7 Del. Admin. Code § 1135-11.0
The federal conformity rules under 40 CFR Part 51, Subpart W (July 1, 1994), in addition to any existing applicable State requirements, establish the conformity criteria and procedures necessary to meet the requirements of Clean Air Act §176(c) until such time as this conformity implementation plan revision is approved by EPA. Following EPA approval of this revision to the applicable implementation plan (or a portion thereof), the approved (or approved portion of the) state criteria and procedures would govern conformity determinations and the Federal conformity regulations contained in 40 CFR Part 93 (July 1, 1994), would apply only for the portion, if any, of the State's conformity provisions that is not approved by EPA. In addition, any previously applicable implementation plan requirements relating to conformity remain enforceable until the State revises its applicable implementation plan to specifically remove them and that revision is approved by EPA.
7 Del. Admin. Code § 1135-11.0