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Union Ice Company January 26, 1993 1320 Weber Street, Stockton, California Work Plan to Install Monitoring Wells Page 2 3.0 PROPOSED MONITORING WELLS WHF is proposing to install three (3) two inch (2") monitoring wells using a 8 7/8 inch OD hollow stem auger down gradient of the warehouse where the leak occurred. The leaf: occurred beneath the building, and due to the numerous pipes containing ammonia, brine and water beneath the building, it is not safe, or feasible, to drill into the floor of the warehouse. The other factor considered in deciding against drilling into the floor is that the integrity of the warehouse floor itself would be violated, and if that occurs, the soil beneath the floor will freeze and then lift and destroy the floor of the warehouse. A site map showing the existing monitoring wells, the proposed wells and the ground water gradient is included in this work plan. The proposed well locations are approximate as under ground utilities have not been located to our satisfaction. W11F has proposed three (3) wells as we do net know the precise location of the leak, and also the size of the warehouse dictates that if ground water has been impacted we want to be sure of intercepting the plume of contamination. The proposed wells will be installed to a depth of twenty five feet (25') below ground surface. The wells will be screeneet from fift=. feet (15') below the surface to feet (25" below the surface. 4.0 WELL CONSTRUCTION All materials used in well construction will be thoroughly cleaned prior to introduction into the boring. A Bentonite or cement and Bentonite grout will be placed at the bottom of the boring as necessary. After the sea! has been allowed to set long enough to support the casing (PVC) with end cap and factory perforations for placement into the saturated zone the casing will be placed in the boring. The screen and filter pack will be as noted in the well constriction drawing. The casing and end caps will be threaded and no glue will be used to cement the casing : ,ecticns together. The filter pack will extend 2 feet above the perforated zone. A Bentonite seal 2-3 feet thick will be placed in the annular space above the filter pack followed by a cement grout to the surface. Seai and filter pack elevations may change based on the underlying geology. The wells will be protected by cristy boxes installed flush with the ground surface.