The Lower Darby Creek Superfund Site in Darby Township, Pennsylvania is nearing a critical junction in its cleanup cycle. The Record of Decision (ROD), a technical document that delineates EPA’s chosen remediation method, will be released to the public soon. This is a welcome step given that EPA has been jugging the site with very little progress since its inclusion in the National Priorities List (NPL) in 2001.However, it is increasingly apparent that the ROD will suggest a particular kind of remedy that is not suitable for the site.
The site consists of two landfills – the Clearview Landfill and the Folcroft Landfill. Folcroft remains under evaluation and will be dealt with separately. Clearview and how to contain its waste are the subject of the ROD. In previous evaluations, EPA proposed and seemed to be pushing for the implementation of a non-traditional cap for the landfill. This non-traditional cap is known as an evapotranspiration (ET) cap and consists of a thick layer of soil covered by various forms of vegetation. The idea behind it is that rain water that falls over the landfill will be trapped in the soil and then soaked up by the plants to be used and evaporated into the surrounding air. In principle, this kind of mechanism is possible and the solution is sound. But this breaks down when you take into account various other factors.
An ET layer is not suitable for the Lower Darby Creek site because of the climate and geo-hydrology. This kind of cover prevents water infiltration in locations that possess greater levels of soil evaporation and plant transpiration (collectively termed evapotranspiration) than precipitation. Arid and semiarid climates such as that of the Midwest are suitable for this kind of cover. However, Darby Township receives 42.05 inches of rain every year, a figure almost twice as high as it average evapotranspiration level. In addition, the site is located on a floodplain that experiences a massive flooding event on average every 6-8 years.
All of these factors make an ET layer as the permanent cap for the Clearview Landfill an extremely inefficient and non-protective remedy. As the announcement of the ROD approaches, it is CHEJ’s hope that EPA takes the health and well-being of the residents surrounding the site as their top priority and decides against an ET layer.