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FMS #24 Site Investigation Report
<br />California Armv National Guard
<br />Cancer Risk Hazard Index
<br />Cumulative: 111-06 0.024
<br />a 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 (ughn) _ [Concentration (ppbv) - 1,000] x MWx41.5957
<br />where:
<br />MW = molecular weight of the compound (g/mole); 41.5957 = constant ((mole•ltg-L]/[m3-g•[tL]), 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; DISC, 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.cehha.ca.gov/risk/ChemicalDB/index.asp ).
<br />day/yr
<br />= days per year
<br />DTSC
<br />= Department of Toxic Substances Control
<br />FMS
<br />= Field Maintenance Shop
<br />glmole
<br />granas per mole
<br />kg
<br />= kilogram
<br />ppbv
<br />Table 3-8. Risk and Hazard Estimates — Inhalation of Volatile Organic Compounds
<br />yrs
<br />= years
<br />lxg/m3
<br />_ micrograms per cubic meter
<br />Future Conditions — Unrestricted
<br />(Residential) Land Use
<br />Stockton FMS #24 Site,
<br />Stockton, California
<br />Description _
<br />Variable
<br />Value
<br />Equations
<br />Attenuation Factor, Future Residential
<br />a
<br />0.0009
<br />_
<br />dimensionless
<br />_
<br />Cancer Risk:
<br />Averaging Time, carcinogens
<br />AT,
<br />70
<br />yrs
<br />Averaging Time, noncarcinogens, adult
<br />AT.,;,.
<br />24
<br />yrs
<br />1d
<br />IRA xEFxEDa x ET
<br />IRA xEFxED, xET
<br />Risk = URF x x 70 kg xJC
<br />� �-
<br />a'r x
<br />Averaging Time, noncarcinogens, child
<br />ATne,�
<br />6
<br />yrs
<br />20 m3
<br />BW,,x ATS x 365 days 1 year BW� x ATS x 365 days 1 year
<br />Body weight, adult
<br />BW,,
<br />70
<br />kg
<br />Body weight, child
<br />BW,,
<br />15
<br />kg
<br />Chemical Concentration in indoor air
<br />Ca;r
<br />chemical -specific
<br />µg/m3
<br />Soil -Gas Concentration
<br />CsQ;i-gas
<br />chemical -specific
<br />[Lg/nO
<br />Noncarcinogenic Hazard:
<br />Exposure Duration, adult
<br />ED,,
<br />24
<br />yrs
<br />Exposure Duration, child
<br />ED,
<br />6
<br />yrs
<br />1IRA"
<br />Hazard =
<br />x EF x ED x ET
<br />x C x
<br />LRA, x EF x ED x ET
<br />r
<br />Exposure Frequency
<br />EF
<br />350
<br />days/yr
<br />20 m3 1
<br />•
<br />R"- BW,, x AT,,,, x 365 days I year
<br />BW� x AT,, x 365 days
<br />f year
<br />Fraction of EF breathing air at the site
<br />ET
<br />1
<br />unitless
<br />RfC x x
<br />Inhalation Rate, adult
<br />IRA,,
<br />20
<br />m3/day
<br />1 d 70 kg
<br />Inhalation Rate, child
<br />IRAQ
<br />10
<br />m3/day
<br />where:
<br />Inhalation Reference Concentration
<br />RfC
<br />chemical -specific
<br />gg/m3
<br />Can• — Cr x Csoil—gas
<br />Inhalation Unit -Risk Factor
<br />URF;
<br />cbernical-specific
<br />(}tg/i )-E
<br />Soil Gas
<br />Molecular
<br />Cancer
<br />Hazard
<br />Concentrations
<br />Weight
<br />Csoil-gas b
<br />a`
<br />Ca;r URF; d
<br />Risk % of RfC d
<br />Quotient
<br />% of
<br />Compound
<br />(ppbv)
<br />(glmole)
<br />(lag/rn)
<br />(dimensionless)
<br />(liglm3) W/m3)-1
<br />(dimensionless) Total (pg/rn)
<br />(dimensionless)
<br />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
<br />4%
<br />Naphthalene
<br />13
<br />128.16
<br />6.93E+01
<br />0.0009
<br />6.24E-02 3.40E-05
<br />1.IOE-06 79% 9.00E+00
<br />2.22E-02
<br />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
<br />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
<br />1%
<br />Cancer Risk Hazard Index
<br />Cumulative: 111-06 0.024
<br />a 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 (ughn) _ [Concentration (ppbv) - 1,000] x MWx41.5957
<br />where:
<br />MW = molecular weight of the compound (g/mole); 41.5957 = constant ((mole•ltg-L]/[m3-g•[tL]), 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; DISC, 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.cehha.ca.gov/risk/ChemicalDB/index.asp ).
<br />day/yr
<br />= days per year
<br />DTSC
<br />= Department of Toxic Substances Control
<br />FMS
<br />= Field Maintenance Shop
<br />glmole
<br />granas per mole
<br />kg
<br />= kilogram
<br />ppbv
<br />= parts per billion by volume
<br />yrs
<br />= years
<br />lxg/m3
<br />_ micrograms per cubic meter
<br />B-19 December 2007
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