The county engineer may require a greater minimum grade to facilitate drainage according
to paving type or other provisions. The grades of all streets shall be kept as low
as possible; however, paved local streets shall not have a grade exceeding 14 percent
at any time. Paved collector streets shall not have a grade exceeding 12 percent at
any time or more than a ten percent grade for greater than 500 feet in length. Gravel
local and collector streets shall not have a grade more than 12 percent and ten percent
at any time, respectively.