I want to find out how to build my own doggie septic system in my yard for depositing dog waste, i.e.-how big of a hole to dig for 1 dog and for 4 dogs, what to line it with(will a galvanized or plastic garbage can with a lid and the bottom cut out work?), and what kind of enzymes should I use and how much/often?
This site should help you with just what you are looking for
and here is another one
This site offers a commercial system and enzymes
and this site has more info
In general these systems do not work in freezing weather only in warmer weather. Also they are not as effective to use in soils with heavy clay content.
Hope this helps you!