ALCOSAN Sewage Discharge: Avoid Allegheny County Waterways for 48 Hours
Residents of Allegheny County, Pennsylvania, are being advised to avoid contact with local waterways for the next 48 hours following a power outage that caused a significant discharge of untreated wastewater into the Ohio River. The advisory, issued by the Allegheny County Sanitary Authority (ALCOSAN), aims to protect public health during a period of increased bacterial contamination.
The incident began on evening, between and , when a full power outage struck the ALCOSAN wastewater treatment plant. According to Doug Jackson, ALCOSAN operations director, the plant experienced a cascading failure of its three power feeds from Duquesne Light. “I’ve been with the authority for almost 36 years and I’ve never experienced a time where we’ve lost all of our feeds from the utility and caused this event to occur,” Jackson stated.
During the approximately two-hour outage, ALCOSAN was unable to process incoming wastewater, causing the plant’s “wet well” – a holding area for wastewater – to reach capacity. This resulted in the discharge of an estimated 20 million gallons of raw sewage directly into the Ohio River. While this volume is substantial, ALCOSAN officials note that the plant typically treats around 270 million gallons of wastewater daily, putting the overflow into context.
The advisory specifically recommends that recreational users limit contact with the river water while boating, fishing, water skiing, or engaging in other activities. This precaution is based on the increased presence of bacteria associated with untreated wastewater, which can pose a health risk through ingestion or contact with skin, particularly through open wounds.
ALCOSAN serves approximately 850,000 people across Allegheny County. The timing of the outage was particularly concerning, as the region had already experienced significant rainfall, leaving the system near capacity. This meant that all new wastewater arriving at the plant during the outage had to be diverted directly into the rivers.
The authority acted swiftly to notify partnering water agencies and the Pennsylvania Department of Environmental Protection (PADEP) about the incident. Duquesne Light restored power to the facility on night. ALCOSAN has stated it will continue to monitor the situation and provide updates as needed.
This event mirrors the advisories ALCOSAN issues during periods of heavy rainfall, when stormwater overwhelms the sewer system, leading to similar overflows. Jackson explained that the current advisory is “really to advise folks to try to avoid contact with the waterways, because there is a higher level contributed by our overflows, primarily bacteria in the rivers.”
While ALCOSAN does have an emergency generator, its capacity is limited and reserved for critical functions necessary to prevent catastrophic failure of plant systems. The generator is not capable of powering the entire wastewater treatment process. Jackson noted that the reliability of Duquesne Light’s service had historically led to a lack of contingency planning for a complete power loss. “The on-site generation that we would need for as large of [an] electricity supply [as we use] had never been factored into our contingency planning, just because of the reliability and service that we’ve gotten over many, many years from Duquesne Light.”
ALCOSAN plans to conduct a thorough review of the incident to determine if the discharge could have been prevented. This review may lead to capital expenditures aimed at improving the plant’s resilience to power outages. The authority is already undertaking upgrades to its system with the goal of reducing the frequency of these overflows, even during storm events. Jackson emphasized that preventing these discharges is a priority, despite their occasional occurrence due to weather conditions.
Individuals who experience symptoms such as nausea, vomiting, diarrhea, or skin irritation after contact with the affected waterways should consult a healthcare professional. While the risk to public health is considered moderate, minimizing exposure during the 48-hour advisory period is the most prudent course of action.