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x <br /> Wm. J. Hunter & Associates 2220 Loma Vista Dr. <br /> Registered Geologists ; „ ., )� La ;; Sacramento, CA 95825 <br /> Petroleum& Mineral Appraisers t is° '{`�'-"Tk Tk I� EAI-TI1 (916) 972-7941 <br /> FAX (916) 972-1683 <br /> IIDEC l Pli 2: 10 <br /> November 16, 1993 J <br /> E€4 <br /> Linda Turkatter, REHS <br /> San Joaquin Co. PHS <br /> ' <br /> Environmental !Health Division <br /> 445 No. San Joaquin Street , <br /> Stockton, CA 95202 f <br /> Ref: 2969 Loomis Road (Site Code 2015; ) Quarterly Report, <br /> monitoring wel'1 data <br /> Dear Ms. Turkatte; <br /> i . <br /> We have enclosed a copy of the field log, ichain of custody form:, <br /> 1 and laboratory analysis of a water sample taken from MW #1 on <br /> September 20 . "1993. Water level measurements were taken in all <br /> three 'wrells as directed by your office, but water samples were j <br /> not collected ��from MW #2 or #3. The results of the laboratory <br /> I anlysis shows ::Nthat only Benzene was detected, at 0 . 9 ug/L, in the <br /> water sample collected by Del-Tech from MW 41. The sample taken <br /> in June from the same well measured 2. 7 ug/L Benzene, 27.0 ug/L , <br /> Xylene, and 3'r0 mg/L of TPHG. Measurements also show that the <br /> t. water table has dropped approximately 2 feet since June, but is <br /> still above the lowest levels recorded in September, 1992. <br /> `i i <br /> We have also included an', updated exhibit showing the directions ��- <br /> of hydraulic gradients as indicated by the nine water level <br /> ` measurements taken to data. They are colored on the attached <br /> EXHIBIT A to assist in analyzing the data, which continues to <br /> show that the "'directi.on of flow is not stable; it has been <br /> measured to date in a 360-degree radius with no consistent <br /> established pattern. <br /> An analysis of the data indicates that there are no withdrawal <br /> + or injection points within the zone of influence, and that the <br /> variations in'Idirection are most likely due to permeability <br /> differences within the sands & shales beneath the site. The <br /> hydraulic gradient is essentially circular, with no definite <br /> direction. <br /> Based on the nformation', obtained to date, it is recommended that j <br /> the present monitoring and sampling technique be continued at <br /> f least until next spring. ' If the results continue to follow the <br /> existing pattern, it is suggested that a meeting be held with <br /> yourstaff toIdiscuss the next step - possibly a proposal for <br /> treating the water beneath the site to remove the contamination. <br /> It certainly does not appear that additional monitoring points ' <br /> i are warrantedl�considering the lack of a definite gradient. <br /> 1 <br /> k" <br />