NEWBERRY — Representatives from Newberry County Public Works met last Thursday with SCS Engineers and with the Department of Health and Environmental Control to discuss a corrective measures assessment for the closed Newberry Landfill.
Steven C. Lamb, vice president of SCS Engineers, presented the assessment. He said the methane gas and groundwater issues do not pose an imminent threat to the environment or public health due to the overall site setting and its impact on ground water.
That said, Lamb and DHEC agree the methane that is there needs to be cleaned up and phased measures be put into place to prevent future adverse affects to groundwater.
“We need to clean what is already there and work to prevent future impacts (of pollution) to ground water,” Lamb said.
As a Class 3 closed landfill, the ground water is monitored and methane gas is monitored via perimeter probes.
Lamb said the site, which closed in 1996 in accordance with DHEC regulations for closure, reported previously elevated methane gas readings at perimeter probes so in the mid 2000s DHEC requested off side wells be installed on the facility, on the portion on the other side of I-26.
As part of monitoring the landfill over time, more intervention was required. Methane gas probes were added in 2006 and passive gas ventilation was installed in 2009 in the trash area.
It was hoped the passive intervention systems would be enough to correct the problem but subsequent readings showed SCS Engineers active measures such as vents involving pumps, motors or vacuums, were needed.
An example of an active measure is use of an extraction pump or a blower with a vacuum to suck gases up from the sub-surface.
Lamb reported three options:
1. Install landfill gas extraction wells within the waste.
2. Dig a perimeter cut-off trench, such as the trench currently in use but add pipes and a vacuum.
3. Install gas extraction wells in the soil, not the waste part of the landfill. The wells would be between the waste and the property boundary.
He said installing wells within the waste is intrusive because one must actually dig into the waste, some of which is 18 to 20 years old.
At that age the waste is not at its peak of methane gas production to flare off gas or use it for energy. There also would be permitting issues for the flare. Lamb said it is possible but unlikely this option would help.
For option 2, a trench over 2,000 feet long and 15 to 18 feet deep is required. But groundwater still could go under the trench.
“For option 3, gas extraction wells would pull the gas out. We feel it will work and is cost effective using technology that’s been proven across the country,” Lamb said.
The action comes in phases and is adjusted over time depending upon how the Class 3 solid waste disposal facility responds. A phased approach could include a trench or wells within the landfill.
For the proposed measures, the same wells are used and re-posting stays the same.
“If things work in our favor over time,” Lamb said, “the five wells across the state could go away. Just 17 to 18 years into post closure of the landfill.”
Newberry County Administrator Wayne Adams asked about a time frame for moving forward.
“I just want to make sure we are doing the right thing,” Adams said. “The (landfill measures are) the number one capital project priority of Newberry County Council for the 2014-15 year.”
Lamb said he needed time to bid and would need about six weeks to produce biddable drawings. Per his estimate, the corrective measures likely would be operational by early 2015.