Restoration of existing opens in waste water concrete tank

[NADOR123]

Hi every body,

I am reviewing a design of reinforced concrete section to close seven circular opens ( one foot diameter each and one foot apart (edge to edge) . the seven opens are located at the corner of dividing wall between a 22'x 60'tank and 18' x 60'tank with 15' hieght and the seven open are located one foot high from the bottom slab.

The design proposed two 12" section walls (one on each side) 15’ long and 5' high with one layer of rebar (#6 @ 12" vertically embedded 8" to the bottom slab & # 4@12" Horizontally) matching the original reinforcement of the wall to replace rebars that has been cut during the coring of the seven opens.

I am not sure if having 3 feet section of concrete (12" new wall section + 12" of existing wall) 15 long X 5 feet high (height of original wall dowels) is really required
to close the seven holes.

I think that design is ignoring the structural value of 5' high of the existing wall because the dowels through the seven holes were cut. I feel that solution is over-designed.
Is anyone has better idea of closing the holes and keep the wall structurally sound to handle the liquid pressure if one tank is fool and the other side is empty. At the same time I am trying to reduce the cost ($ 21,000).

Thank You for your kind help

 

[Ltwine]

If the wall can support the condition (one side full, one side empty) with the 7 holes closed (assuming there is shut-off mechanism of some kind), then you can simoly plug the holes with some details to hold the plugs to resist push-out by hydrostatic pressure, but not for carrying flexural stress (the original wall will).

If the existing 7 holes were designed to be open all the time, means the wall wasn't design for full unbalanced load, then the 5' addition maybe is justified.

 

[NADOR123]

The wall originally designed to support the full unbalanced load but the seven holes have been cored later to use both tanks at the same time without shut-off mechanism.

Thanks

 

[Ltwine]

So the wall strength has been compromised, then the 5' additions could be the simplest solution without further damage the existing wall by chipping/drilling.