Outdoor shooting ranges may be allowed upon the granting of a conditional use permit, provided that no range shall be established within two miles of any residential development having a density of more than one dwelling unit per acre. Said permit shall be valid initially for not more than five years, and may thereafter be renewed upon reapplication to allow continued operation an additional period of time of not more than five, for an indefinite number of times but subject to any additional conditions or requirements that the Board of Adjustment may deem appropriate.