| The North Penn Area 6 Superfund Site (NPA6 Site) addresses multiple sources of contamination and a broad contaminant plume that underlies a large portion of Lansdale, Pennsylvania. Tetrachloroethene (PCE), trichloroethene (TCE), and associated degradation products are the primary contaminants of concern. EPA originally identified 26 facilities in the Lansdale area as possible sources of contamination due to their use of site-related solvents. These 26 properties were grouped into two operable units (OUs) for soil contamination that would address source control through soil remediation. OU1 addressed 20 properties where EPA would perform remedial activities. OU2 will address the six remaining properties where the owners/operators will complete the work with EPA oversight. The groundwater contamination underlying the area is addressed in the OU3 Record of Decision (ROD) signed in August 2000. OU3 includes groundwater extraction and treatment of the contaminated groundwater at 10 source locations. Of these 10 locations, six are funded by Superfund (Fund-lead) and four are funded by potentially responsible parties (PRP). Groundwater remedies for five of the Fund-lead locations have been constructed and are the focus of this optimization evaluation report. EPA Region 3 requested that an optimization evaluation be conducted to identify potential opportunities to improve these five OU3 systems and to identify potential options for replacing or supplementing the existing remedies. |