FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

• PreTiminary Environmental Assessment Report Pittman Elementary School,Stockton,CA December 10,2003 Page 22 • Table 16—Site Conce tual Model Source Media PathwayReceptors Pesticide Application soil in estion dermal abso tion residents dust in air inhalation residents Metals in Soil soil in estion dermal abso tion residents dust in air inhalation residents soil in-ti- dermal abso tion residents VOCs in Soil dust in air inhalation residents vapors inhalation residents SVOCs in Soil soil ingestion,dermal absorption residents dust in air inhalation residents F nncure Assessment Calculations The concentration in the exposure media used for the exposure assessment was the highest concentration detected at the site. As calculated in the spreadsheets included in Appendix C, the residential exposure scenario included a six-year exposure period for a child of highest soil ingestion [200 milligrams (mg)/day] per body weight [15 kilograms (kg)]. Additionally, a 24-year exposure duration was assessed for adults by using a soil ingestion.rate of 100 mg/day and an adult body weight of 70 kg. As shown in the calculations included in Appendix C, the DTSC PEA defaults for dermal surface area, adherence, exposure frequency, exposure duration, and dermal penetration were used in calculating dermal doses. For inhalation exposure to dusts, a dust-in-air concentration of 50 micrograms per cubic meter (µg/m3) was assumed (PEA Guidance Manual p. 2-25). The DTSC PEA default rate of 10 cubic • meters (m3)/day for a child and 20 m3/day for an adult were used as default inhalation rates (1999). Exposure analysis calculation methods are those of DTSC (1999) as performed using Microsoft Excel spreadsheets included in Appendix C. The exposure point concentration values chosen for the calculations are the highest concentrations of constituents detected in soil samples collected at the site as presented in the tables included in Appendix C. The Johnson and Ettinger Model for Subsurface Vapor Intrusion Into Buildings uses an averaging time of 70 years for carcinogens, an averaging time of 30 years for noncarcinogens, an exposure duration of 30 years, and an exposure frequency of 350 days per year. Exposure analysis calculation methods were performed using Microsoft Excel spreadsheets included in Appendix C. The media values chosen for the calculations are the highest concentrations of constituents detected in soil gas or groundwater samples collected at the site as presented in the tables included in Appendix C. The United States Soil Conservation Service Classification of soil at the site was determined for the site through particle size analysis of a soil sample from the site (Appendix Q. 8.2.3 Risk Assessment Methods TOTiCi y Assessment A toxicity and environmental fate profile was developed for all contaminants using the California Office of Environmental Health Hazard Assessment (OEHHA) Cancer Potency Factors and the USEPA Integrated Risk Information System(IRIS). See toxicity data for detected constituents in Appendix C. Rick and Heard Characterization As summarized in Table 17, beryllium, cadmium, cobalt, nickel, hexavalent chromium, aldrin, alpha- BHC, beta-BHC, delta-BHC, gamma-BHC, alpha-chlordane, DDD, DDE, DDT, dieldrin, endosulfan II, ih1 CONDOR