City to Shore Up Eroded Drainage Canal

Before another season of rain bears down on Simi Valley, the City Council agreed Monday to spend more than half amillion dollars to shore up the main drainage canal through the center of town--the badly eroded Arroyo Simi.

Winter thunderstorms in 1995 tore away hundreds of yards of earth in the channel, undermining its banks and threatening to deluge the city sewer plant, said Public Works Director Ronald C. Coons.

High water in the drainage channel also chewed away earth around a steel structure that protects the earthen stream bed that covers two large sewer lines crossing the arroyo.

City contractors made a temporary fix that summer--dumping wire mesh-wrapped rocks into place to prevent further erosion. But a sturdier repair is needed, Coons said.

So, council members voted 5 to 0 Monday night to pay Thousand Oaks contractor Pacific Rim Grading $226,800 to rebuild the northern embankment of the Arroyo Simi near the city’s sewage-treatment plant.

Without this crucial work, Coons said, the arroyo could change course and damage the sewage plant that sits beside it. The Arroyo Simi carries rain runoff from the mountains surrounding Simi Valley down into Calleguas Creek, which eventually drains into the sensitive wetlands of Mugu Lagoon.

“If the toe of the slope [along the embankment] should fail and then cause it to be undermined, the slope would be in jeopardy of failing as an embankment in keeping the arroyo in line,” he said. “It could have endangered the plant property.”

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The council also agreed to pay $288,700 to C.A. Rasmussen of Simi Valley to reinforce the earthen stream bed, shore up rocky banks and a steel stream bed stabilizer near the sewer pipelines. The stabilizer is a thick sheet of corrugated steel sunk into the stream bed, spanning from bank to bank.

This work will hamper erosion caused by future flooding that might damage two sewer lines--one 12 inches in diameter and the other 33 inches--as they cross the arroyo just west of Madera Road.

The council also approved a handful of smaller contracts totaling $31,800 for soil testing, surveying and archeological monitoring services during the digging and construction.