Eddie,

If you read the links that Russ so considerately posted, you will see a similar situation to yours which was posed by ETW.

It really is a good news bad news joke to hit a spring. Someone mentioned above that according to the NRCS, "more times than not, they do not reverse". That isn't very good odds in my opinion...in fact just over 50/50. My own policy is to cover all springs with at least 2 feet of clay. I have not hit one as extensive as you described with gravel, but have seen many in the process of pond building and always cover them.

It might be worth your trouble to bring in a civil engineer to have a look at your situation. In the absense of an engineering evaluation, my advice is to mitigate your risks and cover it up.