Water line break spills 610,000 gallons in west Sonoma County

A well driller tore into a 48-inch water main beneath a ranch near Forestville on Monday, spilling an estimated 610,000 gallons of precious fluid into the surrounding countryside, the Sonoma County Water Agency said.

The loss represented an amount equal to about 1.4 percent of the county’s average daily water use, but was a blow, given the current water shortage, water agency personnel said.

“It was gushing,” said Brad Sherwood, an agency spokesman who was on the site Monday off of Vine Hill Road.

The concrete main, dubbed the Cotati Aqueduct, serves Forestville, Cotati, Rohnert Park, Petaluma and northern Marin County, carrying water from the Mirabel intake on the Russian River, the water agency said.

There was no interruption in water service, as stored water was being delivered to consumers, instead, agency personnel said.

Crews were still removing water from the pipeline Monday evening and probably wouldn’t start repairs until Tuesday, Sherwood said.

The leak occurred around 11:30 a.m. when a rig from Les Petersen Drilling and Wells was digging a well for a new vineyard on some grazing land at Vine Hill Ranch, located south of River Road on Vine Hill Road, Sherwood and property owner Mike Verkunder said.

The concrete aqueduct runs through the property along an easement and is buried about eight feet deep, so that the upper surface is about four feet below ground, Sherwood said.

It’s not clear what went wrong, but the driller struck the side of the pipeline, tearing an irregular, 6-inch hole, Sherwood said.

The spill saturated the soil, causing the sodden earth to cave in on it at one point later in the day, and leaked into an otherwise dry tributary of Green Valley Creek, water agency personnel said. Additional water was drained out of the pipe upstream so the section of pipeline could be replaced.

Biologists did not believe there was any immediate risk to local wildlife, but the dechlorination tablets were being used to dechlorinate the water and monitoring was set up to ensure no harm came to Green Valley Creek, Sherwood said.

He said the water agency had not received a required notice alerting them to the work near the aqueduct, and the drilling company was looking into what went awry with the paperwork.

Verkunder, who was away from the ranch when the rupture occurred, said the location of the drill was marked, in part to avoid interference with the aqueduct, and he was unclear how the mistake was made?“It’s a terrible accident, that’s for sure,” he said. “Absolutely tragic. I feel badly about it, and I’m sure everybody involved does.”

You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com.