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Wm. I Hunter & Associates 11�C ", i- 2220 Loma Vista Dr Registered Geologists �' Sacramento, CA 95825 Petroleum & Mineral Appraisers pm (916) 972-7941 FAX (916) 972-1683 June 26, 1997 Steven Sasson, Sr REHS San Joaquin County PHS Environmental Health Division P O Box 388 Stockton, CA 0388 Ref . First Quarter 1997 Groundwater Monitoring Report for 2315 No. Eldorado Street, Stockton Dear Mr Sasson; We have enclosed a copy of the field report, water analysis results, a gradient map, and maps showing lines of equal concen- trations of benzene, ethylbenzene, toluene, xylene, & TPHg for the above site The work was performed on March 27 , 1997, by Del-Tech Geotechnical Support Services as directed by our office . PLATE I shows the potentiometric surface based upon the 3/27/97 sampling event The gradient continues to be to the northeast at about 00551 /ft ' , or 29 ' /mile • The water table was measured at an average depth of 33 . 93 ' bgl , a rise of 6 51 feet since the November, 1997 sampling. TABLE A summarizes the results of all water analyses taken since monitoring began, it shows that MW-3 continues to record the highest levels of all measured compounds, with MW-5 second MW-1 & MW-4 have shown the lowest . A review of the total levels of BTEX from the 6 wells recorded during the July & November 1996 and the March, 1997 samplings is summarized below COMPOUND 7/1996 11/ 1996 3/1997 Units - ug/L BENZENE 51, 450 37 , 237 52 , 270 E .BENZENE 4 , 890 4 , 666 4 , 380 TOLUENE 52 , 800 29 , 860 52, 400 XYLENE 28 , 770 21 , 430 25, 590 TOTALS 137, 910 93 , 193 134, 640 Total levels of TPH as gasoline increased slightly between November, 1996 and March, 1997 from 297 8 ug/L to 320 6 ug/L The increase in levels measured during the latest sampling may be due in part to the rise in the water table to the highest level since monitoring began in October, 1994 0 1