PRM 220kV Connection Project. Draft Erosion and Sediment Control Plan

Transcription

1 PRM 220kV Connection Project Draft Erosion and Sediment Control Plan Prepared by: Campbell Stewart SouthernSkies Environmental Ltd Reviewed by: Michael Parsonson SouthernSkies Environmental Ltd Date 7/5/13 Version: Issue 01-2 Copyright 2010 Transpower New Zealand Limited. All rights reserved. This document is protected by copyright vested in Transpower New Zealand Limited ( Transpower ). No part of the document may be reproduced or transmitted in any form by any means including, without limitation, electronic, photocopying, recording or otherwise, without the prior written permission of Transpower. No information embodied in the documents which is not already in the public domain shall be communicated in any manner whatsoever to any third party without the prior written consent of Transpower. Any breach of the above obligations may be restrained by legal proceedings seeking remedies including injunctions, damages and costs.

2

3 PRM 220kV Connection Project Document Version Control Version Date Nature of Amendment Issue /4/13 Draft Issue /5/13 Final (For Lodgement) Transpower New Zealand Limited All rights reserved. Page 2 of 21

4

5 PRM 220kV Connection Project 1. Introduction Transpower New Zealand Limited The Paraparaumu 220kV Supply Connection Scope and Application Structure Site Description Location Topography and Geography Construction Phase Project Timetable Project Works Access Tracks and Platforms Foundation Construction Pole Erection Stringing Conductors Paraparaumu Substation Switchyard Construction Summary of Earthworks Personal Roles and Responsibilities Construction Methodology Access Tracks Platform Formation Spoil Areas Principles of Erosion and Sediment Control General Principles Erosion and Sediment Design Philosophy and Process Environmental Monitoring and Auditing Monitoring and Measurement of Erosion and Sediment Control Rainfall Response and Contingency Emergency Response Procedures Appendices Appendix 1 Erosion and Sediment Control Plans Transpower New Zealand Limited All rights reserved. Page 3 of 21

6

7 PRM 220kV Connection Project 1. Introduction 1.1. Transpower New Zealand Limited Transpower New Zealand Limited ( Transpower ), as owner and operator of the National Grid, is proposing the construction of a new 220 kv supply connection to the Paraparaumu Substation from existing 220 kv lines on the Kapiti Coast. This new supply connection is an alternative to re-aligning the existing 110 kv Paekakariki Takapu Road A Line ( PKK TKR A ) to facilitate the construction of the Transmission Gully Project (TGP). Transpower has been working with the NZ Transport Agency ( NZTA ) to realign the PKK TKR A Line as part of the Transmission Gully roading project. Transpower was formed in 1994 as a state owned enterprise following the separation of the Electricity Corporation of New Zealand (ECNZ). It is wholly owned by the New Zealand Government and subject to the State Owned Enterprises Act The Paraparaumu 220kV Supply Connection The TGP requires the realignment of 24 towers PKK TKR A in Transmission Gully. Through the investigations into the potential realignment of the existing 110 kv network, Transpower investigated the potential for a new 220 kv supply connection at Paraparaumu. Various options were investigated with the preferred option comprising the construction, operation, maintenance and protection of two new 220kV pole transmission lines between the Bunnythorpe Haywards A and B Lines and a new substation located adjacent to the existing Paraparaumu Substation. The existing section of the two 110kV lines extending north from the existing Paraparaumu substation and connecting to the Bunnythorpe Haywards A and B Lines and that section of 110kV lines between the Pauatahanui substation and the Paraparaumu substation would be removed. The new supply connection would eliminate the need for the re-alignment of the PKK-TKR A Line through Transmission Gully as this section of transmission line would be removed. The advantages of the proposal include: removal of the PKK TKR A Line through Transmission Gully which would more readily facilitate the design and construction of the TGP, avoid the visual impact of the existing and re-aligned transmission line when viewed from the new TGP, provides a greater electricity supply connection to the Kapiti Coast for future growth, and potentially lower cost depending on transmission option selected Scope and Application The Erosion and Sediment Control Plan (ESCP) has been developed to address the potential sediment implications from earthworks associated with the Paraparaumu 220 kv supply connection project. The overall ESCP comprises several parts that deal with specific construction activities. The ESCP details the principles, procedures and practices that will be implemented to minimise the potential for sediment discharge from the site Transpower New Zealand Limited All rights reserved. Page 4 of 21

8 PRM 220kV Connection Project 1.4. Structure The ESCP has been prepared to fulfil the expectations of the Greater Wellington Regional Council erosion and sediment control requirements. This ESCP has been prepared to minimise the potential for sediment discharge from the site by ensuring adequate erosion and sediment control principles, procedures and practices to be adopted for the project. 2. Site Description 2.1. Location The proposed Paraparaumu 220 kv Supply Connection WRK-WKM C Line is located in the lower North Island within the Kapiti District, east of Paraparaumu (about 50km north of central Wellington). The proposed substation would be located immediately to the east of the existing Paraparaumu substation at the base of the Akatatawa Ranges, with the proposed 220 kv lines extending in a north easterly direction for a distance of approximately 800m from the proposed substation to connect to the existing Bunnythorpe Haywards A and B lines. The general area is dominated by a mix of urban and rural uses, as well as the National Grid comprising existing transmission lines and substation. The proposed substation is adjoined to the north, south and west by urban activities, reflecting the underlying Operative Kāpiti Coast District Plan Residential zoning. The proposed 200 kv lines would predominantly be located within rural land used for primary production activities such as dairying and dry stock grazing and which presently features existing transmission lines. A significant portion of the adjoining wider environment is used for plantation forestry. The Kapiti Coast is located some 3km to the west of the proposed substation. In terms of communities, the area to the west is urban in nature and comprises the urban area of Paraparaumu to the northwest, Raumati and Raumati South to the west and south respectively, and Waikanae to the north. The rural residential settlement of Nikau Valley is located to the north east Transpower New Zealand Limited All rights reserved. Page 5 of 21

9 PRM 220kV Connection Project Figure 1 Site Plan 2.2. Topography and Geography The area of the proposed Paraparaumu 220 kv Supply Connection is characterised by a predominantly rural landscape but also incorporates the eastern section of the Paraparaumu urban area and some pockets of rural-residential development. The topography of the area is a mix of flat areas and steeply sloping land forming part of the Tararua Foothills (also known as the Akatarawa Ranges). The existing Paraparaumu substation is located on the base of a valley on the edge of the foothills. This adjoins the existing eastern edge of residential development in Paraparaumu as this extends into a contained area of residential development at the northern end of Valley Road. The rural landscape containing the proposed line forms part of the larger elevated backdrop to Paraparaumu which includes the existing BPE-HAY A and B lines. To the north of Paraparaumu substation, the Tararua foothills comprise a series of uplifted landforms which includes Nikau Ridge, the ridgeline to the east of Paraparaumu and Lindale. Beyond this, pockets of rural-residential development have been established within Nikau Valley with some dwellings also elevated to obtain long distance views west towards the coast. To the north of the area is the Paraparaumu Scenic Reserve which is a large area of remnant and regenerating indigenous vegetation. In the south-west portion of the wider project area, Mataihuka (Raumati) Escarpment forms a distinct edge to the coastal plain and separates Valley Road from the larger coastal plain. Some residential development has also occurred at the northern end of the Mataihuka (Raumati) Escarpment and enables a similar elevated outlook from residential properties. In the valley to the east of the Mataihuka Escarpment is the Kapiti Golf Course and Club and rural-residential properties along Valley Road Transpower New Zealand Limited All rights reserved. Page 6 of 21

10 PRM 220kV Connection Project To the east of Valley Road, the Tararua foothills rise to form a series of low ridges following a north to south alignment, which contains diverse vegetation patterns including plantation forestry and pockets of inland indigenous vegetation remnants. The existing alignment of the BPE HAY A and B Lines extends along the western toe of this landform elevated above Valley Road. The proposed Paraparaumu 220 kv Supply Connection project area includes two areas of Outstanding Landscape, being Foothills of the Tararua Ranges and Wavecut escarpment behind Paraparaumu as identified in the Operative Kapiti Coast District Plan. This landscape area generally extends along the Tararua foothills and includes the skyline observed from the coastline. In addition, all ecological areas identified in the Operative Kapiti Coast District Plan are classified as Outstanding Landscapes. The Proposed Kapiti Coast District Plan changes the location, extent and classification of Outstanding Landscapes, with the amount of land classified as Outstanding Landscape significantly reduced. The land to the west and north east of the Paraparaumu substation previously identified as the Wavecut escarpment is no longer an Outstanding Landscape and is identified as a Significant Amenity Landscape. Under the Proposed Kapiti Coast District Plan 2012, the proposed transmission lines would partially traverse the Otaihanga Foothills and Nikau Escarpment, an area identified as Significant Amenity Landscape and considered as having important landscape values. The proposed transmission lines avoid all areas identified as Outstanding Landscape in the Proposed Kapiti Coast District Plan. The location and extent of these landscape areas are shown in the Landscape and Visual Assessment Report in the AEE. It is noted the existing BPE-HAY A and B Lines and MHO-PKK A and Lines in the project area are located within the areas identified as Outstanding Landscapes in the Operative District Plan and Significant Amenity Landscape in the Proposed District Plan. 3. Construction Phase 3.1. Project Timetable The Project works are expected to take approximately 17 weeks to complete following the commencement of activities onsite. The excepted time frames are as follows: 3.2. Project Works Access tracks and platforms 4 weeks Foundations 7 weeks Pole erection 2 weeks Stringing 3 weeks The project involves four stages of construction associated with the installation of the Poles plus the upgrade of the Paraparaumu substation as outlined in the following sections: Access Tracks and Platforms The first stage involves forming access to tower sites and preparing the site for tower construction. Where possible existing tracks will be used and upgraded if necessary. An existing farm track provides access to the site via Nikau Valley road. The track is in good condition and provides access into the centre of the site passing Poles P1 (and Site Tee B) and P2. From P2 the track splits in two. The western fork continues along the ridge in good condition for approximately another 70m to existing Tower T Transpower New Zealand Limited All rights reserved. Page 7 of 21

11 PRM 220kV Connection Project The easterly fork drops off the ridge continuing in a generally southerly direction before again splitting in two. From the ridge line the farm track is in good condition although not to the same quality of the main track from Nikau Valley Road to P2. The eastern fork then back tracks around a gully head crossing a farm pond and heads back in a northerly direction providing access to T271 (Site Tee A). The south western fork heads away from the line before heading back around to the west and connecting with a second track with ends up beneath the new alignment, between the substation and Poles P5 and P6. The tracks are in a good condition and at a good grade. Minor grading to remove rutts and rills is proposed and the progressive placement of aggregate. Water table upgrades will be undertaken as required. Protection matting (to spread load of traffic) is also proposed to be laid where the access track passes over the Vector Gas main. Minor earthworks are required to replace the culvert at the farm crossing. Access to the steeper slopes (P3, P4, P5 and P6) will be undertaken by a tracked vehicle (excavator) without the need for (re) constructing a formal access track. Note historic access track to the existing Poles is visible and where possible will be utilised by the tracked vehicles. To gain light vehicle access into the general vicinity of site P5 and P6 two minor sections of earthworks will be undertaken to connect and upgrade the existing tracks. To gain access to the sites the operating plant (the excavator) will simply track across the grass to avoid land disturbance on the steep visual section of the project. The construction methodology for the installation and erection of these Poles will be different to those where the farm tracks already exist. Due to the absence of formed tracks the concrete and the pole sections will be flown in. Minor benching will be constructed at the foundation site to create a small platform to allow the excavator to sit adjacent to the tower location and auger the pole foundations and to erect the poles. Benching for foundation construction and tower erection will typically consist of a pad measuring approximately 2m x 3m, (total exposed area will be approximately 2.5m x 6m per bench taking into account battering etc), approximately 16m 2 per tower. Material excavated during construction will be stock piled onsite (immediately adjacent) and used for reinstating the area following the construction of the tower foundations and / or tower erection. All site reinstatement works will be completed in accordance with best practice and in accordance with this Plan Foundation Construction The second stage of construction involves the construction of foundations for each tower. Each tower foundation consists of two piles. The piles will be augured. Augured piles involve excavating a hole using an auger and pouring a concrete foundation in which anchor bolts are cast. These will typically generate approximately 12m 3 of spoil per pile. (2 x piles per tower). Spoil generated from foundation construction will be disposed of immediately adjacent to the bench. Any stockpile areas will be grassed seeded immediately. Upon completion of works the spoil will be re-landscaped into the immediate foundation area as part of final reinstatement Transpower New Zealand Limited All rights reserved. Page 8 of 21

12 Pole Erection PRM 220kV Connection Project The third stage of construction is tower erection. The Poles are assembled in sections adjacent to the tower site and lifted into place and bolted together. At the end of this stage the sites which have required benching, and do not require a crane for the stringing stage of construction (Poles P1 and Tee A are required for stringing activities), will be reinstated to as near as possible the original contours as mentioned above and stabilised immediately (seeded and mulched) Stringing Conductors The final phase of construction involves stringing the conductors between each tower. Conductors will be run out from the wiring sites (Tee A and Tee B) Paraparaumu Substation Switchyard Construction Approximately 1,200m 3 of earthworks over an area of approximately 2,400m 2 is required at the Paraparaumu Substation located on Valley Road to construct the switchyard. The proposed switchyard is located directly to the east of the existing switchyard and to the west of Valley Road. The site is generally flat with a minor south to north sloping gradient of approximately 1.2%. The yard will be formed by cut and fill earthworks to RL = 72.4m, which is approximately 2.9m above the existing switchyard level. The following earthworks will be undertaken to construct the switchyard. 1) Up to 300mm of top soil will be stripped 2) A primary access road will be built to the west of the yard 3) A secondary access road will be formed to the east of the yard. 4) The switchyard will be formed by a combination of cut and fill 5) A level area will be formed behind the 33kV control building Sealed access roads will be built to the west and east of the site. The access to the east of the site will be formed off Valley Road, and the access to the west of the site from the area to the south west of the 110kV switchyard. Vehicle access roads will consist of a 6m wide sealed carriageway. Following the topsoil stripping, the works will commence with the construction of the retaining wall. Minor excavation will be needed to create a safe platform to allow forming of the fill retaining wall foundation. It is likely that the excavated area behind the retaining wall will be progressively filled as construction of the wall progresses, in conjunction with the construction of the cut retaining walls to the south of the site. The forming the primary new access road will allow access to the earth works area from the west of the 110kV switch yard. Once the yard is formed the secondary access road will be built Summary of Earthworks Location Description of earthworks Approximate Area (m 2 ) of earthwork Approximate Volume (m 3 ) of earthworks Main track In excellent condition minor trim / grade and placement of metal at location as required. Works undertaken as a grade and cover Isolated over the length of the existing track <500m Transpower New Zealand Limited All rights reserved. Page 9 of 21

13 PRM 220kV Connection Project Culvert installation Track realignment section Platform P1 & Tee B site methodology The culvert installation and associated section track upgrade Two minor sections of track upgrade (a total of approximately 75m in length) is required to connect a section of existing track to the historic tower access tracks below P5 and P6 Site P1 and Tee B structures are adjacent to the main track and minor levelling is required to create a working platform (including a temporary stockpile area). 500m 2 600m 3 800m 2 750m 3 250m 2 350m 3 Tee A Earthworks required to construct a bench and working platform (including a temporary stockpile area). 280m 2 450m 3 P3 and P4 Access to be obtained via tracked plant over grass. Earthworks only required to construct foundation bench for drilling rig. 80m 2 160m 3 P5 and P6 Earthworks required to construct bench and connect to access track 240m 2 320m 3 Substation Earthworks to create level platform 2400m m 3 TOTAL 4,550m 2 4,330m 3 4. Personal 4.1. Roles and Responsibilities The Project Manager will have overall responsibility for construction activities including environmental management. Specific roles in environmental management are as follows: Transpower as consent holder, have ultimate responsibility for ensuring the consent conditions are met as a minimum standard on the project Transpower New Zealand Limited All rights reserved. Page 10 of 21

14 PRM 220kV Connection Project The Construction Manager will report directly to the Project Manager and will play a leading role in overseeing environmental management. In particular, the Construction Manager will ensure appropriate resources and systems are in place to achieve compliance with legal requirements and delivery of environmental enhancements. The Construction Manager will also be responsible, in assistance with the Environmental Advisor, for the implementation, monitoring and review of the ESCP. This will include: Coordination of the development and implementation of appropriate environmental management controls as set out within this plan; Development and provision of training materials on the implementation of the specific environmental management controls as required; Directing audits and reviews, as set out within this document; The Environmental Advisor will adopt an overseeing role and will report directly to the Project Manager and will have responsibility for ensuring the implementation of environmental controls and uptake of environmental enhancements across all project activities. The Environmental Advisor will be a key contact with GWRC and reporting to the Project Manager on environmental performance progress as set out within this document. Specific ESC roles and responsibilities will be updated upon the award of contract. 5. Construction Methodology An aggregate cut and cover methodology is proposed and where appropriate will form the main erosion and sediment control management method given the nature of the works (tracking upgrades and small isolated sites). The methodology will ensure that all stripped surfaces are stabilised at the end of each day. Where a cut and cover methodology is not appropriate specific sediment controls measures will be installed as detailed below Access Tracks The main access track through the farms are in good condition and in some cases only require minor grading and the placement of a hard fill material (aggregate). Where grading is required the area will be covered in aggregate the same day to ensure that at no time are exposed areas left at the end of the day. Where the farm track crosses an ephemeral overland flow path, farm drainage pipes will be installed to protect the track. Any farm drainage pipe installed will be installed at grade and the outlet of the pipe will be stabilised with rock. There are two areas where bulk earthworks are required to upgrade the existing tracks. Where the track crosses the existing farm pond upgrade works will be required including the installation of a culvert. As part of these works approximately 600m 3 earthworks will be required to upgrade the track over approximate 500m 2. In addition two minor sections of track upgrade (a total of approximately 75m in length) will undertaken to connection a section of existing track to historic tower access tracks. The total area of earthworks will be approximately 800m 2. For the access to the steeper tower locations (P3, P4, P5 and P6) a construction methodology has been specifically chosen to avoid the requirement to excavate a formal track into the area. The excavator will simply track across the grass to avoid land disturbance on the steep visual section of the project Transpower New Zealand Limited All rights reserved. Page 11 of 21

15 Platform Formation Platform P1, P2 and Tee B and Tee A PRM 220kV Connection Project Heavy plant (cranes and drilling rig) are used to construct the tower foundations and Poles themselves. This plant requires a 2mx 3m pad / platform to accommodate the required plant. Tee A Structure site, the site nearest to A line 271 provides workable space adjacent to the tower. Benching will be required for a Hiab type crane needed to assist in pole erection and the connection to the line. A small crib wall maybe required to create a suitable level platform. The site will be required for wiring purposes and a small puller machine will be able to setup on the same space required after pole erection is completed. Concrete trucks will be able access this site in dry conditions. The total area of works at Tee A will be approximately 280m 2 including a designated 80m 2 area for stockpiling (approximately 450m 3 ) Site Tee B structures are again near the main track and with minor benching to created a working platform. The total area of works at Tee B will be approximately 250m 2 including a designated 100m 2 area for stockpiling (approximately 350m 3 ). Site P2 is located immediate adjacent to the access track. A 5m x10m platform will be created for construction. Platforms P3, P4, P5 and P6 Poles 3 and 4 are down a steep spur ridge next to the existing MHO-PKK A & B poles. There is evidence of an old access track possibly dating back to the 1920 s to the existing poles however it is not considered suitable and any re-establishment of the track would require significant earthworks. The ridge is estimated to be approximately graded at 1:5 and is only suitable for tracked vehicles in dry conditions. It is apparent that the ridge has been flattened and has possibly been used for pole replacement in more recent times. The methodology for these sites are as follows: Access the site with a 12 ton digger and establish small benches to allow pole foundation installation. The same digger may be used to bore pile holes. Foundation setting materials may be able to be taken into site by the digger or flown in. The steel reinforcing cage, holding down bolt cage and concrete would all be flown in. No earthworks to create a track would be undertaken. Once the foundation is complete the first section of each pole will need to be transported into the sites by digger and bulldozer. The first section is the heaviest and would need to be erected by the digger. Subsequent sections will be erected by helicopter. Poles 5 and 6 follow a similar construction methodology as sites P3 and P4, with some minor access works required in addition to the foundation bench. Access will be gained from the same ridge as P3 and P4 following the fenceline downhill. The existing access to the old adjacent pole sites (below and to the west of P5 and P6) will be upgraded as it will be required for the dismantling of the pole line and will also provide easier access for the construction workers to the general area. The wiring of the lines will require no additional earthworks. Setup points will be Tee A and Tee B plus a setup down near the substation. A pilot line to pull the conductor will be flown out first. Once the conductor is pulled through each strain site must be accessed for final sagging and termination. Remote sites will require pole platforms to enable the aerial line work to proceed. There will be flown onto the sites if required. No additional earthworks will be required. Reinstatement will be carried out as the works progress Transpower New Zealand Limited All rights reserved. Page 12 of 21

16 Spoil Areas PRM 220kV Connection Project Where excess spoil is produced through formation of tracks and platforms, the spoil will be stockpiled adjacent to the foundation for later reinstatement Principles of Erosion and Sediment Control General Principles The key principle to be employed for an Erosion and Sediment Control Plan are to undertake land disturbing activities in a manner that reduces the potential for erosion of bare soils to occur (erosion control) and, to employ treatment devices to treat sediment laden water prior to discharging from the site (sediment control). The basic erosion and sediment control principles applicable to this project are as follows: Minimise Disturbance: Only work those areas required for construction to take place. Stage Construction: Carefully plan works to minimise the area of disturbance at any one time. Protect Steep Slopes: Steep slopes should be avoided where possible, and where disturbed, will be rapidly stabilised. Protect flowpaths and where possible. Progressive and rapid stabilisation of exposed areas. Install Perimeter Controls: Divert clean water away from areas of disturbance and divert runoff from disturbed areas to sediment control measures. Install Detention Devices: Treat runoff by methods that allow sediment to settle out, where practicable. Experience and Training: Make sure an experienced and trained person(s) are responsible for design, installing and maintaining erosion and sediment control practices. Monitor: Inspect, monitor and maintain control measures Assess and Adjust: As construction progresses and the nature of land disturbing activities change, the ESCP needs to be modified to reflect the changing conditions on site Erosion and Sediment Design Philosophy and Process All erosion and sediment control devices will be designed and sized in accordance with Greater Wellington Regional Council guideline Erosion and Sediment Control Guidelines for the Wellington Region 2002 (reprinted 2006) (GWRC Guideline). When the control measures are implemented, they will be As-Built. Following the installation of the specific control devices and completion of the As Builts, bulk earthworks will commence in that area. Routine checks and audits will ensure that the installation is compliant with the ESCP. Exposed areas will be kept to a minimum, and stabilisation or completion to final specifications will be undertaken daily. Where disturbed areas are unavoidable, adequate water supplies will ensure dust suppression is possible. Aggregate will be utilised over the site associated with the farm track upgrades. This the site, and assist in the management of dust. Specific Erosion and Sediment Control Measures and Methods Site Exit Transpower New Zealand Limited All rights reserved. Page 13 of 21

17 PRM 220kV Connection Project Site entry and exit to Nikau Valley Road will be strictly controlled. The site exit will be via a stabilised exit point. A minor upgrade to the existing stabilised exit will be required. The emphasis will be on maintaining the vehicles in a clean state to maximise the effectiveness of the stabilised site exit and further minimise the risk of tracking sediment offsite. If any material is tracked onto a sealed road it will be picked up as soon as possible. Stabilisation and Site Restoration Stabilisation or completion to final specifications forms a key component of the overall environmental strategy. The existing access tracks are in good condition and only in parts need minor grading and the placement of aggregate. This operation will be undertaken in a progressive manner to ensure that at the end of the day all areas are stabilised (a cut and cover operation) Any topsoil bunds and stockpiles will be immediately grassed. The earthworks operations (at the foundations) will be staged and will be progressively stabilised. This methodology will ensure that the site will be in a continual state of progressive stabilisation and completion. The staging and length of works will vary and will be determined by the specific volume of works that can be completed in a day (i.e. a section of minor upgrades will allow for a longer length of works to be completed and stabilised in a day). All stripped surfaces will be completed to final specification or stabilised with an aggregate cover at the end of each day. Where cut and fill batters are created (associated with the foundation benches) that are susceptible to erosion effects, they will be stabilised as soon as possible following completion of works using methods including topsoiling/seeding (where gradient allows), hay mulching or geotextile. Where necessary, sediment control measures will be retained until stabilisation of batters is achieved. All excess fill material and cleanwater bunds that are temporarily created during the construction of the working benches will be pulled back and re landscaped around the poles upon completion. The permanent stabilisation and site restoration will be undertaken in accordance with the Landscape Principles. Perimeter Bunds Where necessary, perimeter bunds will also be installed to prevent cleanwater from other areas entering the work sites. The perimeter bunds will be created from the topsoil stripping to a minimum height of 0.5m. This 0.5m bund height is in excess of the GWRC guidelines sizing requirements for all the proposed catchments within the works area i.e. they will be well in excess of the size required to manage the proposed cleanwater catchments that will drain to each toward the works sites. Using a standard height simplifies construction management, which in turn will lead to more consistent compliance with environmental requirements and outcomes. The topsoil bunds will be grassed as soon as they have been constructed. Perimeter Bund Sizing Summary Clean Water Diversion 5% AEP (24 hr) Catchment Area Peak Flow (m3/s) Base Width Slope Minimum Depth (mm) ha m 2% ha m 2% Plus minimum 300mm freeboard Transpower New Zealand Limited All rights reserved. Page 14 of 21

18 PRM 220kV Connection Project A minimum bund height of 500mm (250mm plus 300mm free board), will be installed across the project which complies with the Erosion and Sediment Control, Guidelines for the Wellington Region based on the 20 year Average Recurrence Interval rainfall event. Note: Rainfall sourced from NIWA High Intensity Rainfall System V3 (HIRDS) Silt Fences Silt fences will be used in and around the foundation locations. The silt fences will be installed in accordance with GWRC guidelines (Table 9) slope length requirements. The silt fences will remain in place at any given site until that site is fully stabilised. Silt fences will also be utilised for the construction of the substation. Dust Control The emphasis of the dust management strategy for the project will be one of prevention. The topsoil stockpiles and bunds will be grassed immediately. The access track upgrades, and platforms will be competed to final specifications and or stabilised with aggregate immediately following construction, which will minimise the extent of exposed areas at any given time. Foundation earthworks operations will be staged and will be progressively stabilised. Truck and vehicle movements off the sealed roads will be limited to the designated access tracks. These roads will be stabilised with aggregate and regularly maintained. Restricting the vehicle movements to the existing access tracks will allow dust control measures to be focussed on highest risk areas. This will be achieved by maintaining the quality of the access roads and wetting if required. Vehicle movements on site will be governed by speed restrictions. Water carts will be made available if required. The Construction Manager will obtain daily forecasts and circulate to appropriate staff. Dust control measures will be put on standby if dry, windy conditions are forecast. Culvert Installation Other than water table and track drainage, one culvert is required where the track crosses the head of a farm pond. The culvert will be less than 6m in length. The historic track across the head of the farm pond will be upgraded including the installation of a culvert. The catchment above the farm pond is approximately 5ha and is ephemeral. The culvert may be permitted under Rule 25 or require resource consent for a controlled activity under Rule 47. It is regarded that the installation of the culvert can be undertaken as a Permitted Activity. Rule 25 River crossings in intermittently flowing streams The placement and use [including any associated; disturbance of any river bed; or deposition on the river bed; or temporary diversion;] of any river crossing [of a width necessary for the crossing, excluding any river crossing that dams a river,] that is fixed in, on, under, or over the bed of any intermittently flowing river or stream which; (1) has a catchment area above the crossing of not more than: 200 ha in any catchment in the Region on the eastern side of the Ruamahanga River; or 50 ha in any catchment in the Region on the western side of the Ruamahanga River; and (2) does not alter the natural course of the stream, including any diversion of water from the natural course during floods; and Transpower New Zealand Limited All rights reserved. Page 15 of 21

19 PRM 220kV Connection Project (3) does not reduce the ability of the river to convey flood flows; and (4) meets any requirements under the Freshwater Fisheries Regulations 1983 and the Building Act 1991; is a permitted activity provided it complies with the conditions specified below. Conditions (1) No contaminants (including but not limited to oil, petrol, diesel, paint, or solvent) shall be released to water from equipment being used for the construction of the river crossing and no refuelling of equipment shall take place on any area of river or lake bed. (2) All material used during construction, but which is not part of the river crossing shall be removed from the river or stream bed and disposed of in an appropriate manner. (3) All reasonable steps shall be taken to minimise the release of sediment to water during construction. (4) The river crossing shall be maintained so that there is no accumulation of debris. The following methodology will be implemented during the installation of the culvert: The works will be undertaken during a forecast period of dry weather; The works are expected to be completed within one day; Sand bag dams will be installed above and below the works area to isolate the work zone. Undertaking the works in the a dry period will allow the works to be undertaken without the need for over pumping; The culvert will be installed at grade with rock installed at the inlet and outlet to provide stabilisation and energy dissipation; Any disturbed area will be stabilised upon completion of works at then end of the day. This will involve clothing within potential flow paths and mulching above the potential stream bank. 6. Environmental Monitoring and Auditing 6.1. Monitoring and Measurement of Erosion and Sediment Control The erosion and sediment control measures will be inspected, and as-builts completed and signed off prior to the commencement of works within the particular area associated with the control. All erosion and sediment control measures will be inspected on a daily basis by the site foreman and on a regular basis by the Environmental Manager or nominated representative. Site monitoring will be undertaken before and immediately after rain as well as during heavy rainfall events. Any required maintenance or improvements to control measures will be undertaken immediately. Sediment retention measures will be cleaned of sediment when 20% full of sediment. All erosion and sediment control measures will be maintained in accordance with GWRC Guideline Transpower New Zealand Limited All rights reserved. Page 16 of 21

20 6.2. Rainfall Response and Contingency Emergency Response Procedures PRM 220kV Connection Project Erosion and sediment control structures will be maintained to a high standard in accordance with GWRC Guideline. This includes daily monitoring of erosion and sediment controls and additional inspections undertaken before, during and immediately after rain rainfall events. Any maintenance identified in these inspections will be undertaken as soon as practicable provisions (such as geotextile) will be available for use where required. The erosion and sediment control devices in conjunction with the monitoring and maintenance regime will serve to minimise adverse effects resulting from severe weather events. Severe Weather Events For the purpose of this project severe weather events are those weather events with a potential to result in significant environmental, quality or health & safety impacts. However the likelihood of a weather event resulting in such impacts will vary according to a range of factors including: Current operations; Extent of bare areas; Ground conditions; Preceding weather conditions. It is therefore important to recognise when these parameters together with weather events may combine to create significant environmental risks. Weather Monitoring The Construction Manager will obtain daily forecasts and circulate to appropriate staff. The MetService issue Special Weather Advisory whenever a weather event is likely to cause significant disruption to the general public or specific industry groups within the next 48 hours, but the weather is not expected to deteriorate to an extent that would require the issue of a Severe Weather Warning. The MetService also issue a Severe Weather Warning whenever there is an expectation that the following weather conditions will occur within the next 24 hours: Widespread rainfall greater than 50mm within 6 hours or 100mm in 24 hours Widespread severe gales with a minimum mean speed of 90km/hr or frequent gusts exceeding 110 km/hr. Severe Weather Actions If a Severe Weather Warning is received or in the event that 40 mm of rainfall over a 24 hours or rainfall of 20mm/hr intensity is recorded, the following actions will be taken: Check erosion and sediment controls are sufficient for the forecast weather conditions; and Carry out additional temporary works if necessary; Prepare to stabilise stockpiles and bare areas as appropriate; Prepare dust control measures if dry, windy conditions are forecast; Ensure all plant and equipment is secure; Halting Operations and Closing Site due to Severe Weather The Construction Manager will be responsible for assessing when adverse working conditions are experienced and operations need to be halted. If severe weather is experienced the Construction Manager will assess on site conditions and direct the closure of the site as appropriate Transpower New Zealand Limited All rights reserved. Page 17 of 21

21 Project Emergency Contacts Management Team Project Manager Jon Mason PRM 220kV Connection Project (The Project Manager should be advised immediately in the event of a significant environmental incident) Construction Manager TBC Environment Advisor Joel De Boer (021) Transpower New Zealand Limited All rights reserved. Page 18 of 21

22

23 7. Appendices Transpower New Zealand Limited All rights reserved.

24

25 7.1. Appendix 1 Erosion and Sediment Control Plans Transpower New Zealand Limited All rights reserved.

26

27 Existing access track in good condition, minor grading and the placement of a hard fill material (aggregate) as required. Cut and cover methodology. No exposed areas left at the end of the day. Tee B works platform area and stringing site Where the farm track crosses an ephemeral overland flow path farm drainage pipes will be installed to protect the track. Any farm drainage pipes will be installed at grade and the outlet of the pipe will be stabilised with rock. KEY Erosion and Sediment Control T271 Run off Perimeter Diversion Bund Silt Fence Super Silt Fence Stabilised Construction Entry/Exit Culvert Stockpile P2 Stockpile location if required Area of Works General Erosion & Sediment Control Notes: Benching and track to be constructed to gain access to P5 & P6 3. P3 and P4 4. Earthworks required to upgrade existing track and install culvert T P5 and P6 Sections of proposed track realignment Refer to specific Substation ESCP Culvert Installation Methodology The works will be undertaken during a forecast period of dry weather; The works are expected to be completed within one day; Sand bag dams will be installed above and below the works area to isolate the work zone. Undertaking the works in a dry period will allow the works to be undertaken without the need for over pumping; The culvert will be installed at grade with rock installed at the inlet and outlet to create a stabilised area and energy dissipation; Any disturbed area will be stabilised upon completion of works at then end of the day. This will involve clothing within potential flow paths and mulching above the stream bank. All erosion and sediment control measures will be inspected on a daily basis. Site monitoring will be undertaken before and immediately after rain as well as during heavy rainfall events. Any required maintenance or improvements to control measures will be undertaken immediately. Sediment retention measures will be cleaned of sediment when 20% full of sediment. All erosion and sediment control measures will be maintained in accordance with Wellington Regional Council guideline Erosion and Sediment Control Guidelines for the Wellington Region 2002 (reprinted 2006) (GWRC Guideline). Erosion and Sediment Controls can be removed following stabilisation of site and sign off from the Project Manager. Final rehabilitation is to be in accordance with Landscape requirements. Extent of works as shown. All locations of controls are indicative and are to be confirmed on site. A Draft CS GM CS no date issue/ revision details by chk appr Drawing status DRAFT Project TRANSPOWER PRM 220kV Connection Project Drawing Title EROSION AND SEDIMENT CONTROL PLAN # 001 scale date As Shown drawing number SSEL-ESC-001 B

28

29 KEY Erosion and Sediment Control Run off Perimeter Diversion Bund Stabilised Construction entry / exit Silt Fence Super Silt Fence Stabilised Construction Entry/Exit Culvert Existing access track in good condition, minor grading and the placement of a hard fill material (aggregate) as required. Cut and cover methodology. No exposed areas left at the end of the day. Stockpile Where the farm track crosses an ephemeral overland flow path farm drainage pipes will be installed to protect the track. Any farm drainage pipes will be installed at grade and the outlet of the pipe will be stabilised with rock. General Erosion & Sediment Control Notes: Area of Works Stockpile location if required All erosion and sediment control measures will be inspected on a daily basis. Site monitoring will be undertaken before and immediately after rain as well as during heavy rainfall events. Any required maintenance or improvements to control measures will be undertaken immediately. Sediment retention measures will be cleaned of sediment when 20% full of sediment. All erosion and sediment control measures will be maintained in accordance with Wellington Regional Council guideline Erosion and Sediment Control Guidelines for the Wellington Region 2002 (reprinted 2006) (GWRC Guideline). Erosion and Sediment Controls can be removed following stabilisation of site and sign off from the Project Manager. Final rehabilitation is to be in accordance with Landscape requirements. Extent of works as shown. All locations of controls are indicative and are to be confirmed on site. A Draft CS GM CS no date issue/ revision details by chk appr Drawing status DRAFT P1 Tee B works platform area and stringing site Project TRANSPOWER PRM 220kV Connection Project Drawing Title EROSION AND SEDIMENT CONTROL PLAN # 002 scale date As Shown drawing number SSEL-ESC-002 B

30

31 KEY Erosion and Sediment Control Run off Perimeter Diversion Bund Silt Fence Super Silt Fence Stabilised Construction Entry/Exit Culvert Stockpile Area of Works General Erosion & Sediment Control Notes: Benching Area 1. All erosion and sediment control measures will be inspected on a daily basis. 2. Site monitoring will be undertaken before and immediately after rain as well as during heavy rainfall events. 3. Any required maintenance or improvements to control measures will be undertaken immediately. 4. Sediment retention measures will be cleaned of sediment when 20% full of sediment. 5. All erosion and sediment control measures will be maintained in accordance with Wellington Regional Council guideline Erosion and Sediment Control Guidelines for the Wellington Region 2002 (reprinted 2006) (GWRC Guideline). 6. Erosion and Sediment Controls can be removed following stabilisation of site and sign off from the Project Manager. 7. Final rehabilitation is to be in accordance with Landscape requirements. 8. Extent of works as shown. 9. All locations of controls are indicative and are to be confirmed on site. A Draft CS GM CS no date issue/ revision details by chk appr Drawing status DRAFT Laydown/ Stringing Area Existing Farm Track Proposed Stockpile Area Project TRANSPOWER PRM 220kV Connection Project Drawing Title EROSION AND SEDIMENT CONTROL PLAN Site Tee A and Laydown Area scale date As Shown drawing number SSEL-ESC-001 A

32

33 Silt Fence Design Details General Erosion & Sediment Control Notes: 1. All erosion and sediment control measures will be inspected on a daily basis. 2. Site monitoring will be undertaken before and immediately after rain as well as during heavy rainfall events. 3. Any required maintenance or improvements to control measures will be undertaken immediately. 4. Sediment retention measures will be cleaned of sediment when 20% full of sediment. 5. All erosion and sediment control measures will be maintained in accordance with Wellington Regional Council guideline Erosion and Sediment Control Guidelines for the Wellington Region 2002 (reprinted 2006) (GWRC Guideline). 6. Erosion and Sediment Controls can be removed following stabilisation of site and sign off from the Project Manager. 7. Final rehabilitation is to be in accordance with Landscape requirements. 8. Extent of works as shown. 9. All locations of controls are indicative and are to be confirmed on site. Drawn CS Approved GM Date Project PRM 220kV CONNECTION PROJECT EROSION AND SEDIMENT CONTROL PLAN STANDARD DETAILS Drawing No. Sheet No. ESCP SSE Revision A