SITE INFORMATION AND CORRESPONDENCE

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hn KLEINFELDER known to have been running at least 5 days prior to sample collection. Field parameters and samples were obtained from the pump cutoff switch flow line. The two groundwater samples were submitted to Superior Precision Analytical for analysis. Total petroleum hydrocarbons as referenced to diesel (TPH-D) were detected in the sample from EW=1 (sample no. 14967) at 11,000 ug/I. Toluene and total xylenes were detected in the same sample at 0.6 ug/l and 5.8 ug/l respectively. Total petroleum hydrocarbons as referenced to gasoline (TPH- G) were not detected at the reporting limit of 500 ug/l in the sample from EW-1. The reporting limit was raised due to interference from other constituents in the sample. Benzene and ethylbenzene were not detected in the EW-1 sample at a 0.5 ug/l reporting limit for each. Benzene, toluene, ethylbenzene, total xylenes, TPH-G and TPH-D were not detected in the sample from MW-2 (sample no. 14966) at the following respective detection limits: 50 ug/I, 50 ug/I, 0.5 ug/l, 0.5 ug/i, 0.5 ug/l, and 0.5 ug/I. The following conclusions were made in our April 13, 1994 of the additional groundwater assessment: 1. Soil contamination above 100 mg/kg was reported to exist in the immediate vicinity of the excavated fuel pipelines at a depth of 9 feet to below the water table. Field screening results with a portable flame ionization detector (FID) during the installation of the monitoring wells indicates that the soil from a depth of 9 to 9-1/2 feet and deeper contains hydrocarbons in the areas near MW-3 and MW-4. It is apparent that the hydrocarbons in the soil is likely caused by capillary upward migration of diesel product from contaminated groundwater. 2. Free product was encountered in MW-1, MW-3, and MW-4 at 2.18, 0.3 5, and 0.53 feet in thickness respectively on February 28, 1994. Diesel was also detected in the sample from EW-1 at 11,000 ug/l. Note that when product thickness measurements were made shortly after well installation, little, if any product was found in the wells. After five days, product thickness increased significantly. In reviewing the water level and product thickness measurements, it is apparent that because the diesel floats on water, a well penetrating this diesel/water interface creates an unconfined depression open to the atmosphere. These conditions cause the diesel fuel to migrate to the well from the surrounding aquifer. The actual free product layer thickness is likely less than that depicted. Diesel and other 24-220176-FOl/CR43-8 (1994) Page 5 of 13 June 3, 1994 Copyright 1994 Kleinfelder, Inc.