RENO, Nev. (AP) - A geological engineer told a federal judge Tuesday that the wall of an irrigation canal built has been built up with poor quality sand and silt over the years and is subject to another failure like the breach that flooded hundreds of Fernley homes in January.
Edward Porter of Reno testified as an expert witness on behalf of lawyers for flood victims seeking a temporary restraining order to restrict flows in the 105-year-old canal owned by the U.S. Bureau of Reclamation and operated by the Truckee Carson Irrigation District.
Bureau officials blamed the Jan. 5 breach primarily on numerous rodent holes that weakened the canal's earthen walls. They said those holes have been filled and maintain the canal is safe to operate at flows of 350 cubic feet per second, about half the maximum level.
But Bob Hager and other lawyers for the flood victims say experts have concluded the failure was due to "historical negligence" by the bureau and the TCID. They want the flows cut back to 150 cfs until further testing is done.
Hager said the top of the original canal - more like a trench - was at ground level and that the canal still is largely structurally sound below ground level. But he said over time the irrigation district dredged material from the canal and piled it on the sides of the canal, forming earthen walls 6- to 8-foot high.
Porter confirmed Tuesday in a hearing in Reno before U.S. District Judge Lloyd George that approximately 8 feet of sediment had built up in the bottom of the canal.
"The sediment has a substantial impact on the capacity of the ditch to carry water flows," he said.
The low-density silt piled on the manmade embankment is subject to "landslide failure, seepage or settling," Porter said.
"The native soils have a greater ability to hold water than the embankment itself," he said.
The embankment is not suited for retaining water and "does not have any engineering value," he said. "Basically it's just junk you want to get out of the ditch."
The hearing on the motion for the restraining order was continuing Tuesday afternoon. The judge did not indicate when he would rule on the request.
(Copyright 2008 by The Associated Press. All Rights Reserved.)