The following planning and design standards shall be complied with, except where the Planning Board finds that, because of exceptional and unique conditions of topography, location, shape, size, drainage or other physical features of the site or because of the special nature and character of the surrounding development, the minimum standards specified herein would not reasonably protect or provide for public health, safety or welfare. Any higher standard required shall be reasonable and shall be limited to the minimum additional improvements necessary to protect the public health, safety or welfare.