The drainage system was the hardest part, mainly because our soil is heavy clay and hard to dig. So we dug down about 3 ft in kind of a v the length of the pen, then placed one of those big (4in I think) pvc pipes that are used for septic tank drain fields, the ones that have the holes in them, in the bottom of the v with holes facing up. then we put a layer of bigish rocks, a layer of smallish rocks, a layer or pea gravel, a thick layer of sand, and then a thick layer of pea gravel on top. the pipe end goes down hill and ends beyond the duck pen in the field. When I let the ducks out in the morning into the run they share with the chickens ( its 50' x50') all I have to do is hose the pen down real good and all the poop and yuck is filtered throug the drain system and comes out pretty clean on the other end where it can water the grass, and viola smell is gone, its nice and clean. The other day just to try it I squirted some dish detergent on the gravel then hosed it down, and you would never know smelly ducks had ever been there.
