Point Reyes Light - December 4, 2003

Tomales sewer work prevents catastrophe

By Ivan Gale

Tomales’ sewer system avoided a catastrophe this fall because of improvement made last January, Karl Drexel, manager of Tomales Village Community Services District said Monday.

The catastrophe nearly occured in September when a county-contracted fencing company broke a sewer main along Irvine Road at Tomales High.

The main is used for pumping sewage from treatment ponds near the school to storage ponds 500 feet uphill. Before the district revamped the pumping system it inherited when in 1999 it took over the North Marin Water District system, sewage from the upper ponds could have flowed back down the main and ended up in Keys Creek.

The problem, as Drexel explained it, was that the main previously emptied treated sewage near the bottom of the storage ponds. That would have allowed wastewater to drain out of the ponds if the main below them was broken.

Drexel, however, redesigned the upper end of the main so that the water being pumped uphill pours into storage ponds from several feet above them. This prevents the main from accidentally draining the ponds.

Before January, a break would have left a single check-valve to prevent the storage ponds from emptying into the ceek, said Drexel. "It would have had the potential to leak over 5 million gallons of treated wastewater," said Drexel.

Manager Drexel has good reason to worry about a sewer main breaking near the storage ponds. When the system was still operated by North Marin, a line broke in October 1996 and one million gallons of wastewater drained into a tributary of Walker Creek and ultimately into Tomales Bay.

The spill forced oyster growers to temorarily suspend harvesting and prompted Tomales to de-annex its sewer system from North Marin.

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