Fixing ‘moving’ dam near Kremmling could cost $15M — Aspen Journalism #ColoradoRiver #COriver

Upstream side of Ritschard Dam, which forms Wolford Reservoir
Upstream side of Ritschard Dam, which forms Wolford Reservoir

From Aspen Journalism (Brent Gardner-Smith):

It could cost $15 million to dig up and recompact the rocks on the downstream side of the dam that creates Wolford Reservoir, north of Kremmling, in order to stop the dam from moving slightly, but steadily.

“It is a pretty significant surgery of the dam,” John Currier, chief engineer at the Colorado River District, told the district board July 22 during a presentation.

Ritschard Dam was built for the river district in 1995 by D.H. Blattner and Sons of Minnesota for $42 million. The dam is 122 feet tall and 1,910 feet wide.

The $15 million estimate to rehabilitate the dam includes a 35 percent contingency factor and is still preliminary, Currier stressed.

The project would include removing the top 25 feet of the dam and then stepping down the downstream face of the dam in layers to get to three “bad acting” zones of poorly compacted rock, some of which are 90 feet inside the dam.

“At some point that movement will compromise the ability of the core of the dam to hold back the water,” Currier said.

Currier said there are “no near-term safety concerns” regarding the dam’s current ability to hold back 66,000 acre-feet of water from Muddy Creek, which flows into the upper Colorado River east of Gore Canyon.

“We’re not in any crisis,” Currier said. “We’re just ready to move this forward.”

Engineers with the district noticed in 2008 that the dam had settled vertically by a foot-and-half instead of just 1 foot, as expected.

The dam has now settled 2 feet, at the rate of about an inch a year. And it has also moved horizontally, by about 8 inches, at a spot 40 to 50 feet below the crest of the dam.

The dam’s impermeable clay core is held in place by rock shells on both the upstream and downstream sides of the dam.

A detail of the rock outer shell on the downstream side of Ritschard Dam
A detail of the rock outer shell on the downstream side of Ritschard Dam

Trouble at some point

The upstream rock shell appears to have settled appropriately in place, perhaps because of varying degrees of water pressure on its face as reservoir levels have fluctuated.

But the downstream shell is still moving.

“At some point that movement will compromise the ability of the core of the dam to hold back the water,” Currier said.

Currier said construction-sequence photos indicate the movement appears to be related to how fill material above and below haul roads was compacted during construction.

The plan is to dig into sections of the shell, remove the poorly compacted rock, and then recompact those zones, mainly using the same rocks.

“The bad-acting layers may be more a function of how the material was placed, not the material itself,” Currier said.

Currier said a consulting engineer at the firm of AECOM had observed that the construction work is essentially “just a big dirt job,” albeit one that will require complicated sequencing and careful on-site supervision by experienced engineers.

Over the last six years staff and consulting engineers have taken a variety of steps to investigate the situation at Ritschard Dam.

A graphic of the issues at Ritschard Dam from the Colorado River District
A graphic of the issues at Ritschard Dam from the Colorado River District

$1.5 million spent

They’ve installed inclinometers, established an expert review panel, developed modeling and conducted lab tests on the core material to establish that the dam did not present an immediate safety problem.

The river district has now spent close to $1.5 million on instrumentation and analysis, Currier said, and recent work on a range of alternatives has given engineers enough information to move from the “what” stage to the “how” stage.

“We have a very good understanding of what solutions might, or might not work, and thus we can we have a great deal more confidence in our solution,” Currier said. “We’re confident that structural rehab is required.”

Currier said that simply storing less water in order to take pressure off the dam won’t solve the long-term problem.

In a memo to the board, Currier wrote “operating at reduced levels slows the deformation rate but does not stop the deformation.”

The river district has been operating the reservoir at 10 feet below normal levels since 2014 as a standard precautionary measure.

Another option looked at was installing a series of concrete columns down through the downstream shell of the dam in order to stiffen it, but Currier said it was ruled out due to higher costs and doubts about its effectiveness.

There is also the opportunity to increase the amount of water the reservoir can hold by increasing the height of the existing spillway, but Currier advised it was better to first just fix the dam to avoid a “permitting quagmire” by trying to also expand the reservoir’s capacity.

Water in the dam would likely have to be lowered or completely drained during the project in order to take enough pressure off the dam. Those lower water levels could cause ripples in regional water-supply operations, especially in a dry year.

But Dan Birch, the district’s assistant general manager, said water-supply concerns would not be the tail that wags the dog of the rehabilitation project and related safety concerns.

However, it was also noted that the project would take 220 days over two construction seasons and would likely have an affect on four years of water operations in all.

“It could have some impact on water operations for one year pre- and one year post-construction,” Currier said.

Currier and other engineers plan on continuing their analysis of the proposed solution, including meeting with the state dam safety engineer in August and continuing to ask a panel of experts to peer review the plans.

A refined proposal will be presented to the River District board in September as part of the district’s annual budget meetings.

Editor’s note: Aspen Journalism is collaborating with the Glenwood Springs Post Independent and The Aspen Times on coverage of rivers and water. The Post Independent published this story on July 27, 2015.

Ritschard Dam repairs are a top priority for Colorado River District officials #ColoradoRiver

Wolford Mountain Reservoir
Wolford Mountain Reservoir

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.

The Colorado River District, et al., are closely monitoring the settling of Ritschard Dam (Wolford Mountain) #ColoradoRiver

Ritschard Dam and Wolford Mountain Reservoir
Ritschard Dam and Wolford Mountain Reservoir

From the Sky-Hi Daily News (Lance Maggart):

Ritschard Dam impounds Wolford Mountain Reservoir, located on Muddy Creek just north of Kremmling. Construction on the Dam was completed in 1995 and falls under the auspices of the dam’s owners the Colorado River Water Conservation District.

Ritschard Dam is an earth-filled dam. As [Jim] Pokrandt explained, “With anything involving earth, settlement is expected.”

Unfortunately, as Pokrandt went on to explain, a portion of the dam has settled faster than the dam designers expected.

“The variations are small, but there is an abundance of caution,” he said…

“We are monitoring the conditions at the dam. The dam is not considered unsafe,” said Bill McCormick, chief of the Dam Safety Branch of the Division of Water Resources.

McCormick explained, “approximately four to five years ago there were anomalous instrumentation readings showing the dam had settled unexpectedly in ways that were not predicted in the design.”

“We have not identified a safety concern that has required us to put a restriction on the reservoir,” he pointed out.

According to Pokrandt, construction equipment visible on the dam is part of ongoing work to install measuring devices to gauge both water levels and movements within the dam.

Data collection and analysis regarding settlement of the earth-fill structure has been under way for several years now and the process will continue.

Pokrandt explained that any construction on the dam undertaken by the District, “will be very expensive” and the District wanted more information and data before any decisions were made regarding new construction.

More infrastructure coverage here.

Colorado River Basin: Denver Water, et al., are operating under the Shoshone Outage Protocol

shoshoneglenwoodcanyon.jpg

Here’s the release from Denver Water (Stacy Chesney/Travis Thompson):

Two back-to-back, drought-plagued winters in Western Colorado have triggered an agreement to “relax” a senior water rights call on the Colorado River at the Shoshone Hydro Plant to allow water providers to store more water this spring, a move that benefits Denver Water and the West Slope.

The Shoshone Hydro Plant is owned by Xcel Energy and is located in Glenwood Canyon. Its senior 1902 water right of 1,250 cubic feet a second (cfs), when called, is administered by the Colorado Division of Water Resources against junior water storage rights upstream that include Denver Water’s Dillon and Williams Fork Reservoirs, the Colorado River District’s Wolford Mountain Reservoir and the Bureau of Reclamation’s Green Mountain Reservoir.

The agreement “relaxes” the call to 704 cfs when river flows are low, or takes a Shoshone call totally off the river when flows are rising, which is the current situation. This practice gives the upstream juniors water rights holders the ability to store water once the spring runoff begins in earnest. Currently, the Colorado River is flowing through Glenwood Canyon at about 825 cfs. (The long-term historical average for this date is about 1,150 cfs.)

Two tripping points activate the agreement: when Denver Water forecasts its July 1 reservoir storage to be 80 percent of full or less, and when the Colorado River Basin Forecast Center predicts spring runoff flows at Kremmling in Grand County will be less than or equal to 85 percent of average. Currently, the reservoir forecast is 74 percent full on July 1 and the Kremmling forecast is 60 percent of average.

Denver Water has already enacted its Stage 2 Drought Restrictions to limit outdoor water use and enact other conservation measures.

The winter of 2012 was the fourth worst on record in the Colorado River Basin and 2013 has been tracking just as poorly. The only improvement between the two winters occurred in March 2013 as storms continued to build snowpack. By this time in 2012, runoff was already under way.
The relaxation period is between March 14 and May 20, in deference to boating season on the river and irrigation needs in the basin.

As for the water that Denver Water gains by the relaxation, 15 percent of the net gain is saved for Xcel Energy power plant uses in the Denver Metro Area and 10 percent is delivered to West Slope entities yet to be determined by agreement between Denver Water and the Colorado River District.

“This is a statewide drought, and we all need to work together to manage water resources for the health and safety of our residents, our economic vitality and the environment,” said Jim Lochhead, CEO/manager of Denver Water. “The Colorado River Cooperative Agreement and the Shoshone Outage Protocol are great examples of the partnership between Denver Water and the West Slope to do just that. Last year, even though the CRCA was not yet in effect, Denver Water released water to the river even though the Shoshone Power Plant was not operating and the call was not on. This year, under the Denver Water-Xcel Energy agreement, the Shoshone call will be relaxed.”

“Relaxing the Shoshone water right in this limited way benefits the West Slope as well,” said Colorado River District General Manager Eric Kuhn. “It might make the difference between having a full supply at Green Mountain Reservoir and not having a full supply. In a year like this every extra drop of water we can store now will help us later.”

Colorado River Cooperative Agreement implementation at hand

coloradorivercooperativeagreementmap.jpg

Here’s a short report from the Associated Press via The Columbus Republic:

Colorado’s largest water utility and more than 30 western slope providers are expected to begin implementing an agreement balancing the Denver-area’s demand for water with the needs of mountain communities as early as next month. According to the Grand Junction Daily Sentinel a project spokesman said Tuesday a few more signatures are needed.

More Colorado River Cooperative Agreement coverage here.

Patty Limerick’s ‘A Ditch in Time: The City, the West, and Water’ book signing Wednesday on the CU campus

aditchintimepattylimerick.jpg

Limerick is a terrific speaker and writer so I’ve been looking forward to her book about Denver Water for a while now. Here’s the book description from the Tattered Cover website.

“The history of water development…offers a particularly fine post for observing the astonishing and implausible workings of historical change and, in response, for cultivating an appropriate level of humility and modesty in our anticipations of our own unknowable future.”

Tracing the origins and growth of the Denver Water Department, this study of water and its unique role and history in the West, as well as in the nation, raises questions about the complex relationship among cities, suburbs, and rural areas, allowing us to consider this precious resource and its past, present, and future with both optimism and realism.

Patricia Nelson Limerick is the faculty director and board chair of the Center of the American West at the University of Colorado, where she is also a professor of history and environmental studies. She currently serves as the vice president for the teaching division of the American Historical Association. Her most widely read book, “The Legacy of Conquest,” is in its twenty-fifth year of publication.

Here’s a review of the book from Jane Earle writing for Your Colorado Water Blog. Here’s an excerpt:

The line [for a history of Denver Water] went back in the budget and, backed by Chips Barry, then Manager of Denver Water, it was passed by the Board. This time, the proposal was to ask Patricia Limerick, Colorado’s McArther prize winning historian, to write the history. And that was my idea. This time, it was [Charlie Jordan] who was incredulous. After all, Professor Limerick was not always kind to the white builders in her history of the West, “The Legacy of Conquest.” But that was why I wanted her: No one could accuse Denver Water of commissioning a coffee table book about the glories of its past if Patricia Limerick was the author. Chips was beguiled by the idea. The rest is history, as they say. This time, literally.

Professor Limerick doesn’t call her book a history of Denver Water. She subtitles it, “The City, the West, and Water.” It’s well named. She has set the story of some of the major events in the development of Denver’s water system in their proper geographic and historic context. The contributions of the people who built the water system and their legacy are stories that needed to be told. They were men of vision who could imagine a great city on the treeless plain next to the (mostly dry) South Platte River.

Here’s an interview with Ms. Limerick from the Colorado Water 2012 website.

More Denver Water coverage here and here.

Drought news: Drawdown of Wolford Mountain Reservoir an opportunity to inspect Ritschard Dam settling

wolfordmountain.jpg

Here’s the release from the Colorado River District (Martha Moore):

The Colorado River District, which owns and operates Wolford Mountain Reservoir, will take advantage of this year’s drought and resulting low reservoir water levels to further monitor movement at Ritschard
Dam.

As with all earthen dams, Ritschard Dam was expected to settle over time. However, over its 16-year life, the dam has settled nearly two-feet, rather than the estimated one-foot. This year’s dry conditions require drawing the reservoir down lower than most years in order to meet contractual and environmental demands for the stored water. Previous monitoring data suggest the settling rate slows as water levels decline. A major drawdown of the reservoir this year will assist in further assessment of the situation.

“The dam is safe. There is no reason for concern over dam failure,” assures John Currier, chief engineer for the Colorado River District. “There are no leaks; the dam is solid. However, we need to determine the cause of continued settling,” added Currier.

About Wolford Mountain Reservoir:

Wolford Mountain Reservoir is located on Muddy Creek, five miles north of Kremmling. It stores 66,000 acre feet of water when full. The reservoir primarily provides water to west slope contract holders when their water rights would otherwise be called out by more senior water users on the Colorado River. Water is released from the reservoir to protect Western Slope water users and to substitute for water diverted by Denver Water at Dillon Reservoir in critically dry years.

Water releases from Wolford also benefit endangered fish in the Colorado River near Grand Junction to enhance flows in the spring time and in late summer during times of lower flows.

Wolford was built in cooperation with and financing from Denver Water and Northern Water, both Front Range transmountain water diverters.

More coverage from Drew Munro writing for the Summit Daily News. From the article:

“This year is a really good test,” John Currier told Kremmling Town Board members Wednesday night, explaining that the reservoir will be drawn down 30-35 feet below full by the end of October.

“The reservoir hasn’t been drawn down like this since 2002-2003,” he added.

Currier, chief engineer for the river district, was at the meeting along with other district representatives to allay rumors that Wolford Mountain is being drawn down to prevent it from failing and to present a progress report about the ongoing investigation into why the dam is moving.

He said the reason the reservoir will be drawn down so far this fall is that Denver Water, which holds a lease for 25,000 acre-feet of “substitution water” annually in the 66,000 acre-foot impoundment, will release all its water this year. That, and Colorado Parks and Wildlife will use another 6,000 acre-feet this fall to augment downstream flows for endangered fish, he said.

In a “normal” year, he said the reservoir is drawn down about 10 feet. When that occurs, he said monitoring instruments indicate the rate of settling slows substantially. What engineers will be looking at this fall is whether there is a point at which the settling slows further or stops as the water level falls.

More Wolford Mountain Reservoir coverage here and here.