FINAL REPORT NO.54. Erosion and Sediment Control Plan - Coastal Reclamation. Tauranga City Council. Private Bag Tauranga 16 August

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1 J:\Jobs\ \6000 Reports\Erosion Management\(Cover).doc FINAL REPORT NO.54 Erosion and Sediment Control Plan - Coastal Reclamation Prepared for Tauranga City Council Private Bag Tauranga 16 August EROSION MANAGEMENT EROSION MANAGEMENT LTD 35 HASTINGS PARADE, PO BOX , DEVONPORT AUCKLAND, NEW ZEALAND TEL/FAX:

2 2 CONTENTS Executive Summary 1.0 Introduction 1.1 General 1.2 Reference documents 1.3 Report layout 2.0 Site description 3.0 Proposed works 3.1 Overview 3.2 Specific areas Rail causeway Foreshore from Memorial Park to The Strand Eastern foreshore reclamation option (Matapihi) Matapihi archaeological reclamation 4.0 Erosion and sediment control 4.1 Overview 4.2 Rail causeway 4.3 Foreshore from Memorial Park to The Strand 4.4 Eastern foreshore reclamation option (Matapihi), 4.5 Matapihi archaeological reclamation 5.0 Monitoring 6.0 Assessment of environmental effects 6.1 Effects of the control measures 6.2 Potential effects on the environment 7.0 Recommended conditions of consent 8.0 Conclusions Drawings Drawing 1 Silt Fence Detail Drawing 2 Floating Curtain Detail

3 3 TAURANGA CITY COUNCIL SOUTHERN PIPELINE EROSION & SEDIMENT CONTROL PLAN COASTAL RECLAMATION EXECUTIVE SUMMARY This Erosion and Sediment Control Plan (ESCP) has been prepared to address the potential generation and discharge of sediment from proposed coastal reclamation and sewer pipeline and walkway construction activities in the coastal marine area (CMA) of Tauranga Harbour. Sediment generation from land based activities, the submarine pipeline and the Ontrack Bridge upgrade associated with the Southern Pipeline are dealt with elsewhere. The proposed works covered by this ESCP involve reclamation activities in the CMA. The works will be narrow in width (generally about 10m wide but up to 19m in width), and will extend over 1800m in length in the CMA. Four separate areas are identified along the route. These areas are the railway causeway, the foreshore from Memorial Park to The Strand, the eastern foreshore option (Matapihi), and the area associated with the Matapihi archaeological site reclamation. The report discusses the erosion and sediment control measures proposed for each of these areas. A fundamental position taken by the ESCP is that sediment retention measures, by themselves, cannot retain all of the sediment that may be generated from construction activities. Instead of relying on sediment control measures alone to retain sediment, the primary emphasis of this ESCP has been directed towards construction methodologies that can minimise the actual generation of sediment. The various sediment control measures proposed in this ESCP will supplement these measures. The different situations anticipated to occur during the works are discussed in the ESCP for each of the four separate areas identified earlier. The proposed works will be long but the narrow width means that the site will be comparatively small (about 2 hectares in total). This small area will have a flat surface consisting of non-erodible rock fill, and the potential levels of sediment from the work areas will therefore be low. These levels will be further reduced by the focused construction methodology and the control measures proposed in the ESCP. Low quantities of sediment only are expected to be discharged from the site after treatment. Any sediment discharged from the works is expected to be fine textured material and be widely dispersed by the physical environment of the harbour. These fine textured sediments may have temporary and localised effects on the clarity of the harbour s receiving waters. These waters also often have poor clarity, particularly during storm events when the discharge from the works is likely to occur. Overall, it is considered that the potential sediment loss from the proposed activity will be low and is not likely to be significant in relation to a very much larger receiving environment that is naturally turbid. A number of consent conditions are recommended at the end of the report.

4 4 1.0 INTRODUCTION 1.1 General This Erosion and Sediment Control Plan (ESCP) has been prepared to address the potential generation and discharge of sediment from construction activities associated with a proposed sewer pipeline and walkway along the eastern foreshore of the Te Papa peninsula in the coastal marine area (CMA) of Tauranga Harbour. A variety of measures to control this potential discharge of sediment are detailed in the report. The potential environmental effects that may arise from the discharge of sediment from the works are briefly discussed in the Assessment of Environmental Effects section of this report, and more fully described in reports by ASR and Cawthorn contained in the main AEE. 1.2 Reference Documents URS Drawing Numbers C to 006 Foreshore Walkway/Pipeline URS Drawing Numbers C to 255 Details of Foreshore walkway/pipeline URS Drawing Number G Railway Causeway Widening URS Drawing Number G Eastern (Matapihi) Foreshore 1.3 Report Layout This report has been prepared in conjunction with a number of other documents and reports prepared in support of the proposal. It is attached with the overall documentation that, for the purposes of this erosion and sediment control report, is termed the Main AEE. This report focuses on potential sediment related issues associated with the proposed reclamations in the CMA and has been generally prepared as a stand alone document. 2.0 SITE DESCRIPTION This ESCP addresses works proposed in the coastal marine area along the south-eastern end of the Tauranga Harbour railway causeway, along the western foreshore from Memorial Park to The Strand, the eastern (Matapihi) foreshore temporary and permanent reclamations, and the Matapihi archaeological site. The causeway has an east to west orientation and extends for some 580m westward from the shore to the rail bridge. It presently consists of a concrete walkway on the south side of the rail line with the embankment itself consisting of rail ballast rock, grasses and various weeds and shrubs down to an intertidal rock rip rap protected embankment. The harbour is tidal through this area with intertidal sediments consisting of medium to coarse textured sand. The toe of the outer 100m of rail embankment before the bridge is below Mean Low Water Springs (MLWS). The Memorial Park to Strand section is much more developed with residential dwellings present landward of the coastal area and extensive foreshore protection works. The land is relatively flat at the southern end and steepens to the north to form 15-20m high cliffs. The foreshore protection works consist of measures such as rock gabion or concrete walls and rock boulders. The only places where no sea wall armouring exists are along the Council road reserves (First, Second and Fourth Avenues). An intertidal beach zone of varying width is present; particularly near First Avenue.

5 5 The eastern (Matapihi) foreshore section presently consists of a concrete walkway with a small open drain crossing near the end of Matapihi Road. The rest of the area is undeveloped. Beach sediments generally consist of medium to coarse sand (with typically up to 10% of fine grained soils) together with occasional rock. The relative coarseness of the sand is indicative of low to moderate near shore energy. 3.0 PROPOSED WORKS 3.1 Overview It is proposed to undertake beach reclamation works in order to construct the proposed pipeline and walkway. The works will involve the placement of rock fill against existing land and into which the proposed pipeline will be laid. The reclamations will vary in width but will typically extend about 10m to 12m out from the existing shoreline. Temporary fill is proposed along the outside edge of the reclamation to temporarily bulk out the reclamation to facilitate construction. This temporary material is termed construction fill in this ESCP and will be removed at the completion of the works. A temporary 19m wide reclamation is proposed during construction at the southern end of the Matapihi section of works. The proposed works are predominately located within the intertidal zone of the harbour with the toe of the proposed reclamation being usually either close to or above the MLWS level. Only in a few places will the proposed reclamation extend below MLWS. The medium to coarse textured sand material present along the route is sufficiently competent such that the placement of rock fill can be carried out directly onto a geotextile fabric laid over the sand. This would occur after some slight tidy up and/or the removal of unsuitable material such as rocks etc. Unsuitable material will be removed off site. Any existing rock rip rap will be removed and placed on the recently completed fill to fulfil a temporary protection role during construction. The geotextile fabric will be laid on the prepared surface and reclamation filling then undertaken. The pipe will then be laid into a 1.5 to 2m deep trench excavated into the new reclamation area. Following this, construction of the 3m wide walkway will be undertaken. All temporary fills and reclamations will then be removed and the final erosion protection measures e.g. rock rip rap installed along the outer surface of the reclamation. Sand will then be placed against the completed reclamation from near Memorial Park along to Arundel Street for beach replenishment purposes. 3.2 Specific Areas Four separate work areas have been identified. These areas are the works proposed along the south-eastern end of the rail causeway, those along the western foreshore from Memorial Park to The Strand, those along the eastern foreshore option (Matapihi), and finally works associated with the Matapihi archaeological site reclamation. Particular details associated with each of these briefly discussed as follows Rail causeway The proposed reclamation along this section of the route will be approximately 580m in length. These works will be all above MLWS for all but the western most 100m where levels drop below MLWS. Clean rock is to be end tipped directly onto the laid geotextile followed

6 6 by compaction of the deposited material. The fill proposed for this purpose will be imported graded rock, such as or similar with minimal fine textured material. Rock with a greater proportion of fine textured material may be used above the Mean High Water Springs (MHWS) mark. For the submarine pipeline option, a metal sheet pile coffer dam approximately 20m long and 10m wide will be constructed at the western end of the area below MLWS to enable construction of a pipe joint structure. Specific sheet piles are proposed to minimise seepage. This structure will be in place for up to a year after which it will be removed. The pipe within the causeway embankment along this section of the route will be laid after completion of the proposed bridge upgrade or submarine pipeline works and will be above the MHWS level Foreshore from Memorial Park to The Strand The proposed reclamation from Memorial Park to the Strand will be approximately 1000m in length and will include some 90m of temporary reclamation extending from Memorial Park to Sixth Avenue. This temporary reclamation is for construction purposes only and will be removed at the completion of the works. A reno mattress base with a 1m deep outer gabion key is proposed to be constructed as a base under the rock fill as long term protection against possible coastal erosion. Construction will involve the removal of up to 500mm depth of existing foreshore followed by the placement of the geotextile with the pre-constructed reno mattresses then laid over the geotextile. A gabion key 0.5m wide by 1m depth is proposed along the outer edge of the proposed works with much of this work to be undertaken below MLWS. Following the placement of the reno mattresses, the covering rock fill will then be placed into position. The pipe will be laid once the reclamations have been completed. The 1.5 to 2m deep trench through this section means that the pipe will generally be in the intertidal level along the foreshore and that the trench will be tidally inundated. In relation to the submarine pipeline option, a 20m long by 10m wide metal sheet pile coffer dam will be constructed at the northern end of the area and will extend below MLWS. Following construction, the 90m of temporary reclamation from Memorial park to Sixth Avenue will be completely removed along with the construction fill. A sand beach will be created with imported sand at a generally 5h:1v slope. A number of stormwater outlets are present along the foreshore and these will need to be regraded as required and extended beyond the reclamation and beach replenishment area. Some rationalisation of the outfalls is proposed through the combining of a number of piped systems Eastern foreshore reclamation option (Matapihi) An alternative section of the pipeline route, termed the Eastern Foreshore Option (Matapihi), has been identified along the foreshore from the end of the eastern end of the railway embankment. It will extend along some 130m of foreshore and be up to 19m wide. Some of this work will require a temporary embankment for construction purposes which will be removed at the end of the works. These works will all occur above MLWS.

7 Matapihi archaeological reclamation A 5m wide permanent reclamation is proposed south of Matapihi Road along some 195m of coastline to offer long term protection to an adjacent archaeological site. The works are to consist of a timber retaining wall with toe rock protection. These works will all occur above MLWS. 4.0 EROSION AND SEDIMENT CONTROL 4.1 Overview This ESCP addresses the sediment discharge implications associated with the proposed works described above. On one hand, the proposed works are expected to generate only low levels of fine textured or erodible sediments because of the coarse textured and nonerodible nature of the proposed rock fill. On the other hand, the position of the works in the CMA, together with them extending down to and, in places, beyond MLWS, means that any sediment that may result from the works after treatment will discharge directly to the harbour. Sediment retention measures can never retain all generated sediment, and therefore the primary emphasis has been placed on construction methodology and so minimise the generation of sediment. This will reduce the potential quantity of sediment arising from the proposed works. Some of the methodology proposed below will be common to all works addressed in this ESCP, whereas others apply more to specific activities and construction situations. It should be noted however that other development options exist and the actual method(s) used during construction may vary from that outlined below, depending on the Contractor s construction methodology to comply with the consent conditions. The different scenarios identified for the project are as follows. Methodologies and sediment control measures common to the particular section of works. Construction methodology above MLWS. Construction methodology below MLWS. The coffer dams. Trenching of the pipeline. Beach replenishment. Extension of stormwater outfalls. Walkway construction. Removal of construction fill and temporary reclamations. The proposed erosion and sediment control measures for each of these are discussed for the four general areas identified earlier in Section 3. These areas are the rail causeway, the foreshore from Memorial Park to The Strand, the eastern foreshore reclamation option (Matapihi), and the Matapihi archaeological reclamation. The erosion and sediment control proposals for each of these are discussed in turn as follows. 4.2 Rail causeway a) General A floating sediment curtain or floating silt fence will be positioned 2m away from the toe of the works. This will be removed as works are completed in particular areas.

8 8 Clean graded rock (such as graded ) with minimal fine textured material is to be used as fill through the intertidal range. Rock or fill with more fines may be used above the MHWS level but will be wrapped in geotextile to minimise the migration of fines. The surface of the reclamation will be sloped back to the land during construction as far as practical to direct sediment laden runoff from work areas away from the coast. A 300mm diameter compost filter soxx, silt fence or equivalent sediment control measure will be placed along the top outside edge of the platform during construction. Temporary erosion control protection, such as rock rip rap, will be installed on the outer face of the reclamation. All erosion and sediment control measures will be undertaken in accordance with Environment BOP Erosion and Sediment Control Guidelines for Land Disturbing Activities; Guideline 2001/03. No washing of concrete truck bowls or similar will be undertaken on site. A wheel wash or alternative measure of cleaning vehicles will be installed at the exit point from the site. b) Works above MLWS Machinery activity will be kept out of the water except for the placement of clean rock (northern end). The seabed surface to be filled will be cleared and prepared during the low tide period as the construction progresses. Clean graded rock will be end tipped and progressively compacted. Although some placement of clean rock may occur in the water, work is expected to generally take place above the tide level. c) Works below MLWS Works will occur below water level on occasion. These works, such as site preparation and the placement of rock fill by end tipping, will be protected by the floating sediment curtain. Clean fill only will be deposited directly into water. d) Coffer dam The metal sheet piles will be installed. Where possible this will be done by machine above MLWS, and otherwise by barge at high tide. The sand/sediment within the enclosed coffer dam will be removed as necessary. This material is expected to be stockpiled off site and the area back filled with selected imported material at the completion of the works. Some seepage is expected through the sheet metal walls and this is to be pumped via a sediment retention system or clarifier and back to the sea. e) Trenching of the pipeline No significant sediment related issues are expected from trenching and pipeline installation within the causeway because the works through this section will be above MHWS. f) Walkway construction The final surface will be established prior to construction of the walkway. The outside sediment control measure(s) will be retained through this operation. g) Removal of construction fill A floating sediment curtain will be installed around the work area. Machines will be kept out of the water.

9 9 The sediment control facility will be removed from the top outer edge of the fill. The redundant construction fill material will be removed and trucked off site. All works in the intertidal area will occur above the tidal level. The permanent erosion control protection measures (rock rip rap, concrete etc) will be installed along the outer face of the reclamation. The floating sediment curtain will then be removed. 4.3 Foreshore from Memorial Park to The Strand a) General A floating sediment curtain or floating silt fence will be positioned 2m away from the toe of the works. This will be removed as works are completed in particular areas. Clean graded rock (such as graded ) with minimal fine textured material is to be used as fill through the intertidal range. Rock or fill with more fines may be used above the MHWS level but will be wrapped in geotextile to minimise the migration of fines. Clean sand is to be used for beach reclamation works. The surface of the reclamation will be sloped back to the land during construction as far as practical to direct sediment laden runoff from work areas away from the coast. A 300mm diameter compost filter soxx, silt fence or equivalent sediment control measure will be placed along the top outside edge of the platform during construction. A silt fence or equivalent will be constructed along the landward extent of the works where there a potential offsite discharge from the works site might occur. Temporary erosion control protection, such as rock rip rap, will be installed on the outer face of the reclamation. All erosion and sediment control measures will be undertaken in accordance with Environment BOP Erosion and Sediment Control Guidelines for Land Disturbing Activities; Guideline 2001/03. No washing of concrete truck bowls or similar will be undertaken on site. A wheel wash or alternative measure of cleaning vehicles will be installed at the exit point from the site. b) Works above MLWS Machines will be kept out of the water except to place clean rock. The seabed surface to be filled will be cleared and prepared during the low tide period as the construction progresses. Preconstructed reno mattresses will be placed on the geotextile and clean graded rock end tipped and progressively compacted. This work is expected to generally take place above the tide level. c) Works below MLWS Clean fill only is to be deposited directly into water. The works area will be protected by the sediment curtain. Two construction options for the construction of the outer gabion key are suggested as follows: - One option is to excavate the trench and lay the pre-constructed gabions from a barge or similar positioned over the work area. This work would occur in the water column with discoloured water controlled by the floating sediment curtain. - Another option is to isolate the work area using an appropriate diversion measure (such as water filled portable dams e.g. Aqua Dam), pumping the work area dry by filling the portable dam with pumped out water, and then

10 10 undertaking the works in the dewatered area. The work would then be carried out as discussed for works above MLWS. d) Coffer dam The metal sheet piles will be installed. Where possible this will be done by machine above MLWS, and otherwise by barge at high tide. The sand/sediment within the enclosed coffer dam will be removed as necessary. This material is expected to be stockpiled off site and the area back filled with selected imported material at the completion of the works. Some seepage is expected through the sheet metal walls and this is to be pumped via a sediment retention system or clarifier and back to the sea. e) Trenching of the pipeline No significant sediment related issues are expected from trenching and pipeline installation along this section of the reclamation despite the trench being below MHWS and therefore tidally inundated. This is because of the clean rock to be utilised as fill, and the clean material to be used as pipe bedding material. It is not anticipated that dewatering of the trench will be required. Should dewatering be required, then erosion and sediment control measures are likely to be required (such as pumping into a suitable treatment chamber before discharge). The sediment retention measure (silt fence, filter soxx or equivalent) will be retained along the top outside edge of the fill during this work. f) Extension of stormwater outfalls A number of existing stormwater outlets will need to be regraded and extended through the reclamation to the coast. Some of the stormwater lines are to be combined with a new outfall located along a boat ramp or similar and extended beyond the reclamation and replenished beach area. The following construction methodology is anticipated. The outlet will be installed using the methodology discussed in Sections 4.3 a) and 4.3 b) and the stormwater line constructed to beyond the outer limit of eventual beach replenishment. Any necessary silt fencing or equivalent will be installed between work areas and neighbouring land before works commence on the land. All new pipe work will then be undertaken to the point of connection with the existing stormwater line. Connection work will be undertaken when there is little or no flow through the piped systems. Piped flow will be blocked with sand bags or similar and any ponded water pumped around the works area. The pipe connection works will then be undertaken and which should be completed within the day. At the completion of these works, the sandbags and pump will be removed and stormwater allowed into the new pipeline. g) Walkway construction The final surface will be established prior to construction of the walkway. The outside sediment control measure(s) will be retained through this operation. h) Removal of construction fill and temporary reclamation A floating sediment curtain will be installed around the work area. Machines will be kept out of the water. The sediment control facility will be removed from the top outer edge of the fill.

11 11 The redundant construction fill material will be removed and trucked off site. All works in the intertidal area will occur above the tide level. The permanent erosion control protection measures (rock rip rap, concrete etc) will be installed along the outer face of the permanent reclamation. A beach is to be created from Memorial Park to Sixth Avenue. The floating sediment curtain will then be removed. i) Beach replenishment Sand is to be laid down between tides and pushed into place by machinery. Clean sand only is to be used and no particular sediment retention measures are proposed. 4.4 Eastern foreshore reclamation option (Matapihi), a) General A floating sediment curtain or floating silt fence will be positioned 2m away from the toe of the works. This will be removed as works are completed in particular areas. Clean graded rock (such as graded ) with minimal fine textured material is to be used as fill through the intertidal range. Rock or fill with more fines may be used above the MHWS level but will be wrapped in geotextile to minimise the migration of fines. The surface of the reclamation will be sloped back to the land during construction as far as practical to direct sediment laden runoff from work areas away from the coast. A 300mm diameter compost filter soxx, silt fence or equivalent sediment control measure will be placed along the top outside edge of the platform during construction. A silt fence or equivalent will be constructed along the landward extent of the works against Matapihi Road. Temporary erosion control protection, such as rock rip rap, will be installed on the outer face of the reclamation. All erosion and sediment control measures will be undertaken in accordance with Environment BOP Erosion and Sediment Control Guidelines for Land Disturbing Activities; Guideline 2001/03. No washing of concrete truck bowls or similar will be undertaken on site. A wheel wash or alternative measure of cleaning vehicles will be installed at the exit point from the site. b) Works above MLWS Machines will be kept out of the water. The seabed surface to be filled will be cleared and prepared during the low tide period as the construction progresses. Clean graded rock will be end tipped and progressively compacted. Although some placement of clean rock may occur in the water, work is expected to generally take place above the tide level. c) Trenching of the pipeline No significant sediment related issues are expected from trenching and pipeline installation despite the trench being below MHWS and therefore tidally inundated. This is because of the clean rock to be utilised as fill, and the clean material to be used as pipe bedding material. It is not anticipated that dewatering of the trench will be required. Should dewatering be required, then erosion and sediment control measures are likely to be required (such as pumping into a suitable treatment chamber before discharge).

12 12 The sediment retention measure (silt fence, filter soxx or equivalent) will be retained along the top outside edge of the fill during this work. d) Removal of construction fill and temporary reclamation A floating sediment curtain will be installed around the work area. Machines will be kept out of the water. The sediment control facility will be removed from the top outer edge of the fill. The redundant construction fill material will be removed and trucked off site. All works in the intertidal area will occur above the tide level. The permanent erosion control protection measures (rock rip rap, concrete etc) will be installed along the outer face of the permanent reclamation. The floating sediment curtain will then be removed. 4.5 Matapihi archaeological reclamation a) General A floating sediment curtain or floating silt fence will be positioned 2m away from the toe of the works. This will be removed as works are completed in particular areas. The timber wall is to be constructed, fabric laid against it and clean fill used as fill through the intertidal range. Fill with more fines may be used above the MHWS level. The fence and filter fabric will be used for sediment control during filling operations. The top of the wall is to be 0.25m above the top surface of the fill and will therefore function as a silt fence during the entire filling operation. A runoff diversion bund or similar will be constructed on the landward side of the works area to intercept and divert any above site flows around the site A silt fence or equivalent will be constructed along the landward extent of the works. Rock rip rap is to be installed as permanent erosion control protection at the toe of the reclamation. This material will be placed by machine from behind the wall. All erosion and sediment control measures will be undertaken in accordance with Environment BOP Erosion and Sediment Control Guidelines for Land Disturbing Activities; Guideline 2001/03. No washing of concrete truck bowls or similar will be undertaken on site. A wheel wash or alternative measure of cleaning vehicles will be installed at the exit point from the site. b) Works above MLWS The seabed surface to be filled will be cleared and prepared during the low tide period as the construction progresses. Machines will be kept out of the water. Only that area that can be filled above the tidal level will be worked. 5.0 MONITORING All erosion and sediment control measures will be inspected on a regular basis as well as before and immediately after rain. Site monitoring will also be undertaken during heavy rainfall events. Any required maintenance or improvements to control measures will be undertaken. This monitoring requirement will be undertaken primarily by the contractor and overviewed by the supervising engineer. All control measures will be maintained in accordance with Environment BOP Erosion and Sediment Control Guidelines for Land Disturbing Activities; Guideline 2001/03.

13 ASSESSMENT OF ENVIRONMENTAL EFFECTS 6.1 Effects of the control measures The proposed works are long and linear and will stretch over about 1800m. Work surfaces will generally be near flat and catchment areas/unit length of retention measure will be low. The measures proposed to control sediment from these areas are those that can be fitted into limited work areas and are proposed to consist of a combination of filter tubes filled with compost (filter soxx), silt fences or similar. Good sediment retention efficiency from these measures is expected and low levels of sediment only are expected to be discharged after treatment. Floating sediment curtains floating silt fences are proposed in the tidal area. It is expected that although they may be less efficient than the land based measures because of tidal and wave energy, they will still retain a significant proportion of any sediment that may be generated from the works. Overriding these measures however is the consideration that sediment retention measures, by themselves, cannot retain all of the sediment that may be generated from construction activities. Because of this, primary emphasis has been directed to minimising the actual generation of sediment through the manner of how construction will be undertaken. These include measures such as using graded clean rock, directing site runoff away from the coast, etc. The Aqua Dams will function more like diversion measures as they will allow areas to be worked in the dry ; they are not treatment measures. The overall effect of the applied construction methodology will be to reduce sediment generation from the proposed works activities. Perimeter sediment control measures will further retain sediment. Together these measures are expected to retain all of the sediment that practically can be retained, and only low levels of sediment are expected to be discharged from the works after treatment. 6.2 Potential effects on the environment The proposed works will be long but the narrow width means that the site will be comparatively small (about 2 hectares in total). This small area will have a flat surface consisting of non-erodible rock fill, and the potential levels of sediment expected from the works will therefore be low. The comprehensive construction measures and methodology discussed in this ESCP are expected to further reduce this level of sediment. Low quantities of sediment only are therefore anticipated to be discharged from the site after treatment through the proposed control measures. Any discharged sediment after treatment is expected to be fine particulate and colloidal material arising from clay sized particles and very fine silts. This material may temporarily degrade local water clarity because the discharge from the sediment retention measures is likely to be turbid. However, this will be to an inter-tidal environment that often has poor clarity, particularly during storm events when the discharge from the works is likely to occur. Any effect that may occur on the clarity of this receiving environment is expected to be local in nature and short lived. Overall, it is considered that the potential sediment loss from the proposed activity is low, and is likely to be insignificant in relation to a very much larger receiving environment that is naturally turbid.

14 14 The effects of sediment from the proposed works have been assessed in more detail in the reports by ASR and Cawthron. 7.0 RECOMEMNDED CONDITIONS OF CONSENT 1.0 The consent holder shall carry out all construction works in general accordance with the application for this consent, and those documents supplied in support of the application. 2.0 Prior to the commencement of works the consent holder shall advise Environment Bay of Plenty of the following; - The identification of appropriately qualified and experienced staff to manage the environmental issues on site; - The identification of staff who have clearly defined roles and responsibilities to monitor compliance with the Consent Conditions, as amended from time to time in accordance with this consent; - Provide details of a chain of responsibility for managing environmental issues and details of responsible personnel. 3.0 The consent holder shall for any given area prepare Erosion and Sediment Control Plan(s). These plan(s) shall comply with consent conditions and (as a minimum) include the following: Erosion and sediment controls; Catchment boundaries for the sediment controls; Supporting calculations if required; Location of the works; Details of construction method to be employed including timing and duration; A programme for managing exposed area including progressive stabilisation considerations; Monitoring and maintenance schedules; and Shall be to an appropriate scale. 4.0 The Erosion and Sediment Control Plan(s) prepared under Condition 3.0 shall be submitted to the Council, and written approval from the Council shall be obtained prior to the commencement of sediment generating activities. 5.0 The Erosion and Sediment Control Plan(s) approved under Condition 4.0 shall be implemented prior to the commencement of the works. 6.0 The consent holder shall ensure that all sediment laden runoff from the site shall be treated by the sediment control measures approved under Condition No significant amendments may be made to the Erosion and Sediment Control Plan(s) and implemented controls (approved under Condition 4.0), unless prior written approval from the Council is obtained. 8.0 All erosion and sediment control measures shall be installed in accordance with Environment BOP Erosion and Sediment Control Guidelines for Land Disturbing Activities; Guideline 2001/03 except where a higher standard is contained in the

15 15 documents referred to in Conditions 1.0 and 3.0 above, in which case this higher standard shall apply. 9.0 The consent holder shall ensure that this consent and these attached consent conditions, and Erosion and Sediment Control Plan(s) approved under Condition 4.0 are forwarded to each earthworking contractor carrying out works under these consents The consent holder shall submit a certificate signed by appropriately qualified and experienced staff, to certify that the erosion and sediment controls have been constructed in accordance with the Erosion and Sediment Control Plan approved under Condition 4.0 of this consent, following the construction of the controls and prior to the commencement of sediment generating activities. This requirement shall also apply to sediment retention facilities that are constructed during site development. Information supplied shall include: i) Location and type of works; ii) ii) iii) Contributing catchment area; Confirmation of compliance with Condition 8.0; and Text detailing the relevant construction methodology A copy of the as-built erosion and sediment control plans shall be kept on site and updated as changes are made. These shall be presented to enable clear interpretation as to the day to day operation and management of erosion and sediment controls 12.0 No sediment retention measures or perimeter controls as approved and implemented under Condition 4.0 are to be removed unless approved by the Council. 8.0 CONCLUSIONS This ESCP addresses the proposed erosion and sediment control implications associated with proposed coastal reclamation and sewer pipeline and walkway construction activities along the Tauranga Harbour. Although it is considered that the nature of the proposed works is such that low levels of sediment only will be generated, it is also recognised that they will occur immediately adjacent to the receiving waters of the Tauranga Harbour. As such, particular attention has been paid to erosion control to reduce the generation of sediment. Various sediment control measures are proposed to supplement these measures.

16 16 DRAWING 1 - SILT FENCE DETAIL from EBOP Erosion and Sediment Control Guideline

17 17 DRAWING 2 - FLOATING CURTAIN DETAIL