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<br /> "�. Soil is removed from the other two liners and examined. The soil is scanned with a Foxboro
<br /> Century 128 Organic vapor analyzer{FII)). OVA readings are noted on the logs. The soil is also
<br /> described and classified according to the Unified Soil Classification System,
<br /> M Soil samples are delivered, under chain of custody, to a laboratory certified by the California
<br /> Department of Health Services(DHS) for hazardous materials analyses. The samples are ana-
<br /> lyzed for petroleum hydrocarbons according to recommendations of Table 2 of the Tri-Regional
<br /> Recommendations.
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<br /> .—, A.3 WELL INSTALLgrION
<br /> { The boreholes are completed as groundwater monitoring wells after drilling. The wells are
<br /> constructed of 4-inch-diameter Schedule 40 PVC flush-threaded casing. The screened interval
<br /> consists of 0.010-inch slotted casing,placed from 10 feet below the water table to 5 feet above it.
<br /> A threaded end plug or a slip cap secured with a stainless steel screw is placed on the bottom of
<br /> the well.
<br /> A filter pack of clean No. 2116 Lonestar,#3 Monterey,or equivalent sands is placed in the
<br /> annular space around the well screen to approximately 2 feet above the top of the screen. Tile
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<br /> sarid is sealed with a Bentonite plug 1-2 feet thick and hydrated with deionized water. A surface
<br /> -seal is then created by placing a cement grout containing less than 5 percent Bentonite from the
<br /> clay to the surface with a T remie pipe or grout pump.
<br /> e j The well is secured from unauthorized entry on the surface in a slightly raised, 12-inch-diameter
<br /> traffic-rated, water-tight steel traffic box that requires a special wrench to open. The traffic box
<br /> F is set is concrete. The well is further secured from unauthorized entre with a locking well cap, .
<br /> "1 A proposed well completion is shown in Figure A-1.
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<br /> A.4 WELL DEVELOPMENT
<br /> s The wells are developed twe days after completion, Development consists of surging the
<br /> 3 screened interval of the well with a 4-inch flapper valve surge block for appro-"nately 15
<br /> minutes. The well is then purged, with a submersible electric pump, centrifugal ump, air-lift f
<br /> pump, or PVC bailer of 2-6 casing volumes of water. The surging and pumping are repeated
<br /> until the water is free of silt and apparent turbidity,for a maximum of 4 hours.
<br /> It ; ; A record of the purging methods and volumes of water purged is mgintained. All purge water is
<br /> contained on the site in properly labeled 55-gallon drums. Purged water is disposed of at an
<br /> E appropriate facility on the basis of the Iaboratory analytical results.
<br /> e42/71050/nov/spa A-2
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