WORK PLANS_FILE 2 - Laserfiche WebLink

Home Browse Search

V CRA STANDARD FIELD PROCEDURES FOR GEOPROBE® SOIL AND GROUNDWATER SAMPLING This document describes Conestoga-Rovers & Associates' standard field methods for GeoProbe® soil and groundwater sampling. These procedures are designed to comply with Federal, State and local regulatory guidelines. Specific field procedures are summarized below. Objectives Soil samples are collected to characterize subsurface lithology, assess whether the soils exhibit obvious hydrocarbon or other compound vapor odor or staining,estimate ground water depth and quality and to submit samples for chemical analysis. Soil Classification/Logging All soil samples are classified according to the Unified Soil Classification System by a trained geologist or engineer working under the supervision of a California Professional Geologist(PG)or a Certified Engineering Geologist(CEG). The following soil properties are noted for each soil sample: • Principal and secondary grain size category(i.e., sand, silt, clay or gravel) • Approximate percentage of each grain size category, • Color, • Approximate water or separate-phase hydrocarbon saturation percentage, • Observed odor and/or discoloration, and • Other significant observations(i.e., cementation,presence of marker horizons,mineralogy) • Estimated permeability Soil Sampling GeoProbe soil samples are collected from borings driven using hydraulic push technologies. A minimum of one and op e ft of drilled depth. Additional soil samples can be collected near the water tab e and at lithologic changes. Samples are collected using samplers lined with polyethylene or brass tubes driven into undisturbed sediments at the bottom of the borehole. The ground surface immediately adjacent to the boring is used as a datum to measure sample depth. The horizontal location of each boring is measured in the field relative to a permanent on-site reference using a measuring wheel or tape measure. Drilling and sampling equipment is steam-cleaned or washed 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 Storage, Handling and Transport 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. j I of t i I