Well I have really painted myself into a corner this time...or should I say, graded myself into a corner...hehe.
Here is my problem. I am building a new house which has a walk out through its poured concrete basement walls which is half under grade and half above grade. I also have windows (in the same corner as the walk out) in the basement which are about 6 inches below the average grade of the lot and surrounding land. Needless to say I have a drainage problem. My basement has flooded twice so far. We will run an in home daycare in this basement when it is finished so the walkout and finished basement are very important to us. I would like to find a creative way to make this work.
This is what I was thinking of doing: Create a multi tiered back yard with drainage solutions for the 2 undergrade tiers.
The full walkout which is the most undergrade will have a 3 foot retaining wall surrounding a set of steps. It has a drain in the concrete slab just outside the door which runs into a 10 by 10 by 4 foot deep hole filled with 3/4 inch stone (is this a french drain?). It also has an extention of the house drain tile which runs to the house sump which I thought could catch the water and route it to the sump for pumping in the event that the rain had filled up the stone water holding area. Will this be adequate? My goal is to catch only the rain that falls above this walkout and find a place for it to go.
Just above the walk out steps but below the 4 basement windows and about 6 inches to a foot below average grade of the lot would be the play area tier for the daycare. It would be a round tier about 35 feet in diameter which would run from one side of the half exposure to the other. I would grade this away from the walkout steps and house so that it would have its lowest area about 25 feet away from the house. We would like to put wood chips or bark in this area for the playground. One problem I have not figured out is how to drain the water which would gather here. This tier is lower than any surrounding land and could not be drained naturally to the culvert or storm sewer. Could I run power for an additional sump? Should I create another french drain?
Finally, after a small 6inch to 1 ft retaining wall with fence the rest of the back yard would grade away from the playground tier.
Right now Its a real mess with the water from the house and 2 surrounding lots eventually draining into the walk out. The soil doen't seem to drain at all and seems to have a very high clay content. I am at the top of a hill which I am guessing should keep me away from ground water rising but I am also sort of in a small 1/2 acre valley in the top of the hill.
Do these ideas sound feasable? Anybody have any other ideas besides to fill in my walk out? I am an engineer (electrical) and hate to think that something cant be done when you put your mind to it. No idea is to crazy.