A large sink hole has developed underneath our sidewalk. The house is located in Valentines, Virginia on Lake Gaston. It is a lake front lot so I don't know if there is an underground spring. The hole became larger following heavy rains from the recent hurricanes. It is now large enough for our grandbaby to fall in and get caught underneath the concrete sidewalk.

Does anyone have a suggestion on determining the cause and then the solution to this problem. We do have restrictions on construction as Virginia Dominion Power controls the property below the high water mark. The sink hole is above the high water mark.