September 25, 2018 - 17:50 admin
SCE prepares Mineral King waterways for winter
September 21, 2018
Driving through Three Rivers and entering Sequoia National Park, one can’t help but notice at least two power houses (Kaweah numbers 1 and 3) and sections of flumes that furnish water to all three local powerhouses (Kaweah No. 2 is off the main highway on Kaweah River Drive).
Together, the three generating stations are capable furnishing 8.5 megawatts of clean, sustainable energy. That’s four times what would be needed to power every household in Three Rivers on the hottest summer day.
The Kaweah canyon system with its Kaweah No. 1 that began operating in 1899 (on Highway 198 ear the Mineral King Road junction), was not the first hydroelectric-generating station built in the U.S., but at the time its power was transmitted a greater distance than had ever been accomplished before anywhere.
The June 29, 1899, issue of the Tulare Times described the achievement of the Mt. Whitney Power Company, which developed and owned Kaweah No. 1.
“The Kaweah River makes all this possible. It can make our orchards prolific, run our cars, drive our machinery, lighten our darkness, and make thousands of people comfortable and happy.”
The East Fork flume that supplies Kaweah No. 1 was also built in 1899. It winds precariously around the contours of the mountains, hanging on steep granite ledges and is supported by long trestles high above the Mineral King Road until it enters a steel penstock above Three Rivers and cascades down 1,300 vertical feet to the powerhouse.
In the first 11 years of the 20th century, four dams were built in Mineral King at Franklin Lake, Monarch Lake, Crystal Lake, and Eagle Lake to help regulate the flow of water released into the East Fork to eventually enter the flume’s intake at Oak Grove. In late summer or early fall, the gate valves on the dams are opened; a month or so later, the gates are closed.
Billy Clough, Kaweah Country character
In the years leading up to 1917 (in 1917, Southern California Edison consolidated the Mt. Whitney Power Company holdings), the job of dam tender for the Mt. Whitney Power Company belonged to William O. Clough, a Mineral King prospector who is credited with the discovery and naming of Clough’s Cave just inside the South Fork boundary of Sequoia National Park. As his job entailed, after closing the valve at Eagle Lake for the winter on November 2, 1917 (this according to his diary found later), Clough departed to close Franklin Lake and the valves at the other two lakes.
Apparently, Clough perished in a snowstorm as he was never heard from again and never made it to his destinations. Some scattered belongings were located the next season in the Franklin canyon following the spring thaw.
In the days of Clough, it was a multi-day endeavor to open or close the valves of all four lakes. Today, the opening and closing task takes a half-day or less, accomplished by an SCE helicopter and two SCE hydrological workers who work the valves and record the season’s high water marks and flow data.
Opening the valves: September 18, 2018
In low flow years like the current one, it is especially important to open Mineral King’s gate valves in late summer to add a few more critical cubic feet per second (cfs) to the flow of the Kaweah River’s East Fork.
On Tuesday, Sept. 18, the workday for the Southern California Edison employees at Three Rivers, including the two charged that day with opening the valves in Mineral King, began like most others, with a 7:15 a.m. meeting to review assignments and safety procedures and to inform everyone as to what they will be doing and what’s expected.
Following the strategy meeting, the entire group formed a circle in an adjacent room where they performed a stretching routine, designed to help each worker avoid muscle pulls and strains while staying flexible and injury-free. Next, the couple dozen workers head out in different directions to jobs consisting of powerhouse maintenance, flume inspection and repair, and overseeing contract work at the penstock being repaired at Kaweah No. 3 near the Sequoia National Park entrance station.
To prepare for their flight to Mineral King Derrick Tito, hydrographer, and Karl Coffman, hydro operator, climbed into their work truck and headed up-canyon to the Ash Mountain Helibase to await the arrival of the SCE helicopter and their pilot. The weather was ideal for a visit to SCE’s four historic dams.
Within an hour, the sleek, distinctively emblazoned SCE green and yellow A-Star helicopter touched down at the Ash Mountain Helibase. After a thorough review of safety procedures and what to do and not do in case of emergency, with Alan Hogan, SCE pilot, the party of four (including John Elliott of The Kaweah Commonwealth onboard to document SCE’s Mineral King work), the light utility helicopter was airborne and on its way up the East Fork canyon.
The 25 miles to the Mineral King Valley was accomplished in under five minutes by air and the helicopter was soon circling the steep Monarch canyon and the Franklin Lakes drainage to ascertain wind direction and spot landing sites near the lakes’ dams. Southeast of the ridge below
Monarch Lake, Pilot Hogan spotted a bald eagle circling hundreds of feet below looking to make its landing in a large nest in the top of a snag of an ancient, bleached-out foxtail pine.
Soon after, Hogan was setting the helicopter down on a relatively flat spot on the flank of Sawtooth Peak and adjacent to the dam at Monarch Lake. Coffman attached the handle to the valve and after several cranks a steady stream of cold, clear lake water gushed from the pipe. Tito found the season’s high-water mark for Monarch Lake and recorded his observations in a log book.
Knowing the flow
As water experts, Coffman and Tito both eyed the added flow below the dam and estimated it at two cfs. Tito said his ability to estimate water flow accurately was based on years of taking similar readings; 16 years in Mineral King alone.
“You can estimate the [standard] flow that comes out of these valve openings then eyeball the width of the channel,” Coffman said, who was participating in his second aerial commute to Mineral King for work. “This flow here at Monarch will add two cfs, and if you add similar flows for the other three lakes that will add up to 10 or 11 cfs.”
Tito said they can actually take readings downstream and calculate exactly what the added flow represents.
“When you think of the total cfs in the river now, this added water represents about a 40 percent increase,” he continued. “In normal circumstances that increase could be the critical difference for Kaweah No. 1 to be up and running at full capacity.”
Rockslide takes Kaweah No. 1 offline
In 2018, the water will provide a more sustainable flow for downstream users, including fish and wildlife. But because a rockslide a couple months ago destroyed a remote section of the East Fork flume, Kaweah No. 1 is currently offline.
No completion date for flume repairs has been set.
All in a day’s work
The process of finding a landing spot and opening the valve on a dam was repeated three more times that day but because Crystal Lake is situated in a such a steep and narrow canyon, the winds created a landing risk, so Hogan thought it prudent to drop two of the passengers — Tito and Elliott — at Eagle Lake while Coffman was transported to open the valve at Crystal Lake.
Tito accomplished the Eagle Lake task by the time the helicopter returned from its Crystal dam destination. The Eagle Lake crew reboarded the helicopter “hot,” which means stay low, board quickly, and don’t get in the way of the whirring blades.
On Monday, Oct. 22, the SCE crew is scheduled to return to Mineral King to inspect the dams and close the gates for the winter, as has been a Kaweah Country tradition for more than a century.