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6, d 21 June 1996 AGE-NC Project No 95-0114 Page 3 of 4 3.2. COLLECTION OF GROUND WATER SAMPLES After stabilization, water samples were collected from each well using new disposable bailers. Immediately upon retrieval, the samples were transferred into 40-m1 EPA vials containing hydrochloric acid as a sample preservative. The samples were transported in a chilled container to Alpha Analytical Laboratories (AAL) in Ukiah, California. Each sample was analyzed for TPH-ss and BTE&X in accordance with EPA methods GCFID/5030 and 602, respectively. 4.0. FINDINGS 4.1. GROUNDWATER GRADIENT AND DIRECTION During the March 1996 sampling,the depth to ground water at the site ranged from 32.20 to 34.63 feet below tops of well casings. The relative ground water elevation at the site increased between 1.77 feet(MW-1)and 3.97 feet (MW-2). Relative ground water elevations are summarized in Table 1. Between December 1995 and March 1996, ground water flow direction rotated from northeast to ? southwest. The calculated gradient for March 1996 is consistent with previous measurements at the r siteGround water flow direction is depicted in Figure 3 - Relative Ground Water Elevation. r Ole 4.2. PETROLEUM HYDROCARBON-IMPACTED GROUND WATER During the March 1996 sampling, TPH-ss was detected in MW-1, MW-2 and MW-3 at concentrations of 200,450 and 2,600,ug/l(micrograms per liter, equivalent to parts per billion: ppb), respectively. TPH-ss or BTE&X were not detected in any of the other samples collected during the March 1996 sampling. Analytical results of ground water samples are summarized in Table 2. The laboratory report(AAL Batch Number 96-0320-018) and chain-of-custody are included in Appendix C. 5.0. CONCLUSIONS AND RECOMMENDATIONS 5.1. HYDROCARBON-IMPACTED SOIL AND REMEDIATION Hydrocarbon-impacted soil remains in the area of the former UST excavation. Additional subsurface investigation may be required in the vicinity of the former UST excavation to determine the lateral and vertical extent of the impacted soil.