WORK PLANS - Laserfiche WebLink

Home Browse Search

Monitoring Wells The ground water monitoring well will be drilled with a hollow-stem auger. Soil samples are typically collected in clean brass or stainless steel tubes of varying diameters and lengths (typically two by six inches). The tubes are typically set in an 18-inch-long split-barrel sampler. For continuous sampling, a two or four foot long core barrel may be utilized. The sampler, attached either to the end of drill rods or on a wire-line hammer device, is conveyed to the bottom of the borehole. When possible, the sampling device is driven its entire length either hydraulically or by repeatedly pounding a 140-pound hammer using a 30-inch drop (blow). The number of drops used to drive the sampler is recorded on the boring log. The sampler is extracted from the borehole and the tubes containing the soil samples are removed. Upon removal from the sampler,the ends of the lowermost tube are typically sealed with Teflon sheeting and plastic caps. The sample may be extruded from the tube and sealed within another appropriately cleaned sample container(e.g.,glass jar). The sealed sample is labeled and handled according to the Quality Assurance Plan. Material from one of the other tubes is screened in the field, when required, according to the Soil Sample Screening method section. The data is recorded on the boring logs at the depth corresponding to the sampling point. All drilling and sampling equipment are either steam-cleaned, or washed with a solution of Alconox° (or equivalent) soap and water and triple rinsed between bore holes and samples to minimize the potential for cross-contamination. Soil Classification As the samples are obtained in the field, the field geologist classifies them in accordance with the Unified Soil Classification System. Representative portions of the samples are then retained for further examination and verification of the field classification. Logs of the borings are prepared indicating the depth and identification of the various strata, the N value and pertinent information regarding the method of maintaining and advancing the borehole. Soil Sample Screening After the soil samples in resealable (Ziploc type) plastic bags have been brought to ambient temperature, the headspace vapors in the bag are screened with a photoionization detector equipped with a 10.2 eV lamp. 2