Geothermal an all-purpose clean energy source

Michael Raffety, July 7, 2013

As a rare June California rainstorm added drama to the skies of northern Nevada a little known revolution has been slowly evolving on the ground.

In the Basin and Range geology that distinguishes northern Nevada from its southern desert area are hot springs and hot wells that are powering this state and wheeling power to California’s Independent System Operator based in Folsom.

Ormat Technologies Inc. (ORO on the NYSE) geothermal power plant in Reno puts out 100 megawatts, enough to power every residence in that city.

Not only that but several subdivisions in Reno have their own 180 degrees Fahrenheit geothermal wells that heat houses and swimming pools in Nevada’s freezing winters. The Peppermill Casino has a 100-degree geothermal source in its parking lot that helps provide hot water. One of the guides on a press tour of geothermal power June 25 even had a backyard capped geothermal well on which sat a doghouse. In the winter the dog didn’t really want to leave his warm doghouse to come inside. That changed when the cap rusted out and the freed well blew up the doghouse. (The dog was uninjured.)

But power generation is not just running hot, steamy water through a pipe to a turbine. Ormat’s success hinges on its binary technology. It’s a heat exchange system on a large scale.

Ormat’s Steamboat Springs complex is recognizable by the odd-looking collection of closely spaced pipes that hug the ground as seen from U.S. 395. Even more is visible now that the six-lane new section of 395 is open after Nevada spent 10 years building it alongside the foothills, bypassing the 45 mph section winding along the valley floor. Open about three months, it is so new it confuses new Garmins.

Another characteristic of Ormat’s Steamboat Springs’ square mile of geothermal property is pine trees and pinion pines. The presence of these trees is a tipoff that the soil is low pH and is a likely site of a geothermal resource.

Ormat’s first Steamboat Springs unit was built in 1983. The press tour that kicked off the Geothermal Energy Association’s National Geothermal Summit looked at the Ormat’s newest Galena Unit, built in 2009. Galena is two generators that together put out 36 megawatts. It is the seventh unit at Steamboat Springs.

Ormat has been able to continue generating power off its geothermal wells because it continually recirculates the water back into the ground. The water comes out of the ground at 300 degrees Fahrenheit, heats pipes containing pentane hydrocarbon, which vaporizes at 80 degrees. The pentane is binary element that turns twin turbines, one clockwise and the other counterclockwise at 1,800 rpm on both sides of the generator. Galena has two sets of generators. When the water is returned into the ground it is 100 degrees cooler. The binary element is cooled back down to a liquid with the aid of cooling fans. The hot water circulates back through the geothermal reservoir and comes back up the pipe at 300 degrees. Pressure is only 100-150 psi.

The value of geothermal is it involves no exhaust. The geothermal water is continually circulating even if the turbines are shut down. The turbines can be instantly reactivated within two minutes.

“It has incredible flexibility. We can ramp up and ramp down,” said Paul Tomsen, director of policy and business development for Ormat.

It is this “clean green” factor of geothermal power that has Ormat talking to the California ISO and will get the company 99 cents a kilowatt. for base load. Wind and solar sells for 60 cents a kilowatt because it requires gas power to back it up, according to Thomsen.

Ormat has been building its seven units on Steamboat Springs over the past 30 years.

From the control room at the Galena unit two operators monitor all seven units at Steamboat Springs and 15 “recovered-energy generation” units as far east as Chicago. These are binary systems that tap into the heat generated by natural gas line compression stations. They generate anywhere from 250 Kw to 6 Mw, partnering with companies like Northern Borders and Kinder Morgan Energy Partners.

A partial list of geothermal and recovered energy projects Ormat has developed includes places like Texas, Alaska, Germany, Austria, Canada, Hawaii, Wyoming, New Zealand, Mexico, Central America, the Azores and Kenya.

Not bad for a $1 billion market cap company headquartered in Reno. The small market cap company issued its first initial public offering of stock in 2004.

About 60 miles east of Reno Ormat has its Brady geothermal power plant. Before its geothermal water is returned to the ground it is used by a nearby onion plant to dry onions and turn them into items for the spice rack. Northern Nevada has geothermal power plants sprinkled all over the place. As the press tour bus headed two and half hors east of Reno four geothermal drilling rigs were spotted on the horizon to the south.Drilling is the biggest risk in he geothermal business, costing $5 million-$8 million and  not always proving productive. Most wells go 1,800 feet deep, though some will go 9,000 feet deep.

Geothermal is not the exclusive province of Nevada. The Geysers in Sonoma County are home to 15 steam operated power plants by Calpine Corp. that produce 725 megawatts of electricity, enough to power a city the size of San Francisco. Calpine rejuvenated the Gesyers by injecting wastewater from Lake County and the city of Santa Rosa.

Ormat has its eye on some geothermal possibilities in Southern California. Nevada has always been noted for its hot springs, from Wally’s Resort to Black Rock Desert, though some are too hot to touch. Forty states have hot springs, including Kansas, which indicates the possibility of geothermal power generation. Oregon likewise has hot springs, one heating a locally famous swimming pool outside Baker City called Radium Hot Springs.

About 150 miles east of Reno and 60 miles south of Winnemucca is the Florida Canyon Mine. When the open pit mine dug down deep enough to hit geothermal water it found that out when it drilled holes and packed in dynamite to be set off the next day. When the miners showed up the next day they found the dynamite had already gone off, set off by the heat near the cap of the geothermal area.

For the time being the mine’s current owner, Jipangu International Inc. out of Japan is putting its mining efforts into the nearby more lucrative Standard Mine, though a permit may be sought in the near future to reopen the Florida Canyon Mine.

What remains of the Florida Canyon Mine, originally opened in 1986, is a mountain of gold-bearing ore — 400 million tons sitting on a thick plastic sheet and covered with drip irrigation that has a weak arsenic solution that leaches through the heap of material and send out 50 ounces of gold-silver combination per day. Half the mountain of material dug out of the open pit mine has been restored to natural vegetation and yet gold is still leaching out of the bottom even though it is no longer receiving the arsenic irrigation, according to mine superintendent Joel Murphy.

The leach field takes 30,000 gallons of water a day. Half a million gallons will evaporate on a hot day. So the mine operators have to do a lot of pumping to keep the heap leach field watered. The water they have to work with is 225 degrees F. It is fed into a pond where it is cooled and then sent to two pump houses. One of those pump houses feeds into a 50 Kw generator that helps reduce the electrical expense of pumping and provides additional cooling for the water.

This 50 kw generator is an experiment backed by a nearly $1 million Department of Energy grant, which is why Geothermal Summit participants were all abuzz about President Obama’s June 25 speech on reducing carbon emissions.

The Electra Therm Inc. system fits in a small cargo container, complete with forklift slots underneath. The heart of the generator is a titanium heat exchanger. Geothermal hot water runs through the heat exchanger and heats a refrigerant called penta fluoropropane lubricated with a little oil. It is also called HFC R49F1 and it boils at 58 degrees F.

The generator unit is safe enough to put inside a building, said  systems engineer Andrew Oxner.

The titanium in heat exchanger is very lightweight. Oxner, on the way to the mine, told a story about how America got a large supply of titanium. A geology graduate of the University of Nevada, Reno, Oxner recalled finding the remains of an SR-71 Blackbird spy plane in the desert that had hit the ground at Mach 4 after the crew had made the highest altitude ejection in 1969. Russia has the largest supply of titanium. The U.S. imported a lot of titanium in the late 1950s “to make golf clubs.” Instead it went into making the SR 71, which in turn was used to spy on Russia.

Now that most of the SR-71s have been junked they may be reincarnated as a titanium heat exchanger on an Electra Therm 4000 portable 50 kw geothermal generator, remotely operated by a cell phone app.

Less than 10% of Domestic Irrigation customers switch

Michael Raffety

Mountain Democrat, 2/14/13

The Domestic Irrigation water rate category was eliminated as of Jan. 1, but only just under 9 percent of the DI customers qualified and applied for conversion to the Small Farm or Agriculture Metered Irrigation rate, according to a report given to the El Dorado Irrigation District Board of Directors Feb. 11.

There were 1,230 Domestic Irrigation water rate customers, according to Interim Utility Rate Manager Jenny Downy, but only 108 qualified for the Small Farm or AMI rates. The remaining 1,122 customers have been changed to the Single-Family Residential water rate.

Domestic Irrigation was discontinued after EID completed a Cost of Service Study and found it did not meet the principles established in the Cost of Service Study. Further it was a subsidized rate class and because it was closed to new applicants as the district waited for attrition to whittle down its rate class members, it no longer fit the “fair and equitable” provisions of Proposition 218.

To qualify for the Small Farm rate property owners had to have a certain amount of property under cultivation and pass an inspection by the county Agricultural Department. That inspection is renewed every three years.

In the same report given it was noted that the staff has been auditing AMI accounts. Out of 225 audited 73 were identified as “needing field verification.” After field audits 33 customers were mailed letters “informing them we were unable to determine if they currently qualified for the AMI rate.” They were asked to reapply if their property met the criteria for the ag rate.

Director George Osborne was first elected to the board in 2001 as a candidate that was part of a successful recall election. One of the issues in the recall was the board’s elimination of the Domestic Irrigation Rate, which Osborne promised to restore. He succeeded in getting the board to overturn previous action eliminating the DI rate.

Eventually, though, that rate class was frozen. There were 2,700 Domestic Irrigation water rate customers, but that rate did not attach itself to the property, so when property was sold a DI customer disappeared. By March of 2012 when the DI rate was highlighted at an EID workshop, the number had been whittled down to 1,300.

As of Aug. 27,. 2012, there were 1,230 Domestic Irrigation Customers and Jan. 1 there were none, though 108 qualified for a switchover to one of two existing ag rates.

COLA added: EID employees to pay bigger share of benefits

Michael Raffety

Mountain Democrat, 2/26/13

A three-year contract extension amending four articles of the Memorandum of Understanding originally reached with El Dorado Irrigation District Employees Association in 2010 will save the district $3.1 million over the next three years, according to EID Human Resources Director Vicki Hoffman.

As a result of the Public Employees Pension Reform Act employees will have to pay 50 percent of pension costs, which will be the 8 percent that is the employee’s portion of pension contributions. The employer also has an 8 percent match, but it is the employee’s share that is used first upon retirement. The employer’s match is only consumed if the employee outlives his portion of the pension.

The Letter of Understanding employees agreed to Feb. 15 means the district will no longer pay 100 percent of the employees’ 8 percent. In March the employees will pick up 2 percentage points of the 8 percent. Another 2 percentage points will be shifted to the employees in November. The employees had been paying 4 percentage points of their CalPERs costs since Jan. 1, 2012.

The EID board approved the LOU 4-1 in a public meeting Feb. 25.

New employees will have to pay the full 8 percent immediately, the LOU stated. New employees will also have to wait to age 62 instead of 55 to retire. The pension calculation for new employees is 2 percent, the same as county employees. Older employees at EID are on the 2.7 percent at 55 formula.

Additional savings come from increasing the share of health benefit costs for employees. Using the Kaiser plan as a benchmark, the Letter of Understanding states that if Kaiser premiums increase 10 percent for dependants of employees and retirees the cost sharing will go “up to a maximum of 85 percent-15 percent split. That cost sharing split becomes permanent in 2016.

And, “Plans that exceed the cost of the benchmark plan require a greater employees/retiree contribution.”

The sweetener that helped the employees agree to take-backs was cost of living increases in 2014, 2015 and 2016 based on the Consumer Price Index but not to exceed 2 percent.

Additionally 50 percent of the employees in 2014 will be eligible for a 5 percent merit step increase. For water treatment plant and sewer plant operators that means additional education is required to advance a step. The top step is Step 5. By 2016 only 10 percent of employees will be eligible for merit increases, Hoffman told the board.

In an email followup Hoffman told the Mountain Democrat that this year 46 percent are not eligible for merit increases because they are at the top step. in 2014  67 percent are not eligible, in 2015 the figure not eligible is 79 percent and in 2016 it will be 90 percent.

Between cost of living increases, merit pay and pension reform the cumulative savings of the three-year life of the LOU is $822,000, according to Hoffman’s PowerPoint presentation.

“I’m disappointed we’re still giving out raises,’ said Director Alan Day, who voted against approving the LOU.

“You pay for experience,” said Board President George Osborne, adding that employees, especially certificated ones will go to higher paying districts.

“The health care (plan) had a little more, but it’s nibbling around the edges,” Day said.

“We don’t yet know what the impact of Obamacare,” Osborne said.

“I am surprised that the vote was not unanimous because of the significant savings realized for EID’s ratepayers,” Osborne said after the vote. “All board members participated in several months of closed session meetings on this LOU, and the final product reflected all board members’ priorities.”

“I am very pleased that the employees recognized the importance of implementing these pension reforms early. It will generate substantial savings for our district and its ratepayers — which include most of our employees,” said EID General Manager Jim Abercrombie in a statement released after the meeting. “We acknowledge the collaborative effort to reach this agreement, and I truly believe it fairly balances employee and ratepayer interests.”

“The employees recognize the fiscal strain the district has been under for the last few years. Most of us are ratepayers as well as employees and we feel the crunch of rising utility and living costs,” said Employee Association President Doug Venable in a statement released after the meeting. “The association and management were able to reach an agreement that satisfies the priorities of budget reduction and long-term stability. Although this contract is an overall loss for our employees, we voted overwhelmingly to ratify the new terms of the MOU. We want to thank management and the district Board of Directors for working with us through this process.”

“I thank the staff for their cooperative firmness but fairness, said Joe Rose, attorney for the Employees Association. “It’s a reasonable compensation package to retain employees. It’s difficult to attract and retain water and sewer workers.”

“Go back to the table. To give half the employees 7 percent is unacceptable, said Sherrie Petersen of El Dorado Hills.

“Our doubling of water rates have a very short-term effect on the cost of living,” Day said.

Greg Prada of Cameron Park noted the water rate increases had been 102 percent. “Two percent and 5 percent on top of that is not fair and equitable to the ratepayers.”

“Sixty-five percent of the operating budget is employee costs.,” Prada said. “You’re locking in rates. This world will not end if this is not approved today.”

Day made a motion to delay the vote for one month to allow the public more time to comment, but failed to get a second. The other four directors voted to approve the deal with the employees union.

Delta Water Master tries to grab EID water

 

Michael Raffety

Mountain Democrat, 1/5/13

Despite adverse court decisions the state is still aiming to take some of the El Dorado Irrigation District’s water rights, many of which predate the Water Commission Act of 1914 and even more predate the 1927 Fiegenbaum Act. That latter act exempted prior water rights from the due diligence requirement as the state applied for unallocated waters to use for the State Water Project and the Central Valley Water Project.

A Dec. 4, 2012, report from the State Water Master to the State Water Resources Control Board calls for the state to take control of all water rights, even those predating 1965 and predating the 1931 law protecting county-of-origin water rights.  The technical term used by the State Water Master is Term 91. That provision would allow the state to force EID to surrender water to the state whenever it called for it.

The state tried to apply that term to EID’s water rights application for 17,000 acre-feet of water from the South Fork of the American River. This water is released from storage in four alpine reservoirs, diverted from the river near Kyburz and sent through 22 miles of canal, flumes and tunnels, all of which originally were built between 1874 and 1876. The water rights for this system — now called Project 184 — date to 1856.

When PG&E owned this project and the 21-megawatt powerhouse the State Railroad Commission ordered in 1919 that the electric company provide El Dorado County Water Users Association 15,080 acre-feet of water. When EID bought Project 184 from PG&E in 1996 it was able to claim an additional 17,000 acre-feet of water. The original state-filed application in 1927 had been for 70,000 acre-feet.

The state granted EID the 17,000 acre-feet in November 1996, but in 2001 decided to add Term 91 to it, making it subject to release for the Delta when called by the state. El Dorado County sued the state, saying it had no right to apply Term 91 to its 17,000 acre-feet of water rights. Concurrent with that the Sierra Club’s legal arm sued, claiming EID didn’t have a pre-1914 right to the 15,080 acre-feet. Those two suits dating from 2001 were consolidated and Judge Lloyd Connolly issued a ruling in 2003 favorable to EID. It voided the state water board’s action to apply Term 91 to its 17,000 acre-feet and also said the board had no jurisdiction to require EID to prove its pre-1914 water rights.

Despite this ruling, the State Water Master, with little legal basis, issued a report stating, “It is the recommendation of this report that the requirement to curtail diversions of released stored water be extended to all water rights holders on a phased basis pursuant to relative water rights priorities where the release of such stored water is being used to meet water quality standards.”

Delta Water Master Craig M. Wilson further specified “curtailment letters”, aka Term 91 notices, should be sent to pre-1965 and pre-1914 water rights holders.

EID General Counsel Tom Cumpston, told the board Jan. 14 that the Delta Water Master and a team of 30 enforcement officers were originally tasked with ferreting out illegal diversions and pumps in the Delta.

“Their own investigation found illegal Delta connections were not a problem,” Cumpston said.

“What the Water Master is suggesting has no foundation in law,” Cumpston said. He noted that the California Supreme Court has said that seniority is the foundation of water rights.

Imposing Term 91 on EID’s pre 1927 water rights “poses a fundamental threat to EID,” Cumpston said.

Altogether EID has 77,590 acre-feet of annual water entitlements, according to the 2012 update of the 2010 five-year water plan it submitted to the U.S. Bureau of Reclamation in September: 7,550 ACF of contract water from Folsom Lake, 15,080 plus 17,000 from Project 184, 33,400 from Jenkinson Lake in Sly Park and 4,560 from ditches and Weber Reservoir. Water rights to diversions from Slab Creek, Hangtown Creek and Weber Creek date back as early as 1853 – 160 years ago.

Additionally, 15,000 acre-feet of water was granted by an act of Congress named after its author, Vic Fazio. That water entitlement is still pending. Also in the future is a pending application for 40,000 acre-feet of water to fill space in existing reservoirs that the Sacramento Municipal Utility Districtis contracted to make available to El Dorado County. That contract also includes a drought storage agreement with SMUD to hold 15,000 acre-feet for EID.

Monday the EID board unanimously approved $196,875 for its share of expenses for the El Dorado Water and Power Authority’s pursuit of water rights for this SMUD reservoir storage.

EID gets a break on state conservation rule

By Michael Raffety

Mountain Democrat, 2-26-14

The El Dorado Irrigation District will get extra credit for using recycled water in meeting the state’s requirement to reduce water consumption 20 percent by 2020.

Legislation passed in 2009 set that 20 percent by 2020 rule.

EID is meeting that goal in part by using as its baseline the daily per capita water use in the 10-year period of 1997-2006. It did that because recycled water supply was less than 10 percent of its total supply in 2008. Out of the four methods offered by the state Department of Water Resources, EID chose Method No. 1 that calculated 80 percent of the base daily per capita use.

That baseline per capita use was 281 gallons per capital daily. That method, along with the baseline calculation mentioned above, was accepted by the state in 2012 after EID submitted its 2010 Urban Water Management Plan.

So how are the district and its customers doing? Currently they are using a little above 240 gallons daily per capita. That is below the 2015 goal of 253 gpcd, but above the 2020 target of 225 gpcd.

The trend has been downward. EID’s 10-year average gallons per capita daily is 277, the five-year average is 254 and the three-year average is 242.

Those figures will trend lower if EID succeeds in getting the state Water Quality Control Board to reduce the amount of recycled water EID is required to send down Deer Creek from 1 million gallons per day to 500,000 gallons per day. That extra half million gallons per day then can be sent into the recycled water system instead of supplementing it with potable water during the summer irrigation season. The more new recycled water customers EID hooks up in El Dorado Hills, the lower its per capita consumption becomes incrementally.

EID seeks to keep more of Deer Creek’s recycled water

Michael Raffety

Mountain Democrat, 2-26-14

“Give us back our water,” the El Dorado Irrigation District will ask of the state water board.

On a 4-0 vote, with Director George Osborne absent, the EID board Monday approved a two-pronged plan for the Wastewater Treatment Plant to quit sending 1 million gallons of high-quality recycled water down the creek every day.

The first element is for EID to seek a temporary exemption from that requirement because of the drought. During the irrigation season it will save 300 out of the average of 436 acre-feet of potable water that are used to supplement the recycled water sold to homes in Serrano, Serrano Golf Course and subdivisions along Latrobe Road. That savings would come from cutting the discharge into Deer Creek in half to 0.5 million gallons per day.

Because of the governor’s emergency drought declaration the district can get a temporary exemption from the 1 mgd requirement for 180 days, with the possibility of one renewal should another drought year follow this one.

The second prong is a longer-term effort to get that 1 mgd cut in half permanently. That requires a petition to the State Water Quality Control Board, a formal environmental review and a hydrology study.

The benefit is a $210,000 savings to the district by substantially reducing the high cost of potable water that it has to sell at the lower recycled water rate as a supplement to meet all the recycled water needs. Potable water costs $1,200 per acre-foot compared to $500 per acre-foot for recycled water, according to Elizabeth Wells, engineering manager for wastewater and recycled water.

The case for the permanent reduction in discharge into Deer Creek is being aided by Dr. Michael Bryan of Robertson-Bryon Inc. Bryan is an aquatic toxicologist, who has consulted on a number of issues relating to the Deer Creek WWTP and has saved the district millions by convincing the state water board not to impose various new discharge requirements. He has been consulting on Deer Creek for 19 years.

Of the 1992 hearings that forced the district into discharging 1 mgd from the Deer Creek plant, Wells said, “We felt the evidence was loosely based and not based on scientific evidence.”

Bryan is providing that evidence, first by doing a detailed hydrologic analysis of Deer Creek. “I’m really impressed by the quality of the modeling,” Wells said.

In discussion with California Department of Fish and Wildlife, it was suggested that EID demonstrate that the creek was historically ephemeral downstream of the plant that was built in 1974, document the extent of surface flows downstream and what would be required to maintain the aquatic community.

What has been completed so far is a hydrologic analysis, gathering of current and past ecological information and development of a hydraulic model for Deer Creek.

That included collection of aerial photos from 1954 through 1973, which show that the riparian vegetation and ecological sources downstream of the sewer plant were doing just fine on their own. Bryan said the water went subsurface during the summer.

“No decrease in riparian density or corridor length is expected under 0.75 or 0.5 mgd scenarios, relative to the existing 1 mgd scenario,” Wells wrote in her report.

The next phase is doing an EIR that would be completed in late 2014 or early 2015. The final phase would be seeking a change in discharge petition from the State Water Quality Control Board.

At the Feb. 24 meeting, the board approved a nearly $26,000 contract for RBI and capitalized labor costs of nearly $30,000 for Wells, Wastewater Operations Manager Vicki Caulfield and Assistant General Counsel Brian Poulsen.

The EIR and petition were budgeted for $300,000 in the next three years of the current five-year Capital Improvement Plan. Wells indicated it could be half that cost if the district’s petition is not protested.

“It’s a water supply enhancement project,” said General Manager Jim Abercrombie.

“We will show there is a higher and better use of the water,” Bryan said.

100-year lifetime: Flume 41 totally rebuilt

By Michael Raffety

Mountain Democrat

One of El Dorado Irrigation District’s biggest and most complicated flume projects is complete with the exception of some mechanical, electrical instrumentation and control work still under way, though the canal has been watered back up.

Project engineer Daryl Noel gave a report to the Board of Directors Jan. 27, including dramatic video footage of two contract workers, secured by safety lines, jack hammering a huge boulder on the hillside, which then rolled downhill and crashed into a section of wooden flume that was to be demolished anyway.

The wood from the flume timbers proved to be so rotten that it could not be recycled as originally planned.

Removing hazardous boulders and trees on the uphill side of the flume to protect the replacement flume against damage was one of the elements that added expense to the project.

The $5.8 million project replaced 700 feet of rickety wooden flume with cast concrete flume sections and relined 600 feet of canal. Also replaced with a concrete structure was Spillway 23. That spillway, part way into the 700-foot-long Flume 41, was a wooden structure whose supporting posts were resting on rocks placed on an unstable slope.

The flume had been relined by PG&E in 1948. Plywood had been added in 1978 to extend its life until a more permanent project could be implemented.

The concrete flume section will have a 100-year lifespan, according to Noel.

Flume replacements, whether concrete or wooden, are done in October when water to the El Dorado Canal is shut off until December.

Work on Flume 41 actually started in the summer, enabled by having previously spent $1.5 million to upgrade and extend Rock Crusher Road, which saved paying $13,000 an hour for helicopter service to bring in equipment and concrete flume sections. Total helicopter services for the construction project would have been $1.5  million-$2 million, according to Noel. Additionally, the new road provides access to other canal sections and saved having to pay a helicopter to remove empty propane tanks and replace them with full ones to run a generator that operates Spillway 23. Now the propane delivery truck can drive to the new generator shed’s propane tanks.

The work done by contractor ProVen during the summer was to stabilize 450 feet of stacked rock wall serving as a base for the flume since 1876. Two years prior Carlton Engineering had drilled into the stacked rock wall and found it to be stable with minimal voids — 30 percent. Carlton and EID engineering staff came up with an innovative design that saved $700,000-$900,000 by not having to replace the stacked rock foundation.

The work done in the summer was to cover the stacked rock wall with rebar and shotcrete. After the shotcrete set up, holes were drilled all the way through the stacked rock wall and into solid granite behind the rock wall. Anchor bolts were inserted and shocrete pumped into the tubes to bind the anchor bolts to wall and base rock.

After the wooden flume was demolished, holes were drilled from the top of the rock wall at 20-foot intervals and shotcrete was pumped in to fill the voids in the stacked rock wall. The rebar-and-shotcrete exterior wall kept the vertically injected shotcrete contained within the stacked rock.

Upstream of Spillway 23 the flume base for 250 feet was unstable. The contractor dug down to base rock and anchored a concrete retaining wall to the base rock and also to the new concrete base for Spillway 23.

On top of the concrete retaining wall another wall of MSE (Mechanically Stabilized Earth), held in by a stepped formation of wire cages, brought the level up to that needed for the concrete flume foundation.

The flume is part of the 22-mile-long El Dorado Canal, which brings water from four alpine reservoirs at 8,000 feet elevation. The water is captured by a diversion dam on the South Fork of the American River near Kyburz and sent into the canal. The whole system, called Project 184, provides one-third of the district’s water and serves customers all the way to El Dorado Hills in the winter when the pumps from Folsom Lake are normally shut down. It also runs a 21-megawatt powerhouse. Water rights associated with Project 184 date to 1856.

EID’s 2014-2018 Capital Improvement Plan lists two major flume projects — Flume 52A estimated at $1.7 million in 2017 and Flume 42-43 estimated at $3.2 million in 2018.

Replacing the El Dorado Conduit, a rusted pipeline clinging to the side of a granite wall and bringing water from Echo Lake to the South Fork of the American River, is estimated to cost $800,000, including engineering and materials.

Replacing the Camp 2 Bridge this year is estimated to be $1 million. In its current condition it cannot support heavy machinery, only pedestrians and a quad runner.

Five flume projects are under study — Flumes 45, 4, 44, 47 and 48.

“What we are doing at this time is reviewing the remaining flumes that are a high priority for replacement to determine the most feasible method for replacement.  That includes replacement with wood, concrete, or bypass with a tunnel. Who will perform the work will be determined later. The current CIP has each flume identified, but that is subject to change based on the upcoming feasibility report.  The board will receive an information item at the Feb. 24 meeting on the subject,” said Cindy Megerdigian, EID water and hydro engineering manager in an e-mail.

The list of tentatively scheduled meetings included on the Jan. 27 board agenda shows feasibility studies for Flumes 42-48 as an information item on the Feb. 24 agenda and again on the March 10 agenda.

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