Owner
Allegheny County Sanitary Authority
Client
J. F. Shea
Cost
$4.5 billion USD
Timeframe
May 2025
— December 2036
Services performed
Optimization of the rock support design of the tunnel junction chamber between the new ‘Wet Weather Pump Station (WWPS) shaft’ and the new ‘Ohio River Tunnel (ORT)’.
Description
The Allegheny County Sanitary Authority (ALCOSAN) Clean Water Plan will reduce the amount of combined sewage overflow by 7 billion gallons per year and eliminate sanitary sewage overflows. The plan involves four major components including the Plant Expansion Program and a new constructed regional tunnel system. The tunnel system itself is split into three major phases starting with the 4.9 miles long Ohio River Tunnel (ORT). The Plant Expansion Program includes a new Wet Weather Pump Station (WWPS) shaft. Dr. Sauer and Partners carries out optimization of the tunnel junction chamber which connects the new WWPS shaft to the new ORT.
Geology
Shale, Siltstone and Claystone.
Location
Pittsburgh, PA, USA
Highlights
- Optimization of rock support design involving steel sets and timbering
- Design of rock support including rock bolts, mesh and shotcrete
- Combined sewer overflow (CSO) tunnels
Proposed Regional Tunnel System (image courtesy of ALCOSAN)
Junction Chamber Rock Support Cross-section