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City to close, seal portion of landfill

Photo

Photo by Mark Kauzlarich

Trucks bring in trash to Phase 2 of Janesville's City Dump. Next year this part of the dump will be capped, like the city is currently doing with Phase 1.

Photo

Photo by Mark Kauzlarich

A bulldozer pushes soil over Phase 1 of the Janesville Dump's capping project. The site will be covered and methane reservoirs are inserted to harvest gas for energy on-site.

JANESVILLE — The city landfill probably will smell less after work is finished in September to seal the easternmost section of the facility, city officials said.

"That's been our experience whenever we permanently cap a phase," Public Works Operations Director John Whitcomb said. "As operations move east to west, as we did at the old landfill, our impact on neighborhoods generally diminishes over time."

The section being closed is the easternmost of the five sections that make up the city dump, which sits west of Kennedy Road, north of Foster Avenue and south of Barberry Drive.

Like other dumping grounds at the landfill, the site is former gravel pits operated by Janesville Sand and Gravel.

Work to close the cell on the landfill's eastern edge got underway the first week of July. Mandy Bonneville, the city's public works solid waste manager, expects the project to be completed by the end of September.

Two other 10-acre cells are accepting waste. Whitcomb said he did not anticipate another cell being opened until 2014.

"When you establish a landfill site … you don't construct all of that landfill space all at once," Whitcomb said. "You generally divide it into various phases or cells. Our permitted landfill is divided into five cells."

The current cell was built in 2004 and has been accepting waste since March of 2005. The cell is filled, but it exceeded its anticipated lifespan by two years. Bonneville attributed that to the city's purchase of a second trash compactor in 2007, which improved trash compaction and extended the site's life.

Whitcomb said the landfill has a projected site life of 13.5 years but is likely to last nearly 20 years, depending on waste flows and densities. Bonneville estimates the city landfill accepts 700 tons of waste daily.

Once closed, the cell will resemble ground previously used as a landfill along Black Bridge Road.

"Ultimately it will be covered in vegetation, with landfill gas collection wells sticking up out of the ground," Whitcomb said

To close a cell, a layer of grading material is applied to give the area a smooth surface. Next, a drainage layer is installed, followed by two feet of compacted clay topped with a plastic membrane. The layers are designed to prevent water from penetrating the landfill and carrying contaminants into the groundwater, Whitcomb said.

Topsoil and more cover materials are laid on top of the plastic before gas collection wells are installed.