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1 � a <br /> PUBLIC HFALTH SEkVI,CES <br /> SAID JOAQUIN COUNTY �' < <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst,M.D., M.RH., Health Officer <br /> 304 East Weber:Avenue,Third.Floor - Stockton,CA ;W2 . 0 <br /> 2�-3420 <br /> JOE TOSTE.. .�3'R.. OCT .�" .Z �0�:� <br /> Tfl:STE FAMS: :IN"C <br /> 24:80 90AD <br /> TRACY CA 9�>3 <br /> ..... . ..7. 6 <br /> . . .. <br /> j .. <br /> RE. Curtiss Pontiac=Cadlilac SITE CODE: 1.077 <br /> 2450 Toste Road <br /> Tracy. CA 95.3.76 <br /> San Joaquin County Public:Health Services, Environmental Health Division, (PH.S/EHi3) <br /> has reviewed the "Wolk Plan Addendum:— September 2001"elated September 19, 2001 <br /> that was submitted on;your behalf by Advanced Gec�Environrnental, Inc. (AGE)and has <br /> th fs�llowing comments;. <br /> The work plan addendum proposes the advancement of six cone penetrometortest <br /> (CPT)borings, but lacks a:stated rationale for the scope of the proposed work. Much <br /> soil and groundwater investigative work has been completed at this site,including two. <br /> CPT borings, but a clear site conceptional model has not been developed. Exactly what <br /> is expected to be::confirmed or disproved by the proposed work? <br /> In the "Cone Penetrometer Testing Report— March 2001" it was reported that 110 - <br /> micrograms per liter(pg/1) of total petroleum hydrocarbons as gasoline (TPHg)and 2.4 <br /> µg11 ofi benzene were detected in the grab groundwater sample collected from the 61 to <br /> 64 foot below surface grade (bsg) interval of CPT-2. It was recommended in the report j <br /> that further investigation be conducted to determine if this contamination may be <br /> migrating to the site from an upgradlent source. PHS/EHD agreed with this <br /> recommendation, but also directed that feasibility testing resume at this site.. The: <br /> submitted work plan addendum did not address the issue of feasibility testing; i <br /> The focus of this site needs to shift from investigation to remediation. The contaminant <br /> concentrations identified in CPT-2 are not high. There is a documented source of ;. <br /> petroleum hydrocarbon contamination at this site, the vertical and lateral,extent of which <br /> have been defined in the soil. The lateral extent of the shallow groundwater <br /> contamination has been defined. The vertical extent of the groundwater contamination <br /> near the source area has not been completely defined. However PHS/EHD needs <br /> further clarification as to why-six CPT borings to 100 feet bsg are needed to verify <br /> whether an offsite source of low-level contamination is migrating onto the subject site at = i <br /> depth, and haw this data will impactor enhance the preparation of a feasibility study. <br /> In December 1999 soil samples from a geoprobe investigation were submitted for ' <br /> physiochemical and micro-bionumeration analysis. Results of the analysis indicated that <br /> petroleum blo-degrading microbe activity at the site was low. It was further stated that <br />' adequate nutrients were present in the soil for microbial growth, but that the pH was <br /> 4uline and.likely contributing to lower general and selective.,microbial enumeration. <br /> A Division of San Soag4ia.Counry Health Care Services <br /> ., ti. <br />