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� 9 <br /> Pi <br /> Mr. t{. C. Winsor <br /> September 9, 1987 <br /> Page 5 <br /> These elevations were used to construct the groundwater elevation <br /> contours shown on Figure 1. The groundwater flow direction has <br /> changed since April 1987 to a more westerly direction. The apparent <br /> mounding effect around Well 12 may be due to the shutdown of Well 12 <br /> in December 1986, coupled with increased pumping of nearby municipal <br /> and irrigation wells in the spring and summer of 1987. Depth to <br /> static groundwater level in Well 12 is shown in Table 2. <br /> Table 2. Depth to Static Groundwater Level, Well 12 <br /> Depth to groundwater, <br /> Date feet <br /> January 6, 1987 52.7 <br /> - February 3; 1987 51.3 <br /> j March 3, 1987 51.0 <br /> April 7, 1987 53.1 <br /> May S, 1987 54.8 <br /> June 2, 1987 56.0 <br /> �- July 7, 1987 58.2 <br /> August 4, 1987 61.3 <br /> Soil and Groundwater Quality <br /> x Selected subsurface soil samples from each borehole drilled in July <br /> ?j 1987 and one groundwater . sample from each monitoring well were <br /> - analyzed for fuel characterization and benzene, toluene, and xylene <br /> at California Department: of Health services (DHS) certified Eureka <br /> ,�. laboratories in Sacramento. Laboratory results for soil samples <br /> i # analyzed are summarized in Table 3. Complete results are shown in <br /> I "" Exhibit D. Benzene concentrations in Samples B-lD, B-lG, B-1I, and <br /> B-22 exceed Regional Board designated levels. Benzene concentra- <br /> "¢ tions in all other soil samples analyzed were below Regional Board <br /> designated levels. It is probable that the gasoline migrated down <br /> towards the groundwater table in the vicinity of Borehole B-1. <br /> f4 Sample B-2I is the bottom-hole sample taken from just above the <br /> 1 groundv°ater surface in Borehole B-2. The benzene concentration in <br /> this sample is probably due to a capillary fringe effect. Toluene <br /> and xylene levels are below Regional Board designated levels in all <br /> ? i soil samples analyzed. No levels have been established for total <br /> T -77 <br /> ---fdel-..hyarocarbans: --'-- <br /> Groundwater samples from monitoring Wells W-1, W-2, W-3, W-4, <br /> W-5, and W-6 were collected by BC personnel or. July 23, 1987. <br /> y Results are summarized in Table 4. Complete results are shown in <br /> a .r Exhibit D. Benzene concentrations in samples from Wells W-1', W-2, <br /> W-3, W-4, and W-5 exceeded DHS action levels for drinking water. <br /> BROWN AND CALD-NELL <br /> _ - 1235 STREET SACRAMENTO.CA OW4•J9161444-0123 - <br />