|
I
<br /> First Ouarter Monitoring and Sampling Report, 1993 May 19, 1993
<br /> Southland Site No 20680, 9110 Thornton Road, Stockton, CA 3
<br /> System Groundwater monitoring was performed according to Groundwater Technology's Standard
<br /> Operating Procedures (SOPS) Copies of the SOPs are Included in Attachment 3
<br /> IAnalysis of the groundwater monitoring data Indicates that groundwater elevations in the monitoring
<br /> wells at the site have increased approximately 4 to 6 feet since December 23, 1992 As of April 2,
<br /> 1993, the average groundwater elevation at the site was 31 86 feet below mean sea level, and the
<br /> average DTW at the site was 43 87 feet below grade
<br /> Since the groundwater levels at the site were first monitored in May 1986, the local groundwater
<br /> elevation has fluctuated seasonally and, in general, has steadily declined Groundwater monitoring
<br /> wells MW-2 through MW-4 and MW-10 could not be monitored on April 2, 1993, because they were
<br /> dry Monitoring wells MW-6 and MW-12 are no longer in service, and at Southland's direction,
<br /> monitoring wells MW-11 and MW-14 are no longer being monitored or sampled The well
<br /> completion data and current status of the monitoring wells at the site are summarized In Table 2
<br />' A potentiometric surface map (Figure 3) was prepared using monitoring data collected on April 2
<br /> I 1993 Figure 3 indicates a groundwater flow direction generally to the east with a gradient of
<br /> approximately 0 002 foot per foot
<br /> MONITORING WELL SAMPLING AND ANALYTICAL RESULTS
<br /> On April 2, 1993, groundwater samples were collected from monitoring wells MW-1, MW-5, MW-7,
<br /> MW-8, MW-9, MW-13, MW-15ABC, MW-16, MW-17ABC, and MW-18 through MW-20, former pumping
<br /> wells PW-1, PW-2, and PW-3, and former recovery well RW-1 The status of monitoring wells not
<br /> sampled on April 2, 1993, is summarized in Table 2
<br /> Samples were collected according to Groundwater Technology's SOPs, copies of which are
<br /> included in Attachment 3 Before sampling, at least 4 well-casing volumes of groundwater were
<br /> removed from each well by hand bailing unless the wells purged dry The groundwater was allowed
<br /> to recover to at least 80 percent of the original static water level before sampling The groundwater
<br /> samples were collected using an Environmental Protection Agency (EPA)-approved Teflon® sampler
<br /> The samples were collected In laboratory-supplied containers, preserved, labeled, and stored on ice
<br /> Samples were transported under chain-of-custody protocol to GTEL Environmental Laboratories, Inc
<br /> a California-certified laboratory in Concord, California Each sample was analyzed for benzene,
<br /> toluene, ethylbenzene, and xylenes (BTEX) and total petroleum hydrocarbons-as-gasoline (TPH-G) j
<br /> using modified EPA Methods 5030/8020/8015
<br /> Analytical results of the samples collected on April 2, 1993, from monitoring wells MW-1, MW-5,
<br /> IMW-7, MW-8, MW-9, MW-13, MW-15ABC, MW-16, MW-17ABC, and MW-18 through MW-20, former
<br /> 12118023
<br /> 5`�_ GROUNDWATER
<br /> L 'j_TECHNOLOGY, INC
<br />
|