(a) The restrictions of the Buy American Act do not apply when the head of the grantee organization or a designee at a level no lower than the grantee's designated awarding official determines that using a particular domestic construction material would unreasonably increase the cost or would be impracticable.

(b) When proposed awards are submitted to the head of the grantee organization or a designee at a level no lower than the grantee's designated awarding official for approval, each submission shall include a description of the materials, including unit and quantity, estimated costs, location of the construction project, name and address of the proposed contractor, and a detailed justification of the impracticability of using domestic materials.