November, 2000

Pennsylvania's Land Recycling Program
Remediation Of Pesticide Residuals In Soils
Of A Former Apple Orchard

In 1997, Realen Limited Partner, Inc. (Realen) retained Leggette, Brashears & Graham, Inc. (LBG) to conduct a site characterization and remedial action investigation of Phase 2 of a Realen development located in West Bradford Township, Chester County, Pennsylvania (subject property). The purpose of the investigation was to characterize and then remediate soils at the subject property that contained pesticide residuals as a result of pesticide applications to apple trees in a former orchard. If successful, the subject property would qualify for cleanup liability protection and relief from deed acknowledgment requirements under the Pennsylvania Land Recycling Program (ACT 2), thereby allowing Realen to develop the subject property.

As part of an earlier Phase I Environmental Site Assessment (ESA), LBG reviewed aerial photographs of the subject property. The earliest aerial photograph available from 1965 showed that the subject property had been used as an orchard. Consequently, LBG contacted the son of the former owner to confirm historic operations at the subject property. During the interview, it was acknowledged that pesticides had been used in the orchard more than 30 years ago. Based on the findings of the ESA, LBG conducted a preliminary soil investigation at the subject property in April 1997 to determine if historic operations had impacted soil quality.

Soil samples were collected to determine if DDT and its metabolites, as well as arsenic, lead and cadmium were present. The results of the preliminary soil investigation indicated that arsenic and possibly lead were present in the soils at concentrations that exceeded the 1997 action levels. Consequently, in May 1997, LBG conducted a baseline soil investigation that included the collection of 88 soil samples from 22 locations throughout the subject property. The findings of the baseline investigation confirmed that arsenic was present in the surface soils at concentrations exceeding the statewide health standard. Conversely, lead was not present in the soils at concentrations that exceeded the statewide health standard.

To delineate arsenic concentrations in the soils at the subject property, LBG completed a final site characterization. This phase of the investigation included performing an X-ray fluorescent analysis (XRF) on soils at the subject property and confirming the XRF results by collecting soil samples for laboratory analysis of arsenic. The results of the final site characterization indicated that for the subject property to qualify for closure under the statewide health standard for arsenic, it was necessary to remediate approximately 1,156 tons of arsenic-impacted soils.

The remedial action consisted of excavating soil in specific areas of the subject property to depths of up to 1.5 feet below grade (ftbg) and transporting soils offsite for proper disposal. Following excavation, LBG established a grid in the field in accordance with the Pennsylvania Department of Environmental Protection (PADEP) Large Site Soil Cleanup Verification. Based on the PADEP Act 2 75-10X rule, LBG collected a total of 116 soil samples throughout the former orchard at depths ranging from 0.5 ftbg to 2.0 ftbg. The 75-10X rule is a statistical ad hoc rule that determines if the true site median concentration is below the cleanup standard. This rule requires that 75 percent of the samples collected for demonstration of attainment be equal to or below the bright line cleanup standard and that no single sample results exceeds the bright line standard by more than ten times.

The results of the post-excavation soil sample analysis indicated that arsenic was detected in 92 of the 116 soil samples. Arsenic concentrations attained the statewide health standard of 12 milligrams per kilogram (mg/kg) in 94 of the 116 soil samples (81 percent) and arsenic did not exceed 120 mg/kg in any of the samples.

The analytical results of the post-excavation soil samples demonstrated attainment of the statewide health standard for arsenic and, therefore, the excavation of soil successfully remediated arsenic at the subject property. The subject property qualified for cleanup liability protection and the relief from deed acknowledgment requirements under Act 2, and as a result, Realen was able to develop the subject property.

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