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11 l 11 w WO : WR sample number,date,time,depth,sampler,and borehole number. The samples are placed in zip- lock bags and stored in a cooler containing ice. Soil is removed from the other two liners and examined. The soil is scanned with a Foxboro Century 128 organic vapor analyzer(FID). OVA readings are noted on the logs. The soil is also described and classified according to the Unified Soil Classification System. Soil samples are delivered, under chain of custody,to a laboratory certified by the California Department of Health Services (DHS) for hazardous materials analyses. The samples are ana- lyzed for petroleum hydrocarbons according to recommendations of Table 2 of the Tri-Regional Recommendations. A.3 WELL INSTALLATION The boreholes are completed as groundwater monitoring wells after drilling. The wells are constructed of 4-inch-diameter Schedule 40 PVC flush-threaded casing. The screened interval consists of slotted casing, placed from 10 feet below the water table to 1 foot above it,or,if confined conditions are encountered,only a 10-foot screen placed at the top of a saturated zone will be installed. A threaded end plug or a slip cap secured with a stainless steel screw is placed on the bottom of the well. A filter pack of clean No. 2/16 Lonestar,#3 Monterey,or equivalent sands is placed in the annular space around the well screen to approximately 2 feet above the top of the screen. The sand is sealed with a Bentonite plug 1-2 feet thick and hydrated with deionized water. A surface seal is then created by placing a cement grout containing less than 5 percent Bentonite from the clay to the surface with a Tremie pipe or grout pump. The well is secured from unauthorized entry on the surface in a slightly raised, 12-inch-diameter traffic-rated,water-tight steel traffic box that requires a special wrench to open. The traffic box is set in concrete. The well is further secured from unauthorized entry with a locking well cap. Proposed well completion diagrams are shown in Figures A-1 and A-2. AA WELL DEVELOPMENT The wells are developed two days after completion. Development consists of surging the screened interval of the well with a 4-inch flapper valve surge block for approximately 15 minutes. The well is then purged,with a submersible electric pump,centrifugal pump, air-lift bailer of 2-6 casing volumes of water. The surging and pumping are repeated until the water is free of silt and apparent turbidity,for a maximum of 4 hours.. A-2