ARCHIVED REPORTS XR0002718 - Laserfiche WebLink

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1 ' pipes may indicate the presence of an underground storage tank beneath Harding Way. No ' further investigation was performed. Analytical results from the W1-1F investigation are ' ' summarized in Table 2. A map of the sample locations is included in Appendix B. ' 33 Installation of Monitoring Wells MW-1 through MW4 Between August and September 1991, three groundwater monitoring wells were installed at the site (MW-1, MW-2 and MW-3) by WHF Environmental. No petroleum.hydrocarbons were detected in soil or water samples collected from the wells. E n z Ate-. - - In 1992, at the request of the PHS/EHD, a fourth monitoring well was installed at the.site (MW-4). Low concentrations of toluene, ethylbenzene and xylenes were detected in soil samples from MW-4 at depths of 21, 31 and 36 feet. Therefore, the PHS/EHD requested . further assessment of the impacted soil in the vicinity of MW-4. Analytical results of soil samples from the installation of MW-1 through MW-4 are.summarized in Table 3. Analytical results of all groundwater samples are summarized in.Table 5. ' 3.4 Installation of MW-5, B17 and B18 ' GeoAudit was retained to further assess the impacted soil in the area . of MW-4. Additionally,because of poor installation/completion and unreliable groundwater depth data, . the PHS/EHD also requested that MW-3 be destroyed and replaced by a new well. borings B17 and B18 were drilled on August 25 and 26, 1993. Boring B17 Two additional g ( ) g g was drilled at an angle of 30° from vertical and extended to a vertical depth of 38 feet. B17 terminated at an angled depth of 45 feet at a point approximately 5 feet north.of the sidewalk on Harding Way. TPH as gasoline and diesel were detected in samples.from,B17 at vertical depths between 15.6 and 37.2 feet at concentrations as great as 4,000 ..ppm. ' Toluene, ethylbenzene and xylenes were also detected in samples from B17.. Boring B18 was drilled to a depth of 40 feet, approximately 20 feet south of MW-4. TPH as gasoline and diesel were detected in samples from B18 at depths of 25 and 35 feet in concentrations as great as 55 ppm. Ethylbenzene and xylenes were detected,in sample B18- 35 at concentrations of 0.082 ppm and 0.13 ppm, respectively. Benzene was not detected in either B17 or B18. The laboratory results of the soil samples are summarized in Table 4. ' On August 25, 1993, MW-5 was installed approximately 20 feet southwest of MW-3. Monitoring well MW-3 was then properly abandoned on September 13, 1993. Analytical results of soil samples from MW-5 are included in Table 4; groundwater samples are included in Table 5. 3.5 Installation of MW-6, MW-7 and MW-8 ' After reviewing the data, the PHS/EHD Technical Review Committee (TRC) determined #MiA.&*S-�Im 6 W a ,