Sat04192014

News

Los Altos studies December flooding, cites wayward debris as major culprit


Photo By: Town Crier File Photo
Photo Town Crier File Photo

Residents of St. Charles Court in Los Altos wade through the nearly knee-deep water after December storms flooded their neighborhood.

Localized flooding hasn’t been a problem since the Dec. 23 storm that dumped more than 4 inches of rain in parts of Los Altos, but city officials are preparing for the next major downpour.

Unretained soil and loose vegetation were primarily to blame for the storm-drain blockage that caused flooding just before Christmas, according to a recent Los Altos Public Works Department report. The report identified problem areas that should be corrected as part of the city’s effort to prevent future incidents.

In assessing storm-response measures, the Public Works analysis concluded that debris was responsible for blocking several storm drains and inlets critical for the proper flow of rainwater into area creeks.

During a Nov. 29 pre-storm inspection of 10 stormwater hot spots – locations with a history of flooding – no problems were detected. The city’s maintenance staff regularly performs debris clearing and pipe obstruction checks to ensure the city’s readiness for flooding, the report noted.

“Our storm preparation activities typically begin in October,” said Los Altos Public Works Director Jim Gustafson. “All of the pipe outfalls that convey stormwater to Adobe, Permanente, Hale and Stevens creeks are inspected and cleared of debris and vegetation as necessary to ensure that they will perform their intended purpose before the first major storm arrives.”

To prevent future flooding incidents, city officials studied the stormwater flowing through manholes and will propose additional capital projects as part of Los Altos’ Storm Drain Master Plan. They also intend to advise residents in flood zones about the availability of sandbags and other measures that can prevent dead vegetation and loose soil from impeding the flow of storm drains.

“All of the above are intended to address conveyance of the 10-year storm event, which is approximately what we had on Dec. 23,” Gustafson said.

The city’s police dispatch team and municipal service center recorded 44 calls from 42 locations across the city during the climax of the Dec. 23 storm. Los Altos received between 1 inch and 4.28 inches of rain in a 24-hour period, resulting in the most significant impact on local streams since 1998, according to the Santa Clara Valley Water District.

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