U.S. EPA orders Marin County sewage collection systems to address chronic sewage spills

The U.S. Environmental Protection Agency today issued enforcement actions requiring nine sewage collection systems in the Sausalito and Mill Valley areas of southern Marin County, Calif. to address chronic sewage spills, improve sewer maintenance and implement long-term programs to renew aging sewer pipes.

Deteriorated conditions of the sewer systems became evident when heavy rains overwhelmed the systems causing over 5 million gallons of sewage to flow into Richardson Bay and San Francisco Bay earlier this year.

“These small, underfunded and undermanaged systems will continue to pose threats to San Francisco Bay if communities fail to upgrade and maintain their systems sustainably,” said Alexis Strauss, the EPA’s Water Division director for the Pacific Southwest region. “We urge the systems to begin to work together and invest in long-overdue assessment, repair and replacement of their wastewater infrastructure.”

The orders were issued to Sewerage Agency of Southern Marin, Almonte Sanitary District, Alto Sanitary District, city of Mill Valley, Homestead Valley Sanitary District, Richardson Bay Sanitary District, Sausalito-Marin City Sanitary District, the city of Sausalito, and Tamalpais Community Services District.

The EPA orders require the sewer systems to employ a number of strategies to reduce sewage spills. In the short-term, the systems are required to implement aggressive sewer cleaning programs aimed at the most problematic pipes. The systems are also required to inspect their sewer pipes and measure wet weather flows that are passed on to the sewage treatment plants. Finally, the systems must develop plans to manage excess flows and implement long-term programs to repair and replace deteriorated sewer pipes.

The EPA encourages the cities and sewer districts to work together to finance, operate and renew their wastewater infrastructure.

“It’s clear from this January’s sewage spills and overflows that aggressive action is needed to protect both public health and the Bay,” said Bruce Wolfe, executive officer of the San Francisco Bay Regional Water Board. “We fully support EPA’s issuance of these enforcement orders.”

Deteriorating pipes, combined with extreme peak flows from rain, overwhelmed the SASM wastewater treatment plant causing January 25 flows to exceed capacity at the emergency holding basins at the plant, where 2.45 million gallons overflowed to Richardson Bay. Another spill occurred on January 31 when operators at the SASM treatment plant failed to operate all of its discharge pumps leading to a 2.7 million gallon spill to Richardson Bay. In Sausalito, the January 25 storm led to a 63,000 gallon spill from a sewer manhole on Marinship Way.

The Sewerage Agency of Southern Marin, located at 450 Sycamore Avenue, treats wastewater from about 28,000 people in the Mill Valley area. The sewage is collected from homes and businesses in networks of sewer pipes that are owned and maintained by five separate sanitary districts and the city of Mill Valley.

Sausalito-Marin City Sanitary District, located at Fort Baker, treats wastewater from about 16,500 people in Sausalito, Marin City and Tam Valley.

When sewage spills occur, prompt posting of affected beaches is required to protect the public. County health departments need to post waterways immediately when these types of discharges occur.