1)The site-specific standard for lead was approved by both PADEP and EPA and utilized the updated Adult Lead Model and exposure assumptions recommended by the USEPA and the PADEP. As part of the remedial investigations, the lead data was compared to the Act 2 SHS MSC, which is 450 ppm, based on the soil to groundwater pathway. This comparison is shown on the figures/tables in the RI Reports and in the 8/27/20 presentation. The approach that was used to calculate the SSS for direct contact was to use the Adult Lead Model recommended by the EPA. The PADEP used the same model to develop an updated non-residential lead direct contact MSC that reflects the current state of the science for lead.
2)DEP did not approve two of the RIRs – AOI-4 and AOI-9 – based on the need for additional offsite characterization, not a level of contamination over other AOIs. The characterization portion of the AOI-11 report was sufficient for approval; however, the fate and transport portion of the AOI-11 reports was not, which is why the report was not approved. Data has been collected from the lower aquifer wells as part of the other AOI remedial investigations since 2013 and reported in the Remedial Investigation Report submitted since 2013.
3)Characterization and delineation of contaminants of concern does not generally require consideration of climate change, sea level rise or worsening storms. Climate change will be considered in future fate and transport efforts and cleanup plans where that type of variable warrants consideration.