In January 2008, 3.5 million gallons of untreated sewage water slid into Richardson Bay in one week due to overflows and alarm-system failures at Mill Valley's Sewerage Agency of Southern Marin (SASM). The Environmental Protection Agency has ordered SASM and several other sewage-management agencies to repair old and damaged infrastructure, but aside from a few system upgrades and some paperwork, physical improvements have been few. Many system weaknesses that caused the January spills still exist beneath the sidewalks and streets of southern Marin, and a fully reliable system may be years in the future.
According to Bruce Wolfe, executive officer with the San Francisco Bay Regional Water Board in Oakland, much of Marin's sewer system was built more than 50 years ago, and the structural integrity of pipes throughout the system has decayed. In an ideal situation, sewage pipes are watertight, Wolfe says. However, cracks and breaches riddle Marin's aging system, and in January huge quantities of runoff during two large storms gushed into the pipes at many still-to-be-identified leakage points.
The Sewerage Agency receives and processes a dry-season average of approximately 2 million gallons of wastewater daily from some 28,000 locals. The flows in January, however, reached 30 million gallons. The facility could not contain the deluge in its 1.7-million-gallon emergency storage tank, and during the first storm, on Jan. 25, plant managers took action to avoid a flood inside the facility.
"They had no option but divert some of that sewage water around the plant," Wolfe says. "That was raw sewage, though on the flipside it was diluted with huge amounts of rainwater."
The day after the spill, an email from SASM to the water board told state officials of the spill, stating that it had occurred weeks prior. Steve Danehy, SASM's general manager, told the Bohemian that it was an honest typo. Due to the communication error, various health and environmental response agencies did not learn of the spill and the subsequent one on Jan. 31 until Feb. 5, 11 days after the first event.
The EPA reacted in early April by ordering SASM, as well as six Marin County water districts whose sewage pipes feed the SASM plant, to submit drafts by Oct. 15 detailing each agency's current system management plans. Some have met the deadline with lengthy documents describing their respective emergency procedure plans and maintenance schedules. The Sewerage Agency, though, recently requested an extension on the deadline, which the EPA has granted, and the sewage center now has until April 2009 to file the paperwork.
The water board issued a fine of $1.6 million against SASM on Sept. 2, which the EPA's division chief of wastewater control, Lila Tang, assures will eventually be paid. However, the cash-strapped SASM may be allowed to complete a "supplemental environmental project" in order to alleviate the financial hardship. Such a project might include funding local residents in repairing their home sewage pipes.
In the investigation following the January spills, officials with the water board discovered that the state emergency notification requirements then in place had been written in the 1970s. The antiquated standards required that agencies report spills by phone within 24 hours and turn in written notification within five days.
"In the age of electronic information, we can do a lot better than that," Wolfe says. The law was updated this summer to require that accidents be reported within two hours.
Currently, SASM is making several upgrades at its facility, according to Danehy. The 25-year-old alarm system which experienced "a breakdown in communications" on Jan. 31 will soon be replaced by a modern system. He also reports that 30 electronic flow monitors will be in place around the Mill Valley area by December, inserted into the pipes at strategic points to provide SASM staff with constant real-time reports on water volume approaching the facility. Contractors are also expanding SASM's emergency overflow tank, doubling its capacity to 3.3 million gallons, a job which Danehy guesses should be completed by late November and which he trusts will be capable of handling most wet-season inflows to the plant.
However, the efficiency of a sewage plant depends on the structural integrity of the pipes that feed it. SASM's facility may be better equipped than it was last winter, but the leaks and breaches that allowed the overflows of January's storms still exist deep within the subsurface system.
"You can make improvements at the plant," Wolfe says, "but to actually locate leaks in the system and reconstruct the lines, that's a multi-year process."
The EPA has set deadlines for such improvements as far in the future as 2013. Until then, five rainy seasons will pass, and Danehy acknowledges the uncertainties ahead.
"With our improvements, we should be prepared for most storm events. Then again, there's no guarantee there won't be problems this winter. You just never know what Mother Nature might deliver."