A proposal to sink hundreds of heat exchange wells for a mixed-use development in Liberty Lake poses a significant risk for groundwater contamination, the community’s water provider says.
Liberty Lake Sewer and Water District is pushing for a more stringent environmental review of the project, which calls for 700 wells to be drilled 450 feet deep to heat and cool homes, apartments and commercial buildings in the Lakemore development planned along East Appleway Avenue.
The 6-inch-wide borings would pass through the Spokane Valley-Rathdrum Prairie Aquifer, which is the sole source of drinking water for about 9,000 residents in that area and hundreds of thousands more downstream in Spokane Valley and Spokane.
Groundwater contamination from the project could cause millions of dollars in damages, said BiJay Adams, general manager of the sewer and water district.
“Even a slight chance of contamination could lead to severe environmental and public health impacts and therefore must be regarded as significant,” Adams wrote Thursday in announcing the district was taking over as lead permitting agency for the proposal.
The city this summer gave the applicant, developer Whitewater Creek Inc. of Hayden, the OK to proceed, saying the developer had agreed to mitigation measures that made a fuller environmental review unnecessary.
But the sewer and water district disagreed and now will require Whitewater Creek to produce an environmental impact statement. Todd Prescott, the company’s co-owner, did not respond to interview requests. In its application to the city, Whitewater Creek says it is trying to create a “highly-sustainable living environment.”
The district’s biggest concern, Adams said in an interview, is the developer has not adequately characterized conditions that far below ground or addressed how the project might alter the flow and temperature of water in the aquifer.
“We don’t know what’s below a couple hundred feet,” the depth of district drinking water wells, he said.
“What’s going to take place if you go through the aquifer and into bedrock?” he said. “Could that introduce (to the groundwater) iron and magnesium and potentially other heavy metals?”
With residents owning and operating the systems, there also is the potential for failure of the wells, inadvertent or deliberate, Adams said. Scenarios could range from minor maintenance problems all the way to bioterrorism, he said.
“In theory you could inject something into these ground source heat pump pipes and pump it up to 150 psi, blow the pipe out and inject cyanide and kill thousands of people,” Adams said.
That is far-fetched, he admitted, but contamination could also happen through reckless maintenance. A homeowner who experiences a well failure might try to seal the well with radiator sealant or another harmful substance, Adams said.
“There’s no regulatory authority over them doing any maintenance themselves to try to seal these units,” he said.
The district also has questions about the effect drilling the wells could have on the aquifer. The wells – two for each unit – would be drilled with rotary mud, which has the ability to contaminate wells downstream, Adams said.
After the holes are drilled, the casings would be pulled up and a bentonite slurry, a clay that absorbs liquid, would be injected to fill in the borings, he said. That’s a worry because the aquifer contains coarse sand and gravels.
“It is thought that this bentonite is not going to stay in the bore hole,” Adams said. “It’s going to migrate through the very coarse material of the aquifer and in time could end up being captured by the district wells, causing contamination issues and clarity issues in our drinking water.”
The heat exchanges would operate using a closed-loop geothermal system, meaning no water is removed from or added to the ground. Instead, each loop would contain a mixture of glycol and water that would circulate through plastic tubes underground, absorb the earth’s heat and bring that heat to the surface.
This would not be the first Inland Northwest development to use subterranean water for heating or cooling needs. The Saranac Building in downtown Spokane, the Fourth and University Medical Building in Spokane Valley, and Kootenai Health and the Salvation Army Kroc Community Center in Coeur d’Alene all use such forms of energy exchange.
Cequel Data Centers, a Liberty Lake data center (originally, Tierpoint), uses a 200-foot encased and capped well to draw up 50-degree water from the aquifer and cool the air in computer server rooms. The water is returned underground about 10 degrees warmer. The Washington Department of Ecology and city of Liberty Lake determined TierPoint’s plan was environmentally beneficial and would not contaminate nearby water.
Ecology gets involved in approving open-loop systems that use groundwater for the heat exchange, but the agency does not require a permit for closed-loop systems.
That’s a problem, Adams said. As ground source heat pumps grow in popularity, the science and regulatory community have not kept up with the potential impacts on groundwater, he said.
“It is a lack of knowledge about the potential threats and safety of these systems coupled with the lack of regulation in environmentally sensitive areas that is of serious concern,” he wrote in a recent letter to the city of Liberty Lake.
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