WORK PLANS_FILE 1 - Laserfiche WebLink

Home Browse Search

ATTACHMENT A FIELD AND LABORATORY PROCEDURES Geoprobe® Boring Procedures The Geoprobe® borings will be advanced using a direct-push, hydraulic and percussion drive- point sampling system. This will involve the driving of a one-inch outer-diameter screen point sampler to groundwater (expected to be approximately 15 feet bgs). Soil samples will be collected every 5 feet. Once to groundwater, the sampler case will be retracted a distance corresponding to the length of an enclosed 1/2-inch x 18-inch stainless steel screen. This disengages an expendable point and allows the slotted screen to extend into the open borehole. The water is then allowed to enter the sampler through the screen for collection. Groundwater will be collected from the boring using a mini-bailer, lowered to the screened interval through the hollow drive tube. The boring will then be continued to approximately 30 feet bgs or until two "clean" soil samples are collected. Determination of "clean" will be based on field evidence including organic vapor concentrations, odor, and staining. A Portland cement seal will be emplaced by tremie pipe in one continuous operation from the bottom of the boring to the ground surface. The samples will be placed on ice for transport to the laboratory accompanied by chain-of- custody documentation. The collected water samples will be submitted to a California State- certified laboratory for analysis. All down-hole drilling and sampling equipment will be steam-cleaned following the completion of the soil boring. Down-hole sampling equipment will be washed in a trisodium phosphate or alconox solution between samples. Groundwater Monitoring Well Installation The monitoring wells will be drilled using 8-inch hollow-stem auger drilling equipment. The wells will be logged by an IT geologist or engineer using the Unified Soil Classification System and standard geologic techniques. Soil samples will be collected at 5-foot depth intervals using a California-modified split-spoon sampler. The sampler will be driven a maximum of 18 inches using a 140-pound hammer with a 30-inch drop. All soil samples for chemical analysis will be retained in brass liners, capped with Teflon squares and plastic end caps, and sealed in ZiplockTM-style bags. The samples will be placed on ice for transport to the laboratory accompanied by chain-of-custody documentation. All down-hole drilling and sampling equipment will be steam-cleaned following the completion of the soil boring. Down-hole sampling equipment will be washed in a trisodium phosphate or alconox solution between samples. \\SACRFP 1\COMMON\rancfp 1\Proj ects\Proj ects\8 80\040\1 a\0102\8 80040_wp.doc