Mapbook Appendix M3 - Auckland Council...Channel Cross Sections - 51-31962T-SKS1, SKS2, SKS3, SKS4...

GHD Centre, Level 3, 27 Napier Street Freemans Bay Auckland 1011 New Zealand T 64 9 307 7373 F 64 9 307 7300 E [email protected] W www.ghd.com

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G:\51\31962\GIS\Maps\Mxd\51_31962_004_RevA_Appendix_M3_Conveyance_Channel_Mapbook_01072014.mxd© 2014. Whilst every care has been taken to prepare this map, GHD (and DATA CUSTODIAN) make no representations or warranties about its accuracy, reliability, completeness or suitability for any particular purpose and cannot accept liability and responsibility of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred by any party as a result of the map being inaccurate, incomplete or unsuitable in any way and for any reason.

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Auckland CouncilTakanini 2a2b ConveyanceProposed Stormwater DesignationMapbook Appendix M3

Job NumberRevision A

51-31962-00

08 Jul 2014

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Data source: Auckland Council - Utilities, Aerials, Floodplains, Contours, Structure Plan Boundaries, Property Boundaries. November 2013. GHD: Designation. December 2013. Created by: jopeeters / kmcdonald / jopeeters

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GHD Centre, Level 3, 27 Napier Street Freemans Bay Auckland 1011 New Zealand T 64 9 307 7373 F 64 9 307 7300 E [email protected] W www.ghd.com

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G:\51\31962\GIS\Maps\Mxd\51_31962_004_RevA_Appendix_M3_Conveyance_Channel_Mapbook_01072014.mxd© 2014. Whilst every care has been taken to prepare this map, GHD (and DATA CUSTODIAN) make no representations or warranties about its accuracy, reliability, completeness or suitability for any particular purpose and cannot accept liability and responsibility of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred by any party as a result of the map being inaccurate, incomplete or unsuitable in any way and for any reason.

0 10 20 30 405

MetresMap Projection: Transverse Mercator

Horizontal Datum: NZGD 2000Grid: NZGD 2000 New Zealand Transverse Mercator

Auckland CouncilTakanini 2a2b ConveyanceProposed Stormwater DesignationMapbook Appendix M3

Job NumberRevision A

51-31962-00

08 Jul 2014

o

Date

Data source: Auckland Council - Utilities, Aerials, Floodplains, Contours, Structure Plan Boundaries, Property Boundaries. November 2013. GHD: Designation. December 2013. Created by: jopeeters / kmcdonald / jopeeters

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Appendix N – Concept design plans Channel Cross Sections - 51-31962T-SKS1, SKS2, SKS3, SKS4

Channel Longitudinal Section Drawing Number - 51-31962T-SKL1

2a Channel Longitudinal Section Drawing Number - 51-31962T-SKL2

100 yr FLOOD EXTENT 37.6 m

PROPOSED DESIGNATION / LONG TERM SETTLEMENT MANAGEMENT AREA 50 m




PROPOSED DESIGNATION / LONG TERM SETTLEMENT MANAGEMENT AREA 48.8 m

This Drawing must not beused for Construction unlesssigned as Approved

Date

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DesignConditions of Use.This document may only be used byGHD's client (and any other person whoGHD has agreed can use this document)for the purpose for which it was preparedand must not be used by any otherperson or for any other purpose.

DO NOT SCALE

Note: * indicates signatures on original issue of drawing or last revision of drawing

GHD Limited

Level 3, GHD Centre27 Napier Street, Freemans Bay, Auckland 1011 New ZealandT 64 9 370 8000 F 64 9 370 8001E [email protected] W www.ghd.com

24 July 2014 - 6:48 p.m. G:\51\31962\200_Takanini\CAD\Drawings\51-31962T-SKS1_20170724.dwgPlotted By: Jesse Peeters

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Q100=23.87 m³/s0.41% NOTIONAL BED SLOPE



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Appendix O – Conceptual Construction Methodology Report

Auckland Council Takanini Stormwater Conveyance Channel

Conceptual Construction Methodology

July 2014

GHD | Report for Auckland Council - Takanini Stormwater Conveyance Channel, 51/32174/03 | i

Table of contents 1. Introduction ............................................................................................................................... 2

1.1 Purpose and scope ......................................................................................................... 2 1.2 Project limitations ............................................................................................................ 2 1.3 Assumptions.................................................................................................................... 3

2. Project background ................................................................................................................... 4

3. Construction .............................................................................................................................. 5 3.1 Conceptual construction staging ...................................................................................... 5 3.2 Proposed earthworks volumes ......................................................................................... 6 3.3 Conceptual construction programme ............................................................................... 7 3.4 Construction traffic .......................................................................................................... 9 3.5 Management of groundwater lowering ........................................................................... 11 3.6 Erosion and sediment control ........................................................................................ 11

4. Summary ................................................................................................................................ 13

Table index Table 1 Construction earthworks volumes .......................................................................................... 7

Figure index Figure 1 Proposed stormwater conveyance channel ........................................................................... 4

Figure 2 Construction staging .............................................................................................................. 6

Figure 3 Site access and egress locations ........................................................................................ 10

Appendices Appendix A – Conceptual construction programme

Appendix B – Construction traffic high level assessment

GHD | Report for Auckland Council - Takanini Stormwater Conveyance Channel, 51/32174/03 | 2

1. Introduction Auckland Council has engaged GHD to assist in analysing the construction feasibility of the proposed conveyance channel for servicing the upper catchment of the greater Papakura central catchment, specifically the Takanini Structure Plan areas 2a, 2b4 and 2b, henceforth referred to as the Takanini 2a2b area.

This report has been prepared to support the Takanini Conveyance Channel Infrastructure Report (GHD, April 2014).

This report outlines a Conceptual Construction Methodology (CCM) for the preferred conveyance option, an open channel, to confirm construction of the conveyance channel is feasible.

1.1 Purpose and scope

This CCM discusses the issues relating to the construction of the proposed stormwater conveyance channel as follows:

� Site constraints;

� Conceptual construction staging;

� Conceptual construction programme;

� Extent of earthworks;

� Construction traffic and vehicle movements; and

� Erosion and sediment control (ESC).

This CCM has been produced to confirm feasibility of constructing the channel in the proposed location, and has been prepared in consultation with the authors of, and in reference to the engineering and technical reports including the following documents:

� Takanini Stormwater Conveyance Channel Infrastructure Report (GHD, April 2014);

� Takanini Stormwater Conveyance Channel Preliminary Geotechnical Appraisal (GHD, April 2014); and

� Construction High Level Traffic Assessment - Internal GHD Memo, April 2014 (attached as Appendix B).

1.2 Project limitations

The project limitations that apply to this report are covered in the Takanini Conveyance Channel Infrastructure Report (GHD, April 2014) and should be referred to when reading this report. In addition to the overarching limitations, the following applies:

· Entry onto private land was prohibited during the development of this CCM and therefore the findings and recommendations provided in this report have been developed through a “desktop” study of the area, through discussion with the GHD design team and with reference to the reports listed in Section 1.1 above;

· This report has been prepared based on a conceptual design of the stormwater conveyance channel and it is understood that additional preliminary and detailed design stages are required to confirm the particular details of the design; and


· A detailed Construction Methodology will be confirmed by the contractor that is ultimately appointed to undertake the physical works on site.

1.3 Assumptions

The assumptions used in the development of this CCM are as follows:

1) The excavation volumes are based on the concept design of the proposed conveyance channel, as detailed in the Takanini Conveyance Channel Infrastructure Report (GHD, April 2014) ;

2) Ground conditions are broadly as those contained in the Takanini Stormwater Conveyance Channel Preliminary Geotechnical Appraisal (GHD, April 2014);

3) That the proposed 4.0 m wide x 2.0 m high box culvert, between Grove Road and the McLennan wetland, does not adversely affect water levels upstream of Grove Road and it is assumed that the construction of this culvert precedes construction of the conveyance channel project;

4) Our investigations thus far have identified that surplus excavated material can be disposed of at the Greenmount landfill. Transporting waste to this location has been assumed in the Construction High Level Traffic Assessment (in Appendix B) for direction of truck movements from the site; and

5) Road and service crossing solutions will be determined at detailed design stage. However, for the purposes of this assessment, road and service crossings have been assumed as follows:

· Cosgrave Road and protection / stabilisation of the 1,200 mm diameter Watercare Services Limited (WSL) Waikato trunk main:

o A pre-cast concrete twin box culvert, 3.0 m wide x 2.0 m high.

· Old Wairoa Road:

o A pre-cast concrete box culvert, 3.0 m wide x 2.0 m high.


2. Project background A concept design for an open channel to capture and convey the 1% Annual Exceedance Probability (AEP) flows within the Takanini 2a2b area (outlined by the dotted purple line in Figure 1 below), has been prepared and is detailed in the Takanini Stormwater Conveyance Channel Infrastructure Report (GHD, April 2014). The following provides a brief summary of that design.

The proposed conveyance channel concept design has a length of 1,543 m along its main route which drains most of the Takanini 2a2b area. A channel branch to the north drains the remainder of the northern area and is approximately 600 m long.

The proposed channel has a maximum depth of approximately 2.7 m from the existing ground surface to the permanent water level due to the flat topography of the catchment. Weirs are proposed in the channel to reduce the groundwater drawdown in the peat soils, thereby reducing potential settlement issues.

A designation area for the channel has been based on the hydraulic conveyance width required for the channel to convey the 1% AEP event flow. The recommended designation ranges from 25 m in the south-east to 50 m in the west, as shown in Figure 1 below.

Figure 1 Proposed stormwater conveyance channel


3. Construction This section describes the conceptual construction activity required to construct the proposed stormwater conveyance channel for the project.

For the purposes of this assessment, we consider that all works required to establish the site, construct the works, reinstate disturbed areas and demobilise from site can be carried out within the designation area.

This assessment has been based on the concept design as detailed in the Takanini Conveyance Channel Infrastructure Report (GHD, April 2014).

3.1 Conceptual construction staging

For the purposes of this report the staging of construction has been divided into a number of stages as follows:

a) Stage 1 – Grove Road to Cosgrave Road

The works would involve site establishment and construction of the conveyance channel between Grove Road and Cosgrave Road, including the northern channel branch that is proposed to extend approximately 600 m northwards towards Walters Road.

For the purposes of this report it has been assumed that construction works will commence at the western end (downstream) of the conveyance channel at Grove Road and will progress eastwards towards Cosgrave Road and then from south to north for the northern channel branch.

b) Stage 2 – Cosgrave Road Crossing

As noted in Section 1.3, for the purposes of this assessment a twin box culvert has been assumed to be the engineering solution for this road crossing. The ultimate engineering solution will be determined at detailed design stage.

Stage 2 will include the works required to establish the construction site, any temporary traffic diversions and the construction of the twin 3.0 m wide x 2.0 m high pre-cast concrete box culvert beneath Cosgrave Road and beneath the 1,200 mm diameter WSL watermain along Cosgrave Road.

c) Stage 3 – Cosgrave Road to Old Wairoa Road (including the Old Wairoa Road Crossing)

Stage 2 of the works must be completed before Stage 3 can commence as the works to reinstate Cosgrave Road must be completed to maintain traffic flows.

Stage 3 of the works will require the construction of the conveyance channel from Cosgrave Road. It is anticipated that works will commence at Cosgrave Road and progress in an easterly direction for approximately 400 m before turning to the south east, crossing Old Wairoa Road in a 3.0 m wide x 2.0 m high pre-cast concrete box culvert and terminating approximately 143 m south of Old Wairoa Road.

Auckland Council has been advised that Stage 3 will most likely be dependent on the progress of development in the eastern area. For the purposes of this assessment it has been assumed that the construction of the Stage 3 will follow on once Stage 2 has been completed.

Figure 2 identifies the construction stage areas.


Figure 2 Construction staging

3.2 Proposed earthworks volumes

Based on the conceptual design cross sections and lengths provided in the Takanini Conveyance Channel Infrastructure Report (GHD, April 2014) , calculations have been carried out to determine the volume of earth that will be required to be excavated from the ground to form the proposed conveyance channel.

Table 1 below, summarises the volume of earth to be excavated from each of the construction stages described in Section 3.1 above.


Table 1 Construction earthworks volumes

Location Construction Stage

Soil Type

Chainage Length (m)

Volume to be Excavated

(m3)*

Bulked Volume -

Transported off Site (m3)* From To

Grove Road to Cosgrave Road

– Northern Section towards Walters Road

1 Peat 0 600 600 35,000 47,000

Grove Road to Cosgrave Road 1 Peat 0 550 550 44,500 60,000

Cosgrave Road – Culvert 2 Peat 550 570 20 700 1,000

Cosgrave Road to Old Wairoa

Road

3 Peat 550 950 400 34,000 46,000

3

Organic Clays and Gravels

950 1550 600 14,500 19,000

Total 2,150 128,000 172,000

*Bulking factors of 1.35 and 1.30 have been applied to the excavated volumes, of peat and organic clays and gravels

respectively, for the purposes of calculating the volume of earth to be disposed off-site and rounded to the nearest 500 m3

As can be seen, a total volume of approximately 128,000 m³ will need to be removed to form the proposed conveyance channel.

3.3 Conceptual construction programme

It is expected that the contractor appointed to undertake the construction of the works will develop his own detailed construction programme. This will be a requirement under the construction contract. The programme and timing of the work will also need to take into account the timeframes for the wider residential developments within the Takanini 2a2b area.

However, to illustrate one way that the works can be carried out and to confirm the feasibility of construction, a conceptual construction programme has been developed and is included in Appendix A.

The conceptual construction programme indicates that the works can be carried out over a period of approximately 23 months, with bulk earthworks being carried out over 2 separate earthworks seasons (November to April) and it is anticipated that the works can be carried out in sequence (i.e. Stage 1, followed by Stage 2 and then finally Stage 3).

Sections 3.3.1 to 3.3.3 describe the conceptual sequence of activities within each of the construction stages that have enabled the conceptual construction programme to be prepared.

For the purpose of this report, the Greenmount Landfill has advised that their facility has the capacity and consents to handle the anticipated volume of material to be removed from the site.

3.3.1 Stage 1 – Grove Road to Cosgrave Road

1) Establish site accesses and exits off the public roads of Grove Road and Cosgrave Road. These works are expected to include the establishment of stabilised construction entrances and/or appropriate wheel wash facilities, signage and traffic management measures and protection / stabilisation for the 1,200 mm WSL trunk watermain.


a. A Corridor Access Request will be submitted to Auckland Transport, who will ultimately determine what traffic management plans will be required to enable these accesses and exits to be constructed, whilst minimising the disturbance to road users.

2) Establish a site compound to contain storage for earthmoving and excavation plant, refuelling, appropriate site offices and worker facilities within the designation.

3) Establish a haul road along the length of the proposed conveyance channel between Grove and Cosgrave Roads. A geotechnical design of the haul road will be carried at detailed design stage. However, it is currently anticipated that the haul road will be constructed using imported clean hardfill, laid on top of a suitably designed geo-grid to prevent the haul road from settling into the underlying peat material.

4) Construct the protection / stabilisation measures for the 1,200 mm diameter WSL watermain in such a way that construction vehicle loads are not transferred onto the pipe.

5) Commence construction/excavation of the conveyance channel. Excavated material will be transported to a stockpile area to:

a. Allow the excavated material to dewater and drain, and

b. Provide a suitable area where material can be loaded onto road truck and trailers and be removed from the site.

6) Dis-establishment from site including the removal of the temporary haul road, stabilisation of exposed earth and / or the establishment of permanent planting.

Based on the concept design, the volume of material to be excavated and removed from site in Stage 1 of the works is approximately 107,000 m3 and will be predominantly peat material. It is intended that this material will be excavated from the ground and removed to an on-site stockpile, where it will be allowed to drain before being loaded onto a road truck and trailer to be transported off site to a licensed tip facility. It is anticipated that excavation works for the conveyance channel will be carried out concurrently with truck loading operations.

Based on an assumed truck loading rate of one truck every ten minutes, between 48-60 trucks per day, 5 days per week; the excavation and transportation works will take approximately 24 weeks to complete.

3.3.2 Stage 2 – Cosgrave Road crossing

1) Establish a site compound to the east off Cosgrave Road.

2) Establish a temporary traffic diversion.

3) Establish / undertake protection, support and/or diversion of the existing 1,200 mm diameter WSL watermain.

4) Construct the proposed crossing (for the purposes of this assessment, a twin 3.0 m wide x 2.0 m high box culvert beneath Cosgrave Road) – including the excavation and removal of 1,000 m3 of material. As noted above the final crossing solution will be confirmed at detailed design stage.

5) Reinstatement of the Cosgrave Road carriageway.


3.3.3 Stage 3 – Cosgrave Road to Old Wairoa Road (including the Old Wairoa Road crossing

1) Establish construction access from Cosgrave Road and Old Wairoa Road, complete with wheel wash and stabilised entrances.

2) Establish a site compound to the east of the Cosgrave Road crossing.

3) Establish a haul road along the length of the proposed conveyance channel between Grove Road and Old Wairoa Road. It is anticipated for the purposes of this assessment that the haul road will be constructed using imported clean hardfill, laid on top of a suitably designed geo-grid to prevent the haul road from settling into the underlying peat material.

4) Commence construction/excavation of the conveyance channel, excavated material will be transported to a stockpile area to:

a. Allow the excavated material to dewater and drain, and

b. Provide a suitable area where material can be loaded onto road truck and trailers and be removed from the site.

5) Establish a temporary traffic diversion on Old Wairoa Road by providing a temporary road formation during the construction of the crossing solution.

6) Construct the crossing solution across Old Wairoa Road (assumed as 3.0 m wide x 2.0 m high box culvert for the purposes of this assessment).

7) Dis-establishment from site including the removal of the temporary haul road, stabilisation of exposed earth and / or the establishment of permanent planting.

Based on the concept design, the volume of material to be excavated and removed from site in Stage 3 of the works is approximately 65,000 m3 and is anticipated to be a mixture of peat, organic silts and sands. It is intended that this material will be excavated from the ground and removed to an on-site stockpile, where it be allowed to dewater to remove surplus ground water present, before being loaded onto a road truck to be transported off site to a licensed tip facility. It is anticipated that excavation works for the conveyance channel will be carried out concurrently with truck loading operations.

Based on an assumed truck loading rate of one truck every ten minutes, between 48-60 trucks per day, 5 days per week; the excavation and transportation works will take approximately 18 weeks to complete.

3.4 Construction traffic

A high-level construction traffic assessment has been carried out based on the assumptions stated in Section 1.3 above and a copy is included in Appendix B. A number of options were considered for flow of construction related traffic into and out of the various work areas and for the diversion of traffic around the works. The recommended site access and egress locations for each construction stage are summarised below and shown in Figure 3. These locations are indicative only, with the final access and egress locations to be determined at detailed design stage.

All access and egress locations for each of the construction sites will be from public roads (Grove Road, Cosgrave Road and Old Wairoa Roads) to the designation area. Traffic management measures, road closures and diversion routes may be required. However, these will be subject to the approval of a Corridor Access Request by Auckland Transport.


Stage 1: Access to the construction site will be from Grove Road and egress will be onto Cosgrave Road.

Stage 2: Access and egress to/from the site for the construction of the Cosgrave Road crossing (assuming an engineering solution of a twin 3.0 m wide x 2.0 m high pre-cast concrete box culvert, or similar) will be from Cosgrave Road.

However during the works traffic diversions will be required for extended periods. Two options have been identified in the Construction High Level Traffic Assessment (see Appendix B), which are subject to confirmation at detailed design stage, the two identified options are as follows:

� Option 1 - Prior to Stage 3 construct a temporary road east and into the Stage 3 construction area, to enable full closure of Cosgrave Road; or

� Option 2 - Complete closure of Cosgrave Road and a diversion around Walters Road, Grove Road and back along Old Wairoa Roads.

Stage 3: Access to the site will be from Cosgrave Road and egress will be onto Old Wairoa Road. For the section of the proposed conveyance channel south of Old Wairoa Road, access to the site will be across Old Wairoa Road and egress will be onto Old Wairoa Road. Old Wairoa Road crossing – the work area will be accessed from Old Wairoa Road. A traffic diversion will be required in the form of a temporary hard pavement, to allow traffic to bypass the construction site during the construction of the crossing (assuming an engineering solution of a 3.0 m wide x 2.0 m high box culvert, or similar).

Figure 3 Site access and egress locations

The traffic assessment concluded that given the low level of additional traffic volumes and the ability to largely avoid residential areas, the construction impacts associated with the proposed stormwater channel are likely to be minimal.

Construction site access Construction site egress Construction site combined access/egress


3.5 Management of groundwater lowering

The geotechnical analysis undertaken in support of this project has identified that minimisation of groundwater lowering is an essential element in the final design of the project. The use of weirs along the channel at regular intervals has been proposed and will assist with maintaining groundwater levels.

During construction, the invert level of the channel will extend below the final permanent water level. The design of temporary works to limit temporary groundwater lowering will be necessary to prevent wider consolidation / settlement. Selection of a competent Contractor will aid in the management of groundwater and should form a focus in the contract document specifications and tender evaluations.

Section 7.2.1 of the Takanini Stormwater Conveyance Channel Preliminary Geotechnical Appraisal (GHD, April 2014) discusses the potential effects of differential ground settlement on existing infrastructure and crossings, including the cracking of flexible road pavements, the rotational failure of structures and power poles, dislocation of connections to manholes and the rupture of buried pipelines. It is expected that any effects found following completion of the project would be assessed and, if necessary, repaired during the defects liability period for the project.

3.6 Erosion and sediment control

During construction erosion and sediment control (ESC) measures will be required to prevent erosion and intercept sediment mobilised due to rainfall. ESC practices will be implemented and managed on-site in accordance with Auckland Regional Council’s Technical Publication 90 (TP90).

Due to the nature of the existing ground conditions through which the proposed channel will pass, the majority of excavated soil will be removed from site to a licensed tip facility as there is very little practical use for the material once it has been excavated.

The construction of the conveyance channel will require some stockpiling of excavated material to provide a temporary drying area and to allow the drier soil to be loaded onto road truck and trailer units for transportation off site.

A Draft ESC Plan (DESCP) is not required at this stage of the project however a DESCP will be required prior to the lodging of any Resource Consents application and Outline Plan of Works.

Prior to the commencement of the construction works a Construction Stage Erosion and Sediment Control Plan, as part of an overall Construction Stage Environmental Management Plan, will be developed by and adhered to by the Contractor appointed to undertake the works and shall, as a minimum, consider and mitigate against the following potential effects:

1) Dust generation and its effect on local air quality;

2) Stormwater runoff and its potential for erosion of the exposed earth and the subsequent deposition within the receiving environment of any sediment generated;

3) Stockpile establishment and management and the collection and treatment of groundwater and stormwater runoff flowing out of any temporary stockpiles. This may require chemicals, such as lime, to neutralise the potential acidic nature of this run-off prior to discharge back into the environment;

4) The progressive stabilisation of the stormwater conveyance channel against erosion and sedimentation as construction progresses and the establishment of any planting measures proposed in any future landscape plan;


5) Transportation of spoil off site, the use of covered trucks will be required to prevent transported soil from blowing out of the truck during transportation along the public road network;

6) ESC measures, not only physical control structures, such as silt fences, decanting earth bunds, sediment retention ponds etc, but consideration should also be given to the management of the ESC measures such as:

a. Carrying out regular inspection of ESCs and the recommendation on minimum maintenance activities and frequencies required to ensure the ESCs perform as required.

7) Weather monitoring and the subsequent control of site construction activity in response to forecast and actual rainfall; and

8) The recording and documenting of any works required to rectify any problems found during routine and reactive inspection and monitoring requirements.


4. Summary This CCM demonstrates that the key issues such as order of construction and potential impacts have been considered.

Based on the concept design, the conceptual construction programme indicates that the works can be carried out over a period of approximately 23 months, with bulk earthworks being carried out over 2 separate earthworks seasons (November to April) and it is anticipated that the works can be carried out in sequence (i.e. Stage 1, followed by Stage 2 and then finally Stage 3). The extent of construction is therefore likely to be across two financial years.

It has also been identified in a high-level traffic assessment that given the low level of additional traffic volume and the ability to largely avoid residential areas, the construction impacts associated with the proposed stormwater channel are likely to be minimal.

The key aspects of this CCM to be considered and addressed in detail at detailed design, tender and construction stages are summarised below:

1. Stabilised site accesses off Grove Road, Cosgrave Road and Old Wairoa Road will be required for safe traffic movement to and from the public road network for site works.

2. Development of a Construction Stage Erosion and Sediment Control Plan, as part of an overall Construction Stage Environmental Management Plan, will be developed by and adhered to by the Contractor appointed to undertake the works

3. Temporary traffic management plans will be required and will need to be approved by Auckland Transport as part of the Corridor Access Request process.

4. A temporary haul road will be required to support truck or Moxy vehicles transporting excavated material to stockpiles within the site for dewatering. This haul road will run the full length of the proposed conveyance channel.

5. The crossing under Cosgrave Road and under the 1,200 mm WSL watermain will potentially require a road closure of Cosgrave Road for a number of weeks and will require detailed design and acceptance by WSL for work adjacent and under their strategic asset.

6. Excavated material will need to be removed from site to an approved disposal facility. To date Greenmount landfill is able to accept this material. The volume of material to be disposed of, based on the concept design and allowing for appropriate bulking factors is estimated to be approximately 172,000 m³. This will be confirmed at detailed design stage.

7. In order to reduce the costs of transportation and disposal, on-site dewatering is recommended. This has a secondary effect of generating humic acid leachate from the dewatering process. This will need to be treated at source prior to its discharge back into the receiving environment, or if this cannot be done, then it will need to be captured and disposed of off-site.

8. Once the bulk excavation has been carried out, construction of weirs to maintain groundwater levels will be an essential element of the works and these are to be constructed in a progressive manner as excavation of the channel progresses upstream.

9. Dewatering of the adjacent ground, both within the proposed designation and beyond will commence once construction has commenced. Management of groundwater levels


during construction is a key element in ensuring that excessive groundwater lowering and subsequent ground settlement does not occur.

10. The selection of competent Contractors to deliver the physical works will be an essential element for successful project completion. This will include management of groundwater adjacent to all existing structures, existing houses and buildings and in particular, the 1,200 mm WSL watermain.

11. The effects of differential ground settlement on existing infrastructure and crossings, must be considered. It is expected that any effects found following completion of the project would be assessed and, if necessary, repaired during the defects liability period for the project.


Appendix A – Conceptual construction programme

YearEarthworks SeasonMonth August September October November December January February March April May June July August September October November December January February March April May JuneTaskStage 1 - Grove Road to Cosgrave Road Conveyance ChannelAccomodation WorksWatercare 1200 Watermain Protection worksEstablish Site Exit onto Cosgrave RoadEstablish Site Access From Grove RoadEstablish Site CompoundEarthworks operationsEstablish ESC MeauresTopsoil StripEstablish Haul RoadEstablish Stockpile AreasBulk Earthworks OperationsMonitor and Maintain ESC MeasuresSite De-MobilisationDecommission Haul RoadStabilisation of Exposed AreasEstablish PlantingStage 2 - Cosgrave Road CulvertEstablish traffic DiversionsWatercare 1200 Watermain Protection worksCulvert ConstructionReinstate Cosgrave RoadRemove Traffic DiversionStage 3 - Cosgrave Road To Old Wairoa RoadEstablish Site Access From Cosgrave RoadEstablish Site Exit onto Old Wairoa RoadConstruct 3 m x 2 m Box Culvert Reinstate Old Wairoa Road Establish ESC MeauresEstablish Site CompoundEstablish Haul RoadEstablish Stockpile AreasBulk Earthworks OperationsMonitor and Maintain ESC MeasuresSite De-MobilisationDecommission Haul RoadStabilisation of Exposed AreasEstablish Planting

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Takanini 2a / 2b Stormwater Conveyance Channel - Conceptual Construction programme1


Appendix B – Construction traffic high level assessment

Mapbook Appendix M3 - Auckland Council...Channel Cross Sections - 51-31962T-SKS1, SKS2, SKS3, SKS4...

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