§ 51.458 - Enforceability of design concept and scope and project-level mitigation and control measures.

(a) Prior to determining that a transportation project is in conformity, the MPO, other recipient of funds designated under title 23 U.S.C. or the Federal Transit Act, FHWA, or FTA must obtain from the project sponsor and/or operator written commitments to implement in the construction of the project and operation of the resulting facility or service any project-level mitigation or control measures which are identified as conditions for NEPA process completion with respect to local PM10 or CO impacts. Before making conformity determinations written commitments must also be obtained for project-level mitigation or control measures which are conditions for making conformity determinations for a transportation plan or TIP and included in the project design concept and scope which is used in the regional emissions analysis required by §§ 51.428 through 51.432 and §§ 51.436 through 51.440 or used in the project-level hot-spot analysis required by §§ 51.424 and 51.434.

(b) Project sponsors voluntarily committing to mitigation measures to facilitate positive conformity determinations must comply with the obligations of such commitments.

(c) The implementation plan revision required in § 51.396 shall provide that written commitments to mitigation measures must be obtained prior to a positive conformity determination, and that project sponsors must comply with such commitments.

(d) During the control strategy and maintenance periods, if the MPO or project sponsor believes the mitigation or control measure is no longer necessary for conformity, the project sponsor or operator may be relieved of its obligation to implement the mitigation or control measure if it can demonstrate that the requirements of §§ 51.424, 51.428, and 51.430 are satisfied without the mitigation or control measure, and so notifies the agencies involved in the interagency consultation process required under § 51.402. The MPO and DOT must confirm that the transportation plan and TIP still satisfy the requirements of §§ 51.428 and 51.430 and that the project still satisfies the requirements of § 51.424, and therefore that the conformity determinations for the transportation plan, TIP, and project are still valid.