ALCOSAN Releases Report to Advance Source Control and Green Stormwater Infrastructure

Controlling the Source provides municipalities information to effectively reduce sewer overflows

Jul 21, 2020, 1:38 PM

Pittsburgh and Allegheny County have a wide variety of terrain and sometimes an even wider ownership structure for sewer infrastructure and property. Often, for municipalities, these can make finding impactful source control projects difficult. Today, the Allegheny County Sanitary Authority (ALCOSAN) addresses this problem with the release of Controlling the Source (CtS), a scientific-based framework to identify where municipalities can implement the most cost-effective projects to reduce wet weather sewer overflows.

“We are very excited about CtS and know it will be key in further reducing sewer overflows and meeting the goals of our Clean Water Plan,” said Timothy Prevost, ALCOSAN’s Manager of Wet Weather Projects. “CtS provides us another opportunity to work very closely with our partner municipalities. Along with the guidance documents we provided last year, municipalities now have a full playbook for planning source control projects that could be further supported by our Green Revitalization of Our Waterways (GROW) program.”

Controlling the Source addresses the four most common source control strategies – green stormwater infrastructure (GSI), direct stream inflow removal (DSIR), infiltration and inflow (I/I) reduction and sewer separation (SS).

The six-step process considers factors such as physical constraints, projects previously identified by ALCOSAN and others, inflow and overflow reduction, overflow reduction efficiencies, and costs. This process has been adapted to each of the four source control methods, resulting in the identification of nearly 200 potential GSI opportunities, 44 new DSIR locations, 100 new potential SS areas, and various I/I reduction opportunities. Several of these opportunities have accompanying concept plans and can be accessed through a new interactive web portal.

Future updates of CtS will allow stakeholders to consider the impact of the implementation of other elements of ALCOSAN’s Clean Water Plan on the potential overflow reduction benefits associated with source control opportunities.

In 2019, ALCOSAN provided municipalities with a guidance manual to support GSI implementation within their communities. The manual outlines best practices and provides guidance related to GSI siting; selection and sizing; cost estimating; construction inspection; and operations and maintenance. An accompanying manual on monitoring all types of source control was also provided.

The GROW program was created in 2016 and, in the first four funding cycles, over $28 million in grants have been awarded for 101 projects that will remove approximately 140 million gallons of overflow.

Controlling the Source can be found on ALCOSAN’s website at