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a, Mr Jeff Wong Page 3 of 10 . with 2-inch diameter, Schedule 40 PVC casing and 0 010-inch slotted screen The filter pack consisted of#2112 silica sand The annular seals contained two feet of bentonite overlain by neat cement/bentonite grout to the ground surface The monitoring wells were secured at the ground surface with above ground well monuments and locking well caps Well construction details are depicted on the boring logs contained in Attachment A ) 0-470 Vapor Well Construction ✓ , � � Vapor well V W 1 was screened from approximat 50 to 70 fee gs The well was constructed with 4-inch diameter, Schedule 40 PVC casing and 0 la=mch slotted screen Filter pack consisted of '/4-inch pea gravel The annular seal consisted of 5 feet of bentonite overlain by neat cementlbentonrte grout Surface completion consisted of a watertight traffic rated flush mount well box and locking well cap Construction details for the vapor extraction test well are shown on the boring log contained in Attachment A i Mud Rotary Drilling From October 8 to October 16, 2003, V&W advanced soil borings MW13C (total depth of 225 feet bgs) and MW14B (total depth of 135 feet bgs) using a mud-rotary drilling rig with a 9'/8-inch rock bit The locations of the wells are shown on Figure 2 Bentonite based drilling mud was maintained in an overbalanced condition (>8 35 lbs/gal) to prevent formation water from the entering the borehole Continuous coring from the ground surface to total depth was attempted in each mud rotary boring using a 94-millimeter split barrel sampler Due to the lack of sample recovery, however, stratigraphy for much of each bore hole was logged by the relative percentage of coarse grained material (sand and gravels) vs fine grained material (silts and clays) present in drilling mud returned to the surface B Zone and C Zone Well Construction Based on stratigraphy of the borings and correlation of the affected domestic well and existing site momtonng wells, screening intervals for wells MW13C and MW14B were from 202 to 222 feet bgs and from 109 to 124 feet bgs, respectively Well MW13C was constructed of 4-inch diameter, schedule 80 PVC casing and 0 010-inch slotted screen Well MW 14B was constructed of 4-inch diameter, schedule 40 PVC casing and 0 010-inch slotted screen Centralizers were placed on the well casing 1n well MW14B at 65 feet bgs and at 115 feet bgs Centralizers were placed on the casing of well MW 13C at 40-foot intervals The filter pack in both wells consisted of#2112 silica sand The annular seals consisted of bentonite (5 feet in well MW13C and 3 feet in well MW1413), overlain by neat cement grout to the ground surface The filter pack and sealing materials were placed into the borehole from the bottom to the top using a tremae pipe Well MW13C was completed with an aboveground well monument Well MW14B was completed with a watertight, traffic-rated, flush- ! mount well box Construction details for wells MW13C and MW14B are illustrated on the respective well logs in Attachment A Table 1 summarizes the construction details of all site wells G IGROUNI)ZEITULEBURG1Reports\HSA_Mud wells Report 2 doe