All freestanding structures, buildings and substantial improvements, with the exception of driveways and utilities when no other location is feasible, are prohibited on slopes of 35% or greater and are prohibited on slopes where soil type is classified as "stony land, steep," by the document entitled "Soil Survey Montgomery County, Pennsylvania," prepared by the United States Department of Agriculture, Soil Conservation Service, dated April 1967, copies of which are on file in the Township Office, 1510 Paper Mill Road, Wyndmoor, Pennsylvania 19118.