The provisions contained herein are adopted to protect public and
private property from damage or destruction resulting from natural
erosion processes occurring within the ravines and bluffs along the
shore of Lake Michigan, or abnormal or accelerated ravine and bluff
erosion resulting from land development and construction activities
occurring on adjacent or nearby properties, and to protect the fragile
ravine and bluff ecosystem from unwarranted damage or destruction caused
by land development and construction activities.
The provisions contained herein shall apply to all land development
and construction activities on all properties abutting ravines and
bluffs as delineated by hashed lines (or shaded areas) on Exhibit A, a
copy of which is attached hereto and made a part hereof.
(1) Building Setbacks:
(a) From Ravines
All building construction shall be on Table Land, but in no case
shall any structure or building foundation be located closer than
twenty (20) feet to the Ravine Area.
(b) From Bluffs
All building construction shall be on Table Land, but in no case
shall any structure or building foundation be located closer than
seventy-five (75) feet to the Bluff Area.
(2) Construction Activity:
(a) Adjacent to Ravines
All construction activity; i.e., grading, excavating, filling,
terracing, tree removal, stockpiling of excavated material, is
prohibited within twenty (20) feet of the Ravine Area, except as may
be necessary to provide site drainage improvements, as may be
approved and/or required by the City Engineer.
(b) Adjacent to Bluffs
All construction activity; i.e., grading, excavating, filling,
terracing, tree removal, stockpiling of excavated material, is
prohibited within fifty (50) feet of the Bluff Edge, except as may
be necessary to provide site drainage improvements, as may be
approved and/or required by the City Engineer.
(3) Site Landscaping:
Upon completion of construction activities, minimal grading and
clearing of existing vegetation may be allowed within the Bluff or
Ravine Area in order to install new vegetation and lawn landscaping.
However, no such grading, clearing or landscaping will be permitted
within twenty (20) feet of the Ravine Edge or within fifty (50) feet
of the Bluff Edge.
(4) Site Drainage:
A Site Grading Permit, approved by the City Engineer, shall be
required before any site grading work may take place. Measures shall
be required to control storm water runoff from impervious areas,
lawns, and footing drains. Wherever feasible, such runoff shall be
collected and carried to established storm drainage facilities located
away from the Ravine or Bluff Area as the case may be. If discharge
into an established storm drainage structure is not feasible, drainage
shall be collected and discharged into the ravine channel or from the
top of the bluff to its base in a manner which minimizes disruption of
the ravine or bluff slope and potential erosion of the bluff toe or
the ravine toe and channel, subject to the specific approval of the
City Engineer.
(5) Channel Modification:
Where the City Engineer finds that an unstable ravine or bluff
slope or toe exists or is likely, or where the configuration of the
ravine channel has resulted in erosion or suggests the probability of
future erosion, channel, toe or slope stabilization measures may be
required by the City Engineer.
(6) Required Information:
Prior to submission to the City of a request for Tentative Approval
of a Plat of Subdivision or review of an Application for a Building
Permit, the owner or agent of the owner of property, subject to this
Section, shall submit to the City Engineer all applicable site
information, including but not limited to topography, existing trees
and vegetation, ravine and/or bluff conditions (including
establishment of the limits of the Ravine or Bluff Area), geological
and soil conditions, proposed plans for landscaping and lawn
installation, and such other information as may be deemed necessary by
the City Engineer in order to implement the policy and requirements of
this Section.
(7) Definitions:
a.) RAVINE AREA - The Ravine Area shall include all property
within or adjacent to a ravine beginning at the point of
intersection of a line with the table land, said line extending from
the toe of the slope upward at a vertical angle of twenty-two (22)
degrees.
b.) RAVINE EDGE - That point on the ravine side of the table land
where the slope of the land first exceeds ten (10) percent.
c.) TABLE LAND - Land where the slope in any direction does not
exceed ten (10) percent.
d.) TOE OF SLOPE - The toe of the ravine or bluff slope is that
point in the ravine or bluff where the slope is less than twenty-two
(22) degrees or where the slope reverses directions. On compound
slopes where there may be more than one possible toe location, the
controlling point shall be whichever toe location provides the
greater ravine or bluff area.
(1) The City Surveyor and Engineer may approve encroachments into
the bluff or ravine setback area for the construction of landscape
features, auxiliary buildings (slab foundation), bridges, wood decks
or other similar facilities, if the City Surveyor and Engineer finds
that:
(a) The proposed construction is appropriate only for requested
location.
(b) The proposed construction will have no significant impact on
the ravine or bluff area.
(c) The proposed construction is of relatively low value, except
for items related to ravines such as vehicular bridges.
(2) The Zoning Board of Appeals may consider variations from the
requirements of this section for construction of habitable facilities
such as room additions or new residences, and construction of
significant auxiliary buildings. In considering such variations, the
following guidelines, in addition to the four findings of fact as set
forth in Section 46-21-(F)-(3), shall be considered:
(a) Construction in the twenty (20) foot setback for the
twenty-two (22) degree slope intersect could be recommended if there
exists adequate toe of slope improvements.
(b) Construction in the twenty-two (22) degree slope angle could
be recommended if there exists adequate slope or other improvements
that effectively increase the stable slope angle.
(c) Variation from building on land that exceeds ten (10) percent
slope but is outside of the twenty (20) foot setback from the
twenty-two (22) degree slope angle could be recommended if entire
slope shows no indication of instability.
(d) Variation from any restriction could be recommended if the
requested construction is less nonconforming than the existing
residence and the ravine or bluff slope does not show any indication
of instability; or if the applicant submits evidence based on
current geotechnical engineering practices such as the Simplified
Bishop Method of stability analysis whereby variables of soil shear
strength, ground water level, unit weight of soil and slope angles
are considered which result in the determination that the particular
slope is stable at an angle greater than twenty (22) degrees.
