Landfill remediation — Leachate concerns to be addressed at Landfill No. 1

The city of Newcastle will soon begin work on the Landfill No. 1 remediation project, a long-anticipated effort to address ground-water contamination issues at the former landfill site south of town.

The project will focus on collecting and safely managing leachate — water that has filtered through waste — by capturing it and pumping it into designated containment ponds, according to Greg Stumpff, the city’s public works supervisor.

Residents can expect increased construction traffic along Rodeo Street throughout the summer and into early fall, including heavy equipment transport, material hauling trucks and contractor vehicles, a letter from the city states.

The landfill, located below Tank No. 2, first opened in 1922 and remained in use until 1986, when Landfill No. 2 along Old Highway 85 became the city’s active disposal site, Stumpff said in an email, citing a previous News Letter Journal article. At closure, the site was capped with a 24-inch soil cover, which met standards at the time.

As previously reported, groundwater issues have persisted at the site for years, with seepage north of the landfill indicating that stormwater has infiltrated the waste layer and created contaminated leachate.

Modern standards, according to Stumpff, now require significantly thicker caps — more than 4 feet of compacted clay — to prevent that type of infiltration. He noted that this will be the standard for the eventual closure of Landfill No. 2.

To address the problem, the city partnered with the Wyoming Department of Environmental Quality’s Landfill Remediation Program.

“Over several years, the City and WDEQ collected groundwater data, monitored conditions and worked with Trihydro, a consulting engineering firm, to complete a Nature and Extent Study. Trihydro evaluated three alternatives and estimated associated costs,” Stumpff said.

The selected remedy includes installing an interceptor trench to collect leachate, pumping the captured water to two treatment ponds located north of the Weston County Sportsman Club building, installing an emergency wastewater connection from the treatment ponds to the Sheridan Street wastewater system, and constructing a methane collection trench adjacent to the Sportsman Club building.

When it comes to funding the project, Stumpff said it is a collaborative effort between the city and the landfill remediation program, which helps communities dealing with “legacy” landfill issues.

“WDEQ LRP is funding 75% of the project, with the city responsible for the remaining 25%. To cover its portion, the city secured a WDEQ Clean Water State Revolving Fund loan,” Stumpff said.

The construction phase was initially estimated at more than $3.5 million, according to Stumpff, but Earth Work Solutions of Gillette submitted the low bid at approximately $2.37 million.

A preconstruction meeting has already been held, and the contractor is expected to begin mobilizing equipment soon, accessing the site via Rodeo Street and the city’s material storage area.

As previously reported, the WDEQ determined that the project qualifies for a categorical exclusion from further environmental review because it is expected to improve environmental conditions and will be constructed in previously disturbed ground.

City officials said they appreciate the public’s patience during construction and encouraged residents with questions to call the city shop at 307-746-2882.