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�'` - i � w',t"'- i�- � „K z�a.'SY k - _a}r -• � e{SP� _4'-i .. � � '� -ter ''7r°-°Yc i� � :"� �� r"� .� ;� h`��,��•'3� �'t �b .� �. Vie, "'_ "r�"-� '� ��;,�� ,e;y�;l, �, ,:� � �° t ynKv. `' ,�a. � «M a 1,y,.� .:.s- �� S�"y-� 'r .� 5 .q'� ,t,"` y�R' # -*p- h'..� �•. n.',t 1.0 M1TE71MODS 1.1 Soil Sampling and Contamination Reduction Sail borings and soil sampling were performed under the direction of a Delta engineer or geologist. The soil borings were advanced using a truck-mounted hollow-stem auger drill rig. To reduce the chances of cross-contamination between boreholes, all downhole drilling equipment was steamed-cleaned between each boring. To reduce cross-contamination between samples, the split-barrel sampler was washed in a soap solution and double rinsed between each sampling event. Soil sampling was done in accordance with ASTM 1586.84. Using this procedure, a 2-inch outside- diameter split-barrel sampler or a 2-inch inside-diameter California-type:ampler is driven into the soil by a 140-pound weight falling 30 inches. After an initial set of 6 inches, the number of blows required to drive the sampler an additional 12 inches is known as penetration resistance, or the "N" value. The N value is used as an empirical measure of the relative density of cohes°onless soils and the consistency of cohesi to soils. Upon recovery,a portion of the soil sample was placed in a glass jar and scaled for later screening with a photoionizatien detector. Another portion of the soy sample was used for classification and description. That part of the soil sample collected in brass tubes within the California-type sampler was stored at approximately 4°C for transport to the laboratory. 1.2 Soll Classincation As the samples were obtained in the Geld, they were classified by the crew chief/geologist in accordance wit1h the Unified Soil Classification System (USCS). Representative portions of the samples were then retained for farther examination and for verification of the field classification. (Jogs of each boring indicating the depth and identification of the various strata, the N value, and pertinent information regarding the method of maintaining and advancing the borehole were mzde. 1.3 Soil Sample ScreeninelhNu Portable Photnionizallon Detector Method After soil samples placed in plastic bags were brought to ambient temperature, the headspace vapors of the soil sample jars were screened with a portable photoionirntion detector equipped with a 10.2 eV lamp calibrated to benzene. The sample jar lid will be opened and the detector probe immediately placed within the headspace of the jar. The highest observed reading was then recorded.