ARCHIVED REPORTS XR0001648 - Laserfiche WebLink

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I were transported to BC Laboratories, Inc in Bakersfield, California Analytical results indicated elevated concentrations of BTEX and TPHg were present in wells MW-1 and MW-2 Based on these ' results, additional groundwater investigation activities were required In September 1989, Dames and Moore completed two soli bonngs, MW-5 and MW-6, as groundwater monitoring wells at the locations shown on Figure 3 The wells were constructed with 4- inch diameter PVC casing and completed as shown on the well logs contained in Appendix A. The wells were installed to depths of 37 5 feet and 42 feet bgs with 10-foot screen intervals Depth to ' water was measured, the wells were developed, and samples were collected The samples were transported to BC Laboratories and analyzed for TPHd, HVOCs, organic lead, and EDB Analytical results indicated well MW-5 contained detectable concentrations of HVOCs Well MW-6 contained no detectable concentrations of HVOCs, TPHd, or EDB During excavation activities in 1995, wells MW-1 and MW-5 were destroyed Replacement wells MW-1R and MW-5R were installed by Spectrum Exploration in November 1995 under the supervision of PHS/EHD at the locations shown on Figure 3 Wells MW-IR and MW-SR were constructed with 4-inch diameter PVC casing and completed to depths of 45 feet bgs with a 25-foot screen interval Well construction logs are included in Appendix A In July 1996, concrete was discovered in the casing of well MW-5R by Smith Technology during monitoring activities The well was property abandoned and well MW-5R2 was installed by Spectrum Exploration in August 1996 at the location shown on Figure 3 Wells MW-5R2 was constructed with 4-inch diameter PVC casing and completed to a depth of 35 feet bgs with a 22-foot screen interval The well construction log is included in Appendix A Depths to water were measured, the wells were developed, and samples were collected The samples were transported to Sequoia Analytical and tanalyzed for TPHg, TPHd, BTEX, methyl tertiary butyl ether (MTBE), and HVOCs Well MW-1R contained elevated concentrations of TPHg Well MW-5R2 contained low concentrations of cis 1,2- ' dtchloroethene, but contained no detectable concentrations of TPHg, TPHd, BTEX, MTBE, or other HVOCs ' All depth to water measurements are summarized in Table 4 Analytical results for petroleum hydrocarbons are summarized in Table 5 and analytical results for HVOCs are summarized in Table 6 The monitoring wells have been monitored intermittently since their installations Wells MW-3, MW4, and MW-6 have never contained detectable concentrations of TPHg or BTEX since their installation in 1990 Well MW-6 has periodically contained TPHd at low levels MW-2 has not contained TPHg since 1990(250 ppb,February 1990) Free product has been present internuttently in well MW-1 since its installation, but has not been present since June 1995 Well MW-1R initially contained elevated concentrations of TPHg which have decreased to nondetectable levels Wells MW-5 and MW-5R2 contained elevated concentrations of TPHg, TPHd, BTEX, and HVOCs Since the excavation activities in September and October 1995, well MW-5R2 contained no detectable concentrations of TPHg or BTEX and detectable concentrations of HVOCs have been below the California Primary Maximum Contaminant Levels(MCLs) • w\943311dosum dm 3 1 S �