Heavy Rains Causing Sewage Overflows Into Sonoma Creek
(BANT) – The Sonoma County Water Agency is still assessing the amount of wastewater overflows in the Sonoma Valley Sanitation District caused by heavy rain this week.
There were nine separate sanitary sewer overflows starting at 2:30 p.m. Tuesday. The Sanitation District is evaluating impacts to public and environmental health.
Most of the overflows into the Sonoma Creek occurred in the Boyes Hot Springs and Fetter Hot Springs area, and two were in Eldridge, Water Agency spokeswoman Ann DuBay said.
She says heavy rain overloads the water collection system’s sewer mains which are being replaced. Leaky private sewer laterals and illegal connections of roof downspouts, yard drains, sump pumps and other non-sewer discharges also increase the amount of wastewater entering the system during rain storms, DuBay said
The Sonoma Valley wastewater treatment plant can treat up to 12 million gallons per day and can store up to 35 million gallons of untreated wastewater. During heavy rain, inflow into the plant can more than triple, Dubay said.
Before the storm on Monday and early Tuesday, inflow was 4 million gallons a day and between 16 million and 17 million gallons a day during the peak of the storm, DuBay said.
Some areas of the Sonoma Valley reported three inches of rain within a 24-hour period, DuBay said.
There also were two wastewater overflows in the Russian River Sanitation District when the river reached 34 feet, two feet over flood stage, DuBay said.
The overflows occurred at the District’s main lift station on Riverside Drive on River Road, DuBay said.
Eleven separate pumping stations transport wastewater from homes and businesses to the Russian River District’s treatment plant, and when inflows from the river and rain storms are high, the pumps cannot keep up with demand, DuBay said.
The District serves the equivalent of 3,200 single-family homes in Rio Nido, Guerneville, Guernewood Park and Vacation Beach. The District hopes to rebuild one pumping station per year, DuBay said.