| A |
area of trench (m2) |
| ABS |
absorption factor (unitless) |
| ACvad |
volumetric air content in vadose zone soil (cm3/cm3) |
| ACH |
air changes per hour (h-1) |
| AF |
soil to skin adherence factor (mg/cm2) |
| AT |
averaging time (days) |
| B |
lipophilic property (unitless) |
| BW |
body weight (kg) |
| CDI |
chronic daily intake (mg/kg-day) |
| CA |
chemical concentration in air (mg/m3) |
| CGW |
concentration of contaminant in groundwater (�g/L) |
| CS |
chemical concentration in soil or sediment (mg/kg) |
| CSFd |
dermal carcinogenic slope factor (mg/kg-day)-1 |
| CSFi |
inhalation carcinogenic slope factor (mg/kg-day)-1 |
| CSFo |
oral carcinogenic slope factor (mg/kg-day)-1 |
| CT |
chemical concentration in tissue (mg/kg) |
| Ctrench |
concentration of contaminant in trench (�g/m3) |
| CW |
concentration of chemical in water (mg/cm3) |
| Dair |
diffusion coefficient in air (cm2/s) |
| Dtrench |
depth of trench (m) |
| DAD |
dermally absorbed dose (mg/kg-day) |
| DAevent |
absorbed dose per event (mg/cm2-event) |
| ED |
exposure duration (years) |
| EF |
exposure frequency (days/year) |
| ET |
exposure time (hours/day) |
| EV |
event frequency (events/day) |
| F |
fraction of floor through which contaminant can enter (unitless) |
| FA |
Fraction absorbed |
| FI |
Fraction ingested from source (unitless) |
| Hi |
Henry's Law constant for contaminant (atm-m3/mol) |
| IF |
intake factor (units vary) |
| IR-A |
inhalation rate (m3/hr) |
| IR-O |
ingestion rate of aquatic organisms (kg/day) |
| IR-S |
ingestion rate of soil or sediment (mg/day) |
| IR-W |
ingestion rate of water (L/hour) |
| kG, H2O |
gas-phase mass transfer coefficient of water vapor at 25�C |
| Ki |
overall mass transfer coefficient of contaminant (cm/s) |
| kiG |
gas-phase mass transfer coefficient of i (cm/s) |
| kiL |
liquid-phase mass transfer coefficient of i (cm/s) |
| kL, O2 |
liquid-phase mass transfer coefficient of oxygen at 25�C (cm/s) |
| Kp |
permeability coefficient (cm/hr) |
| Ld |
distance between trench bottom and groundwater (cm) |
| Lgw |
depth to groundwater (cm) |
| MWH2O |
molecular weight of water (g/mol) |
| MWi |
molecular weight of i (g/mol) |
| MWO2 |
molecular weight of oxygen (g/mol) |
| PEF |
particulate emission factor (m3/kg) |
| Porvad |
total soil porosity in vadose zone (cm3/cm3) |
| R |
ideal gas constant (atm-m3/mol-�K) |
| RfC |
reference concentration (mg/m3) |
| RfD |
reference dose (mg/kg-day) |
| RfDd |
dermal reference dose (mg/kg-day) |
| RfDi |
inhalation reference dose (mg/kg-day) |
| RfDo |
oral reference dose (mg/kg-day) |
| RL |
remediation level for a given medium |
| RLd |
remediation level for dermal exposure |
| RLi |
remediation level for inhalation exposure |
| RLo |
remediation level for oral exposure |
| SA |
skin surface area available for contact (cm2) |
| T |
average system absolute temperature (�K) |
| t* |
time to reach steady state (hours) |
| THQ |
target hazard quotient (unitless) |
| tau |
lag time (hours) |
| V |
volume of trench (m3) |
| VF |
volatilization factor (m3/kg or L/m3) |