ARCHIVED REPORTS_XR0012360 - Laserfiche WebLink

Home Browse Search

fo October 4, 1994 - Page 5 . • were submitted for analysis. TPH-g and BTEX compounds were not detected in any soil samples. Soil analytical data are presented in Table 2 and are shown on Figure 2 Certified analytical reports and chain-of-custody documentation are presented as Attach- ment C Groundwater Analytical Results Monitoring Wells MW-8 and MW-9 were developed and sampled on August 1, 1994 The samples were delivered to a certified laboratory and analyzed for TPH-g and BTEX compounds. TPH-g concentrations were detected at 93 and 110 ppb for Wells MW-8 and MW-9, respectively. BTEX compounds were not detected in either of the samples taken Groundwater Monitoring Wells MW-1 through MW-7 were sampled on August 12, 1994 by MPDS TPH-g was detected in on-site Wells MW-2, MW-3, and MW-6 at concentrations of 180,000, 760, and 11,000 ppb, respectively. Benzene was detected in on-site Wells MW-2, MW-3, and MW-6 at concentrations of 15,000, 110, and 64 ppb, respectively Well MW-4 was the only off-site well to have detectable levels of hydrocafbons TPH-g and benzene were detected at 170 and • 16 ppb, respectively Groundwater analytical data are presented 1n Table 3 and shown on Figure 2. Certified analytical reports and chain-of-custody documentation are presented as Attachment C CONCLUSIONS AND RECOMMENDATIONS The vertical and horizontal extent of hydrocarbons in soil beneath the site were defined to near non-detectable levels during previous site investigations. The results of this investigation show that the lateral extent of dissolved hydrocarbons in groundwater is limited to an area south and east of the former underground storage tanks. The extent of hydrocarbons has been defined to non-detectable levels to the northeast (downgradient) in Well MW-7, and to the north (crossgradient) in Welts MW-1 and MW-5. TPH-g was detected to the southwest (upgradient) in Well MW-8, and to the south (crossgra.dient) in Well MW-9, at concentrations of 93 and 110 ppb, respectively Benzene was not detected in Wells MW-8 and MW-9 Because only very low concentrations of dissolved hydro- carbons were detected in off-site Wells MW-8 and MW-9, and because the hydro- carbon plume appears relatively stable, it is PACIFIC's opinion that further site characterization is not necessary at this time. • PACIFIC recommends that groundwater Monitoring Wells MW-8 and MW-9 be placed on a quarterly groundwater monitoring program to monitor groundwater elevations and evaluate trends in the groundwater chemistry PACIFIC also 31004002/M WINSTAL