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Report:Groundwater-quality Monitoring—January 26,2004: 7500 West Eleventh Street, Tracy, CSI. Page 12 „ 3.0 INTERIM MEASURES TO MANAGE FLOATING PRODUCT IN AREA OF MONITORING WELL MW-7 r As noted in Sections 1.3 and 2.4.1.1, on November 8, 2003, interim measures to remove floating product from the area around groundwater-quality monitoring well MW-7 were initiated. In addition to the November 8, 2003 round, that well was purged of LNAPL on November 15, November 22 and December 21, 2003, and on January 26 and March 30, 2004, as is recorded in Table 3. The procedures used for measuring the thickness of and purging of LNAPL from that well are described below. 3.1 Measurement of Thickness of LNAPL sem. On November 8, 2003 and on each occasion that the well was purged, the thickness of product floating on the groundwater in Monitoring Well MW-7 was measured prior to purging by coating the probe and tape of a groundwater depth meter with a paste that 1R+. changes color when it comes into contact with a fuel hydrocarbon, The paste was applied to the lower approximate one foot of the tape line, as measured �- from the tip of the probe. The pretreated probe line was then carefully and slowly lowered into the well until the meter's alarm sounded. At that point, the probe tape was immediately held steady so that the thickness of floating product was not mis-measured �- by allowing higher portions of the pasted tape to come into contact with floating product. The probe was then carefully withdrawn from the well and the apparent thickness of floating product was recorded by measuring the distance from the probe tip to the highest point on the tape where the paste had changed color. Note: As discussed in SJC's work plan(The San Joaquin Company Inc. 2003a),the thickness of floating product measured in a well is described as the "apparent thickness” and is generally greater than the actual thickness of floating product present in the formation. 3.2 LNAPL Purging Technique 4 +.W When the thickness of floating product in Monitoring Well MW-7 had been measured, a Wilden Model M2, 30 gallon per minute (gpm) capacity, air-activated, diaphragm suction pump was used to lift floating product from the well and discharge it into a 55- gallon steel drum equipped with a closable top. The pump was powered by a trailer- mounted, 185-cubic feet per minute (cfm) capacity, diesel-powered, air compressor. Compressed air was supplied to the pump via a flexible hose, which was attached to the compressor via an air flow regulating valve. The Wilden pump has been dedicated to the purpose of removing floating product from Monitoring Well MW-7 because it becomes a heavily-contaminated when used for that purpose and, thus, it is rendered unsuitable for any other use. �" sic