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EPA On-line Tools for Site Assessment Calculation

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Transport and Leaching from a Release of Fresh Fuel One Dimensional Transport Equation This calculator generates a breakthrough curve* at a receptor and uses a one-dimensional model to determine the First arrival time for a contaminant (above a specified threshold concentration), Maximum Concentration, and Duration of Contaminantion above the specified threshold *The breakthrough curve is the time history of concentration at a receptor located a specified distance from the contaminant source. See bottom of page for equations solved. Inputs Site Name Date Distance Unit ft m   Time Unit days years   Chemical mtbe  benzene  toluene  ethylbenzene  o-xylene  p-xylene  m-xylene  total xylenes    Example Fuel 87 Octane gasoline (1) MTBE  89 Octane gasoline (3) MTBE  93 Octane gasoline (5) MTBE  -----------------  87 Octane gasoline (2) low MTBE   89 Octane gasoline (4) Low MTBE  93 Octane gasoline (6) Low MTBE ' -----------------  87 Octane gasoline (1) Non-MTBE  87 Octane gasoline (2) Non-MTBE   89 Octane gasoline (3) Non-MTBE  89 Octane gasoline (4) Non-MTBE  93 Octane gasline (5) Non-MTBE  93 Octane gasline (6) Non-MTBE  -----------------  Diesel 1 TPH Working Group  Diesel 2 TPH Working Group  Diesel fuel oil 1994  Diesel fuel oil (Alaska)  -----------------  other  Solubility (S) mg/L Optional Revised Solubility (S) mg/L Porosity   Water Saturation Fraction of the pore space filled with water NAPL Saturation Fraction of the pore space filled with NAPL Fraction Organic Carbon   Lens diameter Smear zone thickness Recharge rate in/yr  mm/yr  Soil type sand  clay    Hydraulic Conductivity (K) ft/day m/day ft/min cm/sec gal/day/ft2 Gradient (absolute value) (-i)   Distance (x) Halflife T1/2   Year       Month       Day   Beginning Date Min. Concentration of Concern   mg/L mg/l Default Parameters Fuel composition note: Average Molecular Weight of Fuel (MWo)   Percent Mass Fraction   Intermediate Results Effective Solubility (Cw) mg/L Bulk Density(rB)   Hydraulic Conductivity (K) ft/day m/day ft/min cm/sec gal/day/ft2 Seepage Velocity (qs = v) ft/day ft/yr m/day m/yr Retardation factor (R)   Estimated dispersivity a Beginning Time of Breakthrough Curve First Arrival Breakthrough Curve Through Maximum Concentration Mid Point Additional Point Maximum Completion of Breakthrough Curve (for Pulse Sources) Additional Point Mid Point Ending Duration Above Threashold Advective Travel Time Advective Travel Time First arrival time is earlier than the advective travel time Ratio advective to first arrival time   One Dimensional Transport Equation R = retardation factor [] D = dispersion constant [L2/T] v = seepage velocity [L/T] m = first order decay constant [1/T] with the initial and boundary conditions retardation factor R = 1 + rbkd /q R = retardation factor rb = bulk density = rs(1-q) rs = solids density q = porosity kd = (soil) distribution coefficient = foc Koc foc = fraction organic carbon Koc = organic carbon/water partition coefficient travel time ttr = x R / qs ttr = advective travel time* qs = seepage velocity R = retardation factor x = distance * assuming one-dimensional, steady flow, constant gradient

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Page author: Jim Weaver, of U.S. EPA, Office of Research and Development, Athens Georgia who last modified this content on: April 20, 2003

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