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Wm. J. Hunter & Associates 2220 Loma Vista Dr. <br /> Registered Geologists ;Aj "- "' <br /> r mento, CA 95825 <br /> `Petroleum & Mineral Appraisers , " (916) 972-7941Pp' <br /> %.", <br /> FAX (916) 972-1683 <br /> 93 At is P6 <br /> August 11, 1993 <br /> Linda Turkatte, RENS <br /> San, Joaquin Co. PHS <br /> Environmental Health Division <br /> 445 No. San Joaquin Street <br /> Stockton, CA 95202 <br /> Ref= 2969 Loomis Road (Site Code 2015; ) Quarterly Report, <br /> monitoring well data <br /> Dear Ms. Turkatte; <br /> We have enclosed a copy of the field log, chain of custody form, <br /> and laboratory analysis of a water sample taken from MW #1 on <br /> June 18, 1993. Water level measurements were taken in all three <br /> wells as directed by your office, but water samples were not <br /> collected from MW #2 or 03. The results of the :laboratory <br /> anlysis shows that Benzene, Xylene, & TPH-D were detected in the <br /> water sample collected by Del-Tech from MW #1. A water sample <br /> taken in March from the same well did not show any of the tested <br /> components. <br /> We have also included an updated exhibit showing the directions <br /> of hydraulic gradients as indicated by the eight water level <br /> measurements taken to date. The latest three are shown in color <br /> on the attached Exhibit A. The data shows that the direction of <br /> flow is not stable; it has been measured to date in a 360-degree <br /> radius within a 12 month time period. 1n fact, the direction of <br /> flow changed 180--degrees beween May 16 & June 14 of this year, <br /> and 90-degrees between June 14 & June 18. The depth to the water <br /> table has remained fairly stable since March of this year, <br /> approaching the depths measured in the Spring of 1992. <br /> An analysis of the data to date indicates that there are no <br /> withdrawal or injection points within the zone of influence, and <br /> that the variations in direction are most likely due to permea- <br /> bility differences within the sands & shales beneath the site. <br /> The fact that the water sample obtained from MW #1 in March was <br /> clean, (below detection levels, ) but was found to contain, ben- <br /> zbne, xylene, & TPH-D in June supports the water level measure- <br /> ments discussed above; flow is essentially circular, with no <br /> definite direction. <br /> Based on the information obtained to date, additional investiga- <br /> tive work is not warranted at this time. It is recommended that <br /> the existing program of monthly water level measurements and <br /> quarterly sampling be continued until a stabilized gradient can <br />