FINAL REPORT NO -...

F I N A L R E P O R T N O . 2 0 A

Route Selection Report

Prepared for

Tauranga City Council

Private Bag 12022 Tauranga

5 May 2006

42066678/ROUTE SELECTION REPORT

J:\Jobs\42066678\6000 Reports\AEE Appendices Final Aug 07\Report No. 20A\20A Cover.doc

Contents

Executive Summary-------------------------------------------------------------------------------------------- ES-1

1 Introduction and Background ------------------------------------------------------------------------ 1-1

1.1 Introduction 1-1 1.2 Project Scope 1-1 1.3 Project Philosophy 1-1 1.4 Project Objectives 1-2 1.5 Purpose of Report 1-3

2 Need for the Southern Pipeline ---------------------------------------------------------------------- 2-1

2.1 Mouse Model Review 2-1 2.2 Catchment Options 2-1

3 Route Selection Methodology ------------------------------------------------------------------------ 3-1

3.1 Overview 3-1 3.2 Constraints Mapping 3-1 3.3 Initial and Preliminary Route Options 3-1 3.4 Route Selection Phase 3-2 3.5 Preferred Route Option 3-3

4 Preliminary Route Options ---------------------------------------------------------------------------- 4-1

4.1 Route Corridor Summary 4-1 4.2 Route Options Considered 4-2 4.3 Proposed Works 4-2

5 Summary of Technical Reports ---------------------------------------------------------------------- 5-1

5.1 Technical Investigations Undertaken 5-1 5.2 Hydraulics 5-1

5.2.1 Design Parameters 5-1 5.2.2 Summary of Hydraulic Constraints 5-2

5.3 Geotechnical Assessment 5-3 5.4 Structural Assessment 5-4 5.5 Ecological Assessment 5-5 5.6 Archaeological Assessment 5-6 5.7 Air Quality 5-7 5.8 Traffic 5-7

6 Statutory Considerations ------------------------------------------------------------------------------ 6-1

6.1 SmartGrowth Strategy and Tauranga Tomorrow 6-1 6.2 Resource Management Act 1991 6-1 6.3 Consent Requirements 6-2 6.4 Historic Places Act 6-4

7 Consultation ------------------------------------------------------------------------------------------------ 7-1

7.1 Consultation Objectives 7-1

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Contents

7.2 Consultation Methodology 7-1 7.3 Tangata Whenua 7-2 7.4 Regulatory Authorities 7-5 7.5 Transit and OnTrack 7-7 7.6 Other Stakeholders and Interest Groups 7-8 7.7 Directly Affected Landowners and Occupiers 7-8 7.8 Wider community 7-9

8 Options Discussion -------------------------------------------------------------------------------------- 8-1

8.1 Central Route A 8-1 8.1.1 Summary of key issues 8-1 8.1.2 Central Route A alternatives 8-4

8.2 Eastern Route B 8-5 8.2.1 Summary of key issues 8-5 8.2.2 Eastern Route B alternatives 8-7

8.3 Western Route E 8-7 8.3.1 Summary of Key Issues 8-8 8.3.2 Western Route E alternatives 8-9

8.4 Road Route K 8-9 8.4.1 Summary of key issues 8-10 8.4.2 Road Route K alternatives 8-11

8.5 Chapel Street Route 8-12 8.5.1 Summary of key issues 8-13 8.5.2 Chapel Street route alternatives 8-14

8.6 Cost Estimates 8-14 8.7 Possible Route Optimisation and Staging 8-15

9 Options Assessment ------------------------------------------------------------------------------------ 9-1

9.1 Route Options Assessment 9-1 9.2 Summary Assessment of Route Sections 9-1

9.2.1 Assessment Criteria 9-1 9.2.2 Outcomes of summary assessment 9-2

9.3 Risk Register 9-2 9.3.1 Purpose and Approach 9-2 9.3.2 Outcomes of risk assessment 9-3

9.4 QBL Assessment 9-5 9.4.1 Assessment framework 9-5 9.4.2 Inclusion of risk in the QBL assessment framework 9-6 9.4.3 QBL assessment outcomes 9-6

10 Conclusions -----------------------------------------------------------------------------------------------10-1

10.1 Route Options Assessment 10-1 10.2 Key Issues 10-1 10.3 Assessment Outcomes 10-2

11 Recommendations --------------------------------------------------------------------------------------11-1

11.1 Recommended Route 11-1 11.2 Recommended Actions 11-2


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Contents

FIGURES

Figure 1-1 Southern Pipeline Plan of Catchment Area ............................................................................. 1-4 Figure 3-1 Southern Pipeline Project Activities and Proposed Timeline.................................................. 3-4 Figure 4-1 Summary Plan of Preliminary Route Options ......................................................................... 4-1 Figure 9-1 Summary of Number of Extreme, Very High and High Residual Risks for Each Pipeline Route

Option, as at 19 April 2006 ........................................................................................ 9-4

TABLES

Table 5-1 Hydraulic Constraints ............................................................................................................... 5-3 Table 8-1 Capital Costs and Whole of Life Costs for Each Route Option, at the 85th Percentile After

Inflation and NPV Analysis...................................................................................... 8-14 Table 9-1 Summary of Total Residual Risk Score, and Cumulative Residual Risk Scores for Extreme and

Very High Residual Risks for Each Pipeline Route Option, as at 19 April 2006. ..... 9-4 Table 9-2 Assessment Criteria within the QBL Assessment Framework ................................................ 9-5 Table 10-1 Summary of Route Options - Key Advantages and Disadvantages...................................... 10-3

PHOTOS

Photo 8-1 - Slip road north of Maungatapu Bridge to Matapihi- Central Route A ................................... 8-3 Photo 8-2 - Western Cut Embankment of State Highway 29 near Greenwood Park – Central Route A.. 8-4 Photo 8-3 - Welcome Bay Road – Eastern Route B.................................................................................. 8-6 Photo 8-4 - Railway Embankment – Western Route E ............................................................................. 8-7 Photo 8-5 - Takitimu Road (Toll Road) – Road Route K ....................................................................... 8-12

APPENDICES

Appendix A – Report List Appendix B – Route Option Alignment Plans Appendix C – Preliminary Route Options Summary Plan Appendix D – Summary Assessment Table Appendix E – Risk Register Appendix F – QBL Assessment


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Executive Summary

Overview

Urban expansion within Tauranga City is occurring at the extremities of the existing wastewater reticulation system and further intensification is also expected within existing urban areas. Recent modelling has confirmed that parts of the wastewater network are already reaching capacity and that this capacity may be exceeded in the near future.

Local storage options are able to temporarily relieve pressure in some areas but a strategic city-wide solution is required in order to provide for expected growth in Tauranga.

Options to establish new treatment facilities in the southern parts of Tauranga and to transfer waste to such facilities are considered to be impracticable (for time, cost and environmental reasons). Establishment of new facilities would also be inconsistent with the wastewater approach adopted in the SmartGrowth Strategy, which favours centralised treatment at Te Maunga and discharge of treated effluent via the ocean outfall. (Tauranga City Council has recently secured a 35-year consent for the discharge of treated effluent from the outfall).

Therefore, in order to address the future growth and network capacity issues, it is proposed to construct a new trunk main (the Southern Pipeline) from the Maleme Street Pump Station in Greerton to the Te Maunga Wastewater Treatment Plant (WWTP).

This proposed Southern Pipeline will intercept wastewater flows from southern areas of Tauranga that would otherwise have gone to the Chapel Street WWTP, and will transfer this wastewater to Te Maunga for treatment.

Scope of Southern Pipeline Project

The Southern Pipeline Project is a major investment in the City’s infrastructure with a capital cost of between $60m and $90m. The project has significant social and environmental benefits as it will provide for future growth, manage wastewater flows and minimise the risk of untreated sewage overflows from the existing reticulation.

The current programme is to commence construction in 2007. Depending on the route selected, the works will include:-

• A new trunk main sewer pipeline of between 10 to 19 km in length;

• Maximum pipeline diameters of approximately 1,100 mm in single pipe sections and 800 mm in twin bore sections (e.g. at harbour crossings);

• Major upgrade of the existing Maleme Street Pump Station;

• Upgrade of other existing pump stations, or the construction of new pump stations;

• Upgrades of principal feeder pump stations and associated rising mains;


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Executive Summary

• A harbour crossing by placement of the pipeline on or under the seabed, or construction of a new pipe bridge; and

• Associated facilities including siphon structures, receiving chambers and air control structures.

Pipeline Route Options

Having confirmed the need for the Southern Pipeline, options for the route of the pipeline were then considered. Four possible corridors for the pipeline were identified, based largely on the geography of Tauranga. Following consideration of over 50 individual route sections, a preferred main route option and one or more main alternatives within each of those corridors was identified.

In summary, the corridors considered were:-

• Hairini / Maungatapu / Matapihi (eventuating as “Central Route A”);

• Hairini / Welcome Bay (eventuating as “Eastern Route B”);

• Greerton / Tauranga Central / Matapihi (eventuating as “Western Route E”); and

• Kopurererua Stream Valley / Tauranga Central / Matapihi (eventuating as “Road Route K”).

These main routes are shown on the summary plan at the end of this Executive Summary.

An alternative option which has also been considered during the Southern Pipeline Project is to construct the pipeline to Chapel Street and provide additional storage capacity to allow for wastewater buffering prior to and after treatment. The existing WWTP at Chapel Street would require significant upgrading for this option to become viable.

Assessment of Route Options

The assessment of route options has had regard to various social, economic, environmental and cultural considerations, and has been undertaken in accordance with the decision making requirements of the Local Government Act 2002. Technical investigations and consultation with key stakeholders has been an important part of this process.

A risk analysis approach has also been applied in the assessment of route options, with the intention of maximising opportunity and reducing risk for the project as a whole and for the pipeline route.


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Executive Summary

Key Issues

Key issues arising from the assessment process are summarised below.

• The pipeline will be largely underground, and will have a 100-year design life. Any potential long-term environmental impacts associated with the physical presence of the pipeline are considered to be minor.

• Cultural concerns associated with the transfer of human waste by water and the discharge of effluent to the ocean are acknowledged. Numerous other issues have also been raised by iwi and hapu during the consultation process, with some strongly opposed to one or all of the route options, and some generally supportive of the Project.

• All of the route options for the Southern Pipeline will require a crossing of the Tauranga harbour. The Tauranga harbour has significant conservation, landscape and cultural values. Harbour crossing options which involve placement of the pipeline under the seabed are considered preferable from an economic and landscape point of view. However a crossing over the harbour on a pipe bridge has advantages for maintenance access and also provides an opportunity for dual use (e.g. for other services or for pedestrian / cycle access).

• All route options pass through developed urban areas to varying extents and the construction process could result in significant (but temporary) traffic and community disruption, particularly for those options which pass through the Tauranga Central area.

• Options which traverse the urban area from Greerton to Tauranga Central offer additional advantages over others, as these routes can also address existing capacity constraints in the trunk system from immediately upstream of the Maleme Street Pump Station to the Memorial Park Pump Station, and from Judea Pump Station to the Chapel Street WWTP via Takitimu Drive.

Assessment Outcomes

The routes were assessed against a “Quadruple Bottom Line” (QBL) and risk analysis framework. A QBL assessment framework is one which incorporates consideration of social, economic, environmental and cultural matters. The QBL framework has been prepared in accordance with decision making requirements under the Local Government 2002 (LGA). The LGA also requires Council to consider “other matters” in addition to those categorised as ‘social’, ‘economic’, ‘environmental’ and ‘cultural’. Each of the main route options was scored against the potential short-term and long-term effects and the risks associated with each option quantified.

The ranking of the route options varies depending upon the relative weighting attributed to short-term and long-term impacts. Generally, the options that consistently scored well under this process have been Central Route A and Western Route E (with placement of the pipeline under the seabed by a specialist technique called Horizontal Directional Drilling – HDD). Western Route E (HDD) becomes increasingly favourable as the weighting of the long-term effects increases over the short-term effects. The Chapel Street Route option also scored well, largely because this option avoids the need for a harbour crossing (and therefore the associated cost and environmental impacts).


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Executive Summary

The relative scores arising from the QBL and risk analysis process are a guide only and should not necessarily be a sole determinant of a preferred route for the Southern Pipeline. Other broader strategic considerations include the overall hydraulic flexibility offered by a particular route and the potential for dual use of a pipe-bridge (e.g. for other services or access).

Recommendations

Having regard to the information contained within the report and the supporting investigations, the recommended route for the Southern Pipeline is Western Route E (with HDD). This route follows Fraser Street, Eighteenth Avenue and Devonport Road and then crosses the harbour south of the existing rail bridge to Matapihi. The recommended location for the pipeline as it crosses the harbour is underneath the seabed.

The route meets the overall objectives for the Project and in particular, it offers additional hydraulic flexibility compared to other routes, including the ability to address existing capacity constraints in the trunk system at Memorial Park and downstream of Judea. The Central Route A does not provide the same opportunity for Council to solve the Judea/Glasgow Street to Chapel Street capacity issues as does Western Route E. Route E could also permit additional wastewater from the western side of the city to be transferred to Te Maunga (via Memorial Park), a level of flexibility that is not available with Central Route A. Route E overall also scores highly when all social, economic, environmental and cultural matters are considered.

The option of a bridge for Western Route E cannot be discounted at this stage. Further investigation is required in order to quantify risk associated with HDD and the opportunities for dual use of a pipe bridge.


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SECTION 1 Introduction and Background

1 Introduction and Background

1.1 Introduction

The Southern Pipeline Project (the project) is a project designed to help meet the future wastewater needs of Tauranga City. The project involves the development of a new trunk main and associated pump stations to transport wastewater from southern parts of Tauranga to the Te Maunga Wastewater Treatment Plant (WWTP).

The Southern Pipeline is required because:-

a) Urban expansion is occurring at the extremities of the existing reticulation system, and parts of the existing reticulation will have insufficient spare capacity to accommodate this growth;

b) Unless major works are undertaken at the Chapel Street WWTP (which has limited capacity), wastewater flows need to be transferred away from Chapel Street to the Te Maunga WWTP to adequately treat increasing wastewater flows in the future.

The Southern Pipeline will resolve these issues by intercepting wastewater flows from southern areas of Tauranga that would otherwise have gone to the Chapel Street WWTP, and transporting this wastewater to the Te Maunga WWTP.

An alternative option which has been considered during the Southern Pipeline Project is to construct the pipeline to Chapel Street and to establish additional storage capacity. The existing WWTP at Chapel Street would require significant upgrading for this option to become viable.

1.2 Project Scope

The Southern Pipeline Project commenced in June 2005 based largely on the outcomes of the SmartGrowth planning process, along with confirmation that parts of the existing sewerage network would be reaching capacity within a few years.

In summary, the project involves identification of a preferred pipeline route, securing the necessary consents and approvals, detailed design, construction and commissioning.

The project is currently at the route selection stage. A number of route options for the pipeline have been assessed over the past few months and Tauranga City Council (TCC) is planning to make a decision on a preferred route in May 2006.

1.3 Project Philosophy

The Southern Pipeline is primarily required to cater for increased growth in the southern parts of the City. The general catchment area for the proposed Southern Pipeline is shown on Figure 1-1 at the end of this section. The large “Grasshopper” development currently under construction near Pyes Pa will be a major early contributor of wastewater.


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Earlier expectations for the project were that a pipeline route would be established from the Maleme Street Pump Station to the Te Maunga WWTP via Maungatapu peninsula (named Central Route A) or Welcome Bay (named Eastern Route B). However, as the initial investigations progressed, a number of significant risk areas were identified – primarily associated with land ownership and access to, and ongoing tenure within the State Highway corridor. Accordingly, the scope of the project was broadened and western corridor options (named Road Route K and Western Route E along Fraser Street / Devonport Road) have now also been considered.

These routes vary slightly from the original philosophy in that they may cater for different catchment areas, but would still achieve the overall project objectives to relieve pressure at the Chapel Street WWTP and cater for future growth in the southern parts of Tauranga.

Later in the route selection process, a further option (named Chapel Street Route) was identified which involved construction of the pipeline to the Chapel Street WWTP and the construction of additional raw sewage and treated wastewater storage at that site. This was another slightly different approach to address capacity constraints within the existing system, and was considered as part of the route selection process.

1.4 Project Objectives

The overall objectives for Southern Pipeline Project are to:-

a) Provide for wastewater reticulation of the developing southern areas of Tauranga;

b) Manage wastewater treatment capacity to accommodate future development; and

c) Implement actions arising from the SmartGrowth Strategy, specifically Action 1 of Section 7.4.3 relating to wastewater:

“Implement the Tauranga Wastewater Disposal Strategy which includes discharging effluent via Te Maunga wetlands and the outfall pipeline”.

The more specific objective for the physical works is to construct a new main trunk sewer to transfer wastewater from the Maleme Street Pump Station to the Te Maunga WWTP, that:-

d) Is safe, economical and robust;

e) Protects the environment and public health;

f) Minimises environmental and community disruption during construction, operation and maintenance; and

g) Is generally supported by the community.


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1.5 Purpose of Report

This Route Selection Report focuses specifically on the route options for a new main trunk sewer.

Other work has been undertaken which confirms the need to increase capacity of the City’s existing wastewater system and which considers the alternatives to proceeding with the Southern Pipeline Project. This work is summarised briefly in Section 2 of this report. A full list of reports prepared as part of the current work is included in Appendix A.

The purpose of this Route Selection Report is:

• To summarise work undertaken which confirms the need for the Southern Pipeline;

• To describe the process for identification and assessment of the preliminary route options for the pipeline;

• To report on the assessment of each of the route options; and

• To recommend a preferred route for the pipeline.

A recommendation for a preferred pipeline route is presented in Section 11 of this report. A final decision on the route will be made by TCC, assisted by the information contained within this Route Selection Report and supporting documents.


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Figure 1-1 Southern Pipeline Plan of Catchment Area


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Figure 1-1 Southern Pipeline Plan of Catchment Area


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SECTION 2 Need for the Southern Pipeline

2 Need for the Southern Pipeline

The recent reports which contain background information confirming the need for the Southern Pipeline are the Mouse Model Review and System Analysis (April 2006) and the Southern Catchments Wastewater Options (working draft dated March 2006). The findings of those reports are summarised below.

2.1 Mouse Model Review

The modelling review and broad system analysis was undertaken as part of the Southern Pipeline Project and are reported in the Mouse Model Review and System Analysis Report (April 2006). The main aims of the modelling were to review the TCC reticulation model and confirm its suitability for system assessment relevant to the Southern Pipeline Project and to compare the effectiveness of the proposed Southern Pipeline on system performance with a number of alternatives (e.g. storage).

The MOUSE modelling of the Tauranga City wastewater system indicates that several key areas of the network will be under capacity for wet weather flows in a number of areas by 2011. The areas that appear to be the most sensitive to the proposed development are the trunk system from immediately upstream and downstream of the Maleme Street Pump Station to the Memorial Park Pump Station, and from Judea Pump Station to the Chapel Street WWTP via Takitimu Drive (Glasgow Street area).

Of the options investigated, it is concluded that local storage and upgrade options can be used to relieve the local reticulation around the Maleme Street pumping station and the Anchorage siphon structures in the short term. However, more strategic options such as the Southern Pipeline need to be explored to resolve the capacity issues in the trunk mains and to provide a long-term city-wide solution.

The MOUSE modelling demonstrated that the trunk sewers from Judea to the Chapel Street WWTP are approaching capacity and are surcharged for wet weather flows from the year 2011 onwards. From 2011 onwards unacceptable levels of predicted overflows will also occur unless wastewater from the southern catchments is diverted away from this system. In addition, an upgrade of all the existing trunk mains will be required from Maleme St to Memorial Park by 2016 to prevent these lines surcharging. The model also predicted that the Judea-Chapel Street line is almost full under dry weather flows during 2021.

The Southern Pipeline will prevent the predicted sewage over flows and surcharging in the sewer trunk mains.

2.2 Catchment Options

Prior to making determinations on the route, TCC also wished to confirm that alternative wastewater collection, treatment and disposal options for the southern catchments of Tauranga had been thoroughly investigated, and to confirm the rationale for the pipeline.

The Southern Catchments Wastewater Options Report (April 2006) reviewed the alternative assessments previously undertaken in other reports and considered options for on-site systems or local wastewater treatment and treated wastewater discharges. After review of past issues and options studies for the southern catchments, it was determined that the studies had comprehensively addressed the wider city


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SECTION 2 Need for the Southern Pipeline

wastewater issues and options. There was only limited discussion on alternatives for multiple local satellite treatment and disposal.

TCC’s report on alternatives (Alternatives/Options Assessment Report, October 2004) acknowledges that a localised treatment and disposal system could be considered in some areas but that this is dependant on site and location specific factors.

The Papamoa East greenfield area was the only area identified in the October 2004 report as a possible area where a localised system may be considered in the future. The time to develop such local treatment/disposal solutions would be long (possibly 10 years) and this timeline would not meet the current needs to manage wastewater overflows.

Based on these previous alternative assessment reports, TCC obtained a consent under the RMA for a 35 year period to discharge treated wastewater through the Papamoa ocean outfall, which now represents a significant community asset.

URS’s review report considered alternatives for transporting wastewater (treated or untreated) to the Papamoa outfall. The report concluded that a treated wastewater pipeline was less desirable than an untreated wastewater pipeline as it was less flexible, has similar cost, and would not allow for future connections to the Southern Pipeline.

A pipeline to carry untreated wastewater from the Southern Catchments to Te Maunga would solve the current and predicted sewage management issues for the southern catchments.

This approach to transfer wastewater to the existing treatment plant is consistent with the SmartGrowth Strategy which promotes optimising use of existing infrastructure (such as the existing treatment plants and ocean outfall) before developing infrastructure in new areas (Section 1.4.1 of SmartGrowth).


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SECTION 3 Route Selection Methodology

3 Route Selection Methodology

3.1 Overview

The methodology for selection of a preferred route for the Southern Pipeline is described below and is shown diagrammatically in Figure 3-1 at the end of this section.

In summary, the key phases of the methodology are:- identification of constraints and opportunities, investigation and assessment of route options and selection of a preferred option. Technical, environmental, social, economic and cultural issues have been considered throughout the preliminary phases of the work and will continue to be considered for subsequent phases. Consultation is also being carried out throughout the various phases of the project.

Numerous reports have been prepared as part of the Project to date which cover the technical investigations in detail as support for the comments in this report. These supporting reports are listed in Appendix A.

3.2 Constraints Mapping

The first phase of the route selection process was to identify all the key constraints and other features within the project area which may affect selection of a pipeline route. A series of constraints maps were prepared to illustrate where those constraints occur – this series of maps is generally referred to as the ‘Constraints Map’. The ‘constraints’ include items such as topography, geological features, special environmental areas, archaeological sites, areas of cultural significance and major services.

The Constraints Map was developed on a GIS base, with inputs provided by TCC, EBOP, service authorities and other organisations. Information provided during consultation with various parties and from site visits was also included.

The above constraints mapping phase is presented in Southern Pipeline Constraints, Report No 3 (October 2005).

3.3 Initial and Preliminary Route Options

A wide range of initial route options were identified having regard to the objectives for the project and the information shown on the Constraints Maps. Wherever possible the initial route options were developed to maximise the use of local road reserve and land already in TCC ownership, and to minimise the impact on private property and on sensitive environmental areas.

The initial route options were assessed having regard to engineering and design requirements, land tenure, environmental, cultural and economic issues. The routes identified and an assessment of these routes was presented in the draft Initial Route Options, Report No 7 (November 2005).

On the basis of that initial assessment, the number of potential options for the Southern Pipeline was reduced to a preferred main route option and one or more main alternatives within each of four corridors.


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The four corridors (based largely on the geography of Tauranga) are:-

• Hairini / Maungatapu / Matapihi (eventuating as Central Route A);

• Hairini / Welcome Bay (eventuating as Eastern Route B);

• Greerton / Tauranga Central / Matapihi (eventuating as Western Route E); and

• Kopurererua Stream Valley / Tauranga Central / Matapihi (eventuating as Road Route K).

These “Preliminary Route Options” were then taken forward for further assessment. A revised version of the earlier route options report was presented as a working draft of the Preliminary Route Options, Report No 13 (January 2006). That report has effectively been superseded by this current Route Selection Report, Report No. 20.

3.4 Route Selection Phase

The current phase of the project (December 2005 to April 2006) has involved the development and further assessment of the four main route option corridors. A number of route variations and other options for the Southern Pipeline Project were also identified during this phase of work, including a fifth option to construct the pipeline to the Chapel Street WWTP, which would require construction of additional raw sewage and treated wastewater storage at that location.

In summary, the Route Selection process has incorporated the following key phases of work:-

i) Technical investigations (refer Section 5 of this report);

ii) Consultation (refer Section 7 of this report);

iii) Options assessment (refer Section 9 of this report); including:-

– Assessment of individual route sections;

– Risk analysis – assessment of project risks and main route risks; and

– “Quadruple Bottom Line” assessment under Local Government Act 2002 – comparative assessment between main routes, having regard to social, economic, environmental and cultural matters.

The outcome of this current phase of work will be the selection of a single preferred route for the Southern Pipeline. The current programme is that a decision on a preferred route for the Southern Pipeline will occur in May 2006.


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3.5 Preferred Route Option

Once a preferred route has been selected, further investigation, assessment and design will occur. A full Assessment of Effects on the Environment (AEE) will be undertaken as part of the required resource consent process. For example, resource consents will be needed for a harbour crossing, for any works in conservation areas and for other aspects. Resource consents would generally not be required for the pipeline in local road reserve. The methodology for route selection (amongst other things) will need to be demonstrated in the AEE to meet the requirements of the Resource Management Act 1991 (RMA).

The detailed design and delivery of the preferred option will follow the consenting process. As noted earlier, the current programme is to commence construction in 2007. This timing will be reviewed as the project progresses.


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Figure 3-1 Southern Pipeline Project Activities and Proposed Timeline

Date Inputs Project Phase

April 2005

Jun-Aug 2005

End of Oct 2005

Nov 2005 – Mar 2006

May 2006

May – Aug 2006

Sept-Nov 2006

2007/08

2007/08 to 2009/10

2009/10

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Soc

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Des

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evie

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Project Commencement

Constraints Mapping

Initial Route Options

Preliminary Route Options

Ris

k Detailed Design and Tender Process

Construction

Preferred Route

Preliminary Design

AEE and Consent

Applications

Resource Consents Statutory Process

Scheme Commissioning


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SECTION 4 Preliminary Route Options

4 Preliminary Route Options

4.1 Route Corridor Summary

The locations of the four main route corridors, along with the option to connect to Chapel Street, are shown in Figure 4.1 and each route is also shown on plans in Appendix B.

Figure 4-1 Summary Plan of Preliminary Route Options

Central Route A passes through Hairini, Maungatapu and Matapihi. The key overall objective for this corridor has been to develop the most direct route between Maleme Street and the Te Maunga WWTP. A harbour crossing is required between the Maungatapu and Matapihi peninsulas. Options for the harbour crossing are: to directional drill and place the pipeline under the seabed; to lay a submarine pipe on the seabed surface; and to construct a new pipe bridge, possibly combined with pedestrian and cycle access.

Eastern Route B passes through Hairini and Welcome Bay, and to the rural area of Ngapeke. The key overall objective for this route has been to reduce the extent of work within the State Highway corridor and to establish a route to collect wastewater from the Welcome Bay urban area as well as other parts of southern Tauranga. A harbour crossing is proposed from Asher Road to the Te Maunga WWTP. Options


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for the harbour crossing are to directional drill and place the pipeline under the seabed; or to place the pipe in an excavated trench.

Western Route E passes through the suburbs of Parkvale, Tauranga South and Tauranga Central before crossing the harbour to Matapihi Peninsula, parallel to the existing rail bridge, where it joins the Central Route A corridor. The key overall objective for the Western Route E corridor has been to avoid the SH2/29 corridor and to use existing TCC land. Options for the harbour crossing are: to directional drill and place the pipeline under the seabed; to lay a submarine pipe on the seabed surface; and to construct a new pipe bridge and embankment, possibly combined with pedestrian and cycle access.

Road Route K follows the Takitimu Drive toll route, passes through Tauranga Central and then crosses the harbour to Matapihi Peninsula, parallel to the existing rail bridge. Road Route K also joins the Central Route A corridor at Matapihi. The Road Route K corridor was introduced as an alternative towards the end of the Initial Route Options Phase (September 2005). Key overall objectives for the Road Route K corridor have been to avoid major reinstatement costs associated with works in local roads, and to link to the Judea Pump Station. Options for the harbour crossing are the same as those for Western Route E.

The Chapel Street Route follows Western Route E to Memorial Park, then passes through the Tauranga Central area along Cameron Road and across Marsh Street to Chapel Street WWTP. This route was introduced as an alternative towards the end of the Route Selection Phase (March / April 2006). It has a different overall philosophy to the other route options as it would involve the construction of large storage tanks for both raw sewage and treated wastewater and an upgrade to the treatment plant at the Chapel Street WWTP. The treated wastewater would then be transferred to Te Maunga via the existing reclaimed water pipeline, across the Harbour Bridge. Other route options transfer untreated wastewater to Te Maunga.

4.2 Route Options Considered

Numerous other route variations have also been assessed at various stages throughout the current and earlier phases of the project, and these are shown on Drawing Number 12300-G-104-120 Preliminary Route Options Summary Plan in Appendix C.

4.3 Proposed Works

The Southern Pipeline will incorporate the following key components:-

a) A new trunk main sewer pipeline of between 10 to 19 km in length, depending upon the route option selected;

b) Maximum pipeline diameters of approximately 1,100 mm in single pipe sections and 800 mm in twin bore sections (e.g. at harbour crossings);

c) Associated facilities including siphon structures, receiving chambers and air control structures;


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d) Major upgrade of the existing Maleme Street pump station;

e) Upgrade of other existing pump stations, or the construction of new pump stations, depending on the final route selected;

f) A harbour crossing either by construction of a new pipe bridge, or placement of the pipeline on or under the seabed;

g) Stream crossings over or under streams, including Waimapu Stream, Kaitemako Stream, Otumanga Stream and Kopurererua Stream, depending on the final route selected;

h) Reinstatement works in roads, reserves, private property and coastal areas.

The current programme is to commence construction in 2007/08. Depending on the route selected, and the construction methodology, the construction period will be in the order of 18 – 30 months.


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SECTION 5 Summary of Technical Reports

5 Summary of Technical Reports

5.1 Technical Investigations Undertaken

A full list of reports prepared to date for the Southern Pipeline Project is included in Appendix A.

The technical investigations undertaken that are directly relevant to the route selection process are reported on in the following reports:-

i) Southern Pipeline Project Preliminary Hydraulics Design Report, Draft Report No. 8A Revision 2, prepared by URS New Zealand Limited for Tauranga City Council, 22 December 2005

ii) Southern Pipeline Project Preliminary Geotechnical Report, Draft Report No 11, prepared by URS New Zealand Limited for Tauranga City Council, 26 January 2006

iii) Southern Pipeline Project Harbour Crossing Options Report, Draft Report No 10, prepared by URS New Zealand Limited for Tauranga City Council, 9 January 2006

iv) Southern Pipeline Project Pipeline Route Fatal Flaw Ecological Assessment, Draft Report No 12, prepared by URS and Bioresearches for Tauranga City Council, 7 March 2006.

v) Preliminary Archaeological Assessment Route Options Report, Report No 19, draft report prepared by Mr Ken Phillips of Archaeology BoP Heritage Consultants, for URS New Zealand Limited, 21 March 2006

vi) Southern Interceptor Air Quality Issues, URS memorandum dated 19 January 2006

An interim design/construction methodology summary was also provided by a specialist Horizontal Directional Drilling (HDD) company, AJ Lucas Pty Ltd, to provide specific information on this specialist technique.

The above technical reports have provided input to the options development and route assessment processes described in this report. The findings of the investigations to date are summarised below.

5.2 Hydraulics

The Preliminary Hydraulics Design Report (December 2005) presents the hydraulic design parameters, profiles and hydraulic constraints for the preliminary route options. The report primarily focuses on the hydraulic design and management of the Southern Pipeline so has minimal discussion on feeder pump stations and associated rising mains.

5.2.1 Design Parameters

The design parameters for the following hydraulic components are discussed in the December 2005 Hydraulics Report:-

• Trunk sewers;


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• Design velocities and roughness of pipelines;

• Depth and cover to pipes;

• Manholes and access points;

• Pump stations; and

• Inverted siphons.

Preliminary transient (water hammer) analysis has since been conducted, and it is considered that most pipelines should be able to control water hammer events by using air valve control. Local catchment pump stations and links to the Southern Pipeline have also been reviewed. In most cases upgrades are required and new pipelines will need to be installed as the existing pipelines either have insufficient capacity, or cannot be used as the flow is in the reverse direction, or the diameters or pipe types are not suitable.

The total lengths of the main route options (as shown in plans on Appendix B) are:-

Central Route A 12,500 m

Eastern Route B 13,000 m

Western Route E 13,500 m

Road Route K 18,700 m, including the link from Maleme Street Pump Station to the point where Grasshopper Pump Station injects into the main Road Route K0 pipeline, and 15,700 m excluding this length

Chapel Street Route 9,700 m

Central Route A and Western Route E require upgrades to two existing main line pump stations, although the extent differs between routes. Eastern Route B and Road Route K have three main line pump stations. Eastern Route B has one new pump station and Road Route K two new pump stations (assuming that the Grasshopper pump station cannot be upgraded).

5.2.2 Summary of Hydraulic Constraints

Hydraulic ‘constraint’ is defined in this report as any condition arising from the nature of the pipeline route that requires a hydraulic device and / or has pipe installation issue(s) / water hammer controls to resolve in order to reliably achieve or maintain the design flow in the pipeline.

Examples of hydraulic devices include inverted siphons, inverted siphon structures, pump stations, transient controls and any other major hydraulic control structure. Air valves will be required at regular intervals on all rising mains but are not expected to cause any significant constraint at the valve locations as the structures are not large.


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Examples of pipe installation issues include harbour crossing(s), installation in urban streets and unstable ground. A summary of the hydraulic constraints for each selected route is shown in Table 5-1 (refer to Plans in Appendix B).

Table 5-1 Hydraulic Constraints

Harbour Crossing (Bridge or Directional Drill)

Selected Route Number of Main Pump

Stations

Number of Inverted Siphons

Total Length of Inverted Siphon

(km) (No.) Length

Urban Streets

(km)

Central Route A 2 3 6.6 1 800 m 4.4

Eastern Route B 3 3 3.3 1 1900 m 6.5

Western Route E * 2 2 3.7 1 1600 m 5.5

Road Route K 3 1 1.9 1 1600 to 2100* m 3.3

Chapel Street 2 1 1.9 0 - 9.7 * Depends on minor alternative routes.

5.3 Geotechnical Assessment

The Preliminary Geotechnical Report (January 2006) presents the preliminary geotechnical appraisal for the four main route options considered (i.e. Central Route A, Eastern Route B, Western Route E and Road Route K). The main objectives of the report are to: identify any possible fatal flaws; provide preliminary geotechnical appraisal based on collated geotechnical data; identify areas of risk associated with geotechnical hazards, and provide supporting geotechnical information for the route assessment, HDD assessment across the harbour, and selection process.

The following scope of work was undertaken:

• Obtain and interpret aerial photographs (stereo pairs);

• Collate and review historical geotechnical data from various sources along route options;

• Site walkover assessment of identified geotechnical hazard areas; and

• Perform preliminary geotechnical investigations along route harbour crossing options to determine construction feasibility.

In summary, the key findings of the geotechnical investigations to date are:

i. The Central Route A Maungatapu – Matapihi harbour crossing option is feasible for construction either by directional drilling techniques or via a separate pipe bridge;

ii. Harbour crossing options for Western Route E and Road Route K from Grace Road, Harvey Street or Memorial Park are considered a fatal flaw due to soft / very loose estuarine sediments to depths


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greater than 30m for more than a third of the length. (These route sections were subsequently abandoned for this reason);

iii. A harbour crossing approximately parallel to the existing railway bridge is feasible (from a geotechnical perspective) for construction either by directional drilling techniques or via a separate pipe bridge. A causeway for the pipeline construction can be built parallel to the existing railway causeway without adversely affecting the causeway;

iv. Programmed geotechnical investigations for Eastern Route B across Rangataua Bay were unable to be completed due to concerns raised by local iwi representatives. However, based on available data, it is considered feasible to construct the pipeline crossing using directional drilling techniques;

v. Although a number of relic and active slips were identified, no fatal flaws were identified for any of the landward portions of the project. Most of the issues can be resolved through engineering design. Some locations may require active retention works if the risks cannot be avoided;

vi. Much of the pipeline routes traverse through potentially liquefiable (during both 1 in 500 year and 1 in 2500 year earthquake events) soils. Engineering design / construction to mitigate this risk for the whole length of the pipeline is not cost effective. However all key structures should be designed to survive the design earthquake loads as per the Structural Design Actions code AS/NZS:1170;

vii. Setback distances from relic slips and steep slopes are recommended. Most of the risks due to instability can be avoided by locating the pipeline on the opposite side of the road to the slope / head scarp;

viii. Most of the Road Route K pipeline along the expressway has high potential risks for ongoing settlement and liquefaction during both 1 in 500 year and 1 in 2500 year events;

ix. Some sections of the pipeline routes crossing existing streams / wetlands with shallow groundwater levels will have to be constructed either on bridges, with piled supports, or by directional drilling to minimise settlement and floatation associated risks.

5.4 Structural Assessment

The technical feasibility of five potential pipe bridge crossings of the Tauranga harbour for the Southern Pipeline project have been assessed in the Harbour Crossing Options Report (January 2006). In summary these crossings are:

For Central Route A:-

a) Existing Maungatapu – Matapihi road bridge on State Highway 2 / 29;

b) New pipe bridge adjacent to the existing Maungatapu – Matapihi road bridge; and

For Western Route E and Road Route K:-


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c) Existing Tauranga railway bridge;

d) New pipe bridge immediately adjacent to or near the existing railway bridge.

Copies of construction drawings for both of the existing bridges were obtained in order to assess structural adequacy. Data obtained from the geotechnical investigations was also applied and walkover inspections of both existing bridges were undertaken to assess the existing bridge conditions.

On the basis of the assessment to date, the structural report recommends that neither the existing road nor rail bridge be used for the pipeline because:

i. The existing harbour structures (being the OnTrack rail bridge and Matapihi – Maungatapu SH2/29 bridge) have serious limiting structural loading and foundation issues;

ii. The structures will not safely support the pipe under moderate seismic shaking;

iii. Both structures are founded on materials subject to seismic liquefaction;

iv. Both structures have a limited lifespan considerably less than the required 100 year lifespan required for the Southern Pipeline.

All new pipe bridge options are technically feasible and practicable.

5.5 Ecological Assessment

Preliminary ecological assessments of the potential pipeline routes were carried out by Bioresearches and URS, with the main purpose being to identify any fatal flaws that may arise as a result of significant ecological features. The assessments were carried out on the basis of the potential pipeline routes as at 8 December 2005.

The ecological assessment comprised two stages. The first stage involved a desktop assessment of available information and the second stage consisted of walk over visits to key sections of the potential pipeline routes. The desk study and site visits considered marine, freshwater and terrestrial ecology. A final report was produced to cover the results of both stages of the ecological assessment, the Pipeline Route Fatal Flaw Ecological Assessment (March 2006).

The assessment concluded that while there is no immediate fatal flaw to any of the routes as a result of ecological features, there are several areas of high ecological value that would need to be considered thoroughly and carefully in deciding on the final route and planning the details of pipeline construction.

The main ecological features present along the route and which require particular consideration are:

• Wetland at Waimapu Estuary (Central Route A and Eastern Route B);

• Wetland at Tip Lane (all main routes);

• Wetland at Te Maunga Causeway (Central Route A, Western Route E and Road Route K);


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• Wetland at Waipuna Park (Eastern Route B).

The ecological report identifies several other areas which require further ecological investigation and planning, depending on final route selection. These include various stream crossings and areas of coastline where works could occur.

The report is clear that in all cases the effects on significant ecological areas can be avoided, minimised or managed such that the potential for any fatal flaw to be encountered can be reduced to a minimum.

The proposed alignment at the eastern most end of Central Route A, Western Route E and Road Route K (near the Te Maunga WWTP) has been amended since the earlier phase of work in order to remain within the existing TCC wastewater designation and to avoid the Coastal Habitat Preservation Zone adjacent to the Te Maunga ponds.

Further investigations of the significant ecological areas would need to be undertaken as appropriate for the preferred route, to determine in detail the extent of ecological value present and assist in the identification of appropriate strategies to avoid or minimise effects.

5.6 Archaeological Assessment

A preliminary archaeological assessment of the potential pipeline routes was conducted during December 2005 by archaeologist Ken Phillips. The assessment was largely a desk-top study for this phase of the project, although a visit to the Tuikairangi Block was carried in order to conduct a specific assessment of two archaeological sites in that area. The findings were presented in the Preliminary Archaeological Assessment Route Options report (March 2006).

The archaeological assessment confirms that there are numerous recorded archaeological sites within 100 metres of the proposed pipeline routes, but that none of these recorded sites are likely to be directly affected by any of the main routes.

There are however a number of sites that have the potential to be affected (depending on the extent of land required for construction, or any alignment change) and there is significant potential to encounter unrecorded buried archaeological features on all routes.

There is no information at present to suggest that any of the archaeological features that are known, or which may be encountered, would present a fatal flaw for any of the pipeline routes.

Sections of the route options most likely to impact on unrecorded buried subsurface archaeological sites are located where route options pass through existing or historical harbour margins. The nature of the ground disturbance means that features (such as middens, crop storage pits, artefacts and defensive features) will primarily be exposed in section in a trench. This will limit mitigation to the recording of archaeological stratigraphy and sampling and analysis of archaeological deposits. Where larger areas of ground disturbance are proposed, such as pump station installations, there may be opportunities for monitoring and prior investigation of any identified archaeology.


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If the final preferred route passes through the Tuikairangi Block, prior archaeological investigation and monitoring throughout the work is recommended.

Encountering human remains is likely to be the most significant archaeological issue associated with the pipeline construction. While the archaeological investigation and relocation of human remains can be covered by an Authority under the Historic Places Act (HPA), specific protocols will need to be agreed prior to construction in the event that unrecorded archaeological features or sites are encountered during ground disturbance.

The precise ways in which the archaeological effects will be addressed will be determined during any Resource Management Act (RMA) or HPA approval process.

5.7 Air Quality

A site visit was carried out by an air quality specialist from URS to review the proposed locations of structures such as pumping station and receiving chambers that have a high potential to generate odour, and the results of the air quality assessment were provided in a URS memorandum (January 2006).

No fatal flaws from an air quality / effects point of view for any of the preliminary route options were identified. However, particular consideration will need to be taken in the development of the alignment and design to ensure that potential for odour nuisance from pump stations and receiving chambers is minimised and meets the requirements of the operative Bay of Plenty Regional Air Plan.

Based on the current route alignments, particular locations requiring further consideration of potential odour generation and options to avoid or minimise nuisance effects include:-

• Stephens Place receiving chamber (Central Route A);

• Waitaha and Kaitemako Road pumping stations (Eastern Route B);

• Oropi Road receiving chamber (Western Route E).

If provisions of the Regional Plan cannot be met, a resource consent would be required.

5.8 Traffic

A preliminary transportation and traffic management assessment of the potential pipeline routes has been carried out by Traffic Design Group. The main objectives of the assessment were to identify any possible fatal flaws on the routes, the level of traffic disruption expected with each route and whether mitigation measures available will minimise effects to an acceptable level. The assessment carried out has considered many route alternatives and is principally based on the following routes:

• Central Route A;

• Eastern Route B;


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• Western Route E; and

• Road Route K.

Parts of Routes A, B and K run along the State Highway corridors. Route E runs entirely within TCC land but includes a crossing of SH2 at Fifteenth Avenue and a crossing of SH2 / 29 at the northern end of the route near Te Maunga.

The following outlines the critical transportation issues:

1) Sections of construction taking place within State Highway corridors or running parallel to State highway have the following characteristics:

• Adequate work space exists but due to the high regional importance of the State highway links any unforseen events and delays have the potential to create unacceptable traffic delays and congestion; and

• Further, due to the high speed environment any potential crashes have a higher potential to cause injury.

2) Transit’s future plans at the Hairini roundabout include construction of a grade separated interchange. Transit has indicated that it will require relocation of the sewer at TCC cost if it is placed in a location which affects the intersection upgrade.

3) Welcome Bay Road geographical constraints could result in full road closure at some locations. This is expected to result in significant traffic disruption and re- routing via the state highway network.

4) Local road disruption to residents, schools and businesses is expected on the local arterial routes. These effects are however manageable. They may require some night work or weekend work to avoid peak period delays. Alternative routes are accessibly convenient and suitable for the relatively short period of disruption.

The above outlines some of the issues which have been assessed for each route. The assessments conclude that while there are no immediate fatal flaws to any of the routes as a result of transportation issues, there are several critical features that would need to be considered thoroughly and carefully in deciding on the final route and planning of the details of the pipeline construction. These include individual driveway crossings, intersection crossings and arterial route peak period flow management. These specific matters are described in the transportation assessment and are able to be satisfactorily mitigated by careful management and planning for transportation and access.


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