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� ,��.'•�".,, �r'- �. L� f ,40�'�� s'¢7"` � �v° p �r ��' -�` Y"�, 4u?.' max' ,_M , ' ;" "' _ 9�'� "sFt l �k' f4 �� As ;P` yt�:•?''7:!s ��*v. ui� �"�.. } r,C.�� '. t��w s ;�: J Woodward-Clyde Consuftants 2.0 FIELD INVESTIGATION y ^� The following sections describe WCC field investigation activities beginning August 12, 1991 and ending on August 20, 1991. The field investigation was completed in two phases: the �. subsurface soil investigation and the groundwater inve`igation. The subsurface soil investigatiOn was conducted from August 12, 1991 to August 15, 1991,and the groundwater investigation was conducted on August 20, 1991. 2.1 SOIL INVESTIGATION Three borings were advanced around the gasoline tank excavatio, with a truck mounted Mobile Drill model B-61 equipped with hollow stem augers (Figure 2). The borings were. - �.. advanced to 90 feet (14 feet below the groundwater surface). Soil samples were collected every five feet with a two-inch diameter California, modified sampler fitted with thin walled brass tubes. To collect each soil sample, the a-ugets were advanced to the desired depth,tine drilling assembly was removed from the augers, and the sampling assembly was lowered through the center of the augers. The sampling assembly was driven IS inches into the soil (I2 inches when the resistance was high). The number,of blows required to advance the r� sampler every six inches vrac counted and recorded for each sample in order to estimate the y consistency or density.tit the soil. After the sampling assembly Was driven the prescribed distance,it was rennoved from the augers. The sampler was opened and the brass tubes were removed fro,i the sampler. The soil was extracted from the tube above the bottom tube and was ermined and classified by a geologist according to the Unified Soil Classification - System. The sample was placed in a resealable plastic bag for approximately five minutes 4 and the :headspace was measured for volatile organic compounds (VOC) using a photoionizatiou m.efer(Hnu). The results were recorded in lite field notes. The bottom tube was prepared for laboratory anzlysis. The ends of the brass tube were covered with aluminun foil,ten with plastic caps `'.':Che tube was labeled with-Vie following information: sample identification(boring numberand depth of sample),date sampled,and time sampled. The tube wrs placed in a resealable plastic bag, then placed in an ice chest filled with ice for storage until the samples could be transported m the analytical laboratory. Prior to sampling, the sampling assembly was cleai,ed by scrubbing witl': a solution of alcenox and: 91COMAJWUORMARTMP 10-W-911F71ZT1,11l 2111 • �. ,