ARCHIVED REPORTS XR0009939 - Laserfiche WebLink

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=eAIWAWALAFAII i Working to Restore Nature Sam 11n Drill utt�n s Soil samples were collected from the stockpiled soil by driving a hand-operated percussion sampler fitted with a clean brass sleeve into the stockpiled soil The sleeve was removed from the sampler and promptly sealed with aluminum foil, plastic caps, and Teflon tape The sample was then labeled and placed in iced storage Chain of Custody Records were initiated by the geologist and accompanied the samples to the analytical laboratory Vapor Extraction Well Construction Soil borings chosen for vapor extraction wells were located in soil containing elevated levels of hydrocarbons based on field observations and field screening using a photmomzation detector Soil borings were terminated approximately 1 foot above first encountered groundwater, and the vapor extraction wells were constructed in the boring with threaded- jointed, 4-inch-inner-diameter, Schedule 40 PVC casing No chemical cements, glues, or solvents were used in well construction The screened portion of each well consisted of factory-perforated casing with 0 020-inch-wide slots The well screen extends from the total depth of the well to approximately 15 feet below grade for wells VW-1 and VW-2, and 10 feet below grade for well VW-3 The screen interval was based on field observations and sediments encountered during drilling The annular space in the well was packed with . sorted sand to a point approximately 1 foot above the slotted interval. A bentonite plug was added above the sand pack to seal out cement The remaining annulus was backfilled to grade with a bentornte-cement slurry The vapor extraction wells were completed by installing a traffic-rated, cast-alurmnum utility box over the well head Groundwater Monitoring Well Construction The wells were constructed using clean 4-inch-inner-diameter, thread-pointed, Schedule 40 polyvinyl chloride (PVC) casing. No chemicals, glues, or solvents were used in construction of the wells The screened portion of the monitoring well consists of factory-perforated casing with slots and extends from the total depth of the boring and extends above the depth where water was first encountered Unperforated casing is set from the top of the screen to several inches below surface grade The annular space of each well was packed with sorted sand from the total depth of the boring to approximately 2 feet above the top of the screen A plug of bentonite pellets (approximately 2-feet thick)was placed above the sand to prevent cement from entering the sand pack This seal reduces the possibility that hydrocarbons migrating downward through the overlying sand will infiltrate the aquifer The remaining annulus was backfilled to the ground surface with a mixture of water, cement, and bentonite. The construction details of the individual wells are shown on the Logs of Borings 30003-7