ARCHIVED REPORTS XR0012746 - Laserfiche WebLink

Home Browse Search

'a ' FIELD PR07000LS Soil sameling -- 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 i sampler each successive 6 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 airtight tape. The samples will than be labeled and immediately placed in iced storage for transport to a California State Certified laboratory which will perform the 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 Record will be included in the final report. Construction of_-Monitoring WaIll 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 wi')7 extend from the sri total depth of the well to a depth of approximately 5 feet above measured 9 ground-water levels at the site to allow monitoring throughout the year despite expected seasonal fluctuations of ground rater. The annulus of the well will be packed with #16 Monterey sand, or similar, to approximately 2 feet above the screened interval. A I- to 2-foot-thick s � Wd 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, neat 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 j 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. .ri , k 1 �3 r 5 to 5