Notwithstanding Subsection 15.03.200(1)(d), Provo City Code, a local street abutting a development in the Trellis on the Green PRO zone may be established with a minimum asphalt width of less than twenty-eight (28) feet in order to preserve existing mature trees which have a caliper of ten (10) inches or more at breast height and which would otherwise encroach into the street. Provided, however, that in any event, the asphalt width of such street shall be at least twenty-five (25) feet.