36 C.F.R. § 51.54
Before beginning to construct any capital improvement, the concessioner must obtain written approval from the Director in accordance with the terms of its leasehold surrender interest concession contract. The request for approval must include appropriate plans and specifications for the capital improvement and any other information that the Director may specify. The request must also include an estimate of the total construction cost of the capital improvement. The estimate of the total construction cost must specify all elements of the cost in such detail as is necessary to permit the Director to determine that they are elements of construction cost as defined in this part. (The approval requirements of this and other sections of this part also apply to any change orders to a capital improvement project and to any additions to a structure or replacement of fixtures as described in this part.)
36 C.F.R. § 51.54