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1 <br /> feet) BTEX was nondetectable in five of the s bonn and 1n the other six borings ranged <br /> g � g <br /> from nondetectable to 44 ppm (total xylenes in boring B-16) The extent of TPHg in soil at <br /> depths of 0 to 30 feet is shown on Figure 4 PNAs were nondetectable in all of the 14 samples <br /> tested, with the exception of boring B-16 which contained 3,500 ppm naphthalene at a depth of <br /> 5 feet (Table 2) <br /> In November 1991, four additional borings (B-25 through B-27) were drilled under the <br /> supervision of USTEC and completed as vapor wells Due to the proximity of these bonngs to <br /> ' existing bonngs, no soil samples were collected for laboratory analysis <br /> 3`3 Assessment of Groundwater Contamination <br /> From August to November 1990, USTEC completed borings B-2, B-3, B-6, B-11, B12, and <br /> B-24 as groundwater monitoring wells MWA through MW-6, respectively, to assess the <br /> condition of the groundwater beneath the site (Figures 2 and 3) The bonngs for the <br /> monitoring wells were advanced using 10-inch hollow-stem augers The monitoring wells <br /> were constructed using 4-inch Schedule 40 Polyvinyl Chloride (PVC) well screen with slot size <br /> of 0 010 inches and blank casing The well screen intervals ranged from 65 to 95 feet bgs in <br /> wells MW-1 and MW-2, 59 5 to 89 5 feet bgs 1n well MW-3, 52 to 82 feet bgs in wells MW- <br /> 4 and MW-5, and, 53 to 83 feet bgs 1n well MW-6 Well construction details are presented in <br /> tables prepared by USTEC contained in Appendix A <br /> Initial results from the first groundwater monitoring and sampling event conducted in August <br /> ' 1990 in the newly installed groundwater monitoring wells MW-1 through MW-5 indicated that <br /> all five wells contained detectable petroleum hydrocarbons Cumulative results of laboratory <br /> ' analyses of groundwater samples are summarized 1n Table 4 In August 1990, TPHg was <br /> nondetectable in all wells except MW-1 located immediately east of the former gasoline UST <br /> ' In well MWA, TPHg was detected at 46 parts per billion (ppb) TPHd was detected in four <br /> of the five wells, and ranged from nondetectable 1n well MW-3 to 220 ppb in well MW-1. <br /> ' Benzene was present 1n wells MW-1 and MW-2 at 0 52 and 0 53 ppb, respectively, and was <br /> nondetectable in all other wells Toluene was nondetectable in all wells, except MW-3 where <br /> it was detected at 0 36 ppb, ethyl benzene was nondetectable 1n all wells, total xylenes were <br /> ' present in wells MW-1 and MW-2 at less than 1 ppb PNAs were nondetectable in the three <br /> n 10540061reports1CLO1195 doc 5 <br /> Sian <br /> 1 <br />