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1 t CONCLUSIONS AND RECOMMENDATIONS Detectable, often significant , concentrations of fuel hydrocarbons were detected in all soil and shallow ground- water samples acquired at the site during the course of the activities described herein. Although, as shown, levels of TPH-D and TPH--G in soil generally considered to be of public health and environmental significance were present ' only in the capillary fringe and the saturated zone. Unexpectedly , the highest levels of TPH-D and TPH-G in soil (89 parts per million [ppm] and 410 ppm, respectively) were present in very moist , inorganic dark-brown clay at SBR-9 . As shown on Figure 2 , SBR-9 was advanced at a point near the northwest corner of the on-site building- a location calculated to be upgradient of both of the known former underground storage tank pits . Groundwater contamination was also highest in the sample acquired from SBR-9, ' containing 87 , 000 parts per billion [ppb] TPH-D, 1 , 100 ,000 ppb TPH-G, 690 ppb benzene, 460 ppb toluene , 5 , 500 ppb ethylbenzene, and 13 , 000 ppb total xylenes concentrations ' that appear to indicate the presence of free product as they exceed saturation points for some of the specific compounds referenced . If SBR-9 is a point source of contamination , the presence of the high levels of target analytes in the grab water samples and the moderate levels of analytes in moist to ' saturated soil at 8+ feet acquired from SBR-1 through SBR- 6 , and SBR-8 and SBR-10 are not surprising due to the proximity of these boreholes to SBR-9 and the northeasterly ' direction of groundwater flow calculated for the site . Details concerning the determination of the direction and slope of groundwater flow are enclosed as Appendix C ISO- concentration graphics showing the highest levels of TPH-G in shallow groundwater and soil (at 8-9 feet below ground surface) appear as transparencies designated Figures 4 and 5 Contaminant concentrations in the maist to saturated soil at SBR-5 and SSR-8 as well as the grab water samples from these locations may also be the result of contaminant migration from the area of SBR-9 , although SBR-5 and SBR-8 are also proximate to the areas formerly occupied by the two known underground storage tank pits In consideration of the data acquired to date, and the ability to calculate the zero line of the groundwater plume boundary using soil permeability and hydraulic conductivity data , it is requested that no further plume assessment be required at this time Rather , EPM wishes to propose the following Page 10