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l. Stewart's Beacon Property Phase II-Ground Water Assessment Proposal J Page- 3 perforated(0.04 inch slots)from the bottom of the hole up to one Foot above the aquifers upper surface. Tite filter pack will be constructed of aquarium sand that will extend 2 feet above the the perforations. An annular seal of bentonite grout(Quick Gel&Benseal)will be installed above the sand pack and extend to within 3 feet of the surface. A surface seal will be formed of concrete and a water tight well cover. The well casing will be secured by installing a locking cap, Design of this well is illustrated in Figure 4. After monitoring wells 4 and 6 have been installed,they will be developed and sampled as descry in sections 4.8 and 4.9. The first three monitoring wells(MW#1 thru 3)installed during phase 1 will also be purged and sampled.On the monitoring well installed into the a second aquifer(MW#5);a time-endurance ground water sampling test will be run. This is accomplished by pumping the well continuously for several hours during which Bound water samples are periodically collected throughout the test. The purpose of this is to draw water from as large a radius as possible by creating a cone of depression with an ever enlarging zone of influence. :All ground water samples will be analyzed for gasoline,benzene,toluene,and xylene,(BTX by EPA method 602)at a California certified laboratory. Monitoring well tops will be surveyed for their elevation,above mean seal level(MSL) This s ;> data will be used to calculate water gradient. For the purpose of eiaivating ground water gradient,depth measurements will be collected after ,veil installation,after development and —�' sampling,and two to four weeks after installation. It is also recommended that gradient be ' monitored quarterly for one year to track the flow of ground water. Once this phase of investigation has been completed,the data will be reviewed with the client. If no additional work is needed a report will be written which integrates data from both phases of study and makes recommendations for further action. 4.0 QUALITY ASSURANCE PROGRAM The following measures will be taken by Geological Technics to insure that a high quality study is conducted and that cross contamination does not occur. .. 4.1 Equipment Monitoring well Irjrin4.t will be drilled with a 7.25-inch and a 10-inch(o.d.)hollow stem'continuous flight auger,owned and operated by Osterberg and Stewart,Inc. Soil samples will be collected using a 2-inch(o.d.)modified California split spoon sampler lined with brass sample tubes.