The work is, at least in part, to display the relative size of the sinkhole that's at the center of one controversy surrounding the company's request to the state for permission to cap the geographic feature so more trash may be buried at the landfill.
A track hoe operator was "removing sediment as well as brush" last week, according to Jessica Preston, Waste Management's geologist at the site.
Preston displayed the "feature" at Cedar Ridge on July 21 when she also showed one of the monitoring wells on the property.
Waste Management and the Tennessee Department of Environment and Conservation have an agreement documented in a Memorandum of Understanding (MOU) about what must be done before TDEC can grant permission for use of the eight acres as a repository of garbage.
At the core of the MOU is the basic requirement that whatever is done at Cedar Ridge, it won't harm the environment or, more specifically, ground water sources.
The MOU set forth a series of conditions that include two chief points. If the monitoring wells find water indicating the landfill isn't damaging groundwater, then the expansion might proceed as requested. If soiled water is found, then expansion of the landfill may have to be done with a double liner.
Decades ago, city and county trash dumps were operated with hardly any environmental protections. The Clean Water Act of 1972 has influenced landfill operations.
The Environmental Protection Agency promulgated rules to enforce congressional action that, at first, required clay liners. Subsequently, man-made fabric liners were required. They've been used to collect leachate, or soiled water and other liquids mixed with garbage. Leachate is to be treated and then hauled away for disposal under additional requirements.
Water from at least two new monitoring wells has been drawn and sent to a laboratory for analysis.
The track hoe operator was scooping moist dirt from the land around the sinkhole and placing it in a dump truck so that it could be deposited elsewhere and later used at the landfill. The track hoe rolled on its tracks to one place, dug a new platform and moved closer and closer to the center of the sinkhole.
A few years ago, Waste Management purchased property that fronts Old Columbia Road so that it could excavate dirt to serve as cover for daily deposits of trash.
Cedar Ridge Landfill has not been receiving deliveries of trash from Waste Management customers since Dec. 1, 2010. The company reduced, and then stopped accepting, deliveries because the landfill is close to reaching its capacity. If it's full, a closure plan would have to be used and that has been seen as ending the prospect of using the eight acres that were not permitted for trash disposal when the company received the permit for Cedar Ridge's use as a landfill.
Expansion over the sinkhole is apparently the only option left for landfill expansion on that property.
Sinkholes have been successfully capped at various locations, Preston said on Thursday last week while displaying the geological feature.