Section 52.743 - Continuous monitoring(a) Alternative monitoring requirements established under Section 201.402 of Title 35, IAC must be either: Incorporated into a federally enforceable operating permit or construction permit or submitted to USEPA for approval as a revision to the Illinois State Implementation Plan (SIP). Illinois shall set forth alternative emissions monitoring and reporting requirements to satisfy the intent of 40 CFR part 51, appendix P whenever Illinois exempts any source subject to Section 201.401 from installing continuous emission monitoring systems. Illinois may exempt a source if the source cannot install a continuous emission monitoring system because of physical plant limitations or extreme economic reasons, according to the criteria of Section 201.402 .(b) As codified at 40 CFR 52.737 (USEPA's approval of the Illinois operating permit program for the purpose of issuing federally enforceable construction and operating permits), USEPA reserves the right to deem an operating permit not federally enforceable. Such a determination will be made according to appropriate procedures including operating permit requirements promulgated at 54 FR 27274 (June 28, 1989) and will be based upon either; the permit, permit approval procedures or state or local permit requirements which do not conform with the operating permit program requirements or the requirements of USEPA's underlying regulations. Among other things, underlying requirements include 40 CFR 51.214 and part 51, appendix P and Illinois' approved SIP, 40 CFR part 52 . Should USEPA deem an operating or construction permit containing alternative monitoring requirements not federally enforceable, the underlying continuous monitoring requirements at Section 201.401 of the State rule would be the Federal requirements contained in the SIP to which the source would be subject. This interpretation of the impact of an operating permit deemed not federally enforceable by USEPA on a source to which it was issued was acknowledged by the State in a March 3, 1993, letter from Bharat Mathur, Chief, Bureau of Air, Illinois Environmental Protection Agency, to Stephen Rothblatt, Chief, Regulation Development Branch, Region 5, USEPA.58 FR 17783, Apr. 6, 1993