If the mine is to be realized with out touching the 9 acres of substantially harm its value (law suit avoidance) the 9 acre plow would have to leave a substantial amount of land untouched. Also the company could not cut off access to the 9 acres so an access road to the property would have to be left untouched. Then you would have to worry about lawsuits concerning noise and dust. Power lines and other utilities would have to be maintained to the property.
If you think about the amount of land that would be given up to keep the 9 acres intact and accessible it makes the project very much more expensive.
For those unfamiliar with above ground mining (strip mining is no longer used to mine coal), the land mined is almost always uninhabitable die to harsh slopes. However, mining companies are required by law to reclaim the land mined and as a result the land is landscaped so that it is prime real estate for housing developments, parks, and golf courses.