Sorry if I confused you. That's a consistent problem with us architects; when confronted with the impossible, we simply change the parameters.
In that same vein, I have a suggestion. Instead of flushing it down into the sanitary sewer, why don't you flush it UP (with compressed air) into your vent stack (just imagine how your deposit gets to the teller at the drive-through window of your bank)? Then you can retrieve your stash by going onto your roof with a bent coat hanger. Its a lot cleaner and will fool the narcs just as much!
Your response, please.
Or use a little more air and send it to your buddy's house on the next block.....