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' Project Quarterly Update Report February 21, 1992 Southland, 9110 Thornton Road, Stockton, California Page 4 2.1.3 Soil Sample Analyses Soil samples were collected from boring MW-20 for analyses for BTEX, TPH-as-gasoline 1,2-dibromoethane and total lead Soil samples MW-20-A, MW-20-E, MW-20-1-1, and MW-20-1 were collected for analyses from sod boring MW-20 at 4 5 feet, 20 5 feet, 36 feet, and 415 feet below ' surface grade Analytical results indicate BTEX was not detected in any of the soil samples above method detection limits (MDL) Only soil sample MW-20-H contained a detectable TPH-as-gasoline ' concentration, which was measured at 9 parts per million (ppm) Sod samples MW-20-E, MW-20-1-1, and MW-20-1 were also analyzed for 1,2-dibromoethane and total lead Analytical results Indicate t 1,2-dibromoethane was not detected, and one soil sample, MW-20-E, contained a detectable total lead concentration, which was measured at 5 8 ppm The analytical laboratory reports are presented in Appendix B and summarized In Table 1 Sod samples were not collected from the off- site soil bonngs, MW-18 and MW-19 The results of the soil samples were used to confirm soil remediation in this area 2.2 GROUNDWATER MONITORING The depth to water in the monitoring wells (including new wells MW-18, MW-19, and MW-20) was p g � g monitored three times during this reporting period on October 30, November 26, and December 23, 1991 The monitoring data are presented in Table 2 Groundwater monitoring was performed according to Groundwater Technology Standard Operating Procedure (SOP) 8 (Appendix C) Analysis of the groundwater monitoring data indicates that groundwater elevations have increased ' across the site by about 1 45 feet in the monitoring wells during the period from September 26, 1991, to December 23, 1991 The calculated average groundwater elevation across the site as of ' December 23, 1991, was 35 49 feet below mean sea level (ms]) The average depth to groundwater across the site as of December 23, 1991, was 47 32 feet below ground surface Since the groundwater levels were first monitored in May 1986, the local groundwater elevation has fluctuated seasonally, but has declined steadily The seasonal and overall decline in the groundwater levels is depicted in the hydrographs for monitoring wells MW-7, MW-8, and MW-9 (Figure 3) Monitoring wells MW-7 and MW-8 are representative of the majority of the wells at the �r GROUNDWATER =TECHNOLOGY, INC