The Secretary shall make available to NANA and its successors and assigns the right to use sand, gravel and related construction materials located in Sections 23, 24, 25, 26, 35 and 36 of Township 26 North, Range 24 West, Kateel River Meridian, Alaska, if the Secretary determines either (1) that use of such sand, gravel or related construction material is necessary because there is no other sand, gravel or related construction material reasonably available for the construction, operation, maintenance, expansion or reclamation of the transportation system; or (2) that use of such sand, gravel or related construction material is necessary in order to construct, operate, maintain, expand, or reclaim the transportation system in an environmentally sound manner, consistent with the requirements of Exhibit B of the Agreement. The right to use such sand, gravel and related construction material shall be subject to the terms and conditions of paragraph A of Exhibit B of the Agreement and such other reasonable terms and conditions as the Secretary may prescribe.