By: Wesley E. Stimpson, Technical Practices Committee
The recent revisions to the MCP, most of which became effective June 20, 2014, substantially change how sites with NAPL are characterized and moved through the MCP process. In addition to some new terminology, MassDEP has embraced the fundamental scientific principles describing the behavior of fluid flow in porous media necessary to assess NAPL in subsurface strata. PRPs are now asked to provide multiple lines of evidence to support any endpoint conclusions, and MassDEP will be looking for more data than has historically been provided in support of closing out this type of disposal sites. The NAPL Upper Concentration Limit of 0.5 inches no longer needs to be met, and in fact is no longer available to be used as a component for obtaining an endpoint.