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06/18/02 TUE 10:00 FAX 925 391 7275 TERRA VAC NOR CAL Z002 <br /> 1/' I-W <br /> TERRA <br /> UAC ��.�w • <br /> o <br /> We're gaining new ground. DO *.,-. <br /> �A <br /> December 20,2001 DeM <br /> ChevronTexaco APPMVW 0d�Or0*` R <br /> P.O. Box 5004 fart and don ndSAM DW111Mti�♦ <br /> 6001 Bollinger Canyon Road deviation from requkeMoft Of Wb <br /> San Ramon,CA 94583-0804 �Q O D y <br /> Arm.:Mr. Bob Cochran <br /> Subject: Installation of Additional Sparge Wells <br /> Former Chevron Station 9-4054 <br /> 2103 Country Club Boulevard,Stockton,California <br /> Dear Mr.Cochran: <br /> Terra Vac has requested bids from drilling companies for the installation of three additional air sparge <br /> wells(SP-7,SP-8,SP-9)at the subject location. Vapor concentrations from wells DVE-t and DVE-2 have <br /> been very low in hydrocarbons throughout operations but have contained a relatively high proportion of <br /> methane. In addition, the dissolved oxygen(D.O.)concentration at DVE-1 was recently measured at just <br /> 0.46 mg/L,in contrast to a range of from 2.01 mg/L at DVE-16 to 8.8 mg/L at DVE-5. This indicates that <br /> bioactivity at the western end of the property is under anaerobic conditions and that additional wells are <br /> needed for full coverage. Figure 1 illustrates the approximate locations of the proposed sparge wells. An <br /> additional benefit is that sparge wells near the western property line will establish a barrier to contaminated <br /> groundwater migrating on site. Soil samples will be collected every 5 feet and submitted for analysis of <br /> TPHg/BTEX. Terra Vac will secure well permits from the San Joaquin County Public Health Services, <br /> Environmental Health Division prior to beginning the work. <br /> If you have any questions concerning this report or enclosed documents,please feel free to call me at(925) <br /> 363-7322. <br /> Sincerely, <br /> Terra Vac <br /> Robert A.Dahl <br /> Project Manager <br /> 304212.20 <br />