Michigan Administrative Code › Department - Environmental Quality › Remediation and Redevelopment Division › Environmental Contamination Response Activity › CLEANUP CRITERIA REQUIREMENTS FOR RESPONSE ACTIVITY › Section R. 299.26 - Generic cleanup criteria for soil based on inhalation of hazardous substances in ambient air

Current through Vol. 24-12, July 15, 2024
Rule 26.
(1)
				  Inhalation of hazardous substance emissions in ambient air from soil shall be
				  considered a reasonable and relevant pathway for all facilities.
(2) Generic cleanup criteria for soil based
				  on inhalation of volatile hazardous substance emission to ambient air shall be
				  called volatile soil inhalation criteria (VSIC). Generic cleanup criteria for
				  soil based on inhalation of particulate hazardous substance emission to ambient
				  air shall be called particulate soil inhalation criteria (PSIC). The generic
				  residential VSIC and PSIC are calculated as follows, except as provided in R
				  299.34(3):
EQUATIONS FOR CARCINOGENS:
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where,
VSIC
(Volatile soil inhalation criterion)
= chemical-specific, ug/kg or ppb
TR
(Target risk level)
= 10-5
AT
(Averaging time)
= 25,550 days (70 years x 365 days/year)
IURF
(Inhalation unit risk factor)
= chemical-specific
								(ug/m3)-1
EF
(Exposure frequency)
= 350 days/year
ED
(Exposure duration)
= 30 years
VF
(Volatilization factor)
= chemical-specific,
								m3/kg
and,
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where,
PSIC
(Particulate soil inhalation criterion)
= chemical-specific, ug/kg or ppb
TR
(Target risk level)
= 10-5
AT
(Averaging time)
= 25,550 days (70 years x 365 days/year)
IURF
(Inhalation unit risk factor)
= chemical-specific
								(ug/m3)-1
EF
(Exposure frequency)
= 350 days/year
ED
(Exposure duration)
= 30 years
PEF
(Particulate emission factor)
= chemical-specific,
								m3/kg
EQUATIONS FOR NONCARCINOGENS:
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where,
VSIC
(Volatile soil inhalation criterion)
= chemical-specific, ug/kg or ppb
THQ
(Target hazard quotient)
= 1
AT
(Averaging time)
= 10,950 days (30 years x 365 days/year)
EF
(Exposure frequency)
= 350 days/year
ED
(Exposure duration)
= 30 years
ITSL
(Initial threshold screening level)
= chemical-specific,
								ug/m3
VF
(Volatilization factor)
= chemical-specific,
								m3/kg
and,
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where,
PSIC
(Particulate soil inhalation criterion)
= chemical-specific, ug/kg or ppb
THQ
(Target hazard quotient)
= 1
AT
(Averaging time)
= 10,950 days (30 years x 365 days/year)
EF
(Exposure frequency)
= 350 days/year
ED
(Exposure duration)
= 30 years
ITSL
(Initial threshold screening level)
= chemical-specific,
								ug/m3
PEF
(Particulate emission factor)
= chemical-specific,
								m3/kg
(3) The soil
				  to air volatilization factor (VF) relates the concentration of a contaminant in
				  the soil to the concentration of volatilized contaminant in the ambient air. If
				  the vertical extent of the contaminant source has not been characterized, then
				  the VF shall be calculated based on the infinite equation presented in
				  subdivision (a) of this subrule. If the vertical extent of the contaminant
				  source has been adequately characterized throughout the facility, then the VF
				  shall be calculated either by the finite source equation presented in
				  subdivision (b) of this subrule or the mass balance equation presented in
				  subdivision (c) of this subrule, whichever yields the highest VSIC.
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where,
VF
(Volatilization factor)
= chemical-specific,
								m3/kg
Jave
															s
(Normalized average flux from soil)
= chemical-specific,
								g/m2-second
DA
(Apparent diffusivity)
= chemical-specific,
								cm2/second
Q/C
(Dispersion factor for 1/2 acre)
= 82.33, g/m2-second per
								kg/m3
T
(Exposure time)
= seconds (ED x 3.1536E+7 seconds/yr)
[THETA]a
(Soil air-filled porosity)
= 0.28
								Lair/Lsoil
N
(Total soil porosity)
= 0.43
								Lpore/Lsoil
[THETA]w
(Soil water-filled porosity)
= 0.15
								Lwater/Lsoil
[RHO]b
(Dry soil bulk density)
= 1.5 g/cm3
Da
(Diffusivity in air)
= chemical-specific,
								cm2/second
Dw
(Diffusivity in water)
= chemical-specific,
								cm2/second
H'
(Dimensionless Henry's law constant, where H' = HLC
								x 41)
= chemical-specific, unitless
HLC
(Henry's law constant at
								250 C)
= chemical-specific,
								atm-m3/mol
TAF
(Temperature adjustment factor)
= 0.5
Kd
(Soil-water partition coefficient)
= chemical-specific,
								cm3/g
For organic compounds
= Koc
								(cm3/g) x foc (g/g)
For inorganic compounds
= chemical-specific,
								cm3/g
Koc
(Soil organic carbon partition coefficient)
= chemical-specific,
								cm3/g
foc
(Organic carbon content of soil)
= 0.006 g/g (0.6%)
(b) The
				  simplified finite source model equation for VF shall be calculated as follows:
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					 Image
where,
VF
(Volatilization factor)
= chemical-specific,
								m3/kg
Q/C
(Dispersion factor for 1/2 acre)
= 82.33, g/m2-second per
								kg/m3
C0
(Uniform contaminant concentration at t=0)
= 1.5 E-6 g/cm3
[RHO]b
(Dry soil bulk density)
= 1.5 g/cm3
Jave
																s
(Normalized average flux from soil)
= chemical-specific,
								g/m2-second
Js
(Instantaneous flux from soil at time t)
= chemical-specific,
								g/m2-second
DA
(Apparent diffusivity - see equation above)
= chemical-specific,
								cm2/second
T
(Time)
= seconds
ds
(Thickness of source)
= site-specific, meters
exp(p)
(The base of the natural logarithm raised to power
								(p))
= ep
(c) Mass balance VF shall be calculated as
				  follows:
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					 Image
where,
VF
(Volatilization factor)
= chemical-specific,
								m3/kg
Q/C
(Dispersion factor for 1/2 acre)
= 82.33, g/m2-second per
								kg/m3
AT
(Exposure period)
= scenario-specific, years
[RHO]b
(Dry soil bulk density)
= 1.5 mg/m3
ds
(Average source depth)
= site-specific, meters