I just did mine last summer. I keep my TT at home and did it in the driveway. I had dumped my tanks and flushed them well before I came home and after I got it set up in the driveway completely just like going camping, +-1* both laterally and longitudinally, I took a 5 gal bucket and removed the y cap and let the buildup from the BWV leakage drain into the bucket. I then opened the BWV and let any residual drain out and then disassembled the 3" BWV. I had to remove the y piping and then reassemble with new orings and was careful not to over tighten. I used nitril gloves and was careful not to get any black water splashing around. When I finished I scrubbed the piping down and the driveway under it and everything was fine. I used several pairs of gloves because every time I was into the job i would have to stop so i would remove my glove to prevent cross contamination of the BW residue.
Not a complicated job you just have to pony up working in Dooky!!
LBZ GMC Sierra 2500HD, CCSB, 4WD, D/A,