How do landfills avoid water contamination?
Question: What practices occur at our local waste facilities to prevent contamination of water sources (drinking and otherwise)?
Answer: Waste facilities are broken down into classes with specific requirements. Household trash goes to a Class Three landfill, which must meet strict federal and state requirements to function.
Each class of landfill has different purposes and strategies to prevent contamination. Class One landfills contain land-clearing debris, such as brush and limbs. Class Two landfills accept landclearing debris as well, along with construction and demolition debris, household furniture, industrial waste and animal carcasses.
Class Three landfills hold our household trash, which is called municipal solid waste. For the purposes of this question, we’ll focus on Class Three landfills and how they prevent water contamination.
Class Three landfills are unique because they have a “liner” around the bottom of each unit where waste is held. At the bottom of the waste, there is a physical barrier to protect the soil from absorbing contaminants.
Spartanburg’s landfill has an example of what these liners might look like. The landfill’s liner is made from nonpermeable clay, meaning water can’t penetrate it. The liner is also made up of a thin sheet of flexible plastic called high-density polyethylene.
This liner exists to keep a substance called “leachate” from seeping into the ground below.
Leachate is a liquid that forms when rains seeps through waste and gathers at the bottom. It can also contain liquid from any waste that is decomposing. The combination of liquid and solid waste can be filled with a variety of chemicals that can be hazardous.
Like other wastewater, leachate must be removed and treated.
In Spartanburg, it’s removed through pipes in the ground and treated onsite before it’s treated a second time at a contracted water treatment facility. Greenville’s Twin Chimneys landfill also treats leachate onsite.
Marcia Papin, Greenville County’s Director of Solid Waste, said that the landfill uses a comprehensive approach to keep leachate away from water sources.
“By collecting and diverting leachate away from the surrounding environment, the landfill reduces the risk of groundwater contamination,” Papin wrote in a statement to the Greenville News. “This approach helps contain the leachate within the landfill’s encapsulated system, preventing it from migrating into groundwater sources.”
Class Three landfills must go through a permitting process through the South Carolina Department of Health and Environmental Control and meet standards set by the Environmental Protection Agency. Additionally, South Carolina’s Class Three
landfills must meet state-level requirements, such as groundwater testing and buffer zones.
A Class Three landfill must be at least “1,000 feet from any residence, day-care center, church, school, hospital or publicly owned recreational park.”
That distance is also called a buffer. Buffers are used in environmental settings to help filter out contaminants. Often,
buffers are vegetated strips of land with plants and trees.
Buffers in Class Three Landfills start from where the waste is held, not the exterior boundary of the landfill.
Landfills must also test groundwater for contamination, which must be within limits set by the state.
Over time, landfill units reach a limit of how much trash they can house – similar to how a garbage can gets too full and runs out of room. At a landfill, that’s called a capacity limit.
When waste reaches its capacity limit at a landfill, it is “capped.” It’s sealed into the liner and covered with two feet of clay. It must be monitored for 30 years.
The most recent available data from DHEC reported that South Carolina had 28 active class three landfills in 2022.
In sum, water contamination prevention involves multiple steps.
● A liner prevents leachate from sinking into the ground
● The groundwater is further monitored to ensure that it hasn’t gotten through the barrier
● Leachate is transported through pipes to be treated and have the chemicals removed
● Buffers also work in tandem with the liner system to keep extra space between populated areas and water sources.
Sarah Swetlik covers climate change and environmental issues in South Carolina’s Upstate for The Greenville News. Reach her at sswetlik@gannett.com or on X at @sarahgswetlik.
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