Dry Creek Replacement Cleanfill, SH 58, Porirua - Hutt City Council

Recommendations

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7.0 Mitigation recommendations 7.1 Regenerating manuka and broadleaved forest Despite the assessed minor adverse effect of the proposal on local ecological values, it is our recommendation that the proposed clearance of approximately 0.7 ha of this vegetation (and associated edge effects, localised desiccation and potential weed invasion) should be subject to mitigation. As outlined above, because so little of the original indigenous vegetation remains within the Porirua District, the value of these more advanced areas of regenerating forest and scrub as habitat and refugia is elevated – particularly given the contiguous nature of the application site and the adjacent forested areas of Belmont Regional Park. I have also considered Policy 46 of the RPS in determining a recommendation of mitigation for this proposed loss of regenerating indigenous vegetation. Policy 46 is an interim framework encouraging a precautionary approach to the remediation or mitigation of adverse effects on indigenous biodiversity values where avoiding adverse effects is not practicably achievable. Any mitigation programme should take into account the relative youth and the low to moderate ecological value of the vegetation and habitat, as well as the relative proportion of these vegetation communities remaining in the ecological district. As part of determining mitigation requirements, we would recommend the preferential selection of a mitigation area that has a similar ecological potential to the area of vegetation being removed. Such an area would be expected to have similar physical and habitat characteristics, as well as protection from ungulate and browsing pests. We consider that similar areas with similar vegetation characteristics would regenerate naturally to a similar ecological value within 15 – 25 years. In considering the ecological context of this area with the terrestrial habitat loss proposed, we consider and recommend that a suitable mitigation programme for terrestrial vegetation loss could be undertaken through a combination of the following: 1. Specific restoration planting of manuka, kanuka and broadleaved species in conjunction with / or as part of the permanent land retirement areas immediately adjacent to the proposed freshwater mitigation sites ; 2. The 4,594 m2 of landscape and visual planting proposed on the batter slopes as part of Stage 1 be carried out in such a way (comprising predominantly manuka, kanuka and broadleaved species) that it provides ecological benefit; and 3. Permanent retirement of pasture and facilitation (e.g. enhancement planting of native species) of natural regeneration of additional areas within the proposed freshwater retirement areas proposed. The restoration planting, permanent protection and associated plant and animal pest control will enhance the natural regeneration and, will contribute to long-term ecological improvements occurring in the wider area. Any area where mitigation is proposed should ideally be in close proximity to the vegetation and habitat being lost. As part of this assessment, we did not develop a mitigation package further than these recommendations on the understanding that a detailed mitigation plan was being developed by Tonkin and Taylor based on this assessment. Finally, it is proposed that a condition of consent provide for an environmental management plan to guide the protection and enhancement of both the freshwater and any potential Dry Creek Replacement Cleanfill, SH 58, Porirua | Assessment of Terrestrial Ecological Effects 18
terrestrial mitigation sites. Consistent with the above terrestrial ecological mitigation recommendations, this environmental management plan should include control of invasive pest plants, and management of browsing animals through fencing and pest control mechanisms. This environmental management plan should continue for the operational life of the cleanfill. This plan should include identification of plant and animal pest species to be managed, the timing of this management, and the tools to be used. 7.2 Seepage wetlands As outlined above, these wetlands are considered to have been induced as a result of historical vegetation clearance and ongoing grazing and they are highly modified from stock pugging and constant browsing pressures. We have assessed that mitigation is not required for their loss. However, the freshwater ecological assessment (MWH) requires mitigation for loss of intermittent and perennial streams. The areas identified for this mitigation includes areas of wetland seepages upstream of the project footprint which are greater in extent than those lost beneath the project footprint. These wetland areas will therefore be included within the fenced area and thus protected for as long as they are able to persist beneath a regenerating canopy. 7.3 Wildlife Prior to vegetation removal associated with Stage 4 of the proposed cleanfill, we recommend manual habitat searches and the deployment of a suitable number of ARs in the rank pasture mosaic and young manuka scrub and shrubland in the upper area of the proposed cleanfill to capture any lizard species that may inhabit this area into the main gully system upstream. Any lizards caught should be identified and translocated into the main gully system a sufficient distance upstream of the upper extent of the proposed cleanfill works. The proposed translocation site will be determined as part of application to the Department of Conservation for this transfer. We note that all native lizards are afforded absolute protection under the Wildlife Act 1953 and a permit to trap and translocate lizards will be required from the Department of Conservation. 7.4 Monitoring Recommendations Without management the cleanfill proposal is likely to lead to an increase in the abundance and distribution of exotic weed species, particularly on cleared faces, on exposed areas of cleanfill, and as seed transported to site. Any areas that may be re-vegetated and retired as mitigation for terrestrial habitat loss as part of this proposal will require ongoing control of browsing mammals, both stock (fencing) and animal pests such as goats and possums for the life of the clean fill operation. Without this control the levels of mitigation benefit that are required, are unlikely to be achieved. As part of the management plan, weed and animal monitoring should be undertaken to ensure the mitigation mechanisms outlined above are maintained sufficient to ensure the mitigation requirements envisaged are achieved. This should include aspects of invasive weed establishment and control (during cleanfill staging), animal pest control, fence maintenance and the establishment of enrichment plant species. Dry Creek Replacement Cleanfill, SH 58, Porirua | Assessment of Terrestrial Ecological Effects 19
Page 1 and 2: Dry Creek Replacement Cleanfill, SH
Page 3 and 4: CONTENTS 1.0 Introduction 3 2.0 Met
Page 5 and 6: 1.0 Introduction Boffa Miskell has
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Page 9 and 10: the adjacent Belmont Regional Park,
Page 11 and 12: MAIN HABITATS and FEATURES AREA (ha
Page 13 and 14: These plans and drawings have been
Page 15 and 16: Statement which provides an interim
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Page 19: combined have an area of 0.7 ha. Th
Page 23 and 24: 9.0 References Boffa Miskell. 1998:
Page 25 and 26: Asplenium hookerianum Asplenium pol
Page 27 and 28: Appendix 2 Site Photos Dry Creek Re
Page 29: Photo 7: Looking downstream of main

Dry Creek Replacement Cleanfill, SH 58, Porirua - Hutt City Council

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