County readies for Devil's Gate cleanout

Scaled-down project in July would not bring trucks through La Cañada Flintridge, official says.

June 08, 2011|By Joe Piasecki,
  • The L.A. County Public Works Dept. wants to excavate the area behind the Devil's Gate Dam in Pasadena, photographed on Tuesday, June 7, 2011.(Raul Roa/Staff Photographer)
The L.A. County Public Works Dept. wants to excavate the…

The Los Angeles County Department of Public Works will start work in July to remove 25,000 cubic yards of sediment from the basin behind Devil’s Gate Dam in Hahamongna Watershed Park.

The project is a stopgap measure to prevent valves and other dam works from becoming clogged this coming winter while the county studies options for the eventual removal of roughly 1.5 million cubic yards of mud and debris, most of it deposited after the August 2009 Station fire.

Excavation work, which could begin as early as July 5, would be limited to within about 100 feet of the face of the dam — leaving all wooded areas in the basin intact and eliminating the need for dirt-hauling trucks to pass through La Cañada Flintridge, said Chris Stone, assistant deputy director of Public Works’ Water Resources Division.

“We need to remove sediment that’s accumulated around intake structures to make sure they remain operational over the next one or two winters while we pursue [a study] for the larger project. If we couldn’t operate the valves, we could no longer discharge water downstream, and then it could build up and go over the stow-way” — flooding unchecked into areas below the dam, Stone said.


Dirt removed from the dam face this summer will either be stored temporarily at Johnson Field, an unused Pasadena Water and Power groundwater restoration basin nearby, or hauled out past the southern end of the JPL parking lot, down Windsor Avenue in Altadena and along the Foothill (210) Freeway to a fill area in Irwindale.

Pasadena City Council members are expected to decide on June 20 whether to allow use of Johnson Field, which along with keeping trucks off Windsor would not interfere with maintenance of the park, said Dan Rix, a Pasadena city engineer.

Stone gave a project update on Monday to La Cañada Flintridge City Council members, who expressed concern that one of several potential truck routes still in play for future work involves using Oak Grove Drive to access the freeway.

“In my eyes, you guys are some of the heroes of our debris flow problem, only my biggest concern is the haul route when you start cleaning it out,” said Councilwoman Laura Olhasso, who called for the city to hold a future project scoping meeting.

The eventual removal of millions of cubic yards of sediment would require 300 to 400 truck trips per day out of the basin over several months, Stone said.

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