Central Interceptor Project Australian Tunnelling Conference

12 October 2016presented byDavid Ward

Agenda1. Watercare Services Limited2. The History of Auckland’s drainage3. Why Central Interceptor?4. Project extents5. Ground investigations6. Consenting Framework / Land Ownership 7. Safety in Design 8. Hydraulic Analysis9. Pump Station10.Tunnel & Shafts11.Risks 12.Construction delivery13.Current status14. Next steps

Watercare – Who we are

• Auckland’s water and wastewater service provider

• Council-controlled organisation since 2010

• Serve 1.4 million Aucklanders

• Deliver 326 million litres of water daily

• Treat 400 million litres of wastewater daily

• ~900 staff

Watercare – Where we operate

• Head office in Newmarket

• 5 operational hubs

• 1 laboratory

• Assets include:

• 33 water/wastewater treatment plants

• 16,800 kilometres of water/wastewater pipes

• 90 water reservoirs

• 584 water/wastewater pump stations

• 164,000 manholes

Our legal requirements

• Required by law to keep costs of water supply and wastewater services to its customers (collectively) at minimum levels

• Self-funding through water and wastewater charges and infrastructure growth charges

• Prevented by law from paying a dividend to Auckland Council

• All revenue is used to fund our existing operations / develop new infrastructure

• Required by law to give effect to Auckland Council’s plans

Our journey towards customer centricity: 2010 -2016

Watercare is on a transformational journey towards customer centricity. • In November 2010, we became responsible for the end-to-end provision of services including managing relationships with

around 423,000 customers and 1.4 million Aucklanders.

• Since then, we have been working to standardise the way we transact with and charge our bill payers.

• We have also been working to deliver to our service users ‘Aa’-grade water that meets Drinking Water Standards for New Zealand.

• Watercare’s strategic framework, launched in April 2015, aims to ensure we remain focused on our customers going forward.

Watercare Strategic Framework

Watercare – Health and Safety

• Believe we can be a Zero Harm organisation

• Pursue highest practicable standards and competencies

• Use of Lead indicators

• New H&S management and reporting system

• Applying lessons learnt

• Specify requirements so common baseline, not an advantage

• Significant investment in Watercare staff

Watercare – Financial facts

Watercare’s Asset Management Plan

Capital Expenditure Forecast ($ billion – nominal)

Customer Charges

IGCs

Borrowing

Growth

Level of service

Renewals

2017 to 2026 2027 to 2036

Water $1.9 $2.8

Wastewater $2.8 $3.1

Shared services $0.2 $0.2

TOTAL $4.9 $6.1

History of Auckland’s drainage

• Combined sewer network built between 1914 to 1930

• Expanded in the 1950s

• Some assets still in good condition due to flushing and dilute sewage

• Planned capacity to meet future population growth

Why Central Interceptor

The Drivers

Duplicating an aging asset

Catering for growth

Reducing overflows

video

Staying ahead of population growth

The wastewater system today

Clarks Beach WWTP

Waiuku WWTP

Kingseat WWTP

Kingseat

Clarks Beach

Waiuku

Mangere WWTP

Sou

th W

este

rn

Western

Eastern

Ho

wic

k

Sou

ther

n

Tam

aki E

ast

Orakei

Pukekohe WWTP

Rosedale WWTPKumeu

Huapai Riverhead

West Auckland

South West Auckland

South Auckland

East Tamaki

South East Auckland

Pukekohe

Central Auckland

East Auckland

North Shore

Warkworth

Warkworth WWTP

Snells Algies WWTP

Waiwera WWTP

Army Bay WWTP

Snells/Algies

Waiwera

Hibiscus Coast

The wastewater system 2017 to 2036

South West Sub-Regional

WWTP

Clarks Beach

Kingseat

Waiuku

Pukekohe WWTP

Pukekohe

Mangere WWTP

Rosedale WWTP

Sou

th

Wes

tern

Western

Eastern

Ho

wic

k

Sou

ther

n

Tam

aki E

ast

Orakei

Howick Diversion

Northern

Waterfront

Hillsborough Tunnel and Manukau Siphon

Southern Diversions

Kumeu Huapai

Riverhead

West Auckland

South West Auckland

South Auckland

East Tamaki

South East Auckland

East Auckland

North Shore

Central Auckland

Warkworth

North East Sub-Regional

WWTP

Army Bay WWTP

Snells/Algies

Waiwera

Hibiscus Coast

Duplication of aging assets• The Western Interceptor was

constructed in late 1950s under the Manukau Harbour

• Precast pipes laid in a shallow trench on the sea floor

• Prone to shipping mishaps

• In suspected poor condition

Central Interceptor – Key elements• Main Tunnel

• Link Sewers

• Pump Station

• Emergency Pressure Relief (EPR)

• Drop Shafts (16 sites)

• Air Treatment Facilities

• Vents

• Actuated control gates and related systems

• Surface and subsurface structures (grit traps, weir, control chambers, equipment room, electrical panels, communication aerial)

• Connecting pipes

• Enabling Works (e.g. Roma Road)

• Demolition

• Reinstatement

• Future proofing connections

• 100 year design life

NB: Consented drawings are publicly available.

Main tunnel and associated works

• Deep sewer tunnel between Western Springs and Mangere WWTP

• Gravity flow to terminal Pump Station at Mangere WWTP

• Approx. 13km long

• Up to 110m below ground

• Internal diameter is 4.5m

• horizontal and vertical consent limits

• Approx. 4.4km of connected Link Sewer

• NB Collector Sewers is under a separate project

Main tunnel long section

Main tunnel shaftsName Hydraulic

Internal Diameter

Invert Depth

Notes

Western Springs 12m 26m Tunnel work shaft

Mt Albert 4.5m 37m Off-line drop

Lyon Ave 8.5m 44m

Haverstock Rd 8.5m 49m

Walmsley Park 3m 66m Drilled shaft

May Rd 7.25m & 12m* 69m 2 shafts (drop & tunnel work shaft*)

Keith Hay Park 3m 78m Drilled shaft

PS23 4.5m 27m

Kiwi Esplanade 4.5m 28m

Mangere Pump Station n.a. 31m Dual cell D-wall shaft

Link Sewers

• Link Sewer (LS 1) – LS A No longer required

• Link Sewer (LS 2) – LS B Tunnel between Rawalpindi Reserve and Main Tunnel at Mt Albert. approx1.1km long, up to 37m deep

• Link Sewer (LS3) – LS C Tunnel between existing Pump Station 25 and Main Tunnel at May Rd. approx3.2km long, up to 85m deep

• Link Sewer (LS4) – LS D No long required

Link sewer drives

Link Sewer

Form/to Shaft Name

Sewer diameter

Drivelength

MaximumHydrostatic head

Link B Rawalpindi Reserve to NorgroveAve

2.4m 308m 12m

Link B Norgrove Ave to MAWM 2.4m 797m 20m

Link C PS25 to Miranda Ave 2.1m 332m 10m

Link C Miranda Ave to Whitney Ave 2.1m 612m 22m

Link C Whitney Ave to Dundale Ave 2.1m 583m 29m

Link C Dundale Ave to Haycock Ave 2.1m 722m 33m

Link C Haycock Ave to May Rd 2.1m 966m 56m

Link sewer shafts

Name Hydraulic ID Invert Depth

Notes

Rawalpindi Reserve 5.75m 26m Link B

Norgrove Ave 4.5m 28m Link B

PS25 4.5m 12m Link C

Miranda Ave 4.5m 12m Link C

Whitney Ave n.a. 33m Link C work shaft, backfilled

Dundale Ave n.a. 25m Link C work shaft, future access shaft

Haycock Ave 5.75m 31m Link C

Planned changes from concept (AEE) design

• Alignment:

– Tunnel alignment at Mt Albert War Memorial to accommodate Link Sewer B

– May Road for potential staged construction

– Avoiding St Lukes interchange

– Link Sewer B is now deeper to accommodate flows from CC1

• General site layout – control chamber and other underground construction

• Potential reuse of Manukau Siphon

• Cascade instead of vortex – reduces number of shafts

Other associated scope• H&S and Mining Regulations

• Complying to RMA (Consent Conditions, Designations, Heritage NZ)

• 12 Management Plans as required by the Resource Consents

• Building Survey and Groundwater Monitoring

• Procurement

• Traffic Control

• Identify / confirm underground services

• Community Engagement

• Interface with Mangere WWTP

• Monitoring and Reporting

• BIM

• Operations and Maintenance Manual

• Commissioning and Decommissioning

• Training and Hand Over

• As Built and Asset Register

Ground investigations

• Pre-Central Interceptor investigations (by others)

– Available through Auckland Geotechnical Database – some 500 data points

– 3D Vulcan model built and populated with data from investigations and historic data

• Concept Design:

– 36 land based boreholes, 25 still relevant

• Preliminary Design - Phase 1:

Status – completed 2015

– 94 land based boreholes up to 90m deep

– 24 marine based boreholes up to 45m deep

• Preliminary Design - Phase 2:

Status – completed early 2016

– 26 rotary cored boreholes at shaft sites

– 19 rotary cored holes to check rock interfaces in Chamberlain Park

Other ground investigations

• Geophysics

‒ Acoustic and optical televiewer, gamma

• In situ testing

‒ 76 CPTs, 50 trial pits, 56 hand augers, 32 scala penetrometer tests

‒ Seismic dilatometer tests

‒ Fracture tests

‒ Pressure-meter and lugeon testing

• Lab testing – Soil and Rock Testing

• Contaminated soil sampling and testing

• Long term monitoring

Equipment installed.

‒ 29 vibrating wire piezometer installations with data-loggers

‒ 47 standpipes for dip sampling

Geotechnical overview• Extensive ground investigation

• Providing a Geotechnical Baseline Report (GBR)

• Key risks:

– Basalt interface with alluvium

– Manukau Harbour crossing

– Mixed-face conditions, particularly at Mangere and Western Springs paleo-valleys

– Potential obstructions

– Handling of sticky ECBF spoil

• Few conflicts with near surface utilities or building foundations

Geological long section

Consent overview

Central Interceptor Main Works• Central Interceptor main tunnel and four link sewers

• 19 surface construction sites

• Mangere Pump Station and Emergency Pressure Relief discharge

• Other associated physical works

Combined Sewer Overflow (CSO) Collector Sewers• 8 CSO Collector Sewers

• Multiple surface construction sites (only 6 designated)

• Other associated physical works

Network Discharge Consent for Central Interceptor Catchment Area• Overflow discharges in Central Interceptor catchment area

Land ownership details at shaft sites

3 TBM launch/retrieval sites:• Mangere WWTP (Watercare)• May Road (Watercare)• Western Springs (non-Watercare)

7 Access and Drop Shaft sites:• Kiwi Esplanade (Park)• PS 23 (Watercare)• Keith Hay (Watercare and Park)• Walmsley (Park)• Haverstock (Crown land)• Lyon Ave (Ministry of Education)• Mt Albert War Memorial (Park)

7 Link Sewer Drop Shaft sites:• Haycock Ave (Watercare)• 6 Others (Park)

Safety in design

• ‘No Operators to enter tunnel’ aspiration incorporated into design

• NZ mining regulations incorporated into design

• Worksafe involvement

• Safety in Design Workshops

• HAZOP / CHAZOP Workshops

NZ tunnelling regulations

• cf Queensland Regulations

• Defined Roles

• PHMPs / PCPs / ACoP

• Safe egress

• Broad Brush Risk Assessments

Hydraulic analysis – Physical modellingCascade drop shafts

• Watercare worked with University of Auckland Fluids Laboratory

• Cascade drop shaft modelling complete

Hydraulic analysis – Physical modellingPump station wet well

Modelled the following conditions in Singapore at Nanyang Technological Uni:

• High level

• Low level

• Sediment buildup

• Floatables

Conclusion:

• Layout is suitable for reducing sediment build-up, swirl & vortices

• Baffle wall to be raised

• Chamfers to be added or increased in corners

Control philosophy

• Real Time Control strategy focused on avoiding tunnel over filling

• Fifteen actuated slide gates ranging up to 2.4m in width

• Hydraulic power packs for fail-safe operation

• Gate closure triggered by water level in Mangere Pumping Station wet well

• Other manually operated gates to divert flows and provide safe isolation

Mangere Pump Station

• Live connection to Mangere WWTP

• Emergency Pressure Relief

• Future proof spacing

• Standby generation provision

Mangere Pump Station

• Dual cell to facilitate concurrent construction of pumping station and tunnel

• Approx. 36m deep

• Inlet chamber 12m dia ID

• 6 pumps (total 7.2m3/s)

• D-Wall construction

• Dry and Wet Well 26m dia ID

• Tunnel/pump station construction isolation (WorkSafe)

Mangere Pump Station

Mangere Pump Station

Use of BIM for design

Tunnel segmental lining

• One-pass precast segmental lining with gaskets

• 300mm thick, corrosion resistant

• Dowel and guide rod connections (no bolts)

• 20% alignment rebar reinforcement, 80% steel fibres

Shafts• Excavation and temporary support design

– D-wall specified and designed for pump station

– All other shafts by Contractor, within consent requirements (indicative designs provided)

– Various excavation & support methods in basalt, ECBF, and soft-ground (alluvium)

• Permanent design specified

– Cascade baffle drops

– Dividing wall for future manned access

– Lining

Spoil removal• Approx. 400,000m3 loose volume of

spoil anticipated

• Investigating reuse potential at Watercare sites

• Contractor to provide alternatives

Identified risks

• Ensuring full compliance with tunelling regulations

• Meeting stakeholder and community expectations

• Unforeseen ground conditions*

• Safety during construction and operation

• Tie-ins to live sewer systems

• Competing use of park sites

• Impact on properties above tunnel

• Limited working areas with extensive RMA constraints

* see next slide

Ground conditions risk mitigation• Investigations – Lessons learnt, Field Survey,

Geotechnical, Groundwater monitoring

• Design & Specification – avoid difficult strata, TBM specification to handle conditions

• Construction method statements, TARPs

• Pre & post monitoring – settlement, vibration, correlated to TBM advance, as-builts

• Contracting Strategy, GBR

Watercare’s objectives

• Ensuring full compliance with tunelling regulations

• Safety in construction and operation

• Meet key drivers in timely manner

• Compliant to consent conditions

• Careful management of costs and suppliers

• Consistent approach to stakeholder engagement, management and communication

• Sustainable outcome through accountability and innovation

Proposed procurement strategy• Project fully funded by Watercare

• One lead contractor to deliver the project

• Design - Bid - Build, except for proprietary equipment

• Alternative designs will be considered (as appropriate)

• All temporary works will be the responsibility of the contractor (includes design); TBM segment design

• Traditionally, Three-Stage Tender Process:

– EOI (Expression of Interest)

– Pre-qualification

– RFT (Request for Tender)

• Form of Contract TBD

• Evaluation criteria TBD

Proposed procurement strategy cont.

• All construction materials and the majority of vendor-engineered equipment are to be procured and installed by the Contractor

• Pump sets, VSDs, gates and control systems will receive special consideration

• Insurances

Planned construction start

• Calendar year 2018

• Staging of construction and commissioning

• Timing of other regional projects

The information in this presentation represents Watercare’sthinking to date. It is given in good faith but is not to be relied on inany way in any future contractual arrangements.The information is subject to updating and amendment and finalapproval from Watercare’s Board

Stage 2

Stage 1

Proposed programme

Activity Tentative Date – Calendar Year

Expression Of Interest / Pre-Qualification Q4 2016 – Q2 2017

Tender Period Q3 - Q4 2017

Contract Award Q2 2018

The information in this presentation represents Watercare’s thinking to date. It is given in good faith but is not to be relied on inany way in any future contractual arrangements.The information is subject to updating and amendment and final approval from Watercare’s Board

Current status• RMA Consents obtained / appeals resolved / consent

conditions being executed

• Land purchases & agreements to occupy / property owner approvals in progress

• Stakeholder Engagement Strategy being implemented

• Detailed Design substantially complete

Next steps

• Complete Detailed Design

• Commence procurement activities and industry engagement

• Further Geotechnical Investigation to inform the GBR

• Finalise materials selection

• Complete landowner approvals