WORK PLANS - Laserfiche WebLink

Home Browse Search

P&ect Number 1804BKOI Seotember 17.2003 hours of collection as specified in EPA Method 5035/8260b for volatile organic compound (VOC) analysis. The samples will be maintained at 4° Centigrade and accompanied with a chain-of-custody document during transport to the analytical laboratory. A hydrogen flame ionization detector (FID) will be used during the drilling process to screen the soil samples for the presence of hydrocarbons. A small portion of soil will be paced in a plastic bag and allowed to volatilize for approximately five (5) minutes before measuring the hydrocarbon vapor concentration within the bag. A maximum of three (3) samples from each boring will be submitted for chemical analysis. Samples for analyses will be selected based on the field screening measurements. These samples will be transferred to a California State Certified laboratory under chain of custody control procedures. It is anticipated that samples will be selected primarily from the capillary fringe and shallow saturated zone because the vadose zone soils should not be impacted by PCE due to the distance from the source area (sewer line in north-south alley of the Busy Bee block). Soil Gas Sampling Soil gas sampling will be performed during drilling of each shallow monitoring well boring. One (1) to two (2) soil gas samples will be collected between 30 feet and 50 feet bgs in the perimeter boring locations along Sacramento Street, Lodi Avenue, and Washington Street. Sampling in this depth interval at the perimeter locations is proposed based on E2C's findings during the Phase 1 Site Characterization Study which showed that this interval was most likely to exhibit soil gas VOC detections near the Site and for correlation with previous soil gas sampling data collected from 30 feet to 45 feet bgs by others in a city-wide study. The upper sample will target a finer grained layer that may have allowed volatile organic compound (VOC) migration from the Site along a lithologic contact and the lower sample will target VOC vapors off-gassing from the underlying groundwater anticipated at a depth of approximately 50 feet bgs. At the shallow well locations interior of the groundwater plume, soil gas samples will be collected more frequently than at the perimeter wells. Four (4) soil gas samples will be collected at each of these well locations at depths of approximately 15 feet, 25 feet, 35 feet, and 45 feet bgs. The upper three samples will target the vadose zone using the rationale described above and the lowermost sample will be used to evaluate VOCs off-gassing from the underlying groundwater. Soil gas sampling will be performed in the following manner. The boring will be advanced using hollow-stem auger equipment to within 5 feet of the target sample depth and a Geoprobe Vapor Sampling Tool will be advanced through the augers into undisturbed soil to the desired sampling depth. The sampling tool consists of an expendable drive point holder, drive point with inner O-ring seal, and a steel tubing tong that threads into the point holder. The drive point holder threads onto a 1-inch-outer-diameter steel Geoprobe sampling rod that threads into an adaptor enabling connection to standard sampling rods. Prior to sampling, clean polyethylene tubing will be connected to the stainless steel tubing tong on the point holder and this assembly then will be threaded into the Geoprobe sampling rod. The sampler will be lowered through the augers and driven to the desired depth using a 140-pound drive hammer. The sampler will be pulled back dislodging the expendable point E,C Remediation 3