The URL can be used to link to this page

Home My WebLink AboutFA-114_5189_CA_RPTS_20230731_ F&T Model 3502 Hayes Road • Monroe, North Carolina 28110 113 West Firetower Road, Suite G • Winterville, North Carolina 28590 Phone (704) 845-4010 • (888) 870-4133 • Fax (704) 845-4012 July 31, 2023 Mr. Ken Currie North Carolina Department of Environmental Quality Underground Storage Tank Section Fayetteville Regional Office 225 Green Street Suite 714 Fayetteville, North Carolina 28301 Re: Computer Fate and Transport Model Report John’s Citgo Service, Inc. 211 North Main Street Red Springs, Robeson County, North Carolina Incident #5189 GRI Project #5008 Dear Mr. Currie: GRI presents the results of a fate and transport simulation that was completed for the above referenced site. The modeling effort is to determine if contaminant constituents would reach the spring-fed wetland area within 500 feet of the site. FATE AND TRANSPORT MODEL A fate and transport simulation was performed to determine the feasibility of site remediation by natural attenuation. The reduction of the contaminants of concern in the saturated zone by natural attenuation was estimated using BIOSCREEN, which simulates remediation through natural attenuation of dissolved hydrocarbons at petroleum fuel release sites. The software is based on the Domenico analytical solute transport model and has the ability to simulate advection, dispersion, adsorption, and aerobic decay as well as anaerobic reactions that have been shown to be the dominant biodegradation processes at many petroleum release sites. BIOSCREEN includes three different model types: 1. Solute transport without decay, 2. Solute transport with biodegradation modeled as a first-order decay process (simple, lumped- parameter approach), 3. Solute transport with biodegradation modeled as an “instantaneous” biodegradation reaction (approach used by BIOPLUME models). The model is designed to simulate biodegradation by both aerobic and anaerobic reactions. It was developed through collaboration between the U.S. EPA and the U.S. Air Force. Computer Fate and Transport Model Report John’s Citgo Service, Inc. Red Springs, North Carolina Page 2 of 6 3502 Hayes Road • Monroe, North Carolina 28110 113 West Firetower Road, Suite G • Winterville, North Carolina 28590 Phone (704) 845-4010 • (888) 870-4133 • Fax (704) 845-4012 In addition to the assumptions built into the Domenico Model, several other site-specific assumptions were incorporated into the model based upon field data collected during assessment and monitoring activities. The site-specific assumptions are as follows:  Based on a review of site history, a release was reported in August 1989 and UST Incident #5189 was assigned. Free product was present until 2019. Since the objective of the simulation was to determine the feasibility of remediation by natural attenuation, the calibration effort was focused on replicating site conditions from 2019 to 2023 (the current conditions).  The ground water flow regime was generally to the northeast based on the April 2023 data, as well as historical data.  The hydraulic conductivity calculated from slug tests conducted during the Comprehensive Site Assessment ranged from 0.22 to 15.25 feet per day, with the seepage velocity ranging from 6.424 to 445.3 feet per year with an average groundwater seepage velocity of 181.5 feet per year. Test simulations were performed using this range of velocities and other site specific conditions to determine reasonable water-balance computations for the model calibrations.  The source area is the former UST basin and is extended to include monitoring wells GMW-1, GMW-7, MW-2 and MW-3.  Monitoring wells GMW-3, GMW-8 and MW-5, located approximately 82.5 feet, 118.5 feet and 135.9 feet from the source area, respectively, were used as compliance points to compare the simulated data with actual data. In addition, the reduction of contaminant concentrations in one or more of the source area monitoring wells was also used to compare simulated data with actual data.  Fraction organic carbon was assumed to be 0.001 based on the site conditions.  For gasoline spills, BTEX compounds are usually assumed to comprise the bulk of dissolvable organics in the source zone. Since contaminant specific soil quality data from UST closure activities was not available, to simulate a declining source, the soluble mass of BTEX compounds in soil was assumed based on ground water quality data obtained from the source area during the November 2019 sampling event. It was assumed that the contaminants in the soil were equal to those dissolved in ground water resulting in the reported concentrations. The seasonal high water table was reported at an average depth of 11 feet in the source area during the January 2021 ground water gauging event. For modeling purposes, the volume of contaminated soil was estimated by multiplying the area of the source, with the average water column height of the source area. The volume was converted to kilograms (kg) of contaminated soil and multiplied by the average soil concentration to get the soluble mass in the source zone. This quantity was used to estimate the rate at which the source zone concentration declines. The soluble mass was calculated to be approximately 194 kg using the November 2019 soil sampling data. Please note that this represents the average of contaminant specific concentrations from the source area monitoring wells referenced earlier.  The objective of the model calibration was to predict the trend of contaminant reduction in the source area from the time free product had been eliminated in 2019, in the absence of a secondary source area. The modeling effort was directed towards obtaining a match point for the contaminant concentrations in the source area and down-gradient monitoring wells. Please note that the calibration period was from November 2019 (following the soil excavation) to April 2023, approximately 4 years. Computer Fate and Transport Model Report John’s Citgo Service, Inc. Red Springs, North Carolina Page 3 of 6 3502 Hayes Road • Monroe, North Carolina 28110 113 West Firetower Road, Suite G • Winterville, North Carolina 28590 Phone (704) 845-4010 • (888) 870-4133 • Fax (704) 845-4012  Red Spring, located approximately 430 feet northeast from the source area, was the primary exposure point agreed upon between the NCDEQ and GRI for the model. The modeling effort was designed to determine if contaminant concentrations of benzene and toluene exceeded ten times the surface water quality standards (10x2B) in the sspring. Please note that surface water quality standards for ethylbenzene, xylenes and naphthalene have not been established. Therefore, the modeling effort for these contaminants was only to determine if concentrations of these constituents exceeded MACs in the sspring. Please note that in the case of the spring, the potential exceedance of 2L standards at the spring does not determine the risk classification for the site. Rather, an exceedance of 10x2B will determine whether the spring is at risk.  The closest water supply well, WSW-1, located approximately 328 feet northeast of the source area (down-gradient), was selected as one of the secondary exposure points for the model. Please note that this well is not used for potable purposes and the modeling effort was purely designed to determine if contaminant concentrations exceed the 2L standards in this well. Once the model was calibrated for BTEX constituents and naphthalene, subsequent simulations were run to predict the trend of contamination reduction from the time free product was eliminated until such time as the individual contaminant concentrations exceeded 10x2B (for benzene and toluene) at the spring. For the remaining constituents, the model run was extended to predict whether the individual constituents would reach the distance of water supply well WSW-1 and/or the spring at concentrations exceeding the MACs. This required modeling the individual contaminants with the best-fit source concentrations and increasing the simulation time incrementally until source concentrations (and down- gradient compliance point concentrations) were at or below target levels (MACs). The input parameters for the model are presented in Table 1. BIOSCREEN MODELING SUMMARY Model Calibration  The instantaneous reaction model was used in an attempt to approximate the current plume length (~155 feet).  BTEX constituents and naphthalene exceeded the MACs in at least one source area monitoring well. Therefore, the model was calibrated and simulations were run to determine the fate and transport of these constituents. Please note that only the exceedance of 10x2B standard can be used to determine whether the spring is at risk.  A decaying source was assumed in the model calibration and the source concentrations from 4 years ago (2019) were estimated to match source concentrations for the April 2023 data. Because the source decay term is different for the first order decay and instantaneous reaction models, this simulation focused on matching the instantaneous reaction model. The results of the model calibration have been summarized in Table 2.  Attempts to match the plume using the first-order decay model were unsuccessful. Therefore, the focus of the model was to simulate the plume using the instantaneous reaction model.  The instantaneous model reproduced the observed source concentrations relatively well and provided a reasonable match for the down-gradient compliance points MW-6 and MW-10R for both of the modeled constituents. Please note that the calculated benzene concentration was greater than the observed concentration. This indicates that the benzene in the source area is attenuating faster than the model has predicted. The results of model calibration are included as Appendix A. Computer Fate and Transport Model Report John’s Citgo Service, Inc. Red Springs, North Carolina Page 4 of 6 3502 Hayes Road • Monroe, North Carolina 28110 113 West Firetower Road, Suite G • Winterville, North Carolina 28590 Phone (704) 845-4010 • (888) 870-4133 • Fax (704) 845-4012 Model Simulation  As shown in the plume output for each of the modeled contaminants, it is estimated that from the present (2023), the benzene plume will exceed the MACs off-site (beyond MW-5) in 4 years (2027) and will exceed the MACs in WSW-1 in 18 years (2041). The model predicted that the benzene plume will reach the spring in 25 years (2048). The simulation time was extended to 65 years and more to determine if benzene concentrations at the spring would exceed 10x2B. The model predicted that this standard would not be exceeded and that contaminant concentrations would start declining.  For the simulation of the toluene plume, the model predicted contaminant concentrations will exceed the MACs off-site (beyond MW-5) in 4 years (2027) and will exceed the MACs in WSW-1 in 17 years (2040) . The model predicted that the toluene plume will reach the spring in 18 years (2041) and will exceed 10x2B in 19 years (2042). The results of the model simulation have been summarized in Table 3.  Simulations were also conducted for ethylbenzene, xylenes and naphthalene plumes. The model predicted that the ethylbenzene and xylenes plumes will reach the spring in 2044 and 2051; while the naphthalene plume will not reach the spring. Please note that there is no established 2B standard for these contaminants. For ethylbenzene, xylenes and naphthalene, the 2L standards were predicted to be exceeded at WSW-1 in 2042, 2045 and 2112, respectively.  Simulations conducted for the modeled contaminants with a time period increasing incrementally beyond the above referenced run times showed a decrease of each constituent in the source area and at the compliance points down-gradient. This indicates that the contaminant plumes are attenuating at a faster rate than the rate at which they are migrating offsite. The results of simulations are included as Appendix B. Conclusion  The results of the fate and transport simulation indicate that the benzene plume will not exceed 10x2B at the spring in the simulated time frame and the toluene plume will exceed 10x2B at the spring in 2042 (19 years from the present). Both plumes show declining trends indicating the potential effect of natural attenuating.  Beyond the simulation period, the model predicted that contaminant concentrations would decrease in down-gradient compliance points. This indicates that the plumes are attenuating faster than they are migrating offsite.  Based on the results of the fate and transport model, it appears that the toluene plume will exceed 10x2B in 19 years, therefore, it is recommended that some source concentration reduction measures be employed followed by semi-annual sampling for 2 additional years. A computer model should be run again at that time to confirm if the declining trend is continuing and whether the source reduction measures had the desired effect in reducing the migration and thereby the predicted exposure point concentrations at the spring. Please note that this model does not take into account the effect of water being pumped from any of the nearby water supply wells. The screened interval and well pumping rates are unknown, as well as the quality of the well construction. Please do not hesitate to contact me at (704) 845-4010 or by email at wlr@geologicalresourcesinc.com, if you have any questions or comments. TABLES Date: 07/31/23 Facility ID # : 00-0-0000021055 Data Type Parameter Values Values Values Values Values Source of Data Benzene Toluene Ethylbenzene Xylenes Naphthalene Hydraulic Conductivity 7.76 x 10-5 cm/sec to 5.38 x 10-3 cm/sec 7.76 x 10-5 cm/sec to 5.38 x 10-3 cm/sec 7.76 x 10-5 cm/sec to 5.38 x 10-3 cm/sec 7.76 x 10-5 cm/sec to 5.38 x 10-3 cm/sec 7.76 x 10-5 cm/sec to 5.38 x 10-3 cm/sec Slug Test (2019) Hydraulic Gradient 0.02 ft/ft 0.02 ft/ft 0.02 ft/ft 0.02 ft/ft 0.02 ft/ft Static water level measurements Effective Porosity 0.25 0.25 0.25 0.25 0.25 assumed Seepage Velocity 6.42 ft/yr to 445.3 ft/yr 6.42 ft/yr to 445.3 ft/yr 6.42 ft/yr to 445.3 ft/yr 6.42 ft/yr to 445.3 ft/yr 6.42 ft/yr to 445.3 ft/yr Slug Test (2019) After Calibration Seepage Velocity 26.5 ft/yr 26.5 ft/yr 26.5 ft/yr 26.5 ft/yr 26.5 ft/yr Assumed based on calibration Original Longitudinal Dispersivity 9.4 (ft)9.4 (ft)9.4 (ft)9.4 (ft)9.4 (ft)Based on estimated plume length of 155 ft Transverse Dispersivity 0.9 (ft)0.9 (ft)0.9 (ft)0.9 (ft)0.9 (ft)and Xu/Eckstein relationship. Vertical Dispersivity 0.2 (ft)0.2 (ft)0.2 (ft)0.2 (ft)0.2 (ft)(See BIOSCREEN Manual for details) After Calibration Longitudinal Dispersivity 25.0 (ft)19.1 (ft)3.5 (ft)7.8 (ft)9.4 (ft)Based on calibration to plume length and Transverse Dispersivity 2.5 (ft)1.9 (ft)0.4 (ft)0.8 (ft)0.9 (ft)current plume concentrations. Vertical Dispersivity 0.2 (ft)0.2 (ft)0.2 (ft)0.2 (ft)0.2 (ft) Retardation Factor 1.3 1.9 1.6 2.6 6.4 Calculated from R = 1+Koc x foc x rho/n Soil Bulk Density 1.7 (kg/l)1.7 (kg/l)1.7 (kg/l)1.7 (kg/l)1.7 (kg/l)Estimated foc 0.001 0.001 0.001 0.001 0.001 Assumed Koc 38 L/kg 135 L/kg 95 L/kg 240 L/kg 800 L/kg Literature Electron Acceptor O2 NO3 SO4 O2 NO3 SO4 O2 NO3 SO4 O2 NO3 SO4 O2 NO3 SO4 Background Conc. (mg/l) 1.46 2.50 2.00 1.46 2.50 2.00 1.46 2.50 2.00 1.46 2.50 2.00 1.46 2.50 2.00 Based on April 2023 ground water sampling event. Minimum Conc. (mg/l) 0.91 0.00 0.00 0.91 0.00 0.00 0.91 0.00 0.00 0.91 0.00 0.00 0.91 0.00 0.00 Change in Conc. (mg/l) 0.55 2.50 2.00 0.55 2.50 2.00 0.55 2.50 2.00 0.55 2.50 2.00 0.55 2.50 2.00 Availability per Contaminant (mg/L) 0.11 0.50 0.40 0.11 0.50 0.40 0.11 0.50 0.40 0.11 0.50 0.40 0.11 0.50 0.40 After Calibration 0.11 0.50 0.40 0.11 0.50 0.40 0.11 0.50 0.40 0.11 0.50 0.40 0.11 0.50 0.40 Note: Bold values are BIOSCREEN input screen. Assumed. Electron Acceptor Fe CH4 Fe CH4 Fe CH4 Fe CH4 Fe CH4 Max. Conc. (mg/l)15.50 0.305 15.50 0.305 15.50 0.305 15.50 0.305 15.50 0.305 Avg. Conc. (mg/l)7.90 0.2825 7.90 0.2825 7.90 0.2825 7.90 0.2825 7.90 0.2825 Availability per Contaminant (mg/L)1.58 0.057 1.58 0.057 1.58 0.057 1.58 0.057 1.58 0.057 After Calibration 1.58 0.057 1.58 0.057 1.58 0.057 1.58 0.057 1.58 0.057 Note: Bold values are BIOSCREEN input screen. Assumed. Modeled Area Length 200 ft 200 ft 200 ft 200 ft 200 ft Based on area of affected groundwater Modeled Area Width 100 ft 100 ft 100 ft 100 ft 100 ft plume. Simulation Time 4 years 4 years 4 years 4 years 4 years Based on the date of the release (1989). Source Thickness 19.0 ft 19.0 ft 19.0 ft 19.0 ft 19.0 ft Based on average water column height. Source Concentration 1.73 mg/L 21.85 mg/L 6.40 mg/L 37.5 mg/L 1.60 mg/L Assumed (Based on 2019 ground water sampling data) Monitoring Well Source GMW-3 GMW-8 MW-5 Source GMW-3 GMW-8 MW-5 Source GMW-3 GMW-8 MW-5 Source GMW-3 GMW-8 MW-5 Source GMW-3 GMW-8 MW-5 Based on April 2023 data Distance From Source 0 ft 82.5 ft 118.5 ft 135.9 ft 0 ft 82.5 ft 118.5 ft 135.9 ft 0 ft 82.5 ft 118.5 ft 135.9 ft 0 ft 82.5 ft 118.5 ft 135.9 ft 0 ft 82.5 ft 118.5 ft 135.9 ft Observed Concentration 0.343 0.003 0.002 0.000 4.190 0.017 0.002 0.002 1.251 0.014 0.002 0.001 7.007 0.074 0.005 0.005 0.312 0.012 0.003 0.002 Concentrations in mg/L. Centerline Concentration Array Concentration See Centerline Output (Appendix B) - For Calibration See Plume Output (Appendix B) - For Calibration TABLE 1 SUMMARY OF BIOSCREEN INPUT PARAMETERS JOHN'S CITGO (INCIDENT NO. 5189) Hydrogeology Dispersion Adsorption Biodegradation General Source Data Actual Data OUTPUT Date: 07/31/23 Facility ID # : 00-0-0000021055 Distance (feet) Benzene (mg/L) Toluene (mg/L) Ethylbenzene (mg/L) Xylenes (mg/L) Naphthalene (mg/L) April 2023 Field Data 0.343 4.190 1.251 7.007 0.312 Calibrated Results 0.342 4.192 1.258 7.015 0.316 April 2023 Field Data 82.5 0.003 0.017 0.014 0.074 0.012 Calibrated Results 80 0.005 1.027 0.015 0.076 0.000 April 2023 Field Data 118.5 0.002 0.002 0.002 0.005 0.003 Calibrated Results 120 0.000 0.003 0.000 0.000 0.000 April 2023 Field Data 135.9 0.000 0.002 0.001 0.005 0.002 Calibrated Results 140 0.000 0.000 0.000 0.000 0.000 Current Plume Length ~155 feet TABLE 2 SUMMARY OF MODEL CALIBRATION RESULTS JOHN'S CITGO (INCIDENT NO. 5189) Calibration Time 2019 to 2023 - 4 years Calibration Point Source Area 0 GMW-3 MW-5 GMW-8 Date: 07/31/23 Facility ID # : 00-0-0000021055 Contaminant Mass Percent Biodegraded Benzene 65 2084 176.6 kg 17.4 kg 87% Toluene 23 2042 155.7 kg 38.3 kg 21% Ethylbenzene 29 2048 176.2 kg 17.8 kg 36% Xylenes 35 2054 111.2 kg 82.8 kg 12% Naphthalene 100 2119 168.8 kg 25.2 kg 83% Note: 2019 Creek Simulated year represents the approximate time period estimated by the model when the contaminant concentrations will decrease to at or below target levels. TABLE 3 SUMMARY OF MODEL SIMULATION RESULTS JOHN'S CITGO (INCIDENT NO. 5189) Constituent Current Year Simulation Time From 2019 Simulation Point Simulated Year Soluble Mass Remaining in Source Area Soluble Mass Exiting Source APPENDICES Appendix A Model Calibration Benzene BIOSCREEN Natural Attenuation Decision Support System JOHN'S CITGO Vs (ft/yr)(ft) (ft) K (yr) i (ft/ft) n (-) (ft) (ft) (ft) (ft) Lp (ft) R (-)(yr)View of Plume Looking Down rho (kg/l)(Kg) Koc (L/kg) foc (-) (per yr) t-half (year) DO (mg/L) NO3 (mg/L) Fe2+(mg/L) SO4 (mg/L) CH4 (mg/L) Data Input Instructions: alpha x alpha y alpha z Air Force Center for Environmental Excellence Version 1.4 RED SPRINGS, NC (cm/sec) 0.02 Inst. React. In Source NAPL, Soil 1.0E-3 0.3430 .003 .002 .0 4.6E+0 115 Soluble Mass cells below. (To restore formulas, hit button below). Data used directly in model. Value calculated by model. (Don't enter any data). Observed Centerline Concentrations at Monitoring Wells If No Data Leave Blank or Enter "0" 1 Enter value directly or 2. Calculate by filling in grey ENZENE CALIBRATIO 1. HYDROGEOLOGY 5. GENERAL 6. SOURCE DATA 2. DISPERSION 3. ADSORPTION 7. FIELD DATA FOR COMPARISON 4. BIODEGRADATION 8. CHOOSE TYPE OF OUTPUT TO SEE: Seepage Velocity*26.500 Modeled Area Length* 200 Modeled Area Width* 100 Hydraulic Conductivity 2.2E-03 Simulation Time* 4 Hydraulic Gradient 0.02 Porosity 0.25 19 Source Zones: Longitudinal Dispersivity*25.0 Transverse Dispersivity*2.5 Vertical Dispersivity*0.2 22 0.346 22 0.346 Estimated Plume Length 155 Retardation Factor*1.3 Soil Bulk Density 1.7 194 Partition Coefficient 38 FractionOrganicCarbon Concentration (mg/L) Dist. from Source (ft) 1st Order Decay Coeff* Solute Half-Life 0.15 Delta Oxygen*0.11 Delta Nitrate*0.5 Observed Ferrous Iron*1.58 Delta Sulfate*0.4 Observed Methane*0.057 Width* (ft)Conc. (mg/L)* 22 0.346 or or or or or Instantaneous Reaction Model Variable* Source Thickness in Sat.Zone* 20 1 22 0.346 500.00 1000.00 22 0.346 Source Halflife (see Help): 1st Order 0 20 40 60 80 100 120 140 160 180 200 lambda DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Benzene Calibration Distance from Source (ft) TYPE OF MODEL 0 20 40 60 80 100 120 140 160 180 200 No Degradation 0.345 0.290 0.260 0.223 0.181 0.137 0.098 0.064 0.039 0.022 0.011 1st Order Decay 0.345 0.076 0.017 0.004 0.001 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 0.342 0.228 0.167 0.092 0.005 0.000 0.000 0.000 0.000 0.000 0.000 Field Data from Site 0.3430 0.003 0.002 Time: 4 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0 50 100 150 200 250 Co n c e n t r a t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 20 40 60 80 100 120 140 160 180 200 50 0.342 0.044 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 25 0.342 0.228 0.158 0.073 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0.342 0.228 0.167 0.092 0.005 0.000 0.000 0.000 0.000 0.000 0.000 -25 0.342 0.228 0.158 0.073 0.000 0.000 0.000 0.000 0.000 0.000 0.000 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:4 Years Target Level: 0.001 mg/L Displayed Model: Inst. Reaction Benzene Calibration Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 1.1 (Kg) - Actual Plume Mass 0.2 (Kg) = Plume Mass Removed by Biodeg 0.9 (Kg) (82 %) Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane -0.3 -1.2 +3.9 -1.0 +0.1 (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=4Years) 192.9 (Kg) Current Volume of Groundwater in Plume 0.9 Flowrate of Water Through Source Zone 0.318 50 0 -50 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0 20 40 60 80 100 120 140 160 180 (ft) Co n c e n t r a t i o n ( m g / L ) (ft) Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Toluene DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Toluene Calibration Distance from Source (ft) TYPE OF MODEL 0 20 40 60 80 100 120 140 160 180 200 No Degradation 4.218 3.327 2.727 2.005 1.287 0.716 0.341 0.138 0.047 0.014 0.003 1st Order Decay 4.218 0.486 0.056 0.006 0.001 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 4.192 3.232 2.586 1.806 1.027 0.409 0.003 0.000 0.000 0.000 0.000 Field Data from Site 4.1900 0.017 0.002 0.002 Time: 4 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500 0 50 100 150 200 250 Co n c e n t r a t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 20 40 60 80 100 120 140 160 180 200 50 4.192 2.211 1.573 1.001 0.488 0.101 0.000 0.000 0.000 0.000 0.000 25 4.192 3.231 2.564 1.755 0.969 0.364 0.000 0.000 0.000 0.000 0.000 0 4.192 3.232 2.586 1.806 1.027 0.409 0.003 0.000 0.000 0.000 0.000 -25 4.192 3.231 2.564 1.755 0.969 0.364 0.000 0.000 0.000 0.000 0.000 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:4 Years Target Level: 0.600 mg/L Displayed Model: Inst. Reaction Toluene Calibration Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 7.3 (Kg) - Actual Plume Mass 5.8 (Kg) = Plume Mass Removed by Biodeg 1.5 (Kg) (21 %) Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane -0.4 -2.0 +6.5 -1.6 +0.2 (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=4Years) 186.7 (Kg) Current Volume of Groundwater in Plume 1.6 Flowrate of Water Through Source Zone 0.318 50 0 -50 0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500 0 20 40 60 80 100 120 140 160 180 (ft) Co n c e n t r a t i o n ( m g / L ) (ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Ethylbenzene DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Ethylbenzene Calibration Distance from Source (ft) TYPE OF MODEL 0 20 40 60 80 100 120 140 160 180 200 No Degradation 1.267 1.247 1.114 0.744 0.297 0.061 0.006 0.000 0.000 0.000 0.000 1st Order Decay 1.267 0.037 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 1.258 1.234 1.065 0.590 0.015 0.000 0.000 0.000 0.000 0.000 0.000 Field Data from Site 1.2510 0.014 0.002 0.001 Time: 4 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 0 50 100 150 200 250 Co n c e n t r a t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 20 40 60 80 100 120 140 160 180 200 50 1.267 1.133 0.921 0.579 0.222 0.044 0.004 0.000 0.000 0.000 0.000 25 1.267 1.247 1.114 0.744 0.297 0.061 0.006 0.000 0.000 0.000 0.000 0 1.267 1.247 1.114 0.744 0.297 0.061 0.006 0.000 0.000 0.000 0.000 -25 1.267 1.247 1.114 0.744 0.297 0.061 0.006 0.000 0.000 0.000 0.000 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:4 Years Target Level: 0.600 mg/L Displayed Model: No Degradation Ethylbenzene Calibration Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 2.0 (Kg) - Actual Plume Mass 2.0 (Kg) = Plume Mass Removed by Biodeg 0.0 (Kg) 0 % Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane na na na na na (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=4Years) 192.0 (Kg) Current Volume of Groundwater in Plume 1.8 Flowrate of Water Through Source Zone 0.318 50 0 -50 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 0 20 40 60 80 100 120 140 160 180 (ft) Co n c e n t r a t i o n ( m g / L ) (ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Xylenes DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Xylenes Calibration Distance from Source (ft) TYPE OF MODEL 0 20 40 60 80 100 120 140 160 180 200 No Degradation 7.059 5.752 3.781 1.617 0.423 0.064 0.005 0.000 0.000 0.000 0.000 1st Order Decay 7.059 0.174 0.004 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 7.015 5.657 3.599 1.329 0.076 0.000 0.000 0.000 0.000 0.000 0.000 Field Data from Site 7.0068 0.074 0.005 0.005 Time: 4 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000 8.000 0 50 100 150 200 250 Co n c e n t r a t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 20 40 60 80 100 120 140 160 180 200 50 7.059 0.141 0.003 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 25 7.059 0.174 0.004 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 7.059 0.174 0.004 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 -25 7.059 0.174 0.004 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:4 Years Target Level: 0.500 mg/L Displayed Model: 1st Order Decay Xylenes Calibration Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 11.4 (Kg) - Actual Plume Mass 1.1 (Kg) = Plume Mass Removed by Biodeg 10.3 (Kg) (90 %) Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane na na na na na (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=4Years) 182.6 (Kg) Current Volume of Groundwater in Plume 0.5 Flowrate of Water Through Source Zone 0.318 50 0 -50 0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000 8.000 0 20 40 60 80 100 120 140 160 180 (ft) Co n c e n t r a t i o n ( m g / L ) (ft) Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Naphthalene DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Naphthalene Calibration Distance from Source (ft) TYPE OF MODEL 0 20 40 60 80 100 120 140 160 180 200 No Degradation 0.319 0.134 0.029 0.002 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1st Order Decay 0.319 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 0.316 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Field Data from Site 0.3118 0.012 0.003 0.002 Time: 4 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0 50 100 150 200 250 Co n c e n t r a t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 20 40 60 80 100 120 140 160 180 200 50 0.319 0.107 0.021 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 25 0.319 0.134 0.029 0.002 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0.319 0.134 0.029 0.002 0.000 0.000 0.000 0.000 0.000 0.000 0.000 -25 0.319 0.134 0.029 0.002 0.000 0.000 0.000 0.000 0.000 0.000 0.000 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:4 Years Target Level: 0.006 mg/L Displayed Model: No Degradation Naphthalene Calibration Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 0.5 (Kg) - Actual Plume Mass 0.5 (Kg) = Plume Mass Removed by Biodeg 0.0 (Kg) 0 % Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane na na na na na (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=4Years) 193.5 (Kg) Current Volume of Groundwater in Plume 0.8 Flowrate of Water Through Source Zone 0.318 50 0 -50 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0 20 40 60 80 100 120 140 160 180 (ft) Co n c e n t r a t i o n ( m g / L ) (ft) Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Appendix B Model Simulation Benzene DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Benzene Simulation 2084 Distance from Source (ft) TYPE OF MODEL 0 80 160 240 320 400 480 560 640 720 800 No Degradation 0.331 0.329 0.310 0.280 0.252 0.227 0.206 0.188 0.172 0.159 0.147 1st Order Decay 0.331 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 0.282 0.281 0.244 0.188 0.133 0.085 0.044 0.009 0.000 0.000 0.000 Field Data from Site 0.3430 0.003 0.002 Time: 65 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0 100 200 300 400 500 600 700 800 900 Co n c e n t ra t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 80 160 240 320 400 480 560 640 720 800 200 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 100 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0.282 0.281 0.244 0.188 0.133 0.085 0.044 0.009 0.000 0.000 0.000 -100 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:65 Years Target Level: 0.001 mg/L Displayed Model: Inst. Reaction Benzene Simulation 2084 Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 17.4 (Kg) - Actual Plume Mass 3.0 = Plume Mass Removed by Biodeg 14.3 (Kg) (83 %) Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane -4.3 -19.5 +61.7 -15.6 +2.2 (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=65Years) 176.6 (Kg) Current Volume of Groundwater in Plume 7.0 Flowrate of Water Through Source Zone 0.318 200 0 -200 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0 80 160 240 320 400 480 560 640 720 (ft) Co n ce n t r a t i o n ( m g / L ) (ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Toluene DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Toluene Simulation 2042 Distance from Source (ft) TYPE OF MODEL 0 43 86 129 172 215 258 301 344 387 430 No Degradation 3.567 3.643 3.688 3.627 3.419 3.060 2.566 1.989 1.382 0.857 0.474 1st Order Decay 3.567 0.034 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 3.434 3.524 3.582 3.525 3.311 2.931 2.405 1.786 1.131 0.561 0.146 Field Data from Site 4.1900 0.017 0.002 0.002 Time: 23 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 1.000 2.000 3.000 4.000 5.000 0 50 100 150 200 250 300 350 400 450 500 Co n c e n t ra t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 43 86 129 172 215 258 301 344 387 430 108 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 54 3.434 1.729 1.721 1.693 1.606 1.438 1.186 0.869 0.514 0.192 0.000 0 3.434 3.524 3.582 3.525 3.311 2.931 2.405 1.786 1.131 0.561 0.146 -54 3.434 1.729 1.721 1.693 1.606 1.438 1.186 0.869 0.514 0.192 0.000 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:23 Years Target Level: 0.600 mg/L Displayed Model: Inst. Reaction Toluene Simulation 2042 Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 38.3 (Kg) - Actual Plume Mass 30.4 = Plume Mass Removed by Biodeg 8.0 (Kg) (21 %) Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane -2.4 -10.8 +34.2 -8.7 +1.2 (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=23Years) 155.7 (Kg) Current Volume of Groundwater in Plume 7.8 Flowrate of Water Through Source Zone 0.318 108 0 -108 0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 0 43 86 129 172 215 258 301 344 387 (ft) Co n ce n t r a t i o n ( m g / L ) (ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Ethylbenzene DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Ethylbenzene Simulation 2048 Distance from Source (ft) TYPE OF MODEL 0 43 86 129 172 215 258 301 344 387 430 No Degradation 1.188 1.196 1.203 1.202 1.194 1.179 1.162 1.140 1.104 1.012 0.801 1st Order Decay 1.188 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 1.128 1.142 1.153 1.156 1.148 1.133 1.113 1.089 1.046 0.930 0.662 Field Data from Site 1.2510 0.014 0.002 0.001 Time: 29 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 0 50 100 150 200 250 300 350 400 450 500 Co n c e n t ra t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 43 86 129 172 215 258 301 344 387 430 108 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 54 1.128 0.522 0.490 0.474 0.459 0.443 0.427 0.410 0.384 0.321 0.177 0 1.128 1.142 1.153 1.156 1.148 1.133 1.113 1.089 1.046 0.930 0.662 -54 1.128 0.522 0.490 0.474 0.459 0.443 0.427 0.410 0.384 0.321 0.177 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:29 Years Target Level: 0.600 mg/L Displayed Model: Inst. Reaction Ethylbenzene Simulation 2048 Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 17.8 (Kg) - Actual Plume Mass 11.4 = Plume Mass Removed by Biodeg 6.4 (Kg) (36 %) Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane -1.9 -8.8 +27.7 -7.0 +1.0 (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=29Years) 176.2 (Kg) Current Volume of Groundwater in Plume 8.3 Flowrate of Water Through Source Zone 0.318 108 0 -108 0.000 0.200 0.400 0.600 0.800 1.000 1.200 0 43 86 129 172 215 258 301 344 387 (ft) Co n ce n t r a t i o n ( m g / L ) (ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Xylenes DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Xylenes Simulation 2054 Distance from Source (ft) TYPE OF MODEL 0 43 86 129 172 215 258 301 344 387 430 No Degradation 4.414 4.709 5.016 5.308 5.545 5.650 5.454 4.756 3.548 2.045 0.912 1st Order Decay 4.414 0.002 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 4.143 4.460 4.792 5.109 5.373 5.500 5.314 4.603 3.352 1.778 0.589 Field Data from Site 7.0068 0.074 0.003 0.002 Time: 35 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000 8.000 0 50 100 150 200 250 300 350 400 450 500 Co n c e n t ra t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 43 86 129 172 215 258 301 344 387 430 108 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 54 4.143 2.339 2.434 2.563 2.679 2.734 2.633 2.261 1.607 0.777 0.146 0 4.143 4.460 4.792 5.109 5.373 5.500 5.314 4.603 3.352 1.778 0.589 -54 4.143 2.339 2.434 2.563 2.679 2.734 2.633 2.261 1.607 0.777 0.146 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:35 Years Target Level: 0.500 mg/L Displayed Model: Inst. Reaction Xylenes Simulation 2054 Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 82.8 (Kg) - Actual Plume Mass 72.8 = Plume Mass Removed by Biodeg 10.0 (Kg) (12 %) Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane -3.0 -13.5 +42.8 -10.8 +1.5 (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=35Years) 111.2 (Kg) Current Volume of Groundwater in Plume 8.3 Flowrate of Water Through Source Zone 0.318 108 0 -108 0.000 1.000 2.000 3.000 4.000 5.000 6.000 0 43 86 129 172 215 258 301 344 387 (ft) Co n ce n t r a t i o n ( m g / L ) (ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP Naphthalene DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Naphthalene Simulation 2119 Distance from Source (ft) TYPE OF MODEL 0 43 86 129 172 215 258 301 344 387 430 No Degradation 0.300 0.302 0.304 0.303 0.300 0.292 0.278 0.253 0.214 0.163 0.108 1st Order Decay 0.300 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Inst. Reaction 0.231 0.240 0.248 0.252 0.249 0.238 0.213 0.165 0.086 0.000 0.000 Field Data from Site 0.3118 0.012 0.003 0.002 Time: 100 YearsNext Timestep Prev Timestep Calculate Animation Recalculate This 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0 50 100 150 200 250 300 350 400 450 500 Co n c e n t ra t i o n (m g / L ) Distance From Source (ft) 1st Order Decay Instantaneous Reaction No Degradation Field Data from Site Return to Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0) Distance (ft)Distance from Source (ft)Model to Display: 0 43 86 129 172 215 258 301 344 387 430 108 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 54 0.231 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0.231 0.240 0.248 0.252 0.249 0.238 0.213 0.165 0.086 0.000 0.000 -54 0.231 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 MASS ----------- FLUX Can't calculate mass flux when vertical dispersivity not equal to 0 (mg/day)Time:100 Years Target Level: 0.006 mg/L Displayed Model: Inst. Reaction Naphthalene Simulation 2119 Plume and Source Masses (Order-of-Magnitude Accuracy) Plume Mass if No Biodegradation 25.2 (Kg) - Actual Plume Mass 4.3 = Plume Mass Removed by Biodeg 20.8 (Kg) (83 %) Change in Electron Acceptor/Byproduct Masses: Oxygen Nitrate Iron II Sulfate Methane -6.2 -28.3 +89.4 -22.6 +3.2 (Kg) Contam. Mass in Source (t=0 Years) 194.0 (Kg) Contam. Mass in Source Now (t=100Years) 168.8 (Kg) Current Volume of Groundwater in Plume 2.8 Flowrate of Water Through Source Zone 0.318 108 0 -108 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0 43 86 129 172 215 258 301 344 387 (ft) Co n ce n t r a t i o n ( m g / L ) (ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All Data Plot Data > Target Mass HELP