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� �w .YKrt *Y i++N+• 4 ).. 7t"e h G'41 "� 'T+.' Y <br />• " fib` � P •adv. gfk 'S^�'�, Y • '�' .A' W -' n yfy" <br /> '6 �y �- -W:' I 3 F .'el5',. � .•L.w fat„ <br />..yam <br /> GROUNDWATER <br /> LOLDDI <br /> TECH `OLOG , INC. 1401llalvardDrive,Suitc140,wcslSicramcntu,CA9i691,(9::i)3i2.4 00 <br /> FAX(416)372.8751 <br /> February 10, 1992 Project No. 02320 2241 <br /> Mr. Clint 13. Rogers <br /> Chevron U.S.A., Inc. <br /> 2410 Camino Ranson <br /> San Ramon, CA 94583-0804 <br /> RE: WORK PIAN ADDENDUM'. NO. 2 <br /> CHEVRON SEFVICE STATION NO.9.4275 <br /> 2905 WEST BENJAMIN HOLT DRIVE <br /> STOCKTON,CALIFORNIA <br /> Dear Mr.Rogers: <br /> Groundwater Technology, Inc. presents this addendum to the Work Plan Addendum No. 1 (dated <br /> January 27, 1992) Work Plan for Additional Monitoring Wait Installation, Chevron Sefvrce Station <br /> No, .9-4275, 2905 W. Benjamin Holt Drive, Stockton, California, dated June 1990 (Attachment <br /> A). Addendum No. 1 to the original work plan revi3ed the location, and construction of two <br /> groundwater monitoring ws:!s, and the soil sampling and frequency for the site. The following <br /> items within the work pl2n are amended in this (No. 2) addendum: <br /> The location of one of the monitoring wells <br /> d The drilling of an additional soil baring and installation of a vapor extraction well <br /> for additional soil data and for potential future soil vapor extraction data. <br /> MONITORING WELL LOCATIONS <br /> Two groundwater monitoring wells wall bo installed to investigate the extent of dissolved-gasoline <br /> hydrocarbons. Due to the difficulty in expediently obtaining a Caltrans encroachment permit, the <br /> proposed monitoring well location, west of the site was moved onsite(Figure 1). <br /> VAPOR EXTRACTION WELL CONSTRUCTION <br /> The vapor extraction well will be installed within a soil`boring which will be advanced to <br /> approximately 20 feet below grade, using a truck-mounted drill rig equipped with 8.5-inch outside- <br /> diameter(O.D.)hollow-stem augers.Undisturbed soil samples will be collected at five foot intervals <br /> using a 2.5-inch-O.D. by 2-font-long split-spoon core barrel. The vapor extraction well will be <br /> constructed of 15 feet of 2-inch-diameter schedule 40 polyvinyl chloride (PVC) casing and 5 feet <br /> of 0.020-inch-slotted well screen. A fitter pack of No.2112 lapis lustre sand will be placed around <br /> ~' the well from the bottom to approximately one foot above the top of the well screen. A seal <br /> Wkes throughout the U.S..Canada and overseas <br />