Fix the database, it's that important. I just see no value in doing gymnastics to wrestle things that should be modeled for what they are at the database tier.
If it's a date, store it as such. Decimals, floats, integers? Then that's what they are period.
Get with the database admin, and make it right. You will save yourself tons of headaches, not just in the immediate, but long-term life-cycles of the tools and applications you build will be better off.