Methane remediation project continues at old Viroqua dump after phase one shows mixed results

Oct. 19, 2025

VIROQUA, Wis. — The City of Viroqua’s mandated methane remediation project at the old city landfill is grappling with “wildly inconsistent” methane gas emissions, even as city officials move forward with adjacent residential development plans. The old city landfill site is located at the end of Sands Road or east of Chicago Ave., and just south of where the “Hanson Farm” housing development is soon to be constructed. The landfill or dump was closed in the early 90s when the county constructed a modern landfill that met new DNR standards.

The remediation effort began after the Wisconsin Department of Natural Resources (DNR) issued a notice of non-compliance on May 27, 2025, due to high levels of methane gas leaking around the perimeter of the closed site. Initial investigations revealed explosive gas readings near an adjacent church building, sometimes reaching 20.5% methane by volume, far exceeding the regulatory limit of 1.25% of the lower explosive limit outside the landfill boundary.

Phase One Completed, Monitoring Continues

The city secured a $2.5 million borrowing package, partially funding the project, and rapidly launched phase one work to meet a tight June 30 DNR deadline. City Engineer Sarah Grainger worked with consultant TRC (Mike Amstad) and contractor Badger Environmental to install a passive venting system, involving digging a trench filled with porous rock and pipes, primarily focused on the north and east sides where gas migration was detected.

Phase one was estimated to cost around $187,583, with an initial payment of $145,054 made to the contractor in July 2025. During excavation, crews found that the former dump likely occupies a valley or gully, with natural ground found 15 feet or deeper in some sections, confirming limited information about the old facility, which was essentially “a hole in the ground where the city dumped its waste for years”.

Despite the trench installation, continuous monitoring has shown that methane concentrations fluctuate based on external factors like weather and atmospheric pressure, leading staff to describe the landfill as seeming to be “breathing in and out”. While the initial work has aided detection near the church, monitoring probes on the north side of the property, near the planned Hanson Farm development, continue to show “significantly high concentrations of methane” at times.

Future Steps and Development

With the initial phase complete, the city’s focus is now on long-term compliance and planning the next steps, including further investigation to understand the volatile conditions.

• DNR Compliance: Officials anticipate receiving another DNR letter stating the city is still not fully in compliance, requiring the submission of a new mitigation plan. To support this, the Common Council approved a $22,800 contract extension with TRC in late September 2025 for further investigation, data gathering, and plan submittal.
• Active Remediation Hesitation: Consultants are wary of installing an expensive active gas remediation system (using a blower to extract gas). While the site is generating “high quality gas,” the quantity is low, suggesting a blower might quickly exhaust the gas and become unused equipment. Furthermore, introducing a vacuum system risks pulling oxygen into the site, potentially causing landfill fires.
• Long-Term Monitoring: City staff expect perpetual monthly monitoring will be necessary, requiring the eventual purchase of specialized sampling equipment estimated to cost between $17,000 and $20,000.
• Adjacent Development: The City Council recently voted to move forward with the full infrastructure plan for the adjacent Hanson Farm development. Experts advised that proceeding is viable, contingent on developers installing standard mitigation systems, similar to those used for radon, in all new construction to vent any residual methane or vapors above the buildings. The developers were advised of the pre-existing landfill issue, and City Engineer Grainger noted that certain development activities, such as installing a clay liner for a regional storm pond, could actually help mitigate future gas migration.

The overall project is still estimated to fall within the original ballpark of up to $750,000. The city’s commitment to resolving the environmental concern is seen as a necessary obligation, regardless of the timeline of the adjacent housing development.