ARCHIVED REPORTS XR0006989 - Laserfiche WebLink

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' LUlIeLtLd from V11�-3 and MW--I M I HE was detLf tcd in M\k-4 M I BL tertiary butanol and 1 1 M F �v Lt L dLtLLtcd in VI W-2 No floating pi oduct sheen or petroleum hydrocarbon odor was IiitLd ni thL iuonrtot wLl[s IIll Lvaluation of intrinsiL bioreniediation parainetLrs was not tunduLtLd [ILLaUSL additional nionitoring was ncLessary to evaluate the potential foi uitruzsiL NO]Lmediatlon at ihL site ' (,inundwatci L-IL\atuOn mLasuienients Loilected at the SitL monitor wells on DeLetnber 31 1997 indiLatcd drat ihL aveiapt, depth troth the ground surface to groundwater was approximately 4 ILLI I he a\eragL depth to Wates at the site decreased by approximately 2 feet betvveen ScptLmbet 18 1497 and DccLmber 31 1997 {groundwater Llevation contours estimated using t11L depth-to-watLr measurements LolILLtLd on December 31 1997 Indicated that groundwater %v,k at thL ',ttL was ttLncrallr LoinsisiLnt vv[th the Lsti natLd flow on September 18, 1997 ()n V1,ILh 2- 1998 ( ondor pLr',onnel \verL on site to Londuct quarterly groundwater monitoring I abcnatory anal,,',es of gtoundwater tramples Lollected from thL site monitor wells indicated that ' BI FA I PH-(j and thL selectLd gasohnc oxygenates/additives were not detected at or abovL the laboratory ieported detection limits in the sample collected from MW-1 1-thanol, tertiary- butanol DIP[ I I BF- and f AML were not detected at or above the laboratory reported detection ' limits in anv of the groundwater samples Detection lunits for the analysis of the samples collected from MW-2 and MW-3 were raised, however due to relatively high concentrations of MI 131 in the samplLs collected trom those wells (as described below) Benzene and FPH-O ' weic not detected at or above. ratsLd detLLtion limits and low concentrations of fFX constituents wLte detLOLd In thL ',ample collected from MW-2 M'l131 was detected at i 10,000 ug/l in the \,[W-' ',amplL 13 1 1 X and 11'11-(1 wLrL not deteLtLd at or above the laboratory r(-ported dLtcciiOti Iiinits in the sample collected trom MW-3 M1131 was detected at 1,900 µg/I tri the Vl\k-+ saittple I PH-(j and 13 1 1 X Lon',titticnts werL deteLted in the ~ample collected from M W- VI II3[ was not detectLd at or abo�L thL [aboratory reported dcleLtton limit in tI1L YIW-4 ' sample No floating product sheen tit petroleum hydrocarbon odor was noted in the monitor wells ' Laboratory analytical results of the groundwater samples for the first quarter, 1998, monitoring event were generally consistent with historical quarterly groundwater analytical data MTBE concentrations in samples from MW-2, however increased by more than two orders of magnitude durini., the three sampling events conducted at the site ' (jroundwater elLvation mLamirements cnllLcted at the sste monitor wells on March 27, 1998 tndlcated that the average depth from the ground surface to groundwater was approximately 5 ' tLet f hL avLragL depth to water at the site increased by approximately 1 foot between December 31 1997 and March 27 1998 Oroundwater elevation contours estimated using the depth-to- watei measurements Lollcucd on March 27, 1998 indicated that groundwater gradient at the site W.-IS generally Lonststent with the estimated gradient on September 18, 1997, and December 31, 1997 ' In a telephone Lonversation on March 23 1998, Mr Ronald Rowe of the San Joaquin County Public Health Setvices/Ltivironmental health Department (PHS/GHD) indicated that based on his ieview of the ieport dated December 11, 1997 (referenced above), he was requesting that quarterly groundwater monitoring continue at the site 1-urthermore, he requested that a work plan be prepared lot conducting quarterly surface water sampling and additional investigation of the gasoline oxygenate/additive plume to the east of monitor well MW-2 Condor subsequently piepared the Work Plan - Aciditional Sod and Groundwater Investigation / Surface Water %uinphnir dated May 27 1998 In a faxed note dated June 1, 1998, Mr Rowe approved the work