Notwithstanding subsection (a), the city may deny an application for a second unit or two-unit development if the building official, or designee, makes a written finding, based upon a preponderance of the evidence, that the proposed second unit or two-unit development would have a specific, adverse impact, as defined in subsection (d)(2) of Government Code Section 65589.5, upon public health and safety or the physical environment and for which there is no feasible method to satisfactorily mitigate or avoid the specific, adverse impact.