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B-2 <br /> Upon recovery, a portion of the soil sample is placed into a ziplock bag and sealed for later screening <br /> with a photoionization detector Another portion of the soil sample is used for classification and <br /> description That part of the soil sample collected in brass tubes within the California-type sampler is <br /> stored at approximately 4°C for transport to the Iaboratory <br /> 2.1 Soil Classification <br /> As the samples are obtained in the field, they are classified by the geologist in accordance with the <br /> Unified Soil CIassification System (USCS) Representative portions of the samples are then retained for <br /> further examination and for verification of the field classification Logs of the borings indicating the <br /> depth and identification of the various strata, the N value, and pertinent information regarding the method <br /> of maintaining and advancing the borehole are made <br /> 2.2 Soil Sample Screenmg/liNu Portable Photoiontzation_Detector Method <br /> After the soil sample ziplock bags have been brought to ambient temperature, the headspace vapors of <br /> the soil sample in the bag are screened with a portable photoionization detector equipped with a 10 2 eV <br /> . lamp The sample corner of the bag is opened and the detector probe immediately placed within the <br /> headspace The highest observed reading is recorded <br /> 2.3 Soil Sample Selection <br /> Soil samples selected for chemical and physical analyses are based on field screening results, stratigraphic <br /> location, lithology, and visual observations A minimum of two soil samples are chemically analyzed <br /> per boring, the soil sample producing the highest field screening result, and the sample collected <br /> immediately above first encountered ground water Additional samples may be analyzed based of field <br /> observations <br /> 2.4 Momtormg Well Gravel Pack and Slot Size Selection <br /> The gravel pack is selected such that it will permit the development of a zone of higher hydraulic <br /> conductivity adjacent to the well screen but will not allow piping of the finer-grained formation into the <br /> well bore The slot size of the well screen is selected such that it will retain a minimum of 95 percent <br /> of the gravel pack material <br /> LRP002 066 <br />