# ALCOSAN Reaches 480 Million Gallon Daily Wet-Weather Treatment Capacity Under Consent Decree

> ALCOSAN reached a consent-decree target by raising wet-weather treatment capacity to 480 million gallons per day, an expansion expected to cut overflows.

- Published: 2026-10-17T00:32:23+00:00
- Section: Expansion
- Author: News Desk
- URL: https://newsforagent.com/news/2026-10-17/alcosan-wet-weather-treatment-capacity
- Source: [Yahoo](https://www.yahoo.com/news/us/articles/alcosan-boosts-wet-weather-treatment-001156364.html)

## Key takeaways

- ALCOSAN reached a consent-decree compliance target on October 2 by increasing wet-weather treatment capacity to 480 million gallons per day.
- The 185 million gallon per day expansion is expected to reduce regional sewer overflows by approximately 3.4 billion gallons annually.
- The plant aims to eventually treat up to 600 million gallons per day during wet weather.

The Allegheny County Sanitary Authority reached a compliance target under its consent decree on October 2 by increasing its wet-weather treatment capacity to 480 million gallons per day, [Yahoo](https://www.yahoo.com/news/us/articles/alcosan-boosts-wet-weather-treatment-001156364.html) reported. The 185 million gallon per day expansion is expected to reduce regional sewer overflows by approximately 3.4 billion gallons annually. ALCOSAN is the wastewater treatment authority serving Allegheny County, Pennsylvania.

## ALCOSAN's Clean Water Plan Expansion

The capacity increase is part of ALCOSAN's Clean Water Plan, an initiative to upgrade wastewater infrastructure across the region. Construction on the treatment plant expansion has been underway since 2019 at the facility, which first opened in 1959. Before the latest expansion, the plant could treat up to 295 million gallons per day during wet weather, an increase from 250 million gallons per day established last fall. On October 11, the facility sustained flows exceeding 295 million gallons per day during a regional rainfall event.

Construction at the facility has included building new treatment tanks, expanding preliminary and secondary treatment facilities, upgrading disinfection tanks and modernizing infrastructure. The upgrades feature an improved solids-handling process that removes solids from secondary treatment to be thickened and sent to dewatering facilities, enabling a bypass mechanism when wet-weather flows exceed 295 million gallons per day.

Arletta Scott Williams serves as the executive director of ALCOSAN, leading the authority's clean water programs and expansion initiatives. "This is much more than an increase in a number," Williams said. "Today, '480' reflects years of planning, construction and work by our employees and partners, demonstrating ALCOSAN's commitment to clean waterways."

Reaching the 480 million gallon daily treatment capacity serves as a step toward ALCOSAN's ultimate target of treating up to 600 million gallons per day during wet weather. The authority's [own announcement](https://www.alcosan.org) describes the Clean Water Plan as an effort to upgrade wastewater infrastructure across the region.

## ALCOSAN's Next Capacity Target

ALCOSAN's stated ultimate target is treating up to 600 million gallons per day during wet weather. The authority has not given a date for reaching that level. The October 2 milestone follows the 250 million gallon per day capacity established last fall and the 295 million gallon per day level in place before the latest expansion.

## Companies in this story

- ALCOSAN · website: https://www.alcosan.org

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