Geomembrane Insulation Design

Q: We have a project where the client has requested us to design a soil cover to protect an HDPE liner from melting due to campfires. The locals like to hang out on the summit of this superfund site and have cookouts, and the privately owned site will not be secured after the 30-year post closure is complete. Are you aware of a geotechnical design process for this?

A: “Quasi-Mechanistic 3D Finite Element Model Predicts Temperatures in a U.S. Landfill” by ACS ES&T Engineering sheds light on a design model and computer code that may be useful for the conditions you describe. One needs a relatively thick 24-inch-plus soil layer (note: R-value of soil ranges from 0.25 to 1.5 per inch at 20% moisture content) to insulate a geomembrane from extremely high temperatures such as a campfire. Please note HDPE melts at 130 degrees Celsius and degrades rapidly when temperatures go above 90 degrees Celsius. P.S.: This is a losing proposition. Keep people off the closed site. No good can come from the situation you describe.