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i • Soil in the next sample tube (where available) should be used to describe the lithology and measure volatile organic compound (VOC) concentrations. . Approximately half of the sample from the sample tube will be removed and placed in a resealable plastic bag. The plastic bag will be set aside to allow VOCs, if present, to accumulate in the headspace above the sampled soil. The headspace will then be sampled using a portable photo-ionization detector (PID). The PID probe should be inserted through a hole made in the plastic bag and the highest measurement encountered recorded on the boring log. • Soil and wastewater generated during the field activities will be contained in 55- gallon United Nations approved drums. Well Construction Procedures • The monitoring wells will be constructed of flush jointed, threaded, 2-inch I.D., Schedule 40 polyvinyl chloride (PVC) casing. The well casing will be delivered to the site in factory plastic wrap. The casing will have rubber or Teflon O-ring gaskets at the joints. • The slotted interval will consist of 0.020-inch machined slots.. The filter pack should consist of#3 Monterey Sand. The.slot size and filter pack has been selected with the intent to minimize the amount of native lithologic and filter pack material entering the monitoring well. • A bottom screw cap will be placed on the bottom of the casing. A 10 foot length of slotted casing should be joined to the bottom'screw cap. The screened interval should be set so that no more than 10 feet or no less than 7 feet of well screen is within the water-bearing zone. Blank casing will be used to construct the. remainder of the well. • During placement of the filter,pack, the well will be suspended in the augers. The augers will be lifted 2 to 4 feet and the sand filter pack poured into the annulus. The augers will then slowly be lifted with sand filter pack placed"continuously until the sand is approximately 2 feet above the top of the screen. • An approximately 1 to 2 foot thick zone of bentonite will be placed above the sand filter pack. • The annulus above the bentonite will be grouted with a cement slurry placed by tremmie.if significant water is present in the boring. The cement grout should extend to a depth of approximately 1 foot below the ground surface. A traffic-rated housing will be placed above the well casing and set in concrete. The well housing should be set approximately one-inch above the ground surface. The well number will be recorded on the well monument. A locking device will be installed to minimize the likelihood of unauthorized access to the well. • The grout will be allowed to cure for approximately 48 to 72 hours prior to monitoring well development. N:\sacDP\2001\PRJ\PJ8\8800401 Aa ac.doc B-2 12/12/01