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{ 4. <br /> r <br /> the USCS and was screened for volatile compounds using an OVM. The <br /> soil was screened by emptying soil from one of the sample tubes into a <br /> plastic bag. The bag was then sealed and placed in the sun f o r <br /> approximately 10 minutes. After the volatile compounds were allowed to <br /> volatilize, the OVM measured the vapor in the bag through a small hole <br /> punched in the bag. OVM readings are used as a screening tool only, <br /> since the procedures are not as rigorous as those used in the laboratory. <br /> The OVM readings are listed on the boring logs presented in Appendix D. <br /> Drilling equipment was cleaned with a TSP solution between sampling <br /> intervals to prevent potential cross-contamination. <br /> 6.2.2 Groundwater Extraction Well Construction <br /> Groundwater- extraction well EW-1 was constructed within the hallow-stem <br /> augers using 6-inch diameter flush-threaded, schedule 40, 0.020-inch <br /> slotted PVC well screen and blank casing. The well was screened between <br /> 4 and 19-feet bgs to allow for pumping the entire unconfined water- <br /> bearing zone. The well casing was lowered through the augers and #2/ 12 <br /> filter pack sand was placed in the annular space between ..the well casing <br /> and the borehole from the bottom of the boring to 1-foot above the <br /> �.r screened interval. A 1-foot thick layer of bentonite pellets was placed on <br /> top of the sand pack. The bentonite was hydrated with water prior to <br /> placing the cement sanitary seal. Cement was used to fill the annular <br /> space between the bentonite layer and the surface to prevent surface <br /> water from infiltrating into the well. The well head is protected with a <br /> locking well plug beneath an at-grade, traffic-rated well box. Well <br /> construction details are shown on the boring log in Appendix D. <br /> 6 . 3 Air Sparge Well installation <br /> ASE installed air sparge well AS-] to conduct an air sparging test. Details <br /> of the well cul:'tF'uctiOil are presented below. <br /> 6.3. 1 Drill a Boring for the Installationof an Air- Spagin, Well <br /> On August 14, 2001, Gregg Drilling of Martinez, California drilled boring <br /> AS-1 at the site using a Mobile B-61 drill rig equipped with 8-inch <br /> diameter hollow-stem augers (Figure 4). Air sparge well AS-1 was <br /> subsequently constructed in this boring. The drilling was directed by ASE <br /> associate geologist Erik Paddleford. <br /> 574 West Grant Line Road CAP - January 2002 <br /> -9- <br />