I finally adding in my long planned bog! Thanks everyone for all the info.
It is 14-18 deep with a peat / sand mix. hopefully the fence will shield the plants from the wind we get sometimes. It's a newer neighborhood, so there aren't a lot of old trees to slow things down. The walkway has a slight slope away from the bog, so i won't get runoff.
I am trying the reservoir idea that has been brought up periodically here. That is what the pvc pipe sticking out the top is. I will cut it shorter and paint it dark to hide it. It is a 3.5 gallon plastic container drilled with a ton of holes and then wrapped in landscape fabric. I am sure the water flow to it will be quite slow, but i can at least use it as a "dip-stick" of sorts and i can pump water out of it to maybe help the media from completely becoming stagnant. I bought a little pump that you can just hook up to a cordless drill and hose to do this.
I abandoned making a drain pipe that actually ran through the pond liner into a well where i could let water drain via a valve... but we have pretty harsh winters and didn't want to risk the pipe freezing and then having to dig the whole thing up in the spring.
I haven't added any drain holes as of yet. I want to see how much rain it takes to file it up nicely and then add drain holes as needed. The one corner where i have the rounded rocks is the lowest spill point to take the water away during heavy rains. All the water is from my rain barrels, which i can use to fill the bog through the dryer periods.
I walked all over it to pack it down a bit, but i don't know how long it will take to settle completely. So now all i have to do is plant it up. That tower of straw is my fig tree that need protection in the winter.. in case you are wondering.
Below is the diagram and a stop motion movie to entertainment. My wife got me the "PLANTCAM" stop motion camera for the b-day... which threads all the still images into a movie.. fun little toy to have! It makes it look easy, but i made this bog over a 4 day time frame... and my back hurts!
MOVIE - with audio