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1 <br /> 2.3 Monitoring Well installation <br /> On October 26, 1993, three groundwater monitoring wells were installed at the site (Figure <br /> 1 2) Monitoring well MW-1 was installed between the sidewalk and Yosemite Avenue in the <br /> city nght-of-way to the west of the property MW-2 was installed west of the former tank <br /> cavity, MW-3 was installed southeast of the former dispenser island Ten soil samples were <br /> submitted for analysis. Gasoline compounds were detected at low concentrations in soil <br /> samples from the saturated zone in MW-2, but not in MW-1 or MW-3 Benzene and/or the <br /> other volatile aromatic hydrocarbons were detected above reporting limits in all samples <br /> below 20 feet in MW-2 and in MW-1 at a depth of 40 feet No aromatics were detected in <br /> MW-3 <br /> .4 Groundwater Monitoring <br /> g <br /> ' On November 1, 1993, the depth to groundwater was measured in the three wells, the wells <br /> were purged and samples collected (Table 1) Total petroleum hydrocarbons (TPH as <br /> gasoline) were detected in MW-1 and MW-2 at concentrations of 1,300 parts per billion <br /> ' (ppb) and 31,000 ppb, respectively Benzene was detected in water samples from all three <br /> wells,with the highest concentration (560 ppb)in MW-2 Toluene, ethylbenzene,xylene, and <br /> ' TPH as gas were also detected in both MW-1 and MW-2, but not in MW-3 The gradient <br /> was calculated to be 0 042 ft/ft, with flow oriented N 61° W Laboratory results are <br /> summarized on Table 2 <br /> To confirm gradient flow and direction, the depth to groundwater was measured in each well <br /> on March 1, 1994 Measurements showed an average rise in the groundwater elevation of <br /> 0 91 feet The groundwater flow direction and gradient on March 1, 1994 were calculated <br /> to be 0 044 ft/ft directed N 5911 W <br /> ' 3.0 PROCEDURES <br /> 3.1 -Monlitoring Well Samphiig I , <br /> On March 30, 1994, the water levels in eacli well were measured relative to the 'top of the <br /> ' casing using a Solinst water level meter The depth to groundwater and relative groundwater <br /> elevation of each well'is included in Table 1 <br /> ' After water levels were measured, a purge pump was used to purge each well of standing C !` <br /> water Approximately 8 to 10 gallons of water were removed from each well to stabilize I <br /> temperature, pH and conductivity (Appendix A) Parameters were measured at one-gallon <br /> interval`s using an ICM water analyzer Purge water was stored on-site in 55-gallon drums I. <br /> F After stabilization,water samples were collected from each f well using new, clean, disposable plastic bailers Samples were collected in 40 ml VOA vials andl 1-ljter amber bottles ! ' <br /> ` l I <br /> a�rd�i n�a sNw�iai ' h I <br /> 14 <br /> k it <br /> 1 <br />