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07/13a98 09:22 $209 465 7244 FORT OF STOCKTON 1@ 00 2 <br /> 4 !lE 2 <br /> part of Stockton <br /> General Offices: P.Q. 13OX 2089,SW ddM. CA 95201-2089 <br /> (209) 946-4246/FAX(205 466-7244 Orr(209)456-5985 <br /> July 15, 1998 <br /> VIA FACSIMILE(209)464-0130 <br /> Ms. Carol Oz <br /> Environmental Health SpaciaGst <br /> Sart Joaquin County Public Health Service <br /> Environmental Health Civision <br /> 304 East Weber Averrue <br /> Stockton, California 95202 <br /> Subject Addendum to"Work Plans for Initial Subsurface Investigation of Petroleum <br /> Hydrocarbons"-Site Numbers 1 through 5 <br /> Stie Codes 1282 1282-124-, 1282-10-, and 1237 <br /> Dear Carol: <br /> The Port of Stockton(Port}is pleased to submit this addendum to the subject Worts mans, <br /> prepared as a result of our Juty 13, 1998 rneeting held at your ofi"ece.As collectively agreed at our <br /> meeting, the primacy revision to the Work Plans is that collection of soil samples for petroleum <br /> hydrocarbon compound (PHC)analysis will not be limited to the vadose zone, but may be collected <br /> frame below the water table as well- Your rational was that primarily due to the elevated water table, <br /> the contaminants might have vertically migrated tQ the subsurface soils below the groundwater table. <br /> The following descry the amended procedures for field investitplions at each of the subied sites. <br /> As described in the Work Plans, continuous core samples will be collected utilizing the <br /> Geoprobe direct-push method in the initial boring drilled at each UST site. The core wilE be collected <br /> far the purpose of bion of subsurface lithology, PHC impact, and depth to girour<dwater <br /> at the UST site. The continuous cora samples will be collected in dear plastic or acrylic liners, <br /> labeled, capped, and temporarily stored in ice chests on site. Soil cores%mll be examined for viisual <br /> indications of discoloration and PHC odor,and screened with a portable photoioreir t detector for <br /> the presence of orgW is vapors. Based on soll-core examine0on.a minimum of two soil samples, <br /> spaced 5-feet apart will be seleded from the continuous C"and submitted to the laboratory far <br /> analysis of PHCs, even if the selected samples are collected from below the water table. Soil <br /> samples wM be analyzed for the constituents described in Section 3.2 of the Work Plans, <br /> Examination of the core samples will provide target locations for collection of a minimum of two soil <br /> samples and one gr=ndwater sample In each of the remaining borings at each site. <br /> GENERAL OFFICE: 2201 W. WASHINGTON ST., STOCKTON, SAN JOAQUIN COUNTY, CALIFORNIA <br />