Laserfiche WebLink
FROM Ground Zero Analysis • PHONE NO. : 209 838 9883 �ay. 05 1998 04:32PM P2 <br /> GROUND ZERO ANALYSIS, INC. <br /> ENVIRONMENTAL HEALTH DIVISION <br /> 1714 Main Street 304 E. Weber Ave. I niraoor <br /> Escalon, California 95320 P. O. Box 388, Stoc n CA 95201-0388 <br /> Telephone: (209) 838-9888 Approved <br /> Facsimile: (209)838-9883 Denied ❑ <br /> Conditions teL bELW <br /> May 5, 1998 Date 'S by <br /> I . MAW¢(-11 6-t IriUk TP L�t)Ah <br /> Mr. Ron Rowe '17Lt3n) 04 i2,sJA (�7( '3vk j -1L-. <br /> San Joaquin County-Public Health Services 2 • SJb t t LT i.�UR(A IQ TD <br /> Environmental Health Division <br /> 445 North San Joaquin Street I Ut' a-h.q� <br /> P.O. Box 388 3 OK -TO qo&r-Y -t A0P inCt <br /> Stockton. CA 95201-0388 iJd 11tiS QJAjqCIZ aviA. A'h-1 <br /> tZk�liryJS ("-¢uM. �h5 t�yJiKNt�u( <br /> Subject: Knowles/Roek Property, 102 South Wilson Way, Stockton, California tYc`yr vi).0 D EF <br /> Recommendations for 8260 Analyses - Second Quarter 1998 OS ED iD Dt-I�EWt Ino✓ At--WT <br /> Int SM 19(-4 � p/l6JMVJ,, <br /> Dear Mr. Rowe: + r1� ooit P4 --s Dourn) Sv-6 <br /> sys1 VAuJ5E✓ z 6xti e5 <br /> m,MS HG� ►PI DSK .E� �n/t) TTvYLrYI <br /> Following up on our phone conversation I am writing to present recommen at,o or sampling c >MT7 V ,fig, <br /> groundwater for oxygenate additives by EPA method 8260. C�QRE> a^-161L <br /> As we discussed, high concentrations of MTBE, in conjunction with a dramatic increase in hydrocarbon j�(ne <br /> concentrations, appeared in MW4 in November, 1997. The presence of MTBE in this well was M py 6e�4',tAj <br /> confirmed in December, I997 and again in February, 1998. MTBE was not detected in this well when TD m v4ofh�e <br /> first sampled in July, 1997. This is interpreted as the encroachment of a plume of contamination ,M z156 <br /> originating offsite. Low levels of MTBE have also been twice detected in MW9, north of and generally ,t,s C)P&#o10 <br /> crossgradient from the site. wft1Z�L <br /> On the other hand, it is unclear whether or not diisopropyl ether (DIPE)or tertiary butyl alcohol (TBA) <br /> are consistently present in groundwater in the site area. It is unknown whether the source(s) may be <br /> onsite or offsite UST leaks or other sources (leaking sewers, industry, etc.) The initial round of 8260 <br /> analyses (11/97) reported relatively low concentrations of DIPE and/or TBA in most wells north, east <br /> and west of the former USTs. These constituents were not reported as present in most wells south of the <br /> former USTs nor in the vapor wells installed within the onsite gasoline source area. The second round <br /> of 8260 analyses (02/98)detected DIPE and TBA only in wells MW 11 and MW 12 although the detection <br /> limits were somewhat higher than during the initial sampling. <br /> To meet the objectives listed below while conserving financial resources, the following is suggested: <br /> 1) Monitor the MTBE plume in the vicinity of MW4: <br /> (Sample wells MW3 and MW4) <br /> Sample MW4 for oxygenate additives to gauge changes in concentration. Also sample MW3 in <br /> order to detect plume migration. Both MW3 and MW7 are generally downgradient of MW4 <br />