I build mine from a single piece of plate and install it level in the cc, I put a 2'' dam on the open end of it and a 2'' drain, when I get done cooking I lower the nose and open the drain valve. I have never had to open it while cooking and it's never came close to the top of the grease dam. I guess I could open it while cooking and let it drain but a lot of the fat seems to cook off. I'm sure there are a lot of different ways to do it but I haven't had any problems with my set up and it saves a lot of fab work. jm2cw
The BP in my tank is also flat level. I've had two really big cooks in the last 7 days...30 slabs of ribs, not a space to slip a pencil thru. The BP looks like an absolute mess with big droppings of fat, burnt, spilled and leaking juice. I took a wide dry wall knife as Gizmo suggested, and easily scraped off a shoe box full of carbon-like debris, I don't know if a "drainage" channel would have really worked so far.
I did leave a section of the 56" long BP removable and welded a strip of 1/4 x 2" over each seam to help seal it and a small removal handle. Seems to work. I figured I can fire it up or hose it out when it gets really loaded and open the bottom 2" drain.
Make no mistake, there ain't no powder in this Puff ! And... I'm not really a crazy person but I play one in real life