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October 15, 1991 <br /> Project 310-01.02 <br /> Page 2 <br /> rte` <br /> Findings <br /> Groundwater occurred at an approximate depth of 8 feet below ground surface on i <br /> August 30, 1991,with a northwesterly flow direction at an average gi adient of <br /> 4.004'(Table 1, Figure 3). This data is consistent with,that observed during the <br /> previous groundwater monitoring event,although groundwater elevations have <br /> E decreased in all site wells by 0.03 foot to 0.25 foot. <br /> Groundwater samples coLected from site wells on August 30, 1991,were analyzed <br /> for total petroleum hydrocarbons calculated as gasoline(TPH-gasoline),total <br /> p petroleum hydrocarbons calculated as diesel(TPH-diesel),and benzene, toluene, <br /> i ethylbenzene,and xylenes(BTEX compounds). Detectable TPH-gasoline <br /> concentrations were observed only in Wells U-2 and U-5, at concentrations <br /> 1,700 parts per billion(ppb)and 2,200 ppb respectively. A single occurrence of <br /> detectable TPH-diesel was present in Well U-5 on August 30, 1991 at a <br /> concentration-of 380 ppb. Bznzehe.,concentrations were observed in Wells U-1 F <br /> U,2, U-5 aril U-E,with a mammum concentration occurring in U 5 at 100 ppb: r <br /> Dissolved hydrocarbon concentrations are presented on Figure 4. The certified <br /> analytical reports and Meld data sheets are included in Attachment B. <br /> Additional Investigation <br /> The extent of petroleum hydrocarbons in the soil and groundwater underlying the <br /> site is not currently defined. PACIFIC submitted a technical report dated <br /> August 5, 1991, documenting the results of the soil and groundwater investigation !' <br /> conducted at the site. That report included recommendations to install one off-site <br /> groundwater monitoring well to the north of the site, and one off-sire well to the j <br /> west of the site (Figure 5). PACIFIC is currently in the process of obtaining <br /> private property access agreements to install these monitoring wells. The nest # . <br /> quarterly groundwater sampling event is scheduled for November 1991. ` <br /> f <br /> i1001D2/=1?91 <br /> j <br />