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r <br /> 19 October 2012 <br /> AGE-NC Project No. 97-0312 <br /> Page 10 of 22 <br /> based on recent monitoring events. <br /> When all the information is entered, SESOIL provides a predicted mass loading to <br /> groundwater for each year of the test. The AT123D modeling program used the yearly <br /> predicted mass load to groundwater from SESOIL and hydraulic properties of the aquifer <br /> to estimate the contaminant concentrations in groundwater at a receptor well. To obtain <br /> maximum groundwater concentrations, the receptor well was placed at the down-gradient <br /> edge of the soil contaminant plume. The maximum permitted running time of 100 years <br /> was used for this site. <br /> 3.1.3 Results of Sesoil Modeling <br /> With all parameters entered, using the best available data, SESOIL predicted that no <br /> contaminants would impact groundwater. SESOIL input data was presented in the AGE <br /> prepared Quarterly Report - Fourth Quarter 1999, dated 10 March 2000. <br /> The AT123D model predicts chemical concentrations in groundwater at a down-gradient <br /> receptor well. Since no hydrocarbons were predicted to reach groundwater, this section of <br /> the modeling program was not used. <br /> 4.0. ASSESSMENT OF HYDROCARBON-IMPACTED GROUNDWATER <br /> Between July 1990 and December 2011,approximately 40 groundwater monitoring events <br /> were conducted on Cherokee Truck Stop wells to monitor shallow and deeper dissolved <br /> fuel component concentrations and to characterize groundwater flow direction and gradient <br /> on the site. <br /> In addition, grab groundwater samples were collected from soil borings B-14, B-15 and <br /> B-17 at depths of 65 feet bsg and from CPT-1 and CPT-2 at depths of 66 feet bsg and just <br /> below 100 feet bsg. Laboratory analysis of water samples from the wells and soil borings <br /> indicated that groundwater at the site locally has been impacted by TPH-g, TPH-d, BTEX <br /> compounds and MTBE. `'k +o CW <br /> iwQ <br /> The highest dissolved petroleum hydrocarbon concentrations detected in groundwater <br /> monitoring well samples were detected in the samples collected from co-located monitoring <br /> wells MW-1 and MW-5.TPH-g,TPH-d and benzene have been detected at concentrations <br /> as high as 3,400 lag/I (MW-1), 350,000 lag/I (MW-1) and 840 pg/I (MW-5), respectively, <br /> during the site investigation. Minor concentrations of dissolved petroleum hydrocarbons <br /> have been detected in groundwater samples from monitoring wells MW-2, MW-3, MW-4 <br /> Advanced GeoEnvironmental,Inc. <br /> v <br />