Sewer pipe going
under the riverbed
By Kelly Feser Eells

Call it ambitious. Call it colossal. One thing the Ojai Valley Sanitary District's newest project - the "Meiners Oaks Trunk Sewer Relocation" project - cannot be called is insignificant.

"It's a big deal," said General Manager John Correa, "probably the most environmentally sensitive thing we can do."

He explained that one of the district's major sewer pipelines (serving the Meiners Oaks area and crossing the Ventura River) is partially exposed, and that the exposed portion has been damaged in recent floods, resulting in service outages and sewage spills. At present, 130 feet of pipeline is exposed at the surface of the riverbed - the elevation of which is significantly lower than it was when the pipeline was installed some 40 years ago.

"This is one of the original sewer systems, constructed before the bridge across the river was built," Correa said. "The road at that time was also in the river bottom."

But the most dramatic decreases in elevation occur when the riverbed is "scoured" by flood, such as it was by the El Niño storms of recent years.

In addition to posing a direct and constant threat to the environment, the (exposed) pipe "creates a passage impediment to migrating steelhead." Indeed, a 25-50 portion of pipe is "buried" within three feet of the riverbed surface, while the entire line is situated no deeper than the "collapsible" alluvium, i.e., in the interface between alluvium and bedrock.

"We've been studying this line for three years now," Correa says; "and one of our biggest studies" was geological, with a team of geologists.
"Our goal," he adds, "is to not be in the banks or beds of the river, but to construct a new pipeline that won't be vulnerable to damage from flooding. During the first part of the project - which we expect to have done by the first week of January - we'll be drilling into the bedrock, up to 200 feet deep under the river, at its middle."

The pipeline "will be an inverted siphon, consisting of plastic 'carrier' pipes placed within steel casing, approximately 30 inches in diameter" and a whopping 3,200 feet (or half-mile) long, extending from the eastern abutment of the Highway 150 bridge to within 100 feet of Burnham Road.

The second part of the project, which is slated to begin in March, is the "fitting" process, during which the pipeline and/or siphon will be connected to below-ground hydraulic structures; pipes will be "pulled" into place, and portions of the existing pipeline will be removed (if they are near the riverbed surface).

The project also includes removal of all the old pipe from the Ventura River "after several years of successful operation of the new line."

© 2003 The Ojai Valley News

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