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4 CONCLUSIONS AND RECOMMENDATIONS <br /> 1 On 5 February 1988, Ramcon is reported to have removed five USTs from the site. Verification <br /> samples collected beneath the 10,000 gallon tank contained TPHg and BTEX. In August 1988, <br /> Applied Geosystems drilled four bormgs and converted one of the bonngs into a 2-inch monitor <br /> well Groundwater was encountered at a depth of approximately 40 feet bgs. In April 1991, <br /> Falcon Energy and GAS installed two 4-inch monitor wells. The depth to groundwater had <br /> increased to approximately 45 feet bgs. GAS reported a product layer of approximately 112 foot <br /> at MW-1 and MW-2 The gradient was reported as slight and to the south. Based on the GAS <br /> assessment, several thousand gallons of water were extracted in an attempt to remove the <br /> product layer <br /> Because the reports reviewed prior to initiating the present phase of work did not discuss <br /> monitor well development or the product removal, each of the monitor wells was checked for <br /> a product layer and redeveloped on 4 February 1994. Furthermore, the wells were surveyed to <br /> a permanent datum by a licensed surveyor. <br /> On 7 February 1994, the depth to groundwater was measured; and, the wells were again checked <br /> for a product layer. The depth to groundwater was approximately 48 feet bgs. Due to the <br /> presence of a 0 03 foot layer on MW-3, it was not sampled. MW-1 and MW-2 were purged <br /> and sampled for TPHg and BTEX. The water samples from both wells contained each of the <br /> requested analytes at concentrations well above primary or secondary water quality goals <br /> Based on the depth to groundwater measurements, the gradient was calculated at approximately <br /> 0.3 percent to the southwest. The gradient direction is typically assumed to be the direction of <br /> groundwater flow. This assumption is true under homogeneous and isotropic conditions. <br /> However, homogeneous and isotropic conditions are not typical. In addition, limited lithologic <br /> data, and no hydrologic data, has been collected for this site; and, groundwater extraction (e.g. <br /> =gation or domestic use) or recharge (e.g. rain) can cause seasonal fluctuations which may <br /> result in gradient reversals. Therefore, great care should be used when attempting to correlate <br /> chemical concentrations with groundwater gradient directions. The groundwater at each of the <br /> monitor well locations has been impacted. Furthermore, the surface of the groundwater at MW- <br /> 3 (the down gradient well) was saturated with respect to TPH. <br /> rBasad on the concentrations reported at each of the monitor well locations further assessment <br /> should be performed to evaluate lateral extent of migration of the contaminant plume in each <br /> direction. Because of the sandy silty soils reported by the previous consultants and the moderate <br /> depth to groundwater, I recommend first attempting a qualitative assessment using cone <br /> penetration testing (CPT) and hydropunch sampling Using these results, additional monitor <br /> wells should be installed near the plume's perimeter. Furthermore, at least one boring should <br /> be installed near the presumed source of contamination The boring should be continuously <br /> sampled to allow verification of the CPT study. Because of the volatile nature of gasoline and <br /> the reported soil types, it may be prudent to convert the boring into a vapor extraction test well <br /> 7 <br />