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Ms Pamela Lopez September 18 1996 9647-0771 • Ground water samples were collected through hollow-stem augers at the location of the borings and analyzed for the presence of TPH-g and BTEX The analytical results indicated the greatest concentrations were detected at the location of SBA On the basis of these results, RAH Environmental, Inc, concluded that the source of the petroleum hydrocarbons found in soil boring SBA most probably came from the former UST on the Lopez property The analytical results are included in Attachment 1 In February 1996, Fugro supervised the advancement of five drill holes (1VIW-1, MW-2, MW- 3, SB-A1, and SB-A2) at the locations illustrated on Figure 2 The drill holes were advanced to approximate depths ranging form 20 5 to 35 5 feet Selected sort samples collected from the drill holes were analyzed for the presence of TPH-g and BTEX by US EPA Method 8015M/8020 The analytical results are included in Attachment 1 as Table 3 GROUND WATER MONITORING Ground Water Levels On August 22, 1996, Fugro collected depth to ground water measurements in monitoring wells MW-1 through MW-3 prior to purging and sampling All depth to ground water measurements were recorded according to the Fugro standard operating procedures (SOPS) included as Attachment 2 - Standard Operating Procedures • Ground water level data are summarized in Table 1 Since the last sampling event conducted in February 1996, the ground water elevation in all monitoring wells has decreased an average of 4 24 feet A ground water elevation hydrograph is included as Figure 3 - Ground Water EIevatnon Hydrograph On the basis of the August 22, 1996, measurements, ground water is estimated to flow to the south at an average hydrogeologic gradient of approximately 0 004 feet per foot (ft/ft) (Figure 4 -Potentiometnc Surface Map, August 22, 1996) Water Sampling and Analysis On August 22, 1996, Fugro collected ground water samples at the locations of monitoring wells MW-1 through MW-3 The ground water samples were collected according to the Fugro SOP included in Attachment 1, and were delivered under cham-o£custody documentation to Excelchem Environmental Laboratory, a state-certified analytical laboratory The samples were analyzed for concentrations of • TPH identified as gasoline by modified U S EPA Method 8015, and • Benzene, toluene, ethylbenzene, and total xylenes by U S EPA Method 602 The analytical results are summarized in Table 2 The analytical report and chain-of-custody form are included in Attachment 3 Concentrations of TPH identified as gasoline and benzene are illustrated on Figure 5 -Distribution Map of TPH as Gasoline and Benzene in Ground Water, August 22, 1996 9647onn Aw 2 `--