ARCHIVED REPORTS XR0000211 - Laserfiche WebLink

Home Browse Search

SECTIONTHR ESE 3.9 DATA REVIEW The first step of the risk assessment was to review all data collected that was specific to the site The objective of the data evaluation was to identify chemicals of concern that were related to the former USTs Chemicals were selected as cheriucals of concern (COCl) in accordance with EPA guidance (EPA 1989a) Data collected from 1987 through August 25, 1998 were used for the risk assessment and groundwater unpact analysis The 242 soil samples that were collected from the site (Table 2-1) and the 153groundwater samples(Table 2-2)were evaluated for use in the risk assessment Data were reviewed for Quality Assurance/Quality Control (QA/QC) QA/QC samples that have been collected including equipment blanks, trip blanks, and duplicates of field samples were reviewed Laboratory QA/QC, which includes the analysis of method blanks (AAIB), matrix spikes (MS), matrix spike duplicates (MSD), laboratory control samples and surrogates were also reviewed Data were reviewed in accordance with the EPA documents Functional Guidelines for Organic and Inorganic Data Review (February, 1994a and 1994b) as applicable for the method performed MS and MSD were generally within the respective percent recoveries specified in the laboratory's QA/QC program, unless sample dilution was required due to matrix interference in soil and/or groundwater samples In cases where the MS or MSD percent recoveries were out of range due to matrix interferences, laboratory control spikes were evaluated and found to be within acceptable recovery ranges Therefore, all data were used Risk assessments for sites contaminated with petroleum products are complicated by a general lack of information relevant to exposure to and toxicity of petroleum mixtures, especially total petroleum hydrocarbons Benzene, ethylbenzene, toluene, and xylene (BTEX) are frequently used to represent TPH in the environment BTEX has been quantified separately from TPH for the Shop 10 site and was used in the risk assessment and groundwater impact analysis Of the 242 soil samples analyzed, approximately 25 percent had detectable levels ofBTEX(Table 2-4) Benzene was detected in 65 out of 242 soil samples, 27 percent of the soil samples analyzed 3.11 Soil Samples Details on the soil sampling and analysis can be found in other reports(Woodward-Clyde, 1990, Alton Geoscience, 1992,Environmental Assessors, Inc, 1994, and Geocon, 1996) The soil data used in the risk evaluation were from the investigations documented in theses reports Woodward-Clyde (1990), Alton Geoscience(1992), Environmental Assessor(1994) and Geocon(1996) (summarized in Section 2 5 of this report) Soil data were evaluated based on sampling depth Soil samples were separated ® TAIGGA97MWNA%STOCKTOMREPORl1SHOREPAM DW&FE&9w73o09NA15NA 3-1