Sloping and benching systems not utilizing Option (1) or Option (2) or Option (3) under paragraph (b) of this section shall be approved by a registered professional engineer.
At least one copy of the design shall be maintained at the jobsite while the slope is being constructed. After that time the design need not be at the jobsite, but a copy shall be made available to the Secretary upon request.
Designs shall be in written form and shall include at least the following:
The magnitude of the slopes that were determined to be safe for the particular project;
The configurations that were determined to be safe for the particular project; and
The identity of the registered professional engineer approving the design.