FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

CAMBRIA STANDARD FIELD PROCEDURES FOR MONITORING WELLS This document presents standard field methods for drilling and sampling soil borings and installing,developing and sampling ground water monitoring wells. These procedures are designed to comply with Federal, State and local regulatory guidelines, Specific field procedures are summarized below. SOIL BORINGS Objectives Soil samples are collected to characterize subsurface lithology, assess whether the soils exhibit obvious hydrocarbon or other compound vapor or staining, and to collect samples for analysis at a State-certified laboratory. All borings are logged using the Unified Soil Classification System by a trained geologist working under the supervision of a California Registered Geologist(RG)or a Certified Engineering Geologist(CEG). Soil Boring and Sampling Soil borings are typically drilled using hollow-stem augers or push technologies such as the Geoprobe. Soil samples are collected at least every five ft to characterize the subsurface sediments and for possible chemical analysis. Additional soil samples are collected near the water table and at lithologic changes. Samples are collected using lined split-barrel or equivalent samplers driven into undisturbed sediments at the bottom of the borehole. Drilling and sampling equipment is steam-cleaned prior to drilling and between borings to prevent cross- contamination, Sampling equipment is washed between samples with trisodium phosphate or an equivalent EPA- approved detergent. Sample Analysis Sampling tubes chosen for analysis are trimmed of excess soil and capped with Teflon tape and plastic end caps. Soil samples are labeled and stored at or below 4°C on either crushed or dry ice,depending upon local regulations. Samples are transported under chain-of-custody to a State-certified analytic laboratory. Field Screening One of the remaining tubes is partially emptied leaving about one-third of the soil in the tube. The tube is capped with plastic end caps and set aside to allow hydrocarbons to volatilize from the soil. After ten to fifteen minutes, a portable photoionization detector (PID) measures volatile hydrocarbon vapor concentrations in the tube headspace, extracting the vapor through a slit in the cap. PID measurements are used along with the field observations,odors,stratigraphy and ground water depth to select soil samples for analysis. Water Sampling Water samples,if they are collected from the boring,are either collected using a driven Hydropunch type sampler or are collected from the open borehole using bailers. The ground water samples are decanted into the appropriate containers supplied by the analytic laboratory. Samples are labeled,placed in protective foam sleeves,stored on Page 1 of 3