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• 5 0 CONCLUSIONS <br /> 51 Site Conditions <br /> The soil underlying the site consists of clay and sandy clay with infrequent sand lenses <br /> A series of groundwater measurements by B.M I Well Survey of the EMCON wells indicated <br /> that groundwater elevations ranged from approximately -16 to -20 feet mean sea level (MSL) <br /> Groundwater flow was generally toward the southeast to southwest <br /> During the MARK investigation, groundwater was first encountered the boreholes M a <br /> clayey to clayey sand unit located approximately 41 to 44 feet bgs. The water level rose slowly <br /> to 20 to 25 feet bgs. Groundwater is currently approximately 31 feet bgs, as measured in the <br /> monitoring wells in April 1993 The groundwater gradient has been calculated to be nearly flat, <br /> at 1 foot per 100 feet (0 01 ft/ft) Groundwater flow is toward the east-northeast as shown in <br /> Drawing 1-3. The overall groundwater conditions suggest an environment of sluggish <br /> groundwater movement, and therefore, limited movement of any petroleum hydrocarbons. <br /> 52 Source Removal and Soil Remediation <br /> Petroleum-impacted soil has been excavated from two former UST locations (north and <br /> south pits) and from the former diesel fuel dispenser island area Impacted soil from was <br /> remediated using the HEVEfrO process augmented by bioremediation methods Impacted and <br /> treated soil was disposed offsite <br /> Confirmation sampling and analysis of soil samples from the excavations showed that the <br /> majority of the impacted soil was removed Only minor trace quantities of petroleum <br /> hydrocarbons were left in the floor and east wall of the north pit and the north wall of the <br /> dispenser island excavation because further excavation posed a risk to the structural integrity of <br /> buildings on the site These residual hydrocarbons were subsequently removed using the vapor <br /> FASCLOSE.5 5-1 92-1177102 36 <br />