MN Fisherman,
Okay, here is another test, somewhat more difficult. Get a couple of 5 gallon buckets, or identical containers, place the same amount of holes in the bottom of each, then place the same amount, depth, of tan color soil in one container and black color soil in the other. I think I would use about 12 inches of material in both. Fill both containers with water...wait and see what happens over a 24 hour period, longer if necessary. That way you can compare the "leakability" of both soils side by side.
