WORK PLANS - Laserfiche WebLink

Home Browse Search

1.0 METHODS 1.1 Soil Sampling and Contamination Reduction i Soil borings and soil sampling will be performed under the direction of a Delta engineer or geologist. The soil borings will be advanced using a truck-mounted drill rig utilizing hollow-stem augers. To reduce the chances of cross-contamination between boreholes, all downhole drilling equipment will be steam cleaned between each boring. To reduce cross-contamination between samples, the split-barrel sampler will be washed in a soap solution and double-rinsed between each sampling event. A California-modified split-barrel sampler will be used to extract the soil samples from the soil borings. Soil samples will be collected at 5-foot intervals at each soil boring. Soil sampling will be done in accordance { with ASTM 1586-84. Three 6-inch brass tubes will be inserted into the California sampler to retain the soil sample. Using this procedure, a 2-inch outside-diameter split-barrel sampler or a 2-inch inside-diameter California-type sampler is driven into the soil by a 140-pound weight falling 30 inches. After an initial set of 6 inches, the number of blows required to drive the sampler an additional 18 inches is known as penetration resistance,or the"N"value. The.N value is used as an empirical measure of the relative density of cohesionless soils and the consistency of cohesive soils. I ' Upon retrieval of each soil sample, the bottom brass tube will be capped, sealed,;labeled, and stored on ice at approximately 4°C for transport to a state-certified laboratory for possible chemical analysis. Soils from the middle brass tube will be placed in jars and sealed with aluminum foil for field screening for the presence ' of hydrocarbons with a PID. 1.2 Soil Classirication �i As the samples are obtained in the field, they will be classified by a geologist/engineer in accordance with ASTM D2488-84. Representative portions of the samples will then be returned to the laboratory for further it examination and for verification of the field classification. Logs of the borings indicating the depth and J identification of the various strata,the N value,water-level information and pertinent information regarding �F the method of maintaining and advancing the borehole will be made. Charts illustrating soil classification ,+ procedure and the descriptive terminology and symbols used on the boring logs will also be made. �i