ALCOSAN Turns 60

The ALCOSAN wastewater treatment plant on Pittsburgh’s North Side went into service 60 years ago, but its gestation period began much earlier.

In the 1940s, civic leaders realized the health hazards and environmental damage that came from simply dumping wastewater from homes and businesses into the region’s rivers. Until then, the belief was that “dilution was the solution.” Recognizing that as insufficient was a first step.

In 1946, the Allegheny County Sanitary Authority was created under Pennsylvania’s Municipal Authorities Act to design, construct and operate an interceptor system and treatment plant for residential, commercial and industrial wastewater. Over the next decade, the 59-acre site that ALCOSAN occupies now was transformed from empty land to what then was a state-of-the-art facility.

The ALCOSAN plant has gone through a lot of changes over its lifetime. Some features remain the same on the outside. The signature blue, 300-foot incinerator chimney and the 11-story, 40-foot-diameter wet well, for example. But the plant has been modernized in many ways, with additional treatment capacity that removes additional waste and extensive odor control devices throughout.

Like most 60-year-olds, ALCOSAN needs more updating. That’s why ALCOSAN’s Clean Water Plan calls for expansion of the plant’s capacity, from the current 250 million gallons per day to 600 million gallons per day by 2036.

We’ve created a photo gallery of vintage ALCOSAN photos from our earliest days.


Click here to see some blasts from our past.

Arletta Scott Williams

Arletta Scott Williams
ALCOSAN Executive Director

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