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t <br /> ENVIRONMENTAL HEALTH DIVISION a <br /> 304,E. Weber Ave.Third Floor <br /> `? O'. Box 388,Stoc n CA 95201-0388 <br /> Approved <br /> r Denied 04/03/97 TRC 16:37 FAX 1 415 382 1856 ERI Novato Office - 0002 <br /> w/ Condifions � <br /> by ERI <br /> i ENVIRONMENTAL RESOLUTIONS,INC. <br /> April 3, 1997 <br /> . ELL t11'►'t°wrtbN 5flALA4e ERJ205503.A01 <br /> to Mr.Ronald Rowe,Sr. <br /> Site Mitigation Unit <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> 304 East Weber Avenue,Third Floor <br /> Z �D Stockton,California 95202 <br /> A � Subject: Addendum to Work Plan for Supplemental Environmental Investigation at Unocal <br /> " `SJSPlt� Service Station 5886,2701 March Lane,Stockton,California. <br /> V Peet (.Dm-?4n 1 K f. C,/ly $tf>�(.t5� Mr.Rowe: i <br /> I MAT02a K.A. ,/2 � At the request of 76 Products Company,and pursuant to correspondence from San Joaquin County <br /> Public Health Services,Environmental Health Division(PHS/EHD)dated April 1,1997, <br /> Environmental Resolutions,Inc.(ERI)is submitting this addendum to our work plan(dared Match <br /> 28, 1997)for the subject site. The addendum addresses the vertical distribution of methyl tert-butyl <br /> ether(MTBE)detected in groundwater beneath the site and discloses the chemicals utilized in fuel <br /> mixtures by 76 Products Company. <br /> C/JIIL_ Qa t(OU2b (til <br /> Work outlined in ERI's Work Plan includes: 1)obtaining and reviewing MTBE data from a previous <br /> investigation and fuel inventory reconciliation records;2)obtaining appropriate well permits and <br /> AD✓A�� (`7� iZ L�L,- drilling four on-site soil borings;collecting soil samples;constructing groundwater monitoring wells <br /> Ar. L� �M ,, 6� �Ir ,�/ in these borings;developing and purging the new wells;collecting groundwater samples;analyzing <br /> V-'k iL WGTti selected soil and groundwater samples;and 3)interpreting the data to evaluate the source and extent <br /> of residual hydrocarbons in soil and lateral extent of dissolved MTBE in groundwater,and preparing <br /> a report. <br /> PbozA6 AT I l?, INy The San Joaquin County PHS/EHD response to the work plan requested 76 Products Company <br /> address the vertical distribution of MTBE in groundwater and disclose the chemicals utilized in fuel <br /> ` mixtures by 76 Products Company. In accordance with the correspondence and request from the San <br /> PvrfirV✓ �n! w Joaquin County PHS/EHD,analyses of select soil samples and groundwater samples will include total <br /> 1petroleum hydrocarbons as gasoline(TPHg)and diesel fuel(TEPHd)and benzene,toluene, <br /> ethylbenzene,and total xylene isomers(BTEX)as well as MTBE. Select soil samples will also be <br /> analyzed for permeability,dry bulk density,porosity,and moisture content. No samples will be <br /> Q ,�� ^� collected beneath the existing drains during this investigation. It is our tntderstanding 76 Products <br /> �. <br /> 1 I`G eqQV I Company is following appropriate procedures to close the drains. ERI will collect samples of native } <br /> soil from beneath the drains by either coring the concrete and collecting a sample of native soil from <br /> beneath each drain,or hand angering at an angle to beneath each drain and collecting a sample of 1 <br /> �OA1jVllraA1 IGJ DZU�/ native sou. <br /> i <br /> To address the vertical distribution of MTBE in groundwater.ERI will revise the construction of the <br /> N j" proposed monitoring wells to incorporate duel casings within the proposed borings with discreet <br /> M IMi1141YV) ^10 GQq//l <br /> 74 D1901 DOM,Sulk 6,Novato,C8190rnla 94949 413.392.9103 (FA%415,M-18W) <br /> - - Irdrw Novato •SOSWO <br /> i <br /> + <br /> x � <br /> I <br /> { <br />