One other question. Does anybody see any problem with tieing the drain from my walkout to my exterior and interior drain tile? I have a floor drain in a cement slab at the bottom of some steps which allow access to my half under grade basemet door.
The drain used to go into a 6 foot secion of perforated drain tile which sat in a 10 by 10 by 4 ft field of 3/4 inch washed stone. The original idea was that it would drain through the tile into the washed stone to be sort of a holding tank during heavy down pours. The problem was that it couldn't drain fast enough during heavy down pours. What I wound up with was the drain would overflow, water would run through my walk out door into the basement and the sump would finally turn on about an hour or 2 after the basement was already flooded. The drain now can keep up with a full on garden hose for over 40 minutes.
I modified the drain so that it zig-zags through about 20 feet of perforated tile in the washed stone then tied into the exterior drain tile of the house. I only found about 4 holes in the footings to let the exterior tile drain into the interior tile (which in the heavy clay soil that I have didn't seem like enough) so I also tied the exterior tile into the interior tile with more 4 inch tile and a couple of T fittings. This tile then eventualy goes to the crock and sump pump. My hope is that the 10x10 washed stone field would fill up first, then the exterior tile (with all of its 3/4 inch stone), then the interior (with all of its 3/4 inch stone), and finally the sump would pump out the excess as a last line of defense in the event of a flash flood.
-Does anybody know of a figure of rainfall per square inch over time that I should use for testing the new drain, simulating a heavy heavy down pour? -Anybody see any problems with tieing the 3 drain fields all together?