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Mr.Darin L.Rouse Exxon Company,U.S.A. April 22, 1999 Page 3 borings will be advanced to access the vertical extent of petroleum hydrocarbons in the areas previously identified as impacted. The locations of proposed monitoring wells and soil borings are shown in Figure 2. Each boring location will be sampled and logged at a minimum vertical interval of five feet. Soil samples collected in the field will be logged according to ASTM 2488-84 Unified Soil Classification System,visual manual method. Additionally,each sample will be screened in the field for the presence of petroleum hydrocarbon vapors using a Photoionization Detector(PID). Geologic data, PID reading, and methods used to advance each boring will be recorded on boring logs maintained in the field. tratagraphic location, an PID readings. The samples will be submitted to Sequoia Analytical (a California-certified laboratory) in Redwood City, California for analysis of benzene, toluene, ethylbenzene, and total xylenes (BTEX)using EPA Method 8020,total purgeable petroleum hydrocarbons (TPPH) as gasoline using EPA Method 8015 Modified,and methyl tertiary butyl ether(MTBE)using EPA Method 8260. Ground water beneath the site,based on cumulative depth to water measurements in monitoring wells, has risen above the top of the screen intervals. Delta proposes to install two on-site ground water monitoring wells screened across the historical high water table at the site.The boring for each well will be advanced to a total depth of 20 feet bsg. The proposed wells will be constructed of 2-inch diameter flush threaded Schedule 40 PVC casing and screened with 0.010 machine slotted casing. The screen interval will begin at 5 feet bsg and extend to 20 feet bsg.The annular space of each well will be filled with No.2/12 Lonestar sand to 6 inches above the top of the screen interval and a 1 foot bentonite seal will be emplaced above the filter pack. The remaining annulus will be filled with neat cement to within six inches of surface grade and the top will be completed with a 12-inch diameter traffic-rated well box set in concrete. The proposed well construction details are illustrated in Enclosure C. Each newly installed well will be developed using a surge block and bailer until purge water is relatively sediment free. A ground water sample will be collected from the new wells after the water table has stabilized. Ground water samples will be submitted to Sequoia Analytical for analysis of BTEX,MTBE,and TPPH as gasoline using the previously described EPA Methods. Soil Stockpile Soil generated from drilling activities will temporarily be stockpiled on-site. Soil samples will be collected from the stockpile for chemical analysis to assess disposal options. Following receipt of soil analytical results and acceptance by the designated disposal facility, a licensed waste hauler will be contracted and the stockpile will be removed. Schedule Drilling activities will be scheduled upon approval of the proposed work plan and necessary permits.