Temporary Landfill CoversPublished on 12/10/2020 by Jimmie Eloff
One of the largest challenges facing municipal solid waste and coal ash sites today is the increasing costs associated with treating leachate. One of the most common ways to address this issue is with a temporary geomembrane rain cover. There are a variety of other reasons they may be specified or required by the site owner, local, or state government. Generally, temporary rain covers have a life expectancy ranging anywhere between one to five years (longer is feasible). These can include but aren’t limited to, temporary closure, wildlife protection, odor control, and leachate mitigation. This article will briefly explore the leachate aspect of this application. Leachate starts as rainfall. Rain falling on top of a landfill is the main contributor to the generation of leachate on a specific site. This contaminated water has two options once it seeps through the solid waste. It can be treated onsite or hauled to the local wastewater treatment plant. Costs can vary significantly depending on the volume, the toxicity, and where it is being treated. Typically the costs range between $0.00 - $0.25 per gallon (not including trucking costs). The lower costs typically come from relationships or agreements the landfill may have with the city. In exchange for taking the city’s sludge at a lower or reduced rate, the city will take the landfill's leachate. The higher costs can be associated with highly contaminated leachate that requires onsite pretreatment or hauling costs to the local treatment plant. In temperate regions, leachate treatment can be upwards of 20-30% of the operating cost on some sites.
Image Source: United States Department of the Interior
You can see this map shows the average rainfall per state per year. As stated above there is a direct correlation between the amount of rainfall and the leachate produced on each site. By covering these large areas with a temporary cover, sites can significantly lower their operating cost while protecting the environment. The two main products that dominate this market are string reinforced laminated polyethylene and a woven coated polyethylene. Both have advantages and disadvantages but woven coated material such as GLCoat has exceptional physical properties needed for a demanding environment with exposure to the elements.
Rain Cover Comparison Chart
|Property||Test Method||12mil DuraString||GLCoat 12||GLCoat 16||20mil DuraString||GLCoat 20|
|Grab Tensile (Strength)||ASTM D 7004||100lbs||180 lb.||210 lb.||143 lb.||330 lb.|
|Grab Tensile (Elongation)||ASTM D 7004||17%||20%||20%||17%||20%|
|Tongue Tear||ASTM D5884||46 lb.||50 lb.||60 lb.||63 lb.||89 lb.|
|CBR Puncture Resistance||ASTM D 6241||265 lb.||570 lb.||690 lb.||300 lb.||936 lb.|
|Mullen Burst||ASTM D 3786||100 psi||275 psi||375 psi||170 psi||571 psi|