Sump pump pit or...?

[audetteb]

I have a hole in the basement of my newly purchased home. I presume for a sump pump. However, it has three large pipes coming in to it, two are black, coming in parallel to the wall, the other white PVC, evidently going through the basement wall and outside. I was told that the basement is designed to never leak because of this system. What is this for? Is a sump pump needed in this pit? (which has a small amount of water in it.) A photo is attached.

Thanks!

[Mr T]

That is yoru basement perimeter drain. Anywater that runs down the outside of your foundation is collected by this.. If you get a heavy rain, or have gutter problems that pit will be getting very busy. You need to trace out or contact the builder about that PVC pipe going out. It could be a gravity drain. Can you find it outside? Make sure that water is not allowed to backup around it or you will have a pool in your basement. You may not need a sump pump with that pipe. Critters may get curious about where that pipe goes from teh outside though.. keep that in mind.

[scuba_dave]

My house is near a stream, so a sump pump is a requirement
I have a drain like you do, but in heavy rains the water table rises

As stated you need to verify:
Where that pipe goes
That it remains clear
That it will be above the water table in heavy rains
and that the soil will allow water to drain

[Wgoodrich]

You say you have two black pipes entering that sump pit. I am guessing they are 4" each. A 4" gravity fed drain pipe has the capacity of approximately 300 gallons a minute. Multiply that times 2 and you have a capacity of 600 gallons a minute entering that basement during adverse flooding. This changes depending on your seasonal high water table and your soil consistency around your basement. I would ask a soil scientist to do some test boarings to find how much ground water will be attacking your basement through those two 300 gallon a minute pipes during adverse flood conditions. Then I would ask the builder how many gallons a minute your pump he is installing has and at how much head pressure to the outlet.

I suspect you will be happy with a reasonably dry basement for either a year or two or even twenty. However when you have about 5 days of hard rains one day you will probably come home to as much as 7' of water in the basement. Hope not but probability is on my bet.

A gravity drain if possible is best bet. Even if to the river. If a drain pipe is installed facing downstream even under water that drain will flow due to the ventury effect sucking the water out of the drain by the flow of the river.

Good Luck

Wg