Wastewater Overflows in Sonoma Valley During Storm

Recent heavy rainfall resulted in several wastewater overflows in Boyes Hot Springs and Glen Ellen, according to Sonoma County Water Agency on Monday. Approximately 35,000 gallons spilled from these areas within Sonoma Valley County Sanitation District.

The collection system treats wastewater from approximately 17,000 equivalent single-family dwellings within the City of Sonoma and the unincorporated areas of Agua Caliente, Boyes Hot Springs, Eldridge, Fetters Hot Springs, Glen Ellen, Schellville, Temelec, and Vineburg.

Wastewater maintenance and work crews responded to the overflows.  Staff collected the wastewater, evaluated environmental impacts, and will continue to monitor the collection systems.  The San Francisco Bay Regional Water Quality Control Board, California Department of Fish and Game, Sonoma County Health Services and Fire and Emergency Services were notified.

District crews worked around the clock due to the amount of rain, according to District and Water Agency Director Valerie Brown. 

“Our collection system is more than 50 years old," Brown said. "While replacing old pipes has reduced problems, more work is needed and this means ensuring proper funding for the District.  I applaud the tremendous job of our staff for working in miserable conditions to fix problems quickly.”

Water Agency Chairwoman Shirlee Zane said, “Water Agency staff worked day and night in order to ensure our wastewater collection systems, flood control facilities and water supply operations weathered this most recent storm. By continuing to upgrade and replace aging pipelines and pumps, the Water Agency is working to better protect the community and environment from the impacts of atmospheric rivers and big storms.”

The District registered approximately 6 inches of rain over a 24-hour period from Saturday afternoon to Sunday afternoon. Inflow into its treatment plant grew from approximately 3 million gallons a day (MGD) to more than 17.4 MGD due to the heavy rain. The treatment plant is capable of treating up to 12 MGD and storing 35 MGD of untreated wastewater.

Because the amount of water in Sonoma Creek was so high (flows were more than 7,300 cubic feet per second or the equivalent of about 3.2 million gallons per minute), the wastewater overflows were less than .00004 percent of the flows and had no impact on the environment, according to a Water Agency news release.

The District’s pipeline improvement and replacement projects, including the installation of five smart cover manhole alarm systems, has helped reduce the number of overflows during an extreme storm event, such as the series of storms the service area is currently experiencing.  Smart covers are placed on manholes and send an alarm to sanitation staff when a wastewater collection pipe nears its capacity. Staff is then able to respond to that location and pump wastewater into a collection truck which prevents the overflow.

Overflow information:

Location: Burbank Avenue and Cecilia Drive (Glen Ellen)

Date: 12/23/12

Time: Approx. 11:45 a.m. to 1 p.m.

Amount: Approx. 2,250 gallons

Cause: Rain inundation

Location: Vailetti Drive  and Casabella Drive (Boyes Hot Springs)

Date: 12/23/12

Time: Approx 8 a.m to 6:30 p.m.

Amount: Approx. 3,150 gallons

Cause: Rain inundation

Location: Rancho Vista mobile home park (Boyes Hot Springs)

Date: 12/23/12

Time: Approx. 12:30 p.m. to 6:30 p.m.

Amount: Approx. 18,000 gallons

Cause: Rain inundation

Location: Highway 12 at Brookside mobile home park and Oman Court (Boyes Hot Springs)

Date: 12/23/12

Time: Approx. 12:30 p.m. to 6:30 p.m.

Amount: Approx. 9,000 gallons

Cause: Rain inundation

Location: Meadow Brook mobile home park (Boyes Hot Springs)

Date: 12/23/12

Time: Approx. 9:30 – 11 a.m.

Amount: Approx. 2,275 gallons

Cause: Rain inundation