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Y/ Mr Chuck Carmel June 21 1994 Page 2 Quarterly Sampling Field and Analytical Methods GTI personnel measured depth-to-water, purged each well, and collected groundwater samples at the site A copy of GTI's field notes is included in Exhibit A The purge water generated during this sampling event was temporarily stored on site in 55-gallon barrels then transported off site by Integrated Waste Management All groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPH-G) and benzene, toluene, ethylbenzene, and xylenes (BTEX) by U S Environmental Protection Agency Methods 5030/8020/DHS LUFT Quarterly Sampling Results and Discussion GTI's field notes and the analytical report from the quarterly groundwater sampling are contained in Exhibit A Table 1 in Exhibit B presents the water-level data for this site Table 2 in Exhibit B summarizes hnstorical groundwater flow direction and gradient data for • this site Figure 1 shows the water-level elevations for each well and the contours of equal water-level elevation for March 21, 1994 Figure 2 shows BTEX and TPH-G concentrations for each well sampled, and the approximate extent of benzene in the groundwater Table 3 in Exhibit B presents the groundwater analytical data On March 21, 1994, the general groundwater flow direction was toward the recovery well Historically, groundwater flow direction is to the northeast under an average hydraulic gradient of 001 to 003 Water-level elevations have increased an average of 0 65 feet since the last quarterly monitoring (November 1993) The TPH-G and BTEX concentrations detected in the samples collected this quarter are generally consistent with previously reported results in wells E-2, E-3, E-4, E-5, &-6, E-7, E-8, E-9,E-10,E-11,E-12,BHD-1, and MW-2 The hydrocarbon concentrations detected m BHD- 1 are thought to be attributed to the Chevron station across the street from the ARCO site. Chevron's well MW-1 is located approximately 30 feet to the north of well BHD-1 and near Chevron's former underground storage tank location Samples from Chevron's MW-1 have generally contained similar TPH-G and BTEX concentrations to those in BHD-1 Concentrations of TPH-G in the sample from well E-7 is the lowest since sampling began in 1988 The concentration of benzene in well E-8 is the lowest since sampling began in 1988 Use or disclosure of data contained on this sheet is subject to the restriction specified at the beginning of this document 127Y REPORTSIISr94QTR1UT