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Needed Flume Replacement Increases Reliability and Resilience of Water System

Post Date:12/11/2015 1:14 PM

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Contact: Jesse Saich, Public Information Officer, (530) 642-4127, jsaich@eid.org  


Picture: Flume 44, located directly above Highway 50, is a 67-year-old elevated wood flume that was last replaced in 1948. The flume traverses an active landslide that will be stabilized as part of its replacement.

Placerville, Calif. — The El Dorado Hydroelectric Project is owned and operated under the Federal Energy Regulatory Commission License 184. EID acquired Project 184 in 1999. It consists of four alpine reservoirs located in three different counties, a diversion dam on the South Fork American River near Kyburz, and 22 miles of canals, flumes, and tunnels ending in the El Dorado Forebay. From there, up to 15,080 acre-feet of water is sent to a water treatment plant for consumptive use and the rest is sent down a penstock to the El Dorado Powerhouse to generate state-certified green electricity and then returned to the river.

Flumes are a vital component of this complex water conveyance system. They deliver approximately one-third of EID’s drinking water supply to its customers. The canal and its flumes run through steep and often hard-to-reach terrain in areas prone to landslide and fire, as well as tree and rock fall.

“The canals and flumes in the Project 184 system are an important part of EID’s integrated water system,” said EID General Manager Jim Abercrombie. “Flume replacement significantly reduces the risk of catastrophic failure and enhances EID’s ability to transfer and bank water in Sly Park’s Jenkinson Lake, which is especially important during times of drought.”

Each year, the condition of the wooden flumes along the El Dorado Canal is assessed. EID staff identifies flume sections that are high priority for replacement in order to remain in service. Additional flume sections are identified for replacement in the five-year capital improvement plan and it will be important to remain diligent in addressing these assets to avoid potential failures and outages.

Flume replacement and repairs are performed during the district’s outage period from October 1 to mid-December each year. Large and complex flume projects may be constructed in phases over multiple scheduled canal outages.

The El Dorado Canal system is the primary means of supply to the northern portion of EID’s service area and also contributes significantly to supplying the rest of the service area by gravity. The communities of Pollock Pines, Cedar Grove, and Camino are exclusively served by water from the El Dorado Canal. The Apple Hill and Gold Hill agricultural areas, the city of Placerville, and communities west of Placerville to Cameron Park are served jointly by water from the El Dorado Canal and Sly Park’s Jenkinson Lake. The canal even contributes to supplying El Dorado Hills for a good portion of the year.

The majority of the canal system is constructed on a bench occupying a relatively steep, north-facing slope. This exposed location has been subject to failure, primarily due to natural events including occasional disasters caused by fire and landslide.

On April 9, 1983, a massive landslide destroyed 3,610 lineal feet of the canal and major portions of Highway 50. This event impaired operation of the system for 13 months. The combination of extensive damage and interrupted highway access was a major local disaster during that year affecting more than just water system operations.

“Rebuilding dilapidated flumes in the system helps to enhance water supply and power generation reliability,” said Abercrombie. “And since they are such long-lived assets—with a useful life of 50 or more years—we can use smart debt to pay for this vital infrastructure so it is more equitably spread across the decades of different customers who will benefit from them.”

Recent and Planned Canal and Flume Repairs from Board-Approved Capital Improvement Plan

Flume 42/43—completed during the 2014 outage
Flume 38, 39/40
—construction planned in 2016 to replace existing flumes
Flume 44
—two phases of construction planned in 2016 and 2017 to stabilize the bench and slope and replace the existing flume
Flume 45 Bench Stabilization
—construction planned to commence in 2019
Flume 48
—construction planned in 2020 to stabilize the unmortared hand-stacked rock bench and full replacement of the wood flume structure

 

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EID is a public agency dedicated to providing high quality water, wastewater treatment, recycled water, hydropower, and recreation services in an environmentally and fiscally responsible manner.

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