Landfill Closure Update

December 2013 - A decision by the U.S Forest Service this week will save Teton County $3 million when it recaps the leaking Horsethief Canyon landfill. The decision allows the county’s Integrated Solid Waste and Recycling Division to use 5 acres of excavated trash when it regrades the landfill to Wyoming Department of Environmental Quality specifications. The work was ordered because the dump, unused since 1989, is leaking contaminants.

The county needed Forest Service permission because 17.8 acres of the old landfill sits on federal forest land. “This is huge,” said waste and recycling division chief Heather Overholser. “We’re absolutely pleased with the decision, and excited to move on to the landfill closure planning.” Closing the landfill, south of Jackson, will now cost less than $10 million instead of nearly $13 million, Overholser said. The Forest Service decision also means the transfer station will retain another 3 acres of land once the closure is complete, leaving as many as 10 acres for operations instead of as few as 6, she said. “Not only does it cost less, but we end up with more land that does not have trash underneath it,” she said. All land with trash remaining underneath must be capped and left undisturbed for 30 years, according to the Forest Service decision. 

The $3 million the decision saves the county will be redirected to construct new facilities, Overholser said. Of the $14.58 million specific purpose excise tax voters approved for the closure in November 2012, the waste and recycling center had already budgeted an additional $1.75 million for environmental monitoring and planning for new facilities, she said. The decision means it’s less likely the waste and recycling operation will need more money to complete the project, and it will less costly in the event that they do, Overholser said. How much the new facilities will cost is not yet known, Overholser said, but work will likely include a new scale house and transfer building. 

Building a New Cap

The DEQ ordered Teton County to put a new cap on the old, unused landfill after finding unacceptable levels of methylene chloride leaching from beneath it. This solvent’s leakage from a closed landfill means water has penetrated its cap and that other toxins are likely to follow, according to the Forest Service’s decision letter. The cap placed on the landfill after it was closed in 1989 consists of 24 inches of soil. The new cap will need a foot of sand or its equivalent beneath an impermeable plastic liner, with another foot of sand on top of that, all covered by two more feet of earth revegetated with native plants, according to Forest Service requirements.

The cap, which over the years has settled unevenly, also must meet grading standards dictated by the DEQ for consistency and inclination, Overholser said. It must be steep enough to prevent pooling but not so steep as to allow erosion, she said. The county needs to place fill material on the 17.8 acres of Forest Service land above the transfer station’s current footprint, she said. If the Forest Service had not allowed the county to use old trash excavated from the landfill, the county would have needed to import fill material from elsewhere, which would have significantly increased the project’s cost, Overholser said. 

The agency would also have needed to export old trash at significant expense, she said.Teton County used the 40 1/2-acre landfill from the 1950s until 1989. The county sent its trash to another unlined landfill in Sublette County from then until July 2012, when it began trucking trash to a lined landfill in Bonneville County, Idaho. DeeDee Witsen and Dale Deiter, Bridger-Teton National Forest officials, could not be reached for comment on this story.

- Jackson Hole News and Guide


Watch a brief video about the Teton County landfill closure.


Teton County's landfill project appeared on the special purpose excise tax (SPET) Ballot for the November 6 election. It was approved by the voters. The proposition provides funding for an improved landfill cap at the old Horsethief Canyon Landfill, as well as improvements to solid waste and composting facilities. Although waste has not been buried at Horsethief Canyon Landfill since 1989, groundwater contamination has been discovered at the site and the Wyoming Department of Environmental Quality is requiring Teton County to construct an improved landfill cap and surface water diversion system to improve the condition of the goundwater under the site. Teton County Integrated Solid Waste and Recycling is in the early stages of planning this updated facility.