On May 15, 2020 in Pittsburgh, Pennsylvania, the Allegheny County Sanitary Authority (ALCOSAN) cleared the final hurdle in its plan to correct the engineering mistakes of the past in order to restore the area’s streams and rivers.
For the past century—as with most other major U.S. cities—engineers directed stormwater into the local sewage system. This frequently overwhelms the sewage treatment plants, forcing raw sewage into the rivers; a process referred to as combined sewage overflow (CSO). It will cost $2 billion, but these mistakes are finally about to be undone.
This is the single most important factor in restoring the city’s three rivers. One of which is the Potomac, which supplies the drinking water for most Washington, DC area residents, who will be happy to stop drinking the barely-treated outflow of Pittsburgh toilets.
The approval for this work occurred when ALCOSAN’s Modified Consent Decree with the United States Department of Justice, the United States Environmental Protection Agency (EPA), the Pennsylvania Department of Environmental Protection (DEP), and the Allegheny County Health Department has been approved by the United States District Court for the Western District of Pennsylvania.
“This is the end of a very long, educational and exciting road,” said ALCOSAN Executive Director Arletta Scott Williams.
“I’m pleased that the court and the plaintiffs agreed with our approach for improving the water quality of our rivers and streams, and we are all excited to continue forward with that important goal,” she added.
The Modified Consent Decree (1) allows ALCOSAN to continue forward with its Clean Water Plan, a blueprint for reducing seven billion gallons of overflows from flowing into local rivers and streams, (2) extends time frames in which ALCOSAN must implement its Clean Water Plan, and (3) allows ALCOSAN to propose future amendments to the Clean Water Plan, which might include replacing some proposed control technologies with green infrastructure controls.
To reach the Consent Decree goals, the Clean Water Plan will focus on four key areas:
- Preventing excess water from entering the sewer system This involves use of the latest technology including green infrastructure such as bioswales and rain gardens; lining and repairing pipes to prevent groundwater from seeping into the system; diverting clean streams so they do not flow directly into sewers; and sewer separation projects. To advance this effort, ALCOSAN established Green Revitalization of Our Waterways (GROW), a multi-year, multi-million-dollar grant program that funds projects that municipalities and sewer authorities might not be able to afford otherwise.
- Increasing adaptive management and conveyance capacity ALCOSAN will use adaptive management and base long-term planning on data from green infrastructure, flow-reduction projects, and the latest technology. This provision in the Modified Consent Decree demonstrates the willingness of the parties to the order to consider the use of green infrastructure and other flow-reduction projects in lieu of gray infrastructure where it can be shown to be as impactful in reducing overflows. Under the Modified Consent Decree, ALCOSAN will also expand its conveyance system by adding pipes, diversion structures and tunnels.
- Regionalizing multi-municipal sewers ALCOSAN will also make a good faith effort to assume ownership of certain multi-municipal trunk sewers and related facilities. ALCOSAN has conducted closed-circuit television inspections of these sewers, determined what repairs and improvements are necessary, and is now in the process of working with the municipalities to transfer ownership and make the necessary repairs. With the anticipated addition of more than 200 miles of sewer infrastructure as ALCOSAN’s responsibility, the system will be more efficient and seamless and it will reduce some of the burden on municipalities.
- Expanding the wastewater treatment plant The current capacity of 250 million gallons per day (mgd) makes ALCOSAN the largest wastewater treatment system in the region, but greater capacity is needed. The main pump station already has been upgraded and a new vehicle maintenance garage has been built outside the plant gates, making room to expand the treatment operation. ALCOSAN will expand wet weather treatment capacity of the plant from 250 mgd to 480 mgd and wet weather headworks and disinfection capacity to 600 mgd.
ALCOSAN first entered into a consent decree in 2008 and completed development of a plan to address wet weather overflows in 2012. Although comprehensive, the public challenged ALCOSAN to make the plan more affordable for ratepayers, yet flexible enough to take advantage of advances in the field of green stormwater and wastewater management. In order to meet those requests, further negotiations were necessary and occurred.
The Modified Consent Decree was lodged with the Court in September 2019 to allow for a 60-day public comment period. On May 18, 2020, the plaintiffs in the case filed a Motion with the Court to Approve the Modified Consent Decree. The plaintiffs included copies of all comments filed by the public and the responses to comments prepared by the agencies with their court filing. This Modified Consent Decree replaces the current Consent Decree that was entered on January 24, 2008.
Photo of Pittsburgh by Storm Cunningham.