No surface waters affected
On Feb. 20, approximately 4,000 gallons of raw sewage spilled at the intersection of U.S. 301 and 47th Street in Sarasota after two air release valves (ARV) were struck at that location, Sarasota County Public Utilities Department staff has reported to the Florida Department of Environmental Protection (FDEP).
County crews recovered about 12,000 gallons of mixed raw sewage and rainwater from the site, using a vacuum truck, the report added.
No information was provided in the report about the entity that struck the ARVs.
The initial advisory that staff received indicated that either an ARV or a sewer force main had been broken, the report noted. After county workers arrived on the scene, the report continued, the crews “quickly isolated the [affected sewer force] main and stopped the spill.” Notifications were provided to affected property owners and residents in the area, the report indicated, while other clean-up efforts were “proceeding per protocol.”
The report further noted that no surface waters were impacted.
A formal document detailing the incident will be submitted to the county’s risk management staff members, so they can work to ensure that the entity responsible for the ARV damage reimburses the county “for all costs incurred,” the report to FDEP added.
As Crane Engineering explains, “Air release valves are installed at the highest points in a pipeline where air naturally collects. Air bubbles enter the valve and displace the liquid inside, lowering the liquid level. When the level drops to where it no longer buoys the float, the float drops. This motion pulls the seat away from the orifice, triggering the valve to open and vent the accumulated air into the atmosphere. As the air is vented, liquid re-enters the valve, once again buoying the float, lifting it until the seat presses against the orifice, closing the valve. This cycle automatically repeats as often as necessary to maintain an air-free system.”
The U.S. Environmental Protection Agency explains that sewer force mains “are pipelines that convey wastewater under pressure from the discharge side of a pump or pneumatic ejector to a discharge point. Pumps or compressors located in a lift station provide the energy for wastewater conveyance in force mains.”
The sewer line that was affected is part of the infrastructure associated with the county’s Bee Ridge Water Reclamation Facility, which stands at 5550 Lorraine Road in Sarasota, the report added.