Section 67.6 - Basis of appeal(a) The sole basis of appeal under this part shall be the possession of knowledge or information indicating that the elevations proposed by FEMA are scientifically or technically incorrect. Because scientific and technical correctness is often a matter of degree rather than absolute (except where mathematical or measurement error or changed physical conditions can be demonstrated), appellants are required to demonstrate that alternative methods or applications result in more correct estimates of base flood elevations, thus demonstrating that FEMA's estimates are incorrect.(b)Data requirements.(1) If an appellant believes the proposed base flood elevations are technically incorrect due to a mathematical or measurement error or changed physical conditions, then the specific source of the error must be identified. Supporting data must be furnished to FEMA including certifications by a registered professional engineer or licensed land surveyor, of the new data necessary for FEMA to conduct a reanalysis.(2) If an appellant believes that the proposed base flood elevations are technically incorrect due to error in application of hydrologic, hydraulic or other methods or use of inferior data in applying such methods, the appeal must demonstrate technical incorrectness by:(i) Identifying the purported error in the application or the inferior data.(ii) Supporting why the application is incorrect or data is inferior.(iii) Providing an application of the same basic methods utilized by FEMA but with the changes itemized.(iv) Providing background technical support for the changes indicating why the appellant's application should be accepted as more correct.(v) Providing certification of correctness of any alternate data utilized or measurements made (such as topographic information) by a registered professional engineer or licensed land surveyor, and(vi) Providing documentation of all locations where the appellant's base flood elevations are different from FEMA's.(3) If any appellant believes the proposed base flood elevations are scientifically incorrect, the appeal must demonstrate scientific incorrectness by:(i) Identifying the methods, or assumptions purported to be scientifically incorrect.(ii) Supporting why the methods, or assumptions are scientifically incorrect.(iii) Providing an alternative analysis utilizing methods, or assumptions purported to be correct.(iv) Providing technical support indicating why the appellant's methods should be accepted as more correct and(v) Providing documentation of all locations where the appellant's base flood elevations are different from FEMA's.48 FR 31644, July 1, 1983