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r it CRA Field Screening After a soil sample has been collected,soil from the remaining tubing is placed inside a sealed plastic bag and set aside to allow hydrocarbons to volatilize from the soil. After ten to fifteen minutes,a portable GasTecho or photoionization detector measures volatile hydrocarbon vapor concentrations in the ag's headspace,extracting the vapor through a slit in the plastic bag. The measurements are used along with the field observations,odors, stratigraphy and ground water depth to select soil samples for analysis. Grab Groundwater Sampling Groundwater samples are collected from the open borehole using bailers,advancing disposable Tygori tubing into the borehole and extracting ground water using a diaphragm pump,or using a hydro-punch style sampler with a bailer or tubing. 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 crushed ice at or below 4°C, and transported under chain-of-custody to the laboratory. Duplicates an'd Blanks Blind duplicate water samples are usually collected only for monitoring well sampling programs,at a rate of one blind sample for every 10 wells sampled. Laboratory-supplied trip blanks accompany samples collected for all sampling programs to check for cross-contamination caused by sample handling and transport. These trip blanks are analyzed if the internal laboratory quality assurance/quality control(QA/QC)blanks contain the suspected field contaminants. An equipment blank may also be analyzed if non-dedicated sampling equipment is used. Grouting / If the borings are not completed as wells,the borings are filled to the ground surface with cement grout po�ured� or pumped through a tremie pie. --- —�-" -------------- F:\TEMPLATE\SOPS\G EOPROBE.DOC 2 of 2 ' i