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1 . 30 March 2004 AGE-NC Project No 02-0962 ' Page 5 of 7 4 3 HYDROCARBON-IMPACTED GROUND WATER 1 Grab ground water samples collected from six of the seven soil borings on 30 and 31 October 2003 , were analyzed for the petroleum hydrocarbon products listed in Section 3 2 The following target analytes were detected • TPH-g and TPH-d were detected in ground water samples collected from bonngs B2 and B4, ' at maximum concentrations of 190,000 micrograms per liter(µg/1)TPH-g and 2,200,000µg/1 (TPH-d) in boring B4 Laboratory chromatograms show the TPH-g concentrations were ' detected within the diesel-range spectrum, Indicating that the TPH-g may actually be degraded diesel fuel • MTBE was detected in ground water samples collected from boring B5 at a concentration ' of 15 µg/1 No other target analytes were detected at or above laboratory detection limits in the samples ' analyzed Analytical results from ground water samples are summarized in Table 2 The lateral distribution of TPH-d impacted groundwater is depicted in Figure 3A The laboratory report(CTEL Project No CT214-0311002), quality assurance and quality control (QA/QC) report and chain-of- custody forms are included in Appendix B ` 5 0 SITE CONCEPTUAL MODEL Based on the data collected to date from the soil boring installation and sampling, AGE has developed a site conceptual model for the release,migration and distribution of the contaminants in the subsurface as described below The site surface is essentially flat land that Is developed into a truck and auto plaza(Figure 2) The majority of the ground surface is covered by an asphalt or concrete cap In general, a clayey silt layer ranging from surface grade to approximately 20 feet bsg underlies the assessed portion of the property(Unit 1) Beneath the clayey silt layer is a fine-grained layer consisting of silty sand to fine sand (Unit 2); which is encountered at approximately 20 feet bsg and whose vertical extent in not yet known The informal unit 2 has the characteristics of the an aquifer, or the water table Geologic cross sections are provided as Figures 4 through 10 During site assessment activities in October of 2003;ground water was encountered approximately , I' 19 45 feet to 26 3 feet below bsg Based on Information from quarterly monitoring events performed by AGE at the adjacent Nomellmi Construction Company, ground water flow is generally toward the north to northeast However, this may be greatly modified by local recharge and discharge . patterns Advanced GeoE nviron mental,Inc I '