If the work is federally funded, the federal funding agency must approve the use of a private consultant before the selection. The administering division is responsible for obtaining written approval. 23 CFR §172.5.

If the work is federally funded, the federal funding agency must also concur in writing in a sole source procurement regardless of the amount. 23 CFR §172.7(a)(3); Federal Acquisition Regulation (FAR) 6.303 and 6.304.