Study investigates plant-based landfill caps
Scientists at the Beltsville Agricultural Research Center (BARC), an arm of the US Department of Agriculture, have been working with the US Environmental Protection Agency and private consultants to develop a new method of landfill capping in which vegetation and compost replace conventional geomembrane and clay materials. A pilot study is currently underway at the College Park Landfill in Maryland to assess the effectiveness of the vegetative cap. Six variations are being tested for their water-retaining capacities, with varying soil mixtures and absorptive plant root systems.
A successful landfill cap prevents percolation of precipitation through garbage buried in a landfill, stemming the production of leachate. It also prevents migration of landfill gases like carbon dioxide and methane into the environment. On this second performance criterion, scientists at BARC are looking into the viability of introducing microorganisms into the vegetative caps that would consume or sequester those greenhouse gases.