I have actually.... goes ALOT faster if you have 2-3 people and those big hiking backpacks. You can usually get at least 2 big bags of dirt into one of those (or at least we could).
We actually used the creek that runs right out back of my house. Not that anyone cares to know, but im really surprised by the amount of wildlife around this water source, as its like RIGHT in the middle of a housing community (surrounded on all sides by heavily populated housing).
This is a nice benefit of using nature to get some substrate: gives you a chance to do some field herping, hehe
So far Ive encountered leopard frogs, some kind of turtle (dropped into the water before I could ID and ive never seen it again), a number of very friendly garter snakes(my friend got pics of one of the bigger one drapped over my shoulders just chillin- he sat there calmly for like 20 minutes while we walked off, and didnt get down till I made him!), a number of very unfriendly northern water snakes (including a huge one, about as thick as a soda can and at least 5' long).
The other day I was on a walk, following the creek, and surprised the big water snake, watched it dip into the water, and decided to wait and get a better look (at the time I didnt realize how big it was and thought it might be a copperhead, so I was being careful). About 10-15 minutes and alot of watching later, a big ol' head popped outta the water about 5' away from me.
I watched it for awhile as it began to come out and just then a baby, less than 2' long, came swimming by and bumped into the adult (sending it back down into its hole underwater) and swam upstream. I jumped over this small "pond" and chased the snake upstream abit, eventually catching up to him. I managed to tail him long enough to move him up onto some grass and was trying to get some pics, but he came right at me mouth open! I fell back (resulting in me going backwards, headfirst into the creek)and when i got back up, he was gone.
And that was just during an hour or so walk! Imagine what you can see when you're making a few trips back and forth, lol
(Sorry, I dont hang with alotta people that are into reptiles and such, so I dont get to vent my excitement, hehe)