Utilizing the approved statistical methodologies of Act 2, REPSG conducted a “randomized sequential sampling” of the soil to characterize conditions in the subsurface and determine the true environmental risk at the site. The fill characterization data was evaluated to determine if the ‘true’ site median concentrations of lead, arsenic, and zinc were below the applicable SHS. This evaluation was made by applying the statistical test known as the 75%/10x rule. Specifically, the rule requires 75% of the samples collected for demonstration of attainment be below SHS and no single sample result exceeds the risk-based standard by more than ten times.
It was verified that at least 75% of samples tested were below SHS and no single sample exhibited a concentration more than twice the cleanup standard. Based on the application of the 75%/10x rule, the true site median concentration of lead, arsenic, and zinc was verified to be below the applicable SHS. Attainment of Statewide Health Standard for these analytes in the on-site fill material had been demonstrated.
Following submission of a Final Report by REPSG to the PADEP in October 2004, the Site received approval from the PADEP in November 2004 for remediation at the site to the provisions of the Statewide Health Standard (SHS) under Act 2. The site has since been redeveloped with 16 new residential units.