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FEB-18--99 THU 09:55 AM <br /> FEB. -11' 99(THU) 15:19 UNOCAL �"�" FORTH RE TEL.51'0 94'81 <br /> Peritioner then concluded that the site was suitable for closure as a low-risk groundwater <br /> E' <br /> case and that further site asses cnt or corrective action was not necessary- <br /> By lester to petitioner.dated Mamb 3. 199T, County=ff cowluded that the plume: <br /> of dissolved phase petroleum hydrocarbons was about 130 feet'Iottg and 60 feet wide, that <br /> E! <br /> the average benzene concentrat on witbin the limits of the plunge was 32 ppb, and that the <br /> photo was stable and dam. However, rhe CmM also rokuded that site clos=at <br /> that time was not appropriate with=additional information that aaastraaed that <br /> nantral attenuation was oaxarriag and an cVlanation that natural attentradon would <br /> restore the bereficial•use of mer. <br /> By letter w the CTBT Cleanup Fund Manager dated lune 13, 1997, MWoner <br /> requested that its cane be reviewed for do=*, Petitioner caateaded drat petroleum <br /> hydrocarbon sources(USTs and pion)had been removed ftn�the site, impacted sof <br /> had been ex=vated, SVE had:ta9�c1- -ved additional residial petroleum hycirocarl+ams ixi soil. <br /> Sen product bas never been obaaa v4 MTBE bis nover been d6cted m gromdwa w, the <br /> nearest pubW water supply well is appromarely 800.feet from the sir. and the Coutrtp <br /> W 40=dncd that usessaueut oftbe ca=of a fteted sail and grauidwater is=gila±ta <br /> By let"w to the UST Clemp Fund dated lamiary 15, 1998,County staff <br /> eacpremed concern seprrding petitioner's fulure to define the extent of aftaed soli and <br /> Fmwdwater and to document the volume of affecte4 soil emmvued at*e site_. <br /> In March 1598,tespondinS to the County's request for iaformxdon de raring <br /> thm mortal arten=on was o==mg at the site, pa:moner analyzed groundwater samples <br /> from site wells for selected inorganic costa ds which am tit& ativEe of microbial <br /> metabolism of petroleum hydrocarbons. Thee analyses, in addition to showing that very <br /> active biodegradation was occurring within rhe dissolved phase hydroma plume, also <br /> showed that in shaaaw groundwater, background concaantratiot s of nitrate(about 70 <br /> ppml iron(as high as 3.4 ppm), and Totd Dissolved Solids(1,400 to 1.,200 ppm) <br /> exceeded Scale.MCLS(4$ pptrt 0.3 ppm. and 540 PPM rewecti�ejy)- <br /> II. CONTENTIONS AND FINDING <br />