I have a basement addition with the footers built on crushed rock, 5 feet wide, because of non-clay soil. I have outside AND inside drain tile next to both sides of the footers running to the sump pit. The footers are about 1 foot below the bottom of the basement floor. We didn't want the new basement so low compared to the old basement.
I have set the sump to click on when the water is just under the bottom of the inside drain tile. The thinking was that we didn't want water coming in and then out of the inside drain tile and pulling sedament or weakening the inside of the footers or the floor. I could set sump to turn on at a higher level. The water could rise another foot in the sump pit before it reaches the bottom of the basement floor.
What is the best water level?
I think I am under the water table because when it rains, the sump runs for a few days, floods the backyard, but eventually stops.
Any thoughts on this would be appreciated.
Last edited by scott j; 02-18-2011 at 08:51 PM.
Reason: more info
Adjust the pump so it comes on before any of the drain tiles as seen in the pit are more than half submerged. Should you get basement flooding at the far end of the basement, re-adjust the pump to come on sooner.
You don't know for sure how level or how well sloped towards the pit the various drain tiles are. What counts is that no section of the drain tiles should become full. Otherwise the soil in that area will not desaturate and water could wick up to basement floor level.
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