The Planning and Zoning Commission may require modification of a site plan as a prerequisite for approval (or allow a variance of Property Development Regulation for Section 7.111 D). Such modifications may include, but shall not be limited to, provisions for special yards, open spaces, buffers, fences, walls, and screening; for installation and maintenance of landscaping and erosion control measures; improvements of access and circulation; rearrangements of structures or activities within the site; location and character of signs and such other site plan features as necessary to ensure compatibility with surrounding existing, permitted or proposed physical features or uses or improve internal design based upon the results of the commission's application of the review and evaluation criteria.