david ward - watercare services ltd
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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
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