River Wall Construction Complete

Dec 7, 2021, 11:12 AM

Our North End Plant Expansion (NEPE) construction project has been underway for over a year. Significant progress has been made since construction began in fall 2020. The NEPE includes the addition of two new circular final clarifiers, a new chlorine contact tank, a new chemical storage building and a new outfall that will discharge the daily plant-treated flows into the Ohio River. The NEPE project is critical to meeting our consent decree requirement of increasing our secondary treatment capacity from 250 million gallons per day (MGD) to 295 MGD by 2025.

The ALCOSAN plant is landlocked at its north end. There is minimal space for expansion between the railroad to the east and the Ohio River to the west. To create the real estate needed to build the two new clarifiers and the new chlorine contact tank, a river wall was needed. Construction of this river wall expanded into the river. Appropriate joint permit approval of this design had to be closely coordinated with Pennsylvania Department of Environmental Protection (PADEP) and US Army Corps of Engineers (USACE).

The river wall itself is an impressive structure that spans greater than 1,000 linear feet. It consists of 108 king piles interlocked with sheet piles. Each king pile measures from 60 to 72 inches in diameter. River wall construction began in early summer 2021 and the last king pile was installed the first week of November.

North End River Wall Update

River wall tieback installation is the only remaining portion of ALCOSAN’s North End Plant Expansion construction to be completed. Tiebacks will hold the river wall in place once the construction site is returned to final grade in a few years.


Looking at ALCOSAN’S North End Plant Expansion (NEPE) site from the McKees Rocks Bridge, one will notice a wall along the railroad. The railroad requires support of their property and tracks, and this temporary wall provides that support during construction.

Railroad Support Wall
New Outfall Location

View of the future outfall between king piles 14 and 15.