Professional Services
Awarded to:
GHD, Inc.
Awarded Amount:

Design Services for the CSO Bypass and Disinfection

Project number : S-466
Description :

The Allegheny County Sanitary Authority (ALCOSAN) is soliciting Letters of Interest and Statements of Qualifications from Professional Engineering firms interested in providing Design Services for design of the CSO Bypass and Disinfection Project at its Woods Run Wastewater Treatment Plant.  

This plant expansion design package includes, but is not limited to, following general tasks: 

  • A passive CSO-related bypass flow control structure (to divert up to 305 MGD of primary effluent) consisting of overflow weirs in the primary effluent channel and an overflow channel directly parallel to the primary effluent channel.
  • A single influent conduit connecting the overflow channel (from CSO-related bypasses flow control structure) to the current effluent side of the existing chlorine contact tanks.
  • Modifications to the existing chlorine contact tanks, with interface to the CSO-related bypass flow control structure and tank improvements including: addition of an influent chamber housing air diffusers for sodium hypochlorite mixing, overflow weirs on the effluent side for water level control, and air diffusers in the effluent for sodium bisulfite mixing.  The proposed modifications will reverse the current direction of flow within the tanks.
  • A new building, located where the Maintenance Storage Building (850) and Carpenter Shop (880) are currently situated, will be provided to house sodium hypochlorite storage, feed equipment, and defoamer solution storage 
  • New outfall (Outfall – 002) to Ohio River will be constructed adjacent to the Bypass Disinfection Tank.