I'm not sure if I'm understanding your question correctly, but I have seen this done around here (Michigan) in quite a lot of new construction. Wide concrete steps actually lead down to a concrete pad at basement floor level. This pad has a drain in it. A set of french doors (approx. 6 ft. wide), inswinging I assume, enter into the basement. This brings very nice light into the basement, as well as providing an excellent way to get large objects in and out. You could probably also cover this entrance with a greenhouse-type enclosure. Hope this helps.