Click here to read the summary. Here’s an excerpt:
The Colorado River District owns and operates the Ritschard Dam forming Wolford Mountain Reservoir near Kremmling in Grand County. It is a clay-core, rock fill dam that has experienced settling beyond the amounts normally expected by designers for a dam of this type.
The dam is safe and will connue to be safe in the future, according to the District’s engineering staff. Engineering consultants engaged by the Colorado River District to study the problem since 2009, as well as the Dam Safety Branch of the Colorado Division of Water Resources agree that the dam is safe and poses no danger.
To maintain that standard, after an aggressive five-year investigation that included installation and monitoring of sophisticated instruments to measure the movements, the Colorado River District will decide this year on a renovation and repair scenario.
Since the dam was constructed in 1995, it has settled near its center by about two feet, a foot more than anticipated. Along with this settlement, the crest of the dam has shifted downstream by about eight inches.
Engineering consultants engaged by the Colorado River District to study the problem since 2009, as well as the Dam Safety Branch of the Colorado Division of Water Resources say the dam is safe and poses no danger.
Out of an abundance of caution, Colorado River District Chief Engineer John Currier said enough informaon has been compiled to identify by mid-year the repair options and advise the Colorado River District Board of Directors on the proper one to choose.
Consultants from AECOM (formerly URS) and River District staff briefed the Board of Directors on the condition and analysis of the dam at its January quarterly in Glenwood Springs.
“We as a staff think it is incumbent upon us as an organizaon to really start moving this issue down the road,” Currier said. He noted that computer modeling of the selement suggests that in future years, safety might be compromised, so a solution will be identified this year.
Although Colorado’s chief of dam safety has not placed an operational restriction on the dam, the Colorado River District will continue with the cautionary policy it began in 2014. Once the reservoir fills this spring, it will be immediately lowered by 10 feet in elevation. The lower water level has been shown by instrumentation to slow down settlement trends.
According to Currier, at that lower level, the Colorado River District can still meet its water contracting delivery needs, as well as obligations to endangered fish releases to the Colorado River.
Also still protected is Denver Water’s leasehold interest in a portion of the storage that it employs in dry years to compensate for water it stores in Dillon Reservoir out of priority over Green Mountain Reservoir. At 10 feet down, recreational use will not be adversely affected.
By the Board’s quarterly meeting in July, AECOM and staff will have repair scenarios to consider, including comparative costs.
AECOM engineers told the Board that the culprit in the settlement was a poorly compacted rock fill shell that surrounds the clay core on the upstream and downstream sides.
In such a dam, the clay core material is the impervious element in the dam. The rock fill shell supports the core. All dams, whether concrete or earthen, seep water.
At Ritschard Dam, filters meant to collect seepage are in excellent shape and are doing their job. Seepage does not show any effects from the settlement, Currier said.
More Colorado River District coverage here.
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The Ouray County Water Users Association hopes to score $50,000 in grant dough for engineering #ColoradoRiverMay 17, 2015
From the Ouray County Plain Dealer (Sheridan Block):
Making an effort to be prepared for the state’s uncertain water future, Ouray County water users are taking necessary measures to protect their supply.
In a joint discussion on the state of local waters last month, local water user groups left with a general consensus of pursuing a water engineering analysis, which would analyze data for the Upper Uncompahgre Basin and ultimately provide options for solutions to future water needs.
The analysis is estimated to cost about $50,000, and last week county attorney and representative on the Gunnison Basin Roundtable, Marti Whitmore, submitted a grant application for a joint project to the Roundtable.
“In talking with other people in the region, including people in the Colorado River District, everyone is supportive of such a widely supported and cooperative effort among many water users in Ouray County,” Whitmore told the Plaindealer. “This cooperative effort will benefit everybody. It’s a positive step in a positive direction and I’ve gotten a lot of favorable feedback.”
According to the grant application, the county (which for the project will also include the City of Ouray, Town of Ridgway, Ouray County Water Users Association and various Log Hill water user entities) is requesting $25,000 from the Gunnison Basin Roundtable and $25,000 from the Colorado Water Conservation Board.
More Uncompaghre River watershed coverage here.
Water districts seek study of Kendig Reservoir on West Divide Creek — Aspen Journalism #ColoradoRiverApril 30, 2015
From Aspen Journalism (Brent Gardner-Smith):
The Colorado River District and the West Divide Water Conservancy District are seeking $40,000 from the state to study the feasibility and cost of storing 5,000 to 15,000 acre-feet of water in a proposed Kendig Reservoir on West Divide Creek, 15 miles south of Silt.
The request was made Monday to the Colorado River Basin Roundtable, which reviews grants for the Colorado Water Conservation Board, a state water-supply planning agency.
“We think that now is really a good time to take a good, hard look at Kendig again,” John Currier, the chief engineer for the River District, told the roundtable Monday.
The Colorado River Basin roundtable recently identified Kendig Reservoir as one of its top-priority projects in the ongoing Colorado Water Plan process. (See project sheet).
A grant committee of roundtable members will now review the request, and the roundtable as a whole will vote it at its next meeting, scheduled for May 18.
If approved, the roundtable will send a letter in support of the funding request to the CWCB board.
“Basically dries up”
The dam and reservoir on West Divide Creek could bring late-season irrigation water to 14,000 acres of land on the mesa south of Silt, especially as it could feed an existing network of irrigation canals.
“The reservoir would store the early summer peak flows, which would allow late season irrigation demands to be met more frequently,” a feasibility evaluation from the Colorado and West Divide districts states.
“It would really be planned as a supplemental irrigation supply in West Divide, which is critically water short,” Currier said. “There are roughly 14,000 acres in West Divide that could use more water. The West Divide basically dries up by the end of the irrigation season.”
Other uses could include industrial, domestic, environmental, recreation and hydropower generation. Included among potential industrial uses is water for natural gas and oil operations.
Currier said that while the energy sector would not use nearly as much of the water in a new Kendig Reservoir as agriculture, energy producers would likely highly value the stored water and may contribute to the cost of the reservoir, which was estimated in 2011 to cost $40 million to $65 million.
West Divide Creek is a tributary of Divide Creek, which flows north into the Colorado River just upstream from Silt. The dam would be built in the channel of the stream.
Rights to water
The West Divide Water Conservancy District holds two conditional water rights from 1965 and 1979.
Together, the rights allow for storage of 18,060 acre-feet of water behind a 180-foot-tall dam on West Divide Creek. The dam, as envisioned at that time, would form a reservoir with a surface area of 257 acres.
By comparison, Ruedi Reservoir actively stores 101,280 acre-feet of water behind a dam on the Fryingpan River that is 285 feet tall, creating a reservoir with a surface area of 997 acres.
One goal of the feasibility study is determine the right size for a new reservoir, which would be built on private land that would have to be obtained by the water districts for the project to happen.
The application for money from the Colorado River and West Divide districts to study the feasibility of Kendig Reservoir states that “storable inflow” to the proposed dam site on the West Divide Creek site averages 12,000 acre-feet annually, but can drop to 2,000 acre-feet in dry years.
“This is in a location where you have limited supply in critically dry years,” Currier said. “So they are looking at how much carryover capacity is really required to create a firm yield. And what is that firm yield is a critical piece of this investigation.”
The rights for Kendig Reservoir are junior to the Cameo Call, a group of water districts that divert water under senior rights from the Colorado River, at the red-roofed roller dam east of Palisade. Earlier planning documents for the West Divide project also state that water from the Colorado River could be pumped uphill and stored in the reservoir.
The Divide in “Thompson Divide”?
The headwaters of West Divide Creek are near the western end of Four Mile Road, where Pitkin, Gunnison and Mesa counties come together.
The Garfield-Mesa county line, as it crosses West Divide Creek, would run through the proposed reservoir.
Some consider that Divide Creek is part of the namesake of the “Thompson Divide” area, which describes land on either side of a large ridge, with Divide Creek draining the west side and Thompson Creek the east.
Kendig Reservoir is part of the larger West Divide project that was studied by the Bureau of Reclamation as early as 1937.
The West Divide project was included in the 1956 federal Colorado River Storage Projects Act, which also authorized the dams that create Glen Canyon, Blue Mesa and Flaming Gorge reservoirs.
In 1966 Congress authorized construction of the West Divide project, but federal money was never appropriated for the project.
A fresh look
The original Kendig Reservoir was also intended to store water imported from the Crystal River basin, but the two districts abandoned that component of the project in 2014.
Currier said that was one reason it makes sense to take a fresh look at Kendig.
There is both a lower and an upper Kendig reservoir site. The lower site is the originally proposed location. The upper side is above a major water distribution canal. The two districts will now look at the general area covered by both sites for the optimum location.
“Additional study is required to identify optimal reservoir sizes, potential reservoir operation, the firm yield of the reservoir, geotechnical issues and project costs,” the engineering report states.
In addition to the current request for state money from the Colorado Water Conservation Board, the two water districts are also each proposing to spend $10,000 of their own money on the feasibility study, which is expected to cost $60,000.
The study is to be prepared by Wilson Water Group and RJH Associates, an engineering design firm, according to the application. A summary of the feasibility study report is due Dec. 31.
Editor’s note: Aspen Journalism is collaborating with The Aspen Times and the Glenwood Springs Post Independent on coverage of rivers and water. The Post Independent published this story on Monday, April 27, 2015, as did The Times.
More Colorado River Basin coverage here.
From CBS Denver:
The Ritschard Dam on Wolford Mountain Reservoir near the town of Kremmling has some residents in the area concerned.
There have already been a few public meetings regarding the dam in Grand County. The Ritschard Dam has a clay core and is filled in around that with rocks, but the dam hasn’t held its shape. Something has happened with the settling of all the material over the past two decades.
“In 2009 it was discovered that pieces of the dam have settled faster than was expected by designers,” Jim Pokrandt with the Colorado River District said.
Sophisticated monitors have been placed inside the dam. The crest of the dam has settled down 2 feet, twice as much as expected — and also shifted downstream 8 inches.
“We’ve been studying that since 2009, spent $1.5 million or more on this, and we really can’t say why exactly, other than there could be some compaction issues that date back to construction time,” Pokrandt said.
Engineers have said it’s the river district’s top priority, and not fixing the dam could send a devastating flood down the Colorado River.
“Public safety is not at risk and it won’t be at risk because we’re going to take this quick action,” Pokrandt said.
Exactly how the dam will be secured and fixed won’t be decided until later in the year. One idea is making the dam and reservoir bigger.
“You can imagine that if you’re going to fix a settlement issue you might be scraping off part of the dam and rebuilding it. How much, we don’t know.”
Forty percent of the water in the dam is owned by Denver Water. The rest is to ensure water in the river for endangered fish and water for municipalities on the Western Slope. But making the reservoir hold more water brings in a whole new set of issues.
“It’s premature to talk about what the exact repair scenario could be,” Pokrandt said. “There’s no quick fix.”
The Colorado River District board will likely make a decision on how the dam will be fixed by the end of the year.
More infrastructure coverage here.
From Aspen Journalism (Brent Gardner-Smith):
The Colorado River District board of directors was told last week it is time to address the consistent settling and movement occurring in Ritschard Dam, which holds back 66,000 acre-feet of water to form Wolford Mountain Reservoir, 5 miles upstream of Kremmling.
“The continued movement of the dam at Wolford Mountain Reservoir is the most important issue currently facing the River District,” states a Jan. 8 memo from John Currier, the chief engineer at the district.
Though the dam is far from being at risk of failure, if that happened at some point in the future with a full reservoir behind it, there is the potential for 600,000 cubic feet per second to run down Muddy Creek toward Kremmling, said Jim Pokrandt, communications manager for the district. Eighteen hours later, the massive surge of water would reach Glenwood Springs.
The board discussed the situation at the dam during a regular quarterly meeting in Glenwood Springs.
“We see this continued downward movement of about an inch a year, unabated, with no evidence that it is really going to slow down,” Currier told the River District board. “It is a significant concern and is something we need to address.”
Just 20 years old
The dam has an impermeable clay core that is covered on both the upstream and downstream sides with rock fill, including shale rock excavated on site during construction.
In 2008, engineers working for the river district noticed the dam had settled downward by a foot-and-a-half, instead of the expected normal settling of one foot.
They decided to install monitoring equipment, including inclinometers, which measure slope angles.
Engineers for the river district have since installed an increasingly sophisticated array of monitoring devices. And they’ve verified that the dam has now settled over 2 feet downward.
The dam has also moved horizontally, by 8 inches, at a location about 40 to 50 feet from the top of the dam.
Mike May, an engineer with AECOM, told the river district board that because of “poorly compacted rock fill,” the dam’s rocky outer shells are still moving, especially the downstream shell, and that the clay core of the dam, which is somewhat elastic, is also moving.
While the dam does not have “a global stability problem,” May said the concern is that if enough movement occurs, it could cause cracks in the clay core.
Water could then find its way into those cracks and start transporting material and widening the cracks, and then the dam could eventually be at risk of failing.
“If we lose the integrity of that core, at that point the threat we’re under is essentially having the dam completely fail,” Dan Birch, the deputy general manager of the river district, told his board of directors.
“And the scenario that happens when the dam fails is a lot worse than any flood that Mother Nature could create, and we’re talking just tremendous amounts of devastation and tremendous potential for loss of life,” Birch said.
“It is a very serious situation (that) as an organization we are, have been, and will continue to take very seriously,” Birch said.
State dam expert briefed
Bill McCormick, the chief of dam safety for the state of Colorado, was briefed on the dam’s situation on Jan. 14.
“Everyone involved (including the downstream public and the emergency management community) are now more aware of the dam’s operation than they ever have been before,” McCormick said via email on Jan. 22.
“The extensive investigations and analysis to date show that the dam remains strong and stable but that if left unabated, the movements could ultimately (in decades) create greater damage to the dam structure,” McCormick said. “The safety of the dam is being managed through the river district’s changes in normal operations, which include maintaining a reduced reservoir level and increased surveillance including real-time monitoring.”
The dam was last inspected by the state in November, and there are no restrictions yet in place from the state that would force the river district to lower the water level in the reservoir. The district did, however, voluntarily lower the water level by 10 feet in 2014 to take pressure off the dam.
Dick Davidson, a senior engineer and dam expert with AECOM, told the River Board it was his professional opinion that it was time to move toward a solution.
“We are not in an emergency, by any stretch, but we have definitely stressed our core beyond where we like it to be,” Davidson said. “So let’s figure out what we need to do. Let’s look at our options.”
One option is to spend up to $30 million rebuilding the dam.
Another potential option is to store significantly less water in Wolford Reservoir, which is about two-thirds the size of Ruedi Reservoir, in order to take pressure off the dam. However, that may buy the river district some time but not solve the problem.
A refined set of options is now expected to be brought back to the river district board at both its April and July board meetings.
Editor’s note: Aspen Journalism is collaborating with The Aspen Times and the Glenwood Springs Post Independent on coverage of rivers and water. The Post published this story on Wednesday, Jan. 28, 2015.
More Colorado River Basin coverage here.