June 4 2019 Kathy Murtagh Director Tunnel Redundancy 2 Pressure AqueductTunnel System 1939 1976 Weston Aqueduct Cochituate Aqueduct Sudbury Aqueduct Sudbury Reservoir Chestnut Hill ID: 1018932
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1. Metropolitan Tunnel Redundancy Program UpdateJune 4, 2019Kathy MurtaghDirector, Tunnel Redundancy
2. 2Pressure Aqueduct/Tunnel System (1939- 1976)WestonAqueductCochituateAqueductSudburyAqueductSudburyReservoirChestnutHillReservoirQuabbinReservoirCityTunnelCityTunnelExtensionDorchesterTunnelWachusettReservoirChicopeeValleyAqueductCarrol WTPQuabbin AqueductCosgrove TunnelHultman AqueductMetropolitan Tunnel SystemChicopee Valley Aqueduct
3. 3MetroWest Water Supply Tunnel (2003)WestonAqueductCochituateAqueductSudburyAqueductSudburyReservoirChestnutHillReservoirQuabbin AqueductQuabbinReservoirHultmanAqueductCityTunnelCityTunnelExtensionDorchesterTunnelWachusettReservoirWachusettAqueductCosgroveTunnelChicopeeValleyAqueduct17.6 mile, 12 to 14 foot diameter, deep rock pressure tunnel was brought on-line in November 2003Provides Redundancy to the Hultman AqueductCarrol WTPMetroWestTunnel
4. 4Metropolitan Tunnel SystemCarroll Water Treatment PlantDorchester TunnelShaft 7City Tunnel ExtensionCity TunnelShaft 5/5ANo Redundancy East of Shaft 5Norumbega Tank
5. 5Condition of the Metropolitan Tunnel SystemTunnel system:Concrete-lined deep rock pressure tunnelsSteel and concrete lined vertical shaftsSurface pipe, valves and appurtenancesLittle maintenance required for tunnels and shafts. Little risk of failurePipe, valves and appurtenances need maintenance, rehabilitation, replacement
6. 6Valve Reliability ConcernValves that don’t workValves we can’t operateShaft 8 PRV ChamberShaft 8Shaft 8
7. 7The Great Water Main Break of May 2010Small pipe failures can lead to big problems< 1”250 MGD flow at Shaft 5 break….…came from a small gap in the pipe
8. 8Economic Impact of Water Supply LossThe estimated economic loss of water supply within the Boston Metropolitan area is: ~$208 million per day to businesses ~$102 million per day residents total economic impact of ~ $310 M per dayIf we do nothing, another failure will eventually occurWe Need Redundancy!
9. 9Recommended AlternativeTwo TunnelsTunnels begin at Mass Pike/Route 128Northern Tunnel - 4.5 miles, connects to mid-point of WASM 3 in Waltham/Belmont areaSouthern Tunnel - 9.5 miles, connects to Shaft 7C and southern surface mains10’ finished diameter pressure tunnel200’ – 500’ deep (rock)Mined using TBMsNumber and locations of shafts TBDNo consent decree (this is a water distribution redundancy program)WASM 3Proposed 10-ft Northern TunnelProposed 10-ft Southern TunnelSouthern Spine Surface Mains
10. 10Hydraulic Objectives for Proposed TunnelProvides redundancy for entire metropolitan tunnel systemProvides normal water service and fire protection if existing tunnel system is out of serviceDesigned to meet high day demand. No seasonal restrictionsProvides ability to perform maintenance on existing tunnels year-roundAvoids activation of emergency reservoirsNo boil order!WASM 3Proposed 10-ft Northern TunnelProposed 10-ft Southern TunnelSouthern Spine Surface Mains
11. 11Project CostsMidpoint of construction – Northern Tunnel: $472 million Midpoint of construction – Southern Tunnel: $1,003 million Midpoint of construction – both tunnels is $1,475 millionEstimated time to completion of 17 – 23 years 30% contingency and 4% annual construction cost escalation
12. 12Metropolitan Tunnel Redundancy Program OutlookThe Program is managed by the MWRA Tunnel Redundancy Department (similar to PMD for BHP)The Program is funded in our Capital Improvement PlanDRAFT FY20 CIP Budget includes….Program-Wide Support Services Preliminary Design/Phase 1 Geotech/MEPA ReviewFinal Design(s)Construction Management(s)Tunnel ConstructionsSurface Connections ConstructionsAdministration, Legal and Public Outreach
13. 13Program Organization
14. 14Preliminary Design EngineeringPreliminary geotechnical investigation, route and shaft site evaluations, identify environmental permits needed and prepare required MEPA review Produce significant project documentsPreliminary Geotechnical Data & Design Report Environmental Impact ReportsAlternatives Evaluation & Preliminary Design ReportPreliminary Design DrawingsIt is expected this work can be accomplished within 3 – 3.5 years
15. 15Planned ScheduleProgram Support ServicesAwarded in March 2019Preliminary Design/Phase 1 Geotech/MEPA ReviewIssue RFQ: Summer/Fall 2019Notice to Proceed: first half of 2020Estimate Completed: late 2023 Final DesignStart 2024-ishConstructionStart 2027-ish (D-B-B)
16. 16The Metropolitan Tunnel Redundancy ProgramThank You!