@Johnny Mac Keep in mind this: if your well is contaminated with ground water and there are dissolved chemicals in it, then you just introduced those chemicals into the entire aquifer. They can never be removed and will travel far and wide. You neighbors will not like this.
What does the 100 year flood map for your area look like?
I do like the idea of placing a concrete ring and cap over it for protection. Then regrading the adjacent ground to the new top. Good luck!
