Siding Installed to Low-How to Fix

I had an attached garage installed and the folks that did it ran the siding down to about 8 inches off the ground. Normally that would be OK but I need to do some grading to fix a water problem. The area in question is a "U" shapped area. The first section is the main house, full basement, 2 feet off the ground. The center section is part of the addition, living space on crawl space, also 2 feet off the ground. The last section is the new garage, cinder blocks only come up 8 inches, then the siding (and therefore the OSB and 2X4s behind the siding) starts.
I need to dump a bunch of dirt in that "U" shapped area to help standing water from coming into the basement. I am OK on 2 of the 3 sides, but I don't want to pile dirt on the garage side because I know that will give me problems with rot, termites, whatever. I am looking for some feedback as to how my solution I want to try would work, or a better one.
My Solution: On the garage wall...Take off the bottom row or rows of siding and the starter strip... Dig down to the foundation..Pour a 3 inch thick concrete wall to within a couple of inches of where the other 2 walls have the siding start..Trowel on some concrete right on to the OSB...Trowel on a triangular shaped bead of concrete from the now covered OSB to the outside edge of the new 3 inch thick wall so water will run away from the garage and onto the ground...Replace the starter strip and siding above that point... Backfill and regrade up to 6-8 inches in that whole area slanting away from the house for 8 feet.
Does that sound reasonable? Should I put a plastic barrier against the OSB first? Do you have a better solution??
Thanks...John .
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