Black Hills National Cemetery Boundary Expansion Act (Sec. 3) This bill directs the Department of Veterans Affairs (VA) to: (1) complete environmental, cultural resource, and other due diligence activities on certain federal land to confirm its suitability for inclusion in the Black Hills National Cemetery, South Dakota; and (2) notify, and coordinate with, the Department of the Interior regarding such activities. After completion of such activities and upon receipt by Interior of written confirmation of suitability from the VA, the land shall: (1) be withdrawn from all forms of appropriation under the public land laws, including the mining laws, the mineral leasing laws, and the geothermal leasing laws, for as long as it remains under VA administrative jurisdiction; (2) be treated as property; and (3) be transferred, except for the land within 100 feet of the center of the Centennial Trail, from Interior to the VA for use as a national cemetery. Interior shall publish a notice containing the legal descriptions of such transferred land. The VA shall reimburse Interior for reasonable transfer costs, including survey costs. The cemetery's boundary is modified to include such federal land.