Toxic Landfill Gases

Hazardous Chemical Vapors are Leaking through the Top of an Industrial Waste Dump Along Lake Marion and are Suspected of Contaminating Shallow Groundwater

Hazardous chemical vapors are leaking through the top of an industrial waste dump along Lake Marion and are suspected of contaminating shallow groundwater near the surface of the 36-year-old site.

Nearly 20 different chemicals, some at concentrations above safe drinking water standards, have shown up in groundwater atop a plastic liner installed decades ago to protect the environment from the now abandoned waste dump near Pinewood, according to a recent consulting study.

State regulators have known about the issue for about three years, records show, but they said the contamination isn't a threat to Lake Marion.

Several consultants familiar with the closed landfill, however, say something needs to be done before pollution begins trickling toward the lake from the site. They favor beefing up protective barriers in the landfill's oldest section to safeguard Lake Marion, a plan the state Department of Health and Environmental Control says could cost more than $12 million. The main area of concern is the Sumter County landfill's original and most leak-prone section.

Lake Marion, a water supply source and major recreation destination, is four football fields from the dump. A drainage ditch to the lake is about 75 feet away from part of the landfill.

Clemson University researcher Ron Falta said the state may need to improve the existing cap or install a new cap over the original part of the dump to limit seeping vapors, protect groundwater and shield Lake Marion from potential threats. Installing a new cap would involve dumping more dirt and clay on top of the existing cap and installing another synthetic liner.

A stronger cap over the original section of the landfill not only would help keep toxic vapors inside, but keep rain water from leaking in from the outside, said Falta, who studies the transport of hazardous chemicals.

Falta outlined the vapor problem in a September report for Kestrel Horizons, the site's manager from 2004 until this month. Vapors rising through the landfill may be seeping through the plastic liner or finding holes that have developed in the liner.

"Eventually, the cap may need to be rebuilt to modern standards in order to reduce water infiltration and to reduce contaminated vapor transport through the cap," Falta wrote in Sept. 15 report.

Contaminants in groundwater include solvents and cancer-causing materials, such as benzene and vinyl chloride, records show.

The discovery of toxic vapors and polluted groundwater presents a potentially new set of challenges for state regulators charged with protecting the 100,000-acre lake from toxins buried in the landfill off S.C. 261 in rural Sumter County.

Instead of concerns only about leaks through the bottom of the dump, the top of the landfill also has prompted questions about its stability, documents obtained by The State newspaper show. Leaks near the top and sides of the landfill threaten the environment and could result from a failed top liner, according to Kestrel. The old Laidlaw/Safety Kleen landfill also has a synthetic liner at the bottom.

In a recent interview with The State, DHEC officials contended that vapors found in the soil above the top liner don't pose an imminent threat to the lake and, for now, they do not favor a new cap. The seeping vapors were discovered more than three years ago, records show.

"We're not sure exactly what is going on, but we don't think it's impacting groundwater," DHEC's David Scaturo said when asked about gas rising from the landfill.

Scaturo, however, said the department plans to install more groundwater monitoring wells around part of the landfill to learn more. The agency also will continue to monitor soil gas in the landfill's cover. In a later email to The State, DHEC officials emphasized that there is no "known or suspected environmental threat" from the landfill.

Agency officials also said the landfill gas is not unusual. But Falta said gas from a hazardous waste dump is substantially different than gas at a county landfill.

"A regular landfill takes garbage and it rots," Falta said. "This is all chemical waste. It's chlorinated solvents, pesticides, things like that. This is not anything rotting. You have all these chemicals that are fairly volatile. Some are in drums. Some stuff was just poured in."

DHEC and Kestrel Horizon's principal Bill Stephens have been at odds for months over management of the closed 279-acre dump. From 2004 through much of this year, the company's duties included overseeing toxic water that has built up inside the landfill and making sure plastic liners on the top and bottom of the landfill are working.

Citing millions of dollars in costs paid by DHEC to Kestrel, agency director Catherine Templeton forced the company to resign last summer. Kestrel's final day was Oct. 31. The landfill is now being overseen by two lawyers with background in environmental issues.

One of the key disputes between Kestrel and the state is whether to install systems to prevent leaks from getting into the lake - or whether to continue to monitor for problems that DHEC says may, or may not, develop.

Stephens said the site needs a new cap, a system to extract landfill gas, an improved system to capture contaminated water already inside the landfill, a metal wall to keep polluted groundwater from flowing to the lake and a bigger French drain. The drain could better detect leaks than monitoring wells and act as a barrier for landfill leaks that threaten to escape the site. Falta's Sept. 15 report made some of the same recommendations.

"DHEC appears to need compelling evidence from multiple sources and locations to decide to take action, but our consensus is that if you wait for that, it is going to be too late," Stephens said.

DHEC officials estimated that a new landfill cap and a French drain would cost up to $12.3 million, not including other improvements Kestrel recommends. DHEC also plans a comprehensive study to learn more about future management of the dump.

"The department believes it would be financially irresponsible to spend millions of dollars on a non-event instead of conserving funds for the protection of the environment," agency spokesman Mark Plowden said in last week's email.

While Stephens said landfill gas is a concern, he said it's possible that contamination near the top of the landfill could be coming from liquid hazardous waste that is leaking out of barrels inside the dump. Or, he said, the contamination could be from polluted water already inside the landfill that is welling up, getting through the liner and reaching shallow groundwater above it. A system to capture the contaminated water, or leachate, has apparently clogged up, Stephens said. DHEC officials said they knew nothing of a clogged leachate system.

The landfill, one of the few of its kind in the Southeast, has been a source of scrutiny for decades. The dump took millions of tons of toxic waste from companies, governments and others across the country. Its former owner, Laidlaw Environmental Services, once was among the most influential companies in South Carolina.

After concerns about future cleanup costs surfaced in the early 1990s, Laidlaw successfully lobbied the Legislature and the DHEC governing board to let it avoid establishing a $133 million cash trust fund for a cleanup.

Environmental groups and two state agencies then sued in court, and after 15 years of legal arguments, persuaded the S.C. Court of Appeals to shut down the landfill in 2000. Safety Kleen, which had merged with Laidlaw, filed for bankruptcy and left the state. The settlement established a trust fund, but that fund soon is expected to run out of money, raising the possibility the dump could become a federal Superfund cleanup site.

The landfill was established at Lake Marion at the site of a former cat litter mine. A top regulator at DHEC who was involved in the site's initial permitting later took a job with the landfill's original operator.

Source: The State

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• Environment
• Pollution
• Groundwater Recharge