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• Groundwater Elevation Data Depth to groundwater was obtained from the existing groundwater monitor wells at the site using a water level indicator graduated to 0 01 foot The depth to groundwater measurement was converted to a groundwater elevation for each well and used to construct a groundwater elevation contour map (Figure 2), and calculate the local groundwater flow direction and hydraulic gradient The groundwater surface elevation averaged approximately 73 69 feet below ground surface (bgs) during this monitoring event The groundwater flow direction during this reporting period is to the southwest at a hydraulic gradient of approximately 0 02 ft/ft A summary of data regarding groundwater levels measured through January 27, 1998 is presented in Table 1 Copies of field observations documenting work performed at the site is presented in Attachment I Groundwater Analytical Results The distribution of groundwater sample analytical results obtained from monitor wells at the site on January 27, 1998 is presented on Figure 2 and summarized in Table 2 Gasoline and BTEX were present at detectable concentrations in samples submitted for analysis from monitor wells MW-1 through MW-6, MW-8, and MW-9 Chemical analytical results indicate the highest concentrations of TPHg and benzene are in the vicinity of monitor well MW-1 TPHg concentrations in groundwater samples ranged from 6,570 parts per billion (ppb) in monitor well MW-1, to less than detectable levels in samples collected from monitor well MW-7 and MW-10 Benzene concentrations ranged from below the laboratory method detection Imut(<0 5 ppb) in monitor wells MW-7, MW-9, and MW-10, to 304 ppb m MW-1 MTBE was reported with a concentration of 12 6 ppb in a sample collected from monitor well MW-4, to less than detectable levels in samples collected from monitor wells MW-5 through MW-10 Attachment II contains photocopies of the laboratory analytical reports and the chain-of-custody form Purgewater Purge water generated during groundwater purging was transported by Integrated Waste Management, Inc to Mckittrick Waste Treatment Site, in Mckittrick, California, for treatment and disposal FORTHCOMING ACTIVITIES During the second quarter of 1998, SECOR will conduct additional well monitoring, purging, and sampling activities The results of these activities will be summarized in a quarterly monitoring report to be submitted to you in July 1998 This report presents our understanding of existing conditions at the subject site 2 LCKNRDgm 198 SECOR 7C005-oo1-ol Apnl 15 1999