This question was sent to PADEP who provided the following response:
DEP’s published Statewide health standard nonresidential direct contact numeric value for lead in soil, 1000 mg/kg (milligrams lead per kilogram soil), was based on a target blood lead level in adults of 20 mg/dL (micrograms lead per deciliter of blood). Evergreen derived a site-specific direct contact numeric value in their 2015 risk assessment based on a target blood lead level of 10 mg/dL. This is U.S. EPA’s default value in the Adult Lead Methodology, which was the method used by Evergreen in their risk assessment calculation.