish (Neochanna apoda Gunther). MSc thesis Massey University. Palmerston North.

Reeves P., Meleason M. and Matheson F. 2006: Water and Atmosphere 14(1): 16-17.

APPENDIX 1

SITE PHOTOGRAPHS

Plate 1: Proposed clean-fill site in August 2011. The wetland has small areas of ponded water that were not present in October 2012.

Plate 2: The bottom of the clean-fill site looking into pine forest on the adjacent property.

Plate 3: The stream in the pine forest below the clean-fill site in late October 2012. There was insufficient depth to deploy Gees minnow traps

Plate 4: The stream below the pine forest and immediately above the old sediment retention pond.

Plate 5: Vegetation through which the lower reach of the stream flows to the old sediment retention pond.

Plate 6: The old sediment retention pond.