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'S hr, jam.. x LY d <br /> - � Additional Site Assessent~Work=aPlari n <br /> _ <br /> _ R1PON VICE, 3 <br /> FARM SER -� 1 <br /> .22871Soutlt Highway�99, Ripon California <br /> .lp 4 <br /> x <br /> .1:0. �NTRODUCTION'AND SCOPE_OF-WORK _ ` s -� <br /> 41. <br /> At the request from Ripon Farm Service (RFS), Advanced GeoEnvironmental, Inca (AGE) has' <br /> pr"epared_this=Additional.Site Assessment.Work Plan.for.additional ground water investigation at - ] <br /> 22871 South Highway:99 in Ripon, Califortua .� <br /> 4;L- -- - -" <br /> ' <br /> The scope of work Includes the/:�dv ricernent of three sail liorings ;'bon, will be--66 rnpleteda <br /> _ . .ground water monitoring wells"as required to delineate the-lateral�extent of Hydrocarbon-impacted:,- <br /> = : ground water.If additional soil borings are required;AGE willim-b <br /> 'confi oring and/or well locations - _ <br /> -and construction`with represeiitatives-of the San Joaquin CauntyEiivirorimental Health'Departrnent-= .. <br /> _ (EHD)pridr.:to.drilling.The location of the_site-is illustrated-on Figurre 1. A lilan._of th'e.site=arid the._. <br /> F _ ,proposedwell_locations are depicted on Figure 2 <br /> -_# <br /> This Work Plan Addenduiri is prepared in accordance with therEHD..letter dated=14 September 2004- F <br /> - <br /> . (Appendix A} and�Central Valley'Regional-Water Quality-Control Board(CVRWQCB)guidelines <br /> Ik <br /> - . - <br /> ' for the investigation of underground storage tank(UST) sites} <br /> f REMEDIATIONPROGRESS ' , cls 3 <br /> }: , <br /> �.10`�: x.-00 <br /> Between December 2000 and Di��nlb-er 2003�.a.sorl=vapor extraction(SVE)unit was operational at <br /> - r=the s1te;while-an air 'installed IAS sNysfem ylvas installed at the sitetrill; 2:041.'�peration.of an = - <br /> SVE :unit at-the-site.ceased.in'Ja�a .004_and samples collected of the' soil=vapor from the S _ <br /> F.monitaririg events during the-fourth quarter of 2003 was absent of detectable hydrocarbons,therefore .. - <br /> SVEwasriotrestarted.As.a.resultofthe�remediaiion,dissolveclhy_drocarboriconcentrations.declined-_- <br /> below detection limits m most of the wells°arid remain-below the highest concentrations detected at <br /> `= the site'-. <br /> However, AGE began analyzing:the ground water for exotic-fuel additives m October 2001;well . Y _ <br /> after en began operation.` - -# r f <br /> The leadseavenger 1',2 dichloroethane(1:;2 DCA)was`detedted in sample!from well M.W-4 as high i a �1YeL y <br /> as...300' micrograms per liter (µg/l) <br /> in- June: 2002 and has_decliried in concentrationato 68�µg7 ,, frW' <br /> 1.,2 DCA was also detected in'samples from well MW-Z north of the.:former UST -area .atr '. <br /> Fconcentration°as highas 4.4 µg11-in June-2002'. 1.Dissolved 2.D.CAiconcentrations Have.remained: <br /> stable-acid generally declining;:however; the�conceritrations.jyare-still ab6.vZ the=DHS' Maximumx <br /> n w _ Td r. <br /> r Contaminant Level_(MGL}'of 0:5 µg/1-in drinking:waterr The;hy_ iTpaq- <br /> drocarbon o'sorl has been, <br /> gatedY Site background mfortnation; mcludmg detals .of prelous site assessment work, is s <br /> `presented in Appendix B t <br /> .r' -._ _: z•::C' �, ''• i'`.71 •»--cam, _ -� <br /> a - max - •r * _fj <br /> f ` ' '" a 4.; r r <br /> - TL 'n^#' ';Ya E •^xwY. C. J -. c4 k * Z' <br /> x `�itdvanced GeoEnvironm_ental 7ne." <br /> SOr <br /> �521- <br /> "Ty,., c�i;zi4 <br />