SITE INFORMATION AND CORRESPONDENCE

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Roberts Petroleum Services Facility July 11, 1990 Project No. 1628G Page 3 Sediment brought into the well was then manually bailed. Development of the well continued until no further improvement in water clarity was observable. Approximately 7 well-casing volumes of groundwater were removed from the well. All groundwater removed from the well during its development was placed in drums approved by the Department of Transportation (DOT) and left at the site pending laboratory analytical results. Groundwater Sampling a After development, MW-8 was allowed to recharge for approximaltely 1 week before sampling. Groundwater samples were collected from wells MW-2,MW-4, MW-5, MW-6, MW-7, and MW- 8 on May 2, 1990. Before sampling,Exce1tech measured the depth to groundwater withan electric sounding tape and checked for the presence of free-phase hydrocarbons with a clear acrylic bailer at each well: none were detected. A sampling equipment blank was then collect `d far quality control. Wells MW-1 and MW-3 were not sampled, because MW-1 was dry and the vault box cover could not be removed from MW-3. After the field check, each well was!,purged until pH, conductivity, and temperature readings stabilized. Approximately 3 well-casing volumes of groundwater were removed from each well. Samples were collected with a clean Teflon bailer and preserved in the appropriate laboratory- supplied bottles, labeled with a unique sample number, logged on la chain-of-custody form, and stored in a chilled ice chest for shipment to the laboratory. Equipment rinse water and groundwater removed from the wells were placed in DOT-approved drums and left on-site pending the laboratory analytical results. Exceltech groundwater samplingprotoeoi is included in Appendix B. A groundwater contour map was developed from the depth to groundwater measurements and is a presented as Figure 3. Laboratory Analyses k r Nine soil samples, six groundwater samples, and the sampling equipment blank were submitted under chain-of-custody control to Chemwest Analytical Laboratories, Inc., of Sacramento, California. The samples were analyzed for the presence of total petroleum hydrocarbons as diesel F and gasoline (TPHD and TPHG, respectively) as well as b6izene�, toluene, ethyl benzene, and f xylenes. Laboratory Results Seven of the nine soil samples submitted for analysis were reported to contain petroleum hydrocarbon compounds. Contaminants reported to be in; the samples were TPHG, TPHD, toluene, ethyl benzene, and xylenes. Benzene was not reported to be present in any of the samples, and toluene was reported only in sample 8-5. Samples 8-1 and 8-4 were reported by Chemwest as below the reporting limit. The concentrations detected in each sample are shown on Table 1. Groundwater samples from six of the eight monitoring wells on site were submitted for analysis. Chemwest reported that only the sample from well MW-8 contained petroleum hydrocarbons. Concentrations detected were 520 micrograms per liter (µg/1) TPHG, 6.8 µg/1 benzene, 4.4 µg/1 toluene, 7.0 µg/1 ethyl benzene, and 49 µg/1 xylenes. No TPHD was reported to be present in the sample. �I