I am planning on purchasing and then housing a portable generator in a suncast utility shed I purchased. I need to assure both are level. I plan on placing the shed, housing the generator, on a concrete pad I'll have to build. This project is to be a DIY. I plan on using Quikcrete Crack Resistant Concrete mix and a mold to create it. My concern, before I even begin, is how to provide some kind of drainage for this small slab and maintain a level surface at the same time. I don't know how necessary drainage will be for an approx. 4' x 6' slab sitting in a backyard; but, I would like to avoid mould growth and also keep the generator area relatively dry. Any thoughts or sugestions?