Lessons learned from the Darby Fire
Steps we can take to prevent this from happening again.
Menu
Steps we can take to prevent this from happening again.
By September 7, all of ¾ Mile Flume had been completely destroyed aside from the aluminum lining that had melted into puddles. This meant the loss of ability to bring water to the communities from Murphys to Angels Camp.
The fire had damaged approximately 33,632 square feet of gunite canal and 735 linear feet of wooden flume sections, walk boards, dump gates, deer crossings, and wooden helicopter pads. In order to be able to reestablish a water supply back to the communities using the overland pipe system while Flume 14 was being replaced, the UPA team would first need to immediately repair flumes 9, 10, 11, and 13.
A staff meeting was held at the UPA office to evaluate damaged areas, and discuss how the repairs would be handled. The UPA men would be assigned to new emergency repair duties. UPA was also fortunate to get two individuals from Tuolumne Irrigation District, who volunteered their time to help develop a plan of repair.
Because UPA did not have an accounting system in place to support the accounting needs of these emergency crews, the CCWD was paid to act as a Temp Agency to hire temporary CDF crews and handle payroll. Once this labor force method was agreed upon, the crews were contacted and then sent to CCDWD to sign up for the project.
Flumes 10 &11 were the first areas where debris and burned-out materials were removed from. After relocating all the mud blocks and footing locations, the crews began rebuilding the foundation bents.
Flume 15 remained partially intact, but still had some structural damage in regard to the foundation bent structures. Additionally, the flume had dropped about 2 feet in elevation, so it needed to be raised and repaired before the pumps for the overland pipe system became operational
It was determined that it would take four 200 horsepower, high pressure pumps, with six-inch discharges to pump the 350-foot head of water. The engineers wanted to ensure that this system could continually carry water while the flume was being repaired. They decided to use six-inch discharge pumps, two each, into ten lines. This way, if one pump was to fail or was down for maintenance, we could still maintain the other two-pump system. Approximately 5,000 linear feet of ten-inch pipe would be installed over 2,500 linear feet of land.
Once the plug was removed from the ditch system, major flushing needed to take place. There was lots of debris remaining in the ditches from the fire and from the winter runoff. A tremendous amount of silt and debris had to be dump-gated out and was flushed into our forebays and afterbays.
Once everything was working properly, the pump and pipe system needed to be disassembled, removed from the site, and its entire area of use returned to pre-use condition per Forest Service and Private Land Lease contract. It took approximately two days to fill in the area where we had originally dug out the bank to create a location for the pump pad, re-seed it, and utilize the matting to hold the seed in place. Following that, the culvert that allowed the overland pipes to pass under the road was removed. Next, the overland pipe itself was disassembled and ready for removal from the site, along with the road bridge, concrete hold-downs, rebar stakes and all construction materials. This took place in the three weeks following the start up of the system.
Rebuilt flume system gets back to work
by Sunny Lockwood
“Water is flowing through the ditches, canals, and rebuilt flumes on the Utica Power Authority’s system. Nine months and 14 days after the Darby Fire cut off UPA’s water system, the water was turned back on Wednesday.
Rebuilding the historic three-quarter mile flume was complicated by the steep cliffside terrain and winter weather. Helicopters had to fly in portions of the iron trestle that held the wooden flume boxes.
While crews labored from the fall to this month, a temporary overland pipe system powered by pumps kept about 10 cubic feet a second flowing to the city of Angels Camp, Murphys, and other nearby communities.
When water began flowing Wednesday, UPA operators watched for leaks or other problems, but saw none, said Operator Dave Powell.
He said that the flow was increased to 30 cubic feet a second on Friday. “Angels Creek will have about two-and-a-half cubic feet a second in it and Murphys Creek will have 20 cubic feet a second,” he said.
Water in the restarted system flowed at a rate of 20 cubic feet per second, and there is no longer any need for people to practice emergency conservation, said John Hubbell, UPA field administrator.
“Everything’s fine, we’re back to normal,” he said.
UPA’s two powerhouses – one in Murphys and one in Angels Camp – have been idle since the Darby Fire destroyed the flumes Sept. 5. “
