Combined Sewer Overflow Storage Tunnel
A deep storage tunnel and two shafts that will capture combined sewer overflows before they reach the river.
- Owner
- Confidential
- Region
- U.S. Mid-Atlantic & Northeast
- Market
- Water & Wastewater
- Capital value
- $890M
- Size
- 3.1-mile tunnel · 2 shafts
- Delivery
- Design-Build
- Duration
- 60 months
- Status
- In progress · 2028
What is at stake.
Tunnel boring progress varies with ground conditions, and the baseline assumed the best ground the whole way. Shaft excavation, machine assembly and the river cleanup milestones in the permit all depend on that rate. The owner needed honest production forecasting and an early view of any claim exposure.
How we control it.
What our schedulers and cost engineers are doing on this project.
Production tracking
Daily ring counts and advance rates are compared to the baseline by geologic reach, so slow ground shows up as days, not excuses.
Risk by reach
Monte Carlo analysis models advance rates by ground type, giving P50 and P80 dates for hole-through and substantial completion.
Earned value
A cost-loaded schedule tracks SPI and CPI monthly, separating ground-related variance from performance variance.
Claims readiness
Contemporaneous records and windows analysis are kept current, so any differing site condition claim can be answered on facts.
Where it stands.
A tunnel does not slip all at once. It slips a few feet a day, and you only see it if you count every ring.
Senior scheduler, AdenTurton
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