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! lowered through the augers and #2112 filter pack sand will be placed in the annular space between the well casing and the borehole from the bottom of the boring to approximately 1-foot above the screened interval Approximately 05-feet of coated bentonite pellets will be placed on t o p of the sand pack prior to placing the cement sanitary seal Cement mixed with 3 to 5 percent bentonite powder by volume will be used to fill the annular space between the bentonite layer and the surface to prevent surface water from infiltrating into the well and to prevent conduits f o f the migration of contamination from shallow groundwater into deeper zones The cement seal in this well will be placed using a tremae pipe The well head will be protected with a locking well plug beneath an at- grade, traffic-rated well box (See Figure 6 - Typical Air Sparging Well) TASK 6 -CONDUCT AN AIR SPARGING TEST An air sparging test will be conducted to determine whether air sparging may be an effective method of remediation for the site The air sparging test will be conducted by injecting compressed air into the air sparging well at a rate of approximately 20 to 30 cubic feet per minute (c f m) Pressure and water levels in the surrounding wells will be monitored to determine whether there is any pressure increase in the vadose zone or mounding of the water table A helium gas tracer will also be injected through the air sparge well and a meter will monitor for the presence of helium in nearby wells TASK 7 -PREPARE A CORRECTIVE ACTION PLAN FOR THE SITE Based on the results of the tests outlined above, ASE will prepare a corrective action plan (CAP) for the site This CAP will present several possible remediation strategies for the site including pump and treat, air sparge/vapor extraction, dual phase extraction, in-situ bioremediation and others Pros and cons or each method will be discussed, costs compared, and a method chosen if additional tests are needed to choose or design a method, these will be recommended All of the data a n d results for the feasibility tests detailed above will be discussed and the reports for the tests will be included as appendices Formal boring logs for the newly installed extraction well and air sparge well will also be included as will analytical reports and chain of custodies for any samples collected This report will be submitted under the seal of a California registered civil engineer or geologist Frank's One Stop Workplan — June 2000 -20-