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+ Based on the temperature logs and monitor well information. <br />it appears that 10 to 15 gpm is moving down the casing annulus from the <br />A-Groove, the B-Groove and perhaps the perched aquifer. Mike Hardy <br />estimated the average flow at about 12.5 gpm. In comparing the <br />monitoring results from a nearby Perched aquifer well, the water level <br />had declined three feet in the last quarter. Bentonite pellets were <br />place in the upper portion of the well and this appears to have stopped <br />or certainly reduced the flow out of the Perched Aquifer. A subsequent <br />temperature log indicated temperature increase from 60 to 69F from 200 <br />to 1700 feet. Another source of evidence is the drop in the fluid level <br />in this well from 504 feet BGS to 532 feet BGS. Most importantly, the <br />downward flow has evidenced itself by a need to pump more fluid from the <br />recovery wells to maintain the DS water level within target levels. <br />This will lead to operational problems if this flow is not curtailed. <br />+ NSZ attempted to shut off the flow by trying to do a <br />remedial cement job using three perforations in the casing at 1650 feet <br />BGS. This attempt involved setting a CIBP covered with sand just below <br />the perforations and pumping 9.5 sacks of sodium silicate followed by 75 <br />sacks of cement. After this job was completed, the well was reentered <br />and it was determined (by the absence of cement in the casing) that the <br />cement had not set up because the sodium silicate was being washed away <br />before it could mix with the cement and cause set up to begin occurring. <br />+ As a result of the failure of the sodium silicate <br />alternative, NSI proposed additional options for consideration. One <br />would be too take another stab at the sodium silicate/cement option. <br />Another option would involve injection of cement with lost circulation <br />material such as gilsonite. This is risky because it might result in <br />plugging the three perforations. The prime option, however, was to mix <br />30 barrels of Diesel fuel with bentonite (11 lbs per gallon) and pump it <br />down the casing to the three perforations in the access casing and out <br />into the annulus. Apparently when the diesel/bentonite mixture <br />encounters water it clabbers and will begin bridging below the 1650 feet <br />BGS level. The diesel fuel/bentonite mixture will be followed with an <br />enriched cement mixture that is about 15 lbs. per gallon. The diesel <br />fuel mixture will not mixwith the cement and should set up. A down <br />side is the potential to introduce VOCs into the solution mining process <br />if the diesel fuel gets into the cavity. The use of a temperature <br />sensitive polymer was discussed. NSI indicated that they would discuss <br />the possibility of this technique to work with Halliburton before coming <br />in with a letter laying out a final approache(s). <br />Subsequent to the February 11, 2004, conference call, NSI <br />contacted the cementing engineers and their recommendation (with highest <br />chance of success) is to use the oil/bentonite mix followed by cement. <br />NSI will purchase food grade vegetable or mineral oil to replace the <br />originally proposed diesel. A letter providing details and requesting <br />approval will be forthcoming. <br />Paul Stephen Osborne <br />National Ground-Water Expert <br />Region VIII UIC Program <br />2 <br />