I have a question about the proper height for installing a sump pump in the crock. First let me give you some background info about my installation. The house is new construction (in WI) built in 2007. The builder installed a sump pump per building code requirements. My pump discharge would send the water out across my driveway which in the winter months would freeze and create a large, thick sheet of ice right at the point where my driveway bends, not a very safe situation needless to say. Anyway, due to the sump pumps frequent cycling during the spring time, I decided to have a gravity feed drain pipe installed from the exterior drain tile around the foundation footing, out about 180 feet to daylight. We maintained a positive pitch away from the house while installing the drain pipe to achieve good flow away from the house. When we tied into the exterior drain tile (made of PVC Form-A-Drain) we tried to cut the hole in the side of the rectangular shaped drain tile as close to the bottom of the tile as possible. We then stuck the 4" round drain pipe into the hole we cut and applied some PVC cement. About 6 feet down line, we tied in the 1 1/2" discharge pipe from the sump pump and two of the gutter down spouts, (4"). After a short run of 4" drain pipe, we then stepped it up to 6" pipe for the majority of the 180' run to daylight. Before we covered the trench, we put a garden hose into the crock and turned the water on. We observed water coming out at the daylight point but it would flow out in surges when the sump pump turned on. Now this solved half my problem by redirecting the flow of water out far away from my basement but my other goal was to not have the sump pump ever need to turn on, I wanted gravity to do the work, not the pump. So later that evening after the excavator left, I figured I just needed to adjust the float switch on the sump pump so that it would not kick on as soon. So I unbolted the cover from my crock to check things out. I unplugged the sump pump and ran water into the crock once again. The water level rose to about 12" which happens to be about the middle of the inlet line into the crock from the inside drain tile, (Side Note: I assume that the interior and exterior drain tiles around the footings have crossovers tying them together.) I left the garden hose run for about 15 minutes and the water level in the crock never got above 12". Now, at this point I was unable to go outside and check the drain line at the daylight point since it was dark out and it also happened to be raining at the time (remember, I tied in two down spouts also.) so water flow out the pipe would not necessarily confirm it was from the water I was filling into the crock. I was able to confirm that the sump pump turns on when the water level in the crock reaches 9” and turns off when the water level reaches about 2”.
So, is my solution to keep the sump pump from turning on before gravity has a chance to allow the water to flow away to simply raise the sump pump up about 3 ½”, making the point at which it would turn on at about 12 ½”. Or does the sump pump need be set so that it turns on before the water level in the crock reaches the bottom of the inlet line into the crock to prevent water from puddling in the drain tile and stone below the slab. The last thing I want to do is create a moisture problem in my basement because I have standing water below the slab.
Sorry about the long post