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gn ' ' r v INO Elm c — Y sample number,date, time,depth, sampler,and borehole number. The saml;les 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 INSTALLAI'ION 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 0.010-inc`i slotted casing,placed from 10 feet below the water table to 5 feet above it. 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. 2/15 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 fess 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. A proposed well completion is shown in Figure A-1. A.4 WELL DEVELOPMENT The wells are developed two days after completion. Development consists of surging the screened interval of the well with a 4-itich flapper valve surge block for approximately 15 minutes. The well is then purged, with a submersible electric pump,centrifugal pump,air-lift pump, or PVC 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 record of the purging methods and volumes of water purged is maintained, All purge water is _ contained on the site in properly labeled 55-gallon drums. Purged water is disposed of at an appropriate facility on the basis of the laboratory analytical results. c]rnJ9aahNy9l/f+ A-2