City of Aspen eyes storing water under golf course in lieu of dams, reservoirs

A view of the Aspen municipal golf course from Red Butte. A consulting engineer for the city of Aspen has found that an 'in-situ' reservoir could likely be built to store water under the golf course, which sits on about 75 feet of glacially-deposited rock and gravel. A trench filled in with a clay-like material could be dug around the perimeter of the golf course and water could be poured into the open space in the remaining gravel, and pumped back out as necessary.

ASPEN – In their ongoing search for alternatives to building dams and reservoirs on Maroon and Castle creeks, Aspen officials continue to explore other options, including an underground reservoir that would store water below the city’s golf course.

Aspen City Council reacted favorably to a presentation in May about an “in-situ” or underground reservoir beneath the Aspen Golf Club, with one council member saying it was a “great introductory lesson.”

Aspen City Manager Steve Barwick said last week there is plenty more work to be done.

“City Council had a lot of questions regarding the viability, impact and cost of in-situ storage,” Barwick said, “and they have not yet even begun their review of the storage needs.”

Barwick also said recently that the city does not know exactly how much water it needs to store to meet future needs, but the council is set to hear a presentation on the subject at a July 11 work session.

“All of this, this whole notion of how much water do we need and how much water do we need to store, and all of that, has been based upon very preliminary analysis,” Barwick told the Pitkin County Healthy Rivers and Streams Board on March 16. “And now it’s time to tighten up the whole analysis and do a rational set of studies so we can have a rational discussion with the entire valley about what are we going to do here. How much storage do we need, and where do we want to put it?”

Loose rock and gravel on the edge of the Aspen golf course, showing a glimpse of what might lie below the surface of the course.

Feasible

Don Deere, a geotechnical engineer who has worked on a long list of water storage projects in Colorado, said during his presentation to the council in May that the city’s golf course has the right combination of bedrock and “terraced gravels” required for an in-situ reservoir, in which claylike walls are built in trenches around a rock-filled area to hold water.

“Engineering-wise, it’s feasible,” Deere confirmed this week in a phone interview. “You’ve got to drill it to know for sure if the site’s going to work, but there are some favorable aspects to that site, for sure.”

The 148-acre public golf course is located between lower Castle and Maroon creeks and sits on top of about 75 feet of gravel and river rock left by retreating Ice Age glaciers, said Deere, who is chairman of the civil engineering firm Deere and Ault Consultants, Inc. in Longmont.

An in-situ reservoir under the golf course could hold about 1,200 acre-feet of water, Deere said, which the city could then pump back up to its water-treatment plant if needed.

By comparison, the city has a 10 acre-foot reservoir at its water-treatment plant, which it says amounts to about a day’s use of water for the city’s water system. For comparison, Ruedi Reservoir holds about 100,000 acre-feet of water. Deere called a 1,200 acre-foot reservoir “a small reservoir.”

A potential 170-foot tall dam near Ashcroft on Castle Creek would create a reservoir that holds 9,062 acre-feet of water; a 155-foot dam on Maroon Creek near the Bells would hold 4,567 acre-feet.

The city applied to Division 5 water court in October to maintain its conditional water rights for the two reservoirs on Maroon and Castle creeks, and is facing opposition from 10 parties, including the U.S. Forest Service and Pitkin County.

Much of the opposition is because of the locations of the potential dams and reservoirs, both of which would inundate portions of the Maroon Bells-Snowmass Wilderness. Some opposers also are questioning whether the city really needs to store nearly 14,000 acre-feet of water.

And as the city tries to answer the “how much” question, they’ve also been looking at the “where” and “how” questions.

A graphic from Wilderness Workshop that shows how the potential Maroon Creek Reservoir would behind a 155-foot-tall dam just below the confluence of East and West Maroon creeks.

Exploring options

A study of the idea of storing water in old silver mines around Aspen was also presented at the May 15 work session by another Deere and Ault engineer, Victor deWolfe III.

He said it likely would be expensive and complicated for the city to use the old mines, especially as it would be difficult to maintain control of the water in the complex maze of old shafts and tunnels.

The in-situ option, by comparison, sounded more feasible.

Deere looked at two potential locations for an in-situ reservoir, both on city-owned property, the golf course and the city’s Cozy Point Ranch property at the intersection of Brush Creek Road and Highway 82.

The Cozy Point has a better combination of gravel and bedrock for an in-situ reservoir than the golf course, Deere said, but most of the focus at the work session was on the golf course site, in part because the city currently delivers water from Castle and Maroon creeks to irrigate the golf course.

A graphic from a paper authored by Don Deere shows how the walls of an in-situ reservoir are formed. The paper is called 'Gravel Pit Reservoirs, Colorado's Water Storage Solution.'

A trench, filled in

Deere told the council a reservoir under the golf course could be built by using a long-armed excavator to dig a 3-foot-wide trench around the course through the estimated 75 feet of gravel and river rock down to a solid layer of bedrock.

The trench, which would encircle the golf course, would be filled in with a claylike substance (a soil-bentonite mix) that would hold water. Deere said under the right conditions, such a deep trench, sometimes called a slurry wall, can be dug and filled back in with the claylike material at the rate of about 100 feet a day.

“In a couple of months, on a typical site, I can have a completely lined vessel,” he said.

City-owned water from Castle and Maroon creeks could then be delivered to new and existing ponds on the golf course and allowed to slowly infiltrate into the spaces between the loose rock left in the vessel.

If the city needed to during a drought, it could then pump the water from the new underground reservoir to its water treatment-plant located on a hill behind Aspen Valley Hospital. It’s about a mile from the center of the golf course to the treatment plant.

Water hazards

Councilwoman Anne Mullins asked Deere if the golf course would look the same after an in-situ reservoir was installed.

“I think we’d need to add some ponds, so there would be more water hazards when we’re done,” Deere said, but other than that, “it’s out of sight, out of mind.” And he said this week that after revegetation, no one would even know the in-situ reservoir was there.

As a general rule, Deere said it costs about $10,000 per acre-foot-of water stored to build an in-situ reservoir ­— if favorable soil conditions allow for the standard use of an excavator. But if conditions such as deeper gravel or harder bedrock require a crane and a platform to be used instead, the cost can go up by a multiple of five or six, he said.

Conceptually then, the construction costs of a 1,200 acre-foot in-situ reservoir could range from $12 million to $72 million, according to Deere.

“But we haven’t done a site specific cost estimate for the golf course,” Deere said this week.

He said it would require drilling test holes to know more about the feasibility and potential cost, as it would reveal the true depth of the gravel and the condition of the underlying bedrock.

In May, city officials told the parties in the water court cases that it expected to finish its study of in-situ storage by July. The next settlement conference in the cases is set for the first week of August.

Editor’s note: Aspen Journalism is collaborating with The Aspen Times, the Glenwood Springs Post Independent, the Vail Daily and the Summit Daily on the coverage of water and rivers. The Times published this story on Monday, July 3, 2017.

Update on chatfield storage reallocation project

Proposed reallocation pool — Graphic/USACE

From The Denver Post (Joe Rubino):

After more than a decade of discussion and planning, the Chatfield Storage Reallocation Project is set to begin later this year. The more than two-year construction effort will prepare the reservoir to accommodate an additional 20,600 acre feet of water to meet a variety of municipal, agricultural and industrial needs. Currently, the reservoir holds about 27,000 acre feet of water. Eventually it will hold up to another 20,600 acre feet of water and the the water level could rise as much as 12 vertical feet, officials said.

Beginning in winter and continuing through spring, the swim beach and north boat ramp will be reconstructed to accommodate the future shoreline. By the end of 2019, many other features of the park, including the marina, day use areas and South Platte bridge will be visited by construction crews and earth movers.

The park will remain open throughout construction. Higher water levels will change features along the reservoir’s shore…

The project will cost an estimated $160 million, said Tim Feehan, general manager of the Chatfield Reservoir Mitigation Co., whose eight partners — including Castle Rock, Centennial Water and Sanitation District and the Castle Pines Metropolitan District — will pay that tab in proportion to the amount of water storage each will be granted. Of that, $140 million has already been set aside in escrow.

Groundbreaking awaits final design approval from the Army Corps of Engineers, which built, owns and leases the reservoir to Colorado Parks and Wildlife for recreational use, Roush said. Preliminary designs and a tentative construction schedule are available online at Chatfieldreallocation.org, a project website created by Chatfield Reservoir Mitigation Co.

The swim beach is scheduled to close for reconstruction in late fall and reopen for use by Memorial Day weekend 2018. The beach and park perimeter road will be moved to the west, away from the present shoreline, to accommodate greater water fluctuations, effectively creating another 200 feet of beach area at low water. The parking lot will be expanded and the shower, restrooms and other features will be rebuilt. The north boat ramp also is scheduled to reopen to use by next Memorial Day weekend.

“A lot of the work is going to be done over the wintertime when the visitation is down and when the swim beach is closed and when the boat ramps are closed,” Roush said. “It’s about minimizing the time when the users would not be able to use those areas.”

Fed. appeals court snarls Trump’s directive to rollback environmental regulations — @HighCountryNews

Natural gas flares near a community in Colorado. Federal rules aim to lower risks of natural gas development. Photo credit the Environmental Defense Fund.

From The High Country News (Elizabeth Shogren):

A federal appeals court today dealt a setback to the Trump administration’s broad effort to rollback environmental regulations. The U.S. Court of Appeals for the District of Columbia Circuit blocked the Environmental Protection Agency’s 90-day delay on an Obama administration rule that requires the oil and gas industry to find and clean up leaks that send methane into the air.

The decision reinstates the methane rule but will not end its peril. EPA administrator Scott Pruitt last month proposed delaying the rule for two years while his agency goes through the process of permanently rewriting the rule.

Under the EPA’s Methane rule, the industry had until June 3 to detect leaks on new and modified wells and then 30 days to fix them. Then industry has to detect and repair leaks four times a year.

In general, the Administrative Procedure Act requires agencies to go through a full rule-making process to rescind a rule. That means they have to draft a proposed rule and take public comment before writing a final one. That takes many months. With this and other rules, the Trump administration has tried to temporarily delay them while going through the longer process of erasing them.

“(The) EPA was basically trying to do an end-run around that,” says David Doniger, a lawyer for Natural Resources Defense Council, who worked on the case. “The agency wanted to do anything in its power to keep industry from having to comply.”

In response to questions about how the court’s ruling will impact industry’s requirements under this rule and the agency’s strategy to rollback this and other rules, the EPA press office offered only a brief statement: “We are reviewing the opinion and examining our options.”

USAF delivers new carbon filter to Fountain

Widefield aquifer via the Colorado Water Institute.

From The Denver Post (Bruce Finley):

U.S. Air Force contractors on Thursday delivered the first of two $400,000 carbon filters designed to strip away two perfluorinated chemicals contaminating city water supply wells…

“We’re a public water system making sure we meet the regulations, even the health-advisory level. Our community — this is a priority for them. We’re going to deal with this,” Fountain utilities director Curtis Mitchell said, watching as a crane lowered two 19-foot-tall filtration tanks near a public library.

“This is a huge step forward,” he said, “because it will give us access to some of our groundwater again.”

But farmer Susan Gordon and other residents of the Fountain Creek watershed still are raising questions about the human-health impact of exposure through drinking water.

Gordon for years drank contaminated water from domestic wells and recently received results from a workers comp blood test showing a PFC called PFHxS in her blood at more than 100 times normal level. Three family members and some people who work on the farm with her also had elevated perfluorinated chemicals in their blood.

While she’s healthy now, “who knows what it could mean 10 years from now?” Gordon said. “Not just me, but lots of people living in these communities have been exposed.”

[…]

Fountain shifted city supplies to surface water sources after contamination was detected last year at levels above the EPA limit of 70 parts per trillion. But nearly 80,000 people in Fountain, Security and Widefield, as well as other communities south of Colorado Springs, long have relied on groundwater as a primary source of drinking water.

Water providers in Security have shifted to surface water delivered from a reservoir west of Pueblo along the Arkansas River, and those in Widefield and Stratmoor Hills have put in water-cleaning systems…

It was unclear whether Fountain’s filters would remove PFHxS. Karl Kuching, business development for the Air Force contractor TIGG, said the filters have proved successful removing some of the PFHxS at a site in Washington state.

Removing short-chain PFCs may require more frequent changing of the carbon, which is injected into the tops of tanks in a slurry and, when exhausted, drained out the bottoms, he said. Two tanks are used. When system operators detect a contaminant “breakthrough,” one tank still filters out contaminants while carbon in the first tank is replaced…

Water restrictions last summer reduced water use so that surface water sources met most of the demand. The restrictions might be imposed again after Tuesday, Mitchell said, so untreated well water isn’t tapped.