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• Ainary Environmental Assessment Report Pittman Elementary School,Stockton,CA December 10,2003 Page 20 Table 15—Labo atory Anal tical Results (Northern UST Site —Groundwater Constituent: Acetone Benzene MEK Chloroform Methylene Chloride Toluene MCL: 1 L 150 rSample ID Date 'L3638F-VB4 F-VB108/11/2003 3.7* <1.0 <5.0 <1.0 0.33* <1,0 F-VB2 08/12/2003 15 0.20* 2.8* 0.70* <5.0 <1.0 F-VB3 08/13/2003 <10 <1.0 <5.0 <1.0 0.25* 0.31* 08/12/2003 4.1* <1.0 <5.0 0.99* 0.47* 0.24*Blank 8/13/2003 <10 <1.0 <5.0 <1.0 0.41* <1.0 gg/L:micrograms per liter <:not detected at the reporting limit shown Detected concentrations are below laboratory reporting limits and are estimated(j"flagged). MEK:methyl ethyl ketone,2-butanone MCL:California Department of Health Services Primary Maximum Contaminant Level 7.6 POLYCHLORINATED BIPHENYLS RESULTS .The laboratory analytical results indicate that no PCBs were detected in any of the soil samples. Laboratory report sheets indicating analytical methods used, detection limits, and the results of the analyses are included in Appendix B. No PCBs were detected in the equipment blank sample 3638F-rinsate-8/11/03. • 7.7 HYDRAULIC ELEVATOR RESULTS The laboratory analytical results indicate that no PCBs were detected in the product sample. Laboratory report sheets indicating analytical methods used, detection limits, and the results of the analysis are included in Appendix B. 8.0 HUMAN HEALTH SCREENING EVALUATION 8.1 GENERAL COMMENTS The purpose of this human health screening evaluation is to provide the DTSC Risk Manager with an estimate of the potential chronic health hazard from contamination at the site. The risk and hazard estimates are calculated for exposure pathways most frequently encountered at a residential setting. Due to the generic nature of these assumptions, the risk and hazard estimates are not absolute measures of risk or hazard at the site. This screening evaluation consists of a compilation of methods, models, and assumptions used by the United States Environmental Protection Agency (USEPA) and DTSC to quantify risk/hazard. The default exposure factors chosen for this evaluation are those recommended by the USEPA to represent a reasonable maximum exposure in a residential setting.-Using these default factors, this screening evaluation quantifies the potential lifetime risk and hazard from site conditions for a defined set of exposure pathways. Pathways of exposure evaluated by this method are: 1) inhalation of airborne dust from soils, 2) inhalation of VOCs from soil, 3) inhalation of VOCs from vapors, 4) incidental ingestion of soil, and 5) dermal absorption by direct contact with soil. Water pathways were not evaluated based on reasons stated in Section 4.2. Exposure point concentrations were taken as the highest concentrations of any contaminant in all soil and soil gas samples collected at the site. • ow 1 ILO CONDOR