[Dee2]

My Problem:
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Water is seeping into corner of basement bedroom. Appears to be groundwater coming up through joint where the floor slab meets the foundation wall. Floor slab sits on top of foundation wall footer.

I assume there is some hydraulic pressure below the slab from the fact it is rising up into basement, even though the outside wall daylights. The water must be trapping itself under the slab and finds the interior of the basement before the outside ground. The outside ground slopes away from the house, starting elevation is top of footer.

4" Basement slab rests on the foundation spread footer and foundation wall is daylighted. Wall is 8" poured concrete. Footer is 15"wX7"h.

My Plan:
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To relieve pressure and drain water from beneath basement floor, I plan to drill a horizontal hole through the foundation wall just above the footer.

I plan to intersect the horizontal "drain" hole from within the basement room with a vertical hole so trapped water can enter into the "drain".

My question:
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Any unintended consequences with this plan ?

[ballengerb1]

And after you get the water into your drain hole where will it go? You need to cut a sump pump pit and install a pump with a check valve.

[Dee2]

And after you get the water into your drain hole where will it go?? You need to cut a sump pump pit and install a pump with a check valve.

The drain hole goes outside and drains away from house

[ballengerb1]

If the floor of the basement is slightly above grade, which it must be for your hole to drain, then I am surprised you have any hydraulic pressure pushing ground water inside. Is you home built into a hillside?

[speedball1]

To relieve pressure and drain water from beneath basement floor, I plan to drill a horizontal hole through the foundation wall just above the footer.

If the water comes into your basement from outside you have just opened up a path to the source to enter your basement.

I plan to intersect the horizontal "drain" hole from within the basement room with a vertical hole so trapped water can enter into the "drain".

What drain? The hole you drilled above the footer has turned into a supply for ground water to enter your home.
A much better solution would be to dig in a french drain, (see image) and pipe the overflow down hill from the house. In short I don't think your plan's a working one. Rule of thumb! Stop ground water from coming into your house before it gets in. Good luck, Tom

[Dee2]

If the floor of the basement is slightly above grade, which it must be for your hole to drain, then I am surprised you have any hydraulic pressure pushing ground water inside. Is you home built into a hillside?

Hard to describe lay of land...

Corner with leak is on NE point of house. North side is below grade approx. 6 ft of depth, new clean gutter above.

East side of house is open to air because of north-to-south retaining wall 4 ft east of building, providing a walkspace along east side of building. Walkspace slopes to south for drainage.

South side of house is daylight basement.

[Dee2]

... What drain?.

The horizontal hole is exposed to air, not ground.

[speedball1]

You plan is sort of iffy. How about the areas that are away from the hole? A french drain protects and drains the entire length of the drain, not just a tiny area that the horizontal hole will cover. However it's worth a try and if it don't work you can always cement up the holes and install a french drain or a sump pump. Good luck, Tom

[ballengerb1]

What you have described is a walk out basement and Tom's drain is a solution. If you are trying to drain the hydostatic pressure you would need to have 1/4" drop per 10'.