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' selected as an alternative method of collecting the data A slug test is a method of measuring aquifer characteristics which does not require extracting water from the well The test consists of lowering a solid cylinder (the slug) into and out of the well and measuring the rate at which ' the water level returns to the original static elevation Slug tests were performed on wells MW- 4, MW-6 and MW-8 and the data analyzed using the Aqtesolv computer software The results ' of these tests are presented in Section 3 4 below and in Appendix C 2.5 Tidal Influence Characterization ' The protect work plan also called for an investigation of the possible influence of diurnal tidal effects on the groundwater gradient beneath the site due to the site's close proximity to tidally ' influenced water bodies such as the Stockton deep water channel and the Mormon Slew The work plan called for installation of a water level recorder on one of the new monitoring wells for a period of one week However, due to the problem of maintaining the security of equipment ' and personnel in the downtown area, an alternate approach was used which required significantly less time but still provided the needed information This approach consisted of measuring the water levels in well MW-4 over a period of approximately four and a half hours to see if ' additional study was warranted Results of these measurements indicated a possible minor tidal influence in MW-4 ' 3.0 FINDINGS OF THE INVESTIGATION This section presents the analytical results of groundwater sampling from the five new monitoring wells, presents an interpretation of the geologic and hydrologic conditions of the site, then interprets the analytical data with respect to the geologic and hydrogeologic conditions of the site ' 3.1 Groundwater Sampling Analytical Results P g Yt ' The analytical results of groundwater sampling are presented in Table 1 A complete analytical report is presented in Appendix D These results indicate that gasoline-related hydrocarbon ' compounds are present in several of the wells, with the highest concentrations found in MW-7 with 190 µg/L and 1700 lAglL of benzene and TPH-G, respectively. There were no significant concentrations of TPH-D, EDB or total lead found in any of the wells Figure 3 shows the ' groundwater analytical results plotted on the site map next to the appropriate well locations 3.2 QA/QC Results IResults of the trip blank analyses indicate that sample integrity was maintained during sample transport. The blind duplicate sample, MW-10, showed good correlation with the primary ' sample of MW-5 The equipment decontamination sample, MW-11, showed a trace of benzene which suggests that small quantities of benzene may have remained after sampling the last well on the first sampling day However, due to the order of sampling and the relative benzene ' concentrations found in the wells sampled that day, the benzene trace (3 2 µg/L) does not impact the sampling integrity No hydrocarbons were detected in the second equipment decontamination blank, MW-12 ' xf's/src WP 7 ae oroz