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FMS #24 Site Investigation Report <br />California Army National Guard <br />Maximum detected concentration from any of the four samples collected from 8 feet below ground surface. <br />b Unit conversion for soil gas concentrations: <br />Concentration (pg/m3) _ [Concentration (ppbv) - 1,000] x MWx41.5957 <br />where: <br />MW = molecular weight of the compound (g/mole); 41.5957 = constant ([mole-µg-L]/[m3-g-µL]), based on the Universal Gas Constant (R), unit conversion factors, standard temperature (20°C), and standard pressure (1 atm). <br />Default attenuation factor (Table 2; DTSC, 2005) for future slab -on -grade residential land use <br />d Toxicity values from the California Environmental Protection Agency, Office of Environmental Health Hazard Assessment (http://www.oehha.ca.gov/risk/ChetnicalDB/index.asp ). <br />day/yr <br />= days per year <br />Table 3-8. Risk and Hazard Estimates — Inhalation of Volatile Organic Compounds <br />= Department of Toxic Substances Control <br />FMS <br />= Field Maintenance Shop <br />g/mole <br />Future Conditions — Unrestricted (Residential) Land Use <br />kg <br />= kilogram <br />ppbv <br />= parts per billion by volume <br />yrs <br />Stockton FMS #24 Site, Stockton, California <br />gg/m3 <br />= micrograms per cubic meter <br />Description <br />Variable <br />Value <br />Equations <br />Attenuation Factor, Future Residential <br />a <br />0.0009 <br />dimensionless <br />Cancer Risk: <br />Averaging Time, carcinogens <br />AT, <br />70 <br />yrs <br />Averaging Time, noncarcinogens, adult <br />ATnc,a <br />24 <br />yrs <br />1 d <br />IRA, x EF x ED x ET <br />IRA x EF x ED x ET �i <br />= x 70 kg x <br />Risk URF x <br />C + <br />a`r x [BWaXATX365dayslyear <br />� <br />Averaging Time, noncarcinogens, child <br />AT„o,c <br />6 <br />yrs <br />20 m3 <br />BW, X ATS x365 days l yearJi <br />Body weight, adult <br />BWa <br />70 <br />kg <br />Body weight, child <br />BWc <br />15 <br />kg <br />Chemical Concentration in indoor air <br />Cair <br />chemical -specific <br />µg/m3 <br />Soil -Gas Concentration <br />Csoil-gas <br />chemical -specific <br />µg/m3 <br />Noncarcinogenic Hazard: <br />Exposure Duration, adult <br />EDa <br />24 <br />yrs <br />11 <br />Exposure Duration, child <br />ED <br />6 <br />yrs <br />1IRA <br />Hazard = <br />x EF x ED x ET <br />x x <br />IRA x EF x ED x ET <br />+ <br />Exposure Frequency <br />EF <br />350 <br />days/yr <br />20 m3 1 <br />�Cai. <br />BW, x AT„,,a x365 days l year <br />BW, X AT,,,,, X365 days l year Jjj <br />Fraction of EF breathing air at the site <br />ET <br />1 <br />unitless <br />RfC x x <br />Inhalation Rate, adult <br />IRAs <br />20 <br />m3/day <br />1 d 70 kg <br />Inhalation Rate, child <br />IRAs <br />10 <br />m3/day <br />where: <br />Inhalation Reference Concentration <br />RfC <br />chemical -specific <br />µg/m3 <br />—aX -gas <br />Inhalation Unit -Risk Factor <br />URFi <br />chemical -specific <br />(µg/m3)-i <br />air soil <br />Soil Gas <br />Molecular <br />Cancer <br />Hazard <br />Concentration' <br />Weight <br />Csoil-gas b <br />ac <br />C+air URFi d <br />Risk % of RfC d <br />Quotient % of <br />Compound <br />(ppbv) <br />(g/mole) <br />(pg /M) <br />(dimensionless) <br />(µg/m3) (pg/m3)-' <br />(dimensionless) Total (µg/m3) <br />(dimensionless) Total <br />Volatile Organic Compounds <br />Benzene <br />6.5 <br />78.11 <br />2.11E+01 <br />0.0009 <br />1.90E-02 2.90E-05 <br />2.87E-07 21% 6.00E+01 <br />1.01E-03 4% <br />Naphthalene <br />13 <br />128.16 <br />6.93E+01 <br />0.0009 <br />6.24E-02 3.40E-05 <br />1.10E-06 79% 9.00E+00 <br />2.22E-02 93% <br />Toluene <br />7.1 <br />92.13 <br />2.72E+01 <br />0.0009 <br />2.45E-02 No Toxicity Value <br />-- -- 3.00E+02 <br />2.61E-04 I% <br />m,p-Xylenes <br />19 <br />106.17 <br />8.39E+01 <br />0.0009 <br />7.55E-02 No Toxicity Value <br />-- -- 7.00E+02 <br />3.45E-04 I% <br />Cancer Risk <br />Hazard Index <br />Cumulative: <br />IE -06 <br />0.024 <br />Maximum detected concentration from any of the four samples collected from 8 feet below ground surface. <br />b Unit conversion for soil gas concentrations: <br />Concentration (pg/m3) _ [Concentration (ppbv) - 1,000] x MWx41.5957 <br />where: <br />MW = molecular weight of the compound (g/mole); 41.5957 = constant ([mole-µg-L]/[m3-g-µL]), based on the Universal Gas Constant (R), unit conversion factors, standard temperature (20°C), and standard pressure (1 atm). <br />Default attenuation factor (Table 2; DTSC, 2005) for future slab -on -grade residential land use <br />d Toxicity values from the California Environmental Protection Agency, Office of Environmental Health Hazard Assessment (http://www.oehha.ca.gov/risk/ChetnicalDB/index.asp ). <br />day/yr <br />= days per year <br />DTSC <br />= Department of Toxic Substances Control <br />FMS <br />= Field Maintenance Shop <br />g/mole <br />= grams per mole <br />kg <br />= kilogram <br />ppbv <br />= parts per billion by volume <br />yrs <br />= years <br />gg/m3 <br />= micrograms per cubic meter <br />B-19 December 2007 <br />