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Planning & Zoning in Michigan>Steep Slope Development Standards

Steep Slope Development Standards
This information was adapted from the 'Shiawassee & Huron Headwaters Preservation Project' developed by Oakland County Planning and Carlisle Wortman & Associates.

These model regulations are intended as overlay regulations within areas designated by communities as having steep slopes.


Section _________. Steep Slope Protection Overlay Standards.

(a.) Purpose. This section is intended to protect resources in environmentally sensitive areas to ensure that development does not result in erosion and in flooding during site preparation and the development process. All uses and activities established after the effective date of this Ordinance shall comply with the following standards. Site alternations, re-grading, filling or the clearing of vegetation, or any other activity deemed detrimental to any environmentally sensitive area or resource prior to the submission of plans for subdivision or land development shall be a violation of this Ordinance.

(b.) General Design Standards.
(1) Structures shall be designed in a manner that requires a minimum amount of alternation to the steep slope and that otherwise complies with the grading standards in Subsection (C) of the Ordinance. Except where a geologic hazard investigation report recommends otherwise, multi-level building design and/or terracing shall be used. Otherwise, structures shall be sited on existing level areas of the site.

(2) Particular caution shall be taken to prevent increases in the rate of stormwater runoff and erosion downslope of any steep slope development site. An approved (enforcing agency) permit shall be submitted before any use is approved under the provisions of this Ordinance.

(c.) Specific Design Standards.
(1) Any site disturbance of slopes exceeding fifteen (15%) percent shall be minimized.

(2) No site disturbance shall be allowed on slopes exceeding twenty-five (25%) percent, except under the following circumstances.

a. Grading for a portion of a driveway accessing a single family dwelling when it can be demonstrated that no other routing which avoids slopes exceeding twenty-five (25%) percent is possible.

b. Upon submission of a report by a certified soil or geotechnical engineer indicating that the steep slope may be safety developed and execution of a provision agreeing to hold the (community) harmless from any claims of damages due to approval of such development. If development is allowed to proceed under this subsection, no more than (15%) percent of such areas shall be developed and/or re-graded or stripped of vegetation.

(3) Finished slopes of all cuts and fills shall not exceed three-to-one (3:1), unless the applicant can demonstrate that steeper slopes can be stabilized and maintained adequately.
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