Actions taken to lower methane levels at county landfill
Private consultant takes readings
Though methane gas was recently detected at lower explosive levels at many different points around the county landfill, officials say corrective actions have since been taken to remedy the problem.
A March report on methane levels at the Lower River Road Landfill by a private consultant found methane at concentration levels equaling or exceeding the Lower Explosive Limit of 5 percent at three detection monitoring locations, eight trench vent locations and three methane control wells.
Robert Krasko, the geologist with Georgia Environmental & Management Services Inc. who performed the inspection, said a lack of routine monitoring in the past of methane levels at the landfill had resulted in failures of several of the components of the system used to monitor and vent the methane gas generated at the landfill.
“ Based on the data that’s presented in that report meth-
ane gas is being detected at some of the well locations and along the property line,” Krasko said.
Methane, a highly potent greenhouse gas, is a byproduct of the decomposition process and can be combustible if high concentrations of it are reached in an enclosed space.
Krasko said the LEL levels of methane did not pose an imminent health risk to anyone but could, if allowed to continue, result in the loss of nearby vegetation such as grass and trees due to a lack of adequate oxygen.
The two closest occupied buildings, the landfill scale house used to weigh garbage trucks and the Newton County Animal Control building are only occupied in the daytime. Krasko said no methane was detected at the scale house.
Despite the assurances of officials, some residents on Lower River Road want the county to test for methane gas near their properties.
“ I’m truly alarmed about hearing [ about the] explosive gases,” said J. McKenzie, a resident of Lower River Road at a sparsely attended public meeting last Thursday on the proposed expansion of the landfill. “ I don’t want the landfill there period.”
At the meeting District 4 Commissioner J. C. Henderson asked his fellow commissioners to consider testing for methane across the street from the landfill near the private residences.
“ Those are people that I love,” Henderson said of the residents living on Lower River Road in a speech during Sunday’s Black Easter event. “ We need to be jumping up and down and have them test every inch of soil.”
Because no human lives were in jeopardy, Krasko said the corrective actions on the landfill were given a lower priority level than other landfill sites in the state. Corrective actions were taken on March 13 Krasko said.
While LEL levels of methane gas were detected beyond the fence line of the landfill, Krasko said the geological conditions of the area kept the gas from migrating across the street.
“ If you draw a line from the scale house to the animal control, [ detected methane gas] has all been south,” Krasko said.
According to Krasko, some of the corrugated drainage pipes used to vent the methane gas had become clogged or turned into the ground, preventing free flow venting. Krasko said those pipes have now been fixed, are venting smoothly and will be monitored monthly.
The flare used to burn the methane was also determined not to be working during the inspection. According to Krasko’s report a new igniter and blower motor have been ordered and should be installed shortly.
The Lower River Road Landfill has four waste sites. Of the 88 acres currently permitted for disposal, 14 have been used without a liner system for municipal solid waste while 37 are currently used with a liner system.
“ Historically the old [ Municipal Solid Waste] Unit 1 has had gas migration issues,” Krasko said. “ By current standards it’s too close to the road, but it was permitted at a time when that closeness was allowed. What we see at these old landfills that are unlined is that gas tends to vent to the surface and will migrate a couple hundred feet.”
Krasko said the couple hundred of feet the methane could travel was not far enough for it to cross Lower River Road and come into contact with private residences.
At the Thursday meeting, the BOC approved a proposal to expand the landfill’s capacity by filling unoccupied space between the four waste sites. The proposal entails no new land purchases and would not move the waste closer to private residences but shift it slightly further away.
The proposal also entails moving all waste into a single large landfill lined with several feet of compacted clay and a high- density polyethylene material. Krasko said the combined effect of the liner and clay would create “ an extremely low permeable underlying layer” making it very difficult for methane gas to leave the site.
“Anything that could be released would be released at such a slow rate that the natural environment could assimilate them,” Krasko said.
According to the presentation given at the public meeting by the consultant firm Richardson, Smith, Gardner & Associates, all proposed expansion work will occur within the boundaries of the current solid waste facility permitted in 1987. All current buffers to adjacent property owners and to the river will be maintained.
The shifting of all waste into lined landfills is expected to eliminate any future ground water contamination from existing unlined landfills.
Krasko said because the Georgia Environmental Protection Division had not previously required routine monitoring of methane levels, no monitoring was undertaken by the consultants previously employed by the county to monitor the landfill. When the county switched private consultants, Krasko said his company was hired to monitor methane levels.
“ It took me about two months to get a handle on things,” Krasko said. “ I realized there had been no maintenance on the corrective actions that had been put in place over there.”