ARCHIVED REPORTS_XR0008469 - Laserfiche WebLink

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T � - PROTOCOLS ' Soil Sampling The soil samples obtained from the borings will be collected by advancing each boring to a point ' immediately above the sampling depth, then driving the sampler into the native soil through the hollow center of the auger The sampler will be driven 18 inches with a standard 140 pound hammer dropped 30 inches per blow. The number of blows required to drive the sampler each ' successive fi inches will be counted and recorded on the boring log to give an indication of soil consistency A soil sample from each recovered sample interval, above the saturated portion of the boring, will be analyzed in the field with a photoionization detector or a similar instrument The ' data will be recorded on the boring logs Soil samples selected for chemical analysis will be sealed with teflon sheets or aluminum foil, ' plastic end caps, and adhesiveless tape The samples will then be labeled and immediately placed in iced storage for transport to a California State Certified laboratory which will perform the ti required chemical analyses A chain-of-custody record will be initiated in the field and will ' accompany the samples to the laboratory A copy of the chain-of-custody will be included in the final report. Construction of Monitoring Wells ' The monitoring wells will be constructed of flush thread-jointed, Schedule 40 PVC casing No chemical cements, glues, or solvents will be used in well construction ' The screened portion of the well will consist of factory-perforated casing with 0.020 inch wide slots. The well screen will extend from the total depth of the well to a depth of approximately 5 feet ' above measured ground-water levels at the site to allow monitoring throughout the year despite expected seasonal fluctuations of ground water The annulus of the well will be packed with #3 Monterey sand, or similar, to approximately 2 feet above the screened interval A 1 to 2 foot thick ' bentonite plug will be placed above the sand as a seal against cement entering the sand pack The remaining annulus will be backfilled with a slurry of water, near cement, and 5 percent bentonite ' to a few inches below grade A locking well cap and padlock will be installed on each well head, and a traffic-rated, cast-aluminum utility box with a PVC apron will be placed over each well and set with concrete flush with the surrounding station pad The box has a watertight seal to protect ' against surface water infiltration and requires a specially-designed wrench to open This design discourages vandalism and reduces the possibility of accidental disturbance of the well