2. Mangatawa catchment consents for earthworks, storm water ...

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NZ Transport Agency and Tauranga City Council Mangatawa Drain Flood Bypass and TEM Stormwater AEE through the use of appropriate sediment control devices, as outlined in the Bay of Plenty Regional Council’s Erosion and Sediment Control Guidelines for Land Disturbing Activities (2001). Mangatawa Flood Bypass As with the proposed TEM roadway Stormwater option, a main concern is the potential to cause temporary negative effects on the downstream receiving environments, through sediment inputs from construction and maintenance operations. In addition during operation the flood control structures that convey water need to be able to allow for fish passage. This also applies to the upstream migration of native fish and any instream works should be carried out, outside of key migration periods. The temporary negative effects caused by excess sediment loads should be minimised through the use of appropriate sediment control devices, as outlined in the example erosion and sediment control plan attached as Appendix 13. This has been informed by the Bay of Plenty Regional Council’s Erosion and Sediment Control Guidelines for Land Disturbing Activities (2001). With respect to the freshwater ecology of the Mangatawa Drain, as the proposed activities will result in an increase in the amount of riparian vegetation present, this will be of benefit to the aquatic habitats within the drain, providing shading and cover for fish and macro invertebrates, and increase the potential for the drain to act as a pathway for native fish inhabiting the upper catchment. As the riparian planting will be largely confined to the lower reaches of the drain it is unlikely to result in a significant change to the water quality of the existing drain. Stormwater Treatment Wetland i. Vegetation The element that has the potential to have the most significant effect on the ecology of the area, because of the quality of the existing habitats, is the enlargement of the Stormwater Treatment Wetland and the outlet to Rangataua Bay. With respect to the vegetation and flora within the stormwater treatment wetland, the enlargement of this pond preserves most of the large cabbage trees on this site, then the effect of the overall enlargement on this component of the vegetation will be no more than minor. As an enlarged bund will separate the salt-marsh of the SES from the treatment wetland this is likely to promote the growth of the jointed rush which already dominates this area of the pond. The planting of Carex in the pond and the forebay has the potential to provide nesting habitat. With respect to the Baumea, shown on the planting plans in both the stormwater pond and the forebay, this could grow to such a degree as to eventually fill the pond system, and therefore has the potential to lower the overall capacity of the pond. Provision needs to be made for several ramps down to water level to allow periodic cleaning of the pond. With respect to the potential effects of this proposed development and increased discharge of treated stormwater into Rangataua Bay examination of existing data on the sediment quality and ecology of the bay (Section 6) indicates that the proposed increased discharge to the Bay will not have a significant adverse effect of the water, sediment and overall ecology of the Bay. Status: Final Page 87 April 2009 Project Number: 3932036 NZ1-1552092-Mangatawa Drain Flood Bypass and TEM Stormwater AEE
NZ Transport Agency and Tauranga City Council Mangatawa Drain Flood Bypass and TEM Stormwater AEE The sediment quality in Rangataua Bay is high (concentrations of trace metals, and hydrocarbons less than the guideline values for the protection of aquatic ecosystems or less than the limit of detection), even though this section of the Bay has been receiving untreated stormwater from the existing highway. The quantity of sediment that will be discharged into Rangataua Bay following treatment will be reduced by about 51% and the zinc loads discharged to Rangataua Bay will also reduce by about 4.8%. These reductions represent a net improvement in the discharge of contaminants to Rangataua Bay. The annual copper loads being discharged to Rangataua Bay will increase by about 94%, however, because sediment copper concentrations in Rangataua Bay are below guideline values the increase in copper is unlikely to cause these guidelines to be exceeded. This increase in copper concentrations will not have a significant adverse effect on the sediment quality of the Bay. The proposed enlargement of the treatment pond will not encroach on the Special Ecological Area therefore most of the more significant vegetation within the existing pond area will be retained. The effect of the proposed development on both the vegetation and the avifauna is therefore no more than minor. The proposed discharge to Rangataua Bay is unlikely to have significant adverse effects despite an increase in copper concentrations, though a monitoring programme that includes sediment copper concentration in Rangataua Bay may be appropriate to ensure copper concentrations do not accumulate to levels exceeding guidelines. ii. Herpetofauna Rainbow skinks are an introduced species from eastern Australia and are locally abundant within the Tauranga area. The rainbow skinks within storm water treatment wetland were visually estimated to be abundant. Because this species is not native to New Zealand, their protected status is currently under review. Rainbow skinks are unlikely to be of conservation concern and should not warrant any mitigative effort. Copper skinks are a protected endemic species. Given the survey effort, the six individuals located within storm water treatment wetland suggest that there is a low to medium-density population onsite, which should warrant mitigative effort. This would involve a small-scale pre-construction rescue and relocation of native skinks into adjacent or nearby areas of suitable and secure habitat. This action should not require a formal translocation, however the Department of Conservation and affected iwi should be consulted. The following recommendations should be considered: • Retained habitat will require isolating with a silt fence to prevent relocated skinks from returning into footprint habitats • Retained habitat will require instalment of additional refuges, including small log piles to provide for a possible increase in density of skinks within these areas. • Retained habitat will require enhancement with additional plantings of low-lying scrub-type plants and grasses. Enhanced areas should not be restricted to island areas surrounded by water. Predator control would also required until at least such time as any additional plantings have established and relocated lizards have re-established micro territories. Status: Final Page 88 April 2009 Project Number: 3932036 NZ1-1552092-Mangatawa Drain Flood Bypass and TEM Stormwater AEE
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Mangatawa Drain Flood Bypass and TE
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APPENDIX 7 - Archaeological Assessm
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ARCHAEOLOGY B.O.P. HERITAGE CONSULT
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2 INTRODUCTION Project Background T
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4 ARCHAEOLOGICAL LANDSCAPE Previous
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6 U14/1708 & 1709 Figure 3. Cadastr
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8 Figure 6. Part ML 8133 showing Pt
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10 Hungahunga & Toroa A further ton
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12 APRIL 2008 ARCHAEOLOGICAL SURVEY
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14 Historic Places Act In addition
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APPENDIX 8 - Hydraulic Modelling: M
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Hydraulic Modelling: Mangatawa Drai
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undertake investigations into the d
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Discharge to Papamoa Beach To disch
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• Riparian planting adjacent to t
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2.2 Hydrological Assessment 2.2.1 C
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The Maranui catchment area in the m
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Table 7 - 2% AEP Storm Event Top Sp
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These results include climate chang
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3.3 Maintenance Work in Mangatawa D
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stormwater from the Maranui catchme
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Appendix A Mangatawa Drain Layout P
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Appendix C Runoff Hydrographs
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Appendix E Proposed Lower Mangatawa
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APPENDIX 10 - Drawings 3932036 ck46
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APPENDIX 12 - Drawing 3932036 ck227
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Report Tauranga Eastern Motorway -
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1 Introduction This report describe
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embankment settlement rates, and th
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3.2 Construction Sequence The typic
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concrete contamination as well as s
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Pahse 1 consists of the western sec
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• Installation of Stage 2 decanti
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Appendix A Erosion and Sediment Con
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Activity Status Mangatawa Drain 1.1
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(b) Natural State (River) Water Qua
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6. Reclamation or drainage of the b
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APPENDIX 15 - Legal Descriptions of
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Path: P:\393\3932036\TGI\55_Project
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32 Harington Street PO Box 903, Tau
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32 Harington Street PO Box 903, Tau
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