After automobile hits sanitary sewer system automatic release valve on Bayview Drive in Osprey, about 1,350 gallons of sewage flows onto nearby parking lot

Retention area of private stormwater collection system unaffected by spill, county staff finds

A graphic shows the area of the sewage spill. Image courtesy FDEP

About 5:15 p.m. on Jan. 19, the staff of the Sarasota County Public Utilities Department learned that an automobile had struck an automatic release valve (ARV) in a metal enclosure, and sewage was leaking in the area of 135 Bayview Drive in Osprey, the staff reported to the Florida Department of Environmental Protection (FDEP).

Approximately 1,350 gallons of sewage flowed mostly onto the adjacent dirt parking area, the FDEP report says. “A minimal amount” flowed onto a nearby asphalt parking area and into multiple stormwater structures, the report added.

“Staff was able to act quickly and shut the valve directly in front of the ARV,” ending the leak, the report noted.

The county crew members then were able to trace the private stormwater collection system to a retention area, which they saw had remained unaffected by the spill. In other words, as the report put it, “[N]o liquid made its way to the retention area.”

Approximately 400 gallons was recovered from the stormwater collection boxes through use of the county’s vacuum truck, the report noted. “The rest of the spill was quickly absorbed into the dirt parking area,” it said.

The crew washed down the affected roadway and asphalt parking area, the release pointed out. The clean-up efforts and provision of notifications about the spill to area property owners were “being completed according to protocol,” the report added.

This is another aerial map showing the location of 135 Bayview Drive in Osprey. Image from Google Maps

The crew members completed their work at 6:15 p.m. on Jan. 19, the report said.

The affected utilities equipment is associated with the county’s Central County Water Reclamation Facility, the report noted. That plant stands on Palmer Ranch in Sarasota.

This aerial map shows the location of the Central County Water Reclamation Facility. Image courtesy Sarasota County

In a blog, 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.”

During the County Commission meeting on Sept. 9, 2020, Commissioner Christian Ziegler voiced concerns about the number of ARV-related incidents that had led to county sewage spills.

“I would like to see a plan to protect those [ARVs]” that seem most vulnerable to damage, Ziegler told Public Utilities Director Mike Mylett. “Some things in Publix parking lots are protected more than these ARV valves. … Maybe it’s dropping a cement block in front of them, so cars don’t hit ’em and mowers don’t hit ’em.”

Ziegler added, “I think we need some sort of county comprehensive plan” to prevent such incidents, because “we get blamed for the spill …”

Approximately 5% of the county’s ARVs had redundant protection, Mylett explained in early September 2020. Those were structures that had been hit multiple times in the past, he added.

This diagram illustrates how an ARV works. Image from Burgess & Niple, presented to an Ohio Water Environment Association conference

In response to a Sarasota News Leader question this week about the status of the ARV situation, Media Relations Officer Drew Winchester provided the following information from Mylett: In December 2019, 673 ARVs were evaluated, with staff finding that 35 had been replaced. “Public Utilities has made great progress since the last update, 15 months ago, regarding the sanitary sewer air release valves (ARV),” Mylett continued. To date, he noted, field staff members have surveyed an additional 165 ARVs and replaced 148 of them.

Along with the surveying and replacements, Mylett reported, staff members have been installing bollards around “16 select ARVs.” Those “have been determined to be high risk and or have been damaged by vehicles and mowing equipment previously,” Mylett pointed out.