Each structure shall comply with the performance standards and the design requirements of the Regulatory Program, except that an existing structure may be exempted from the design requirements if it meets: The performance standards of the Regulatory Program; or Those performance standards of the Interim Regulatory Program which are at least as stringent as the comparable performance standards of the Regulatory Program. The Bureau may grant exemptions, only as part of the permit application process, if it finds that no significant harm to the environment or public health or safety will result from use of the structure. An existing structure which does not meet a performance standard of the Regulatory Program, or a performance standard of the Interim Regulatory Program which is at least as stringent as the comparable performance standard of the Regulatory Program, shall be modified or reconstructed to meet the design standard of the Regulatory Program pursuant to a compliance plan, submitted by the applicant and approved by the Bureau, that includes: Design specifications for the modification or reconstruction of the structure to meet the design and performance standards of the Regulatory Program; A construction schedule which shows dates for beginning and completing interim steps and final reconstruction; Provisions for monitoring the structure during and after modification or reconstruction to ensure that the performance standards of the Regulatory Program are met; and A showing that the risk of harm to the environment or to public health or safety is not significant during the period of modification or reconstruction. Before issuance of the permit, the Bureau must find that: The compliance plan under §C of this regulation will bring the existing structure into compliance not later than 6 months after issuance of the permit; The risk of harm to the environment or to public health or safety is not significant during the period of modification or reconstruction; and The applicant will monitor the structure to determine compliance with the performance standards of the Regulatory Program.