Large pipe penetrations in existing tank wall
Large pipe penetrations in existing tank wall
(OP)
The project has a large rectangular tank 47 ft X 19 ft with 11 ft high walls that are 15" thick. It also has pilasters every 7ft that are approx 2'-3" wide. the water slurry level is approx. 10 ft. the tank was built in 1983. We need to install a 20" dia pipe near the bottom of the side wall between the pilasters. We plan to core a 24" dia hole approx 2'-9" above the floor. The wall has #8@12 vertical and #6@12 horizontal that we will cut through. The dowels from the footing will also be cut because of the location of the hole. I am not sure how to address the removal of the bar in the existing wall and so close to the bottom. Any thoughts would be appreciated?






RE: Large pipe penetrations in existing tank wall
RE: Large pipe penetrations in existing tank wall
RE: Large pipe penetrations in existing tank wall
1. Have a testing lab locate the vertical rebar in the tank wall. Position the cored 24" diameter hole to cut the minimum number vertical rebar. I would expect a 15" thick tank wall to have two rebar mats, one with 3", or so, concrete cover from the wall's outer surface, the other with 3" or so, cover from the wall's inner surface. If there are two rebar mats, be sure to have both located by the lab before selecting the core location.
2. Its not clear if the bottom of the cored hole is 2'9" above the tank floor, or if the center of the cored hole is 2'9" above the tank floor. Either way, the dowels from the foundation will still be embedded in the wall at least 1'9".
3. Since the tank is rectangular, NOT circular, there is no hoop stress in the horizontal rebar. I doubt that cutting a couple of horizontal rebar, in a 15" thick wall with fairly low hydrostatic pressure, is a problem.
4. Assuming the 20" pipe that will be connected to the tank has structural strength (say, steel, or ductile iron), I do consider it important to restrain the pipe. This can be done external to the tank and will be important to resist any forces caused by fluid flow. Don't want those forces to resisted by the tank wall - design the pipe restraints do that.
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RE: Large pipe penetrations in existing tank wall