Laserfiche WebLink
Wm. J. Hunter & Associates z OIL ,� r�; 2220 Loma Vista Dr <br /> Registered Geologists =; r � . Sacramento, CA 95825 <br /> Petroleum& Mineral Appraisers .. (916) 972-7941 <br /> . ,_ `i' a k I 1 ; 12 FAX (916) 972-1683 <br /> November 21, 1995 <br /> Steven Sasson, Sr. REHS <br /> San Joaquin County Health Department <br /> Environmental Health Division <br /> 445 North San Joaquin Street <br /> Stockton, Ca 95202 <br /> Ref Tenth Quarterly Groundwater Monitoring Report for 814 E . <br /> Charter Way, Stockton; Site Code 1061 <br /> Dear Mr Sasson, <br /> We am enclosing a copy of the field report, water analysis, and <br /> maps showing groundwater gradients and lines of equal concentra- <br /> tions of benzene, toluene, ethylbenzene, xylene, & TPHg The <br /> field work was performed on October 27 , 1995 by Del-Tech <br /> Geotechnical Support Services as directed by our office. <br /> The attached EXHIBIT A, shows the contours on the top of the <br /> water table on October 27, the gradient is to the east/northeast <br /> at about 13 ' /mile EXHIBIT B summarizes the eleven (11) hydrau- <br /> lic gradients measured to date on the property Except for the <br /> July, 1995 sampling, all of the data indicate a rather stable <br /> gradient to the east The reason for the reversal in the poten- <br /> tiometrsc surface in July cannot be explained based on the data <br /> available at the time this report was prepared. We have not <br /> received any data concerning activities at the Darpetro property <br /> since January, 1995 . <br /> EXHIBIT C shows the approximate contours based on lines of equal <br /> concentration of benzene from the October 27, 1995 sampling <br /> event . They reveal that there has been an increase in the levels <br /> in MW-2 since the July, 1995 sampling, and a decrease in MW-3 . <br /> MW-1 continues to be below detection levels <br /> EXHIBITS D, E, & F show lines of equal concentration of toluene, <br /> ethylbenzene, & xylene based on the 10/95 sampling All of the <br /> maps show an increase in levels of those components towards the <br /> east/northeast, in the direction of groundwater flow <br /> EXHIBIT G shows lines of equal concentration of THPG from the <br /> October, 1995 sampling. The amount measured in MW-2 is <br /> significantly higher than the prior sampling in July - 1, 000 ug/L <br /> vs 170 ug/L - and is the highest since measurements began in <br /> October, 1992 . The reason for this cannot be readily explained. <br /> MW-3 measured lower levels than in July, and MW-1 was below <br /> detection limits . <br /> 1 <br />