CORRESPONDENCE_1965-1989 - Laserfiche WebLink

Home Browse Search

lot The annular space above the gravel packs should be sealed from the top of the gravel pack to the ground surface. A seal of three to five feet of sodium bentonite should be placed directly on top of the gravel pack. The remaining annular apace is sealed with a cement grout from the top of the bentonite to the ground surface. Two grout formulations are acceptable. In those situations where a lower density grout is desirable, such as formations that have taken drill fluid, a cement -bentonite gropt may be used. For general applications a cement -sand grout may be used. The cement -bentonite grout will consist of Portland Cement, finally ground sodium bentonite and potable water in the proportions of 5.2 gallons of water and 2 to 5 pounds of bentonite per 94 -pound bag of cement, with an additional 0.65 gallon of water for each pound of bentonite. The cement -sand mix will consist of Portland Cement and clean 20-40 grade sand and potable water in the proportions of 5.2 gallons of water and 85 pounds of sand per 94 -pound sack of cement. The method of mixing either grout should result in a uniform and smooth mixture. For on-site mixing, the cement -bentonite grout should be blended by first preparing a smooth slurry of the bentonite and water by use of a jet mixer, and then the cement is added to this slurry through the jet mixer. The cement -sand grout should be blended in a sequence in which the cement is added last. For either grout, water should not be held back or extra water added. The aforementioned formulations assumes that all ingredients are dry, uniform, clean, uncontaminated, and lump free at the start of blending. Placement of Crout Seal . Using one of the approved grouts, the remaining annulus will be grouted from the top of the bentonite scul to the ground surface. The grout will be pumped into the HSA; use of a tremie pipe is not required because the HSA acts as a tremie. The HSA will be filled with grout to the ground surface and then a section of HSA can be removed. This process will be repeated until all HSA•a have been removed.