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July 13, 1992 <br /> 10433 382 <br /> Mr. Chuck Kolesar Harding Lawson Associates <br /> Page 3 <br /> screen will be constructed of 4-inch diameter, Schedule 40, flush-joint <br /> threaded PVC. The screen slots will be factory milled, and the slot <br /> size will conform with both the sand pack and aquifer formation. The <br /> screened interval will extend approximately 5 feet above the ambient <br /> water table, to allow monitoring of free-phase petroleum product, if <br /> present. A sand pack of clean water-washed sand (sized to be compatible <br /> with both the aquifer formation and well screen) will be placed adjacent <br /> to the entire screened interval and will extend a minimum distance of 2 <br /> feet above the top of the screen. No screen or sand pack will be <br /> emplaced that interconnects two or more hydrostratigraphic units. A 2- <br /> foot bentonite pellet seal will be placed above the sand pack. Levels <br /> of sand and bentonite will be confirmed by sounding. After the <br /> bentonite seal has hydrated, the annular space above the bentonite seal <br /> will be grouted with a cement-bentonite grout. <br /> After the cement-bentonite grout has set for a minimum of 24 hours, the <br /> well will be developed by swabbing, surging, bailing, and/or pumping. <br /> The well will be developed until it is visibly clear and free of <br /> sediment. Fluids removed from the well during development will be <br /> transferred to an existing onsite treatment system. Ground surface and <br /> well casing elevations will be surveyed to the nearest 0.01 foot by a <br /> licensed Land Surveyor. <br /> After completion and development of the wells, groundwater samples will <br /> be collected and analyzed for total petroleum hydrocarbons calibrated as <br /> gasoline and diesel using EPA Test Method 8015 (modified) and for the <br /> petroleum constituents benzene, toluene, ethylbenzene, and xylenes using <br /> EPA Test Method 8020. <br /> ADDITIONAL WORK <br /> Shallow Extraction Well <br /> One additional onsite shallow aquifer extraction well will also be <br /> completed at the site (Plate 1) . As described in the Evaluation of <br /> Groundwater Extraction Report (HLA, 1992) , Shell is planning to expand <br /> it's onsite shallow groundwater extraction system, to include pumpage <br /> from existing onsite Well MW-23 and the proposed extraction Well EW-1 <br /> (Plate 1) . Well drilling and completion procedures will be the same as <br /> those described above for the monitoring wells. <br />