A sewage spill estimated at 87,751 gallons was reported Thursday, February 6, in the Bon Air shopping center parking lot in unincorporated Greenbrae, behind the Mollie Stone’s market. The preliminary cause was a leak from a pressurized force main operated by the Ross Valley Sanitary District (RVSD), and those responding to the leak said the response was rapid as they noticed flow and pressure changes.
According to the Environmental Health Services (EHS) Division of the Marin County Community Development Agency, the leak was stopped at about 4:30 PM that day when RVSD personnel shut off an isolation valve. Marin EHS identified the accurate spill volume on February 10. Due to the large volume of water flowing in the creek during the rain event, the sewage release was cleared very quickly. There is no evidence of current contamination.
All sewage on the ground or in catch basins was vacuumed for proper disposal and the impacted areas were disinfected with a bleach solution. Water samples have been taken, and warning signage was posted by RVSD.
Marin County Public Health and Marin EHS have not received reports about adverse effects on humans or wildlife in the area and the creek does not show any signs of sewage debris.
EHS has been analyzing the water quality to fully understand the scope of the sewage release. Samples showed a spike in fecal indicator bacteria on February 6 and returned to background levels for two consecutive days on February 7 and 8. As a precaution, signage warning the public about the potential contamination was posted at the spill site, at the outfall into the Corte Madera Creek, and 100 feet upstream and downstream of the outfall, and was scheduled to be removed Wednesday, February 12.
In addition to Marin EHS, the California Office of Emergency Services was notified of the spill as is required by California sanitary districts.
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