HomeMy WebLinkAbout5A Section 1104 Shoreland Report
4646 Dakota Street SE
Prior Lake, MN 55372
PLANNING COMMISSION AGENDA REPORT
MEETING DATE: MAY 2, 2016
AGENDA #: 5A
PREPARED BY: JEFF MATZKE, PLANNER
AGENDA ITEM: CONSIDERATION OF A REQUEST TO RECOMMEND AMENDMENTS TO
SECTION 1104 (SHORELAND REGULATIONS) OF THE CITY CODE RE-
GARDING BLUFF AND STEEP SLOPE AREAS
DISCUSSION: Introduction
The purpose of this agenda item is to consider a request by City staff to amend
Section 1104 (Shoreland Regulations) of the City of Prior Lake Zoning Ordinance
related to bluff and steep slope areas. The primary purpose of these ordinance
amendments is to consider objective criteria that would be allowed for construc-
tion within a bluff impact zone.
History
The most recent bluff ordinance was created in June 2009. At that time, changes
were made to the required design and plan submittal requirements for work
within bluff impact areas. The ordinance for bluff areas was developed in the
1990s under the policies of the Minnesota Department of Natural Resources
(DNR). Since then municipalities have adopted ordinances to coordinate with
state rules.
The Planning Commission held a public hearing for consideration of these
amendment at their April 18, 2016 meeting. At the meeting some public com-
ment was taken regarding general support for the flexibility of the ordinance
amendments which allowed for moderate changes to existing grades and retain-
ing walls with bluff areas. The public also indicated concerns with what was
indicated as excessive permitting requirements for retaining and structural walls
within bluff zones. After closing the public hearing and deliberating the amend-
ments, the Planning Commission voiced support for the overall ordinance
amendments proposed, however, they directed City Staff to review other com-
munities with similar bluff situations to identify other engineering requirements
for permitting within bluff zones.
City Staff has received feedback from the communities of Lakeville, Chanhas-
sen, Inver Grove Heights, and Washington County since the last Planning Com-
mission meeting. These communities expressed similar practices in regards to
regulations, however, they did not generally require a consulting engineer on
behalf of the City for review/inspection. Some cited that the review of the engi-
neering review depended on the scale of the project; and in bluff cases a City
inspector, at a minimum, observes a project alongside a private engineer. Much
like the City of Prior Lake requirement, some communities did indicate a post
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engineering report requirement or movement toward this type of future regula-
tion. A few instances of bluff failures resulting in intensive erosion issues were
explained and the issues were handled through code enforcement procedures
to correct slope stability and erosion with the engineer, contractor, and/or prop-
erty owner for the project.
The City Staff has talked internally about the permitting process for retaining
walls and the Engineering and Building Inspections Department indicates that
the requirements are not exclusive to only bluff areas but extend to any large
retaining wall project over 4 feet in height or a variety of tiers which requires a
building permit. In 2009 the City Council placed this permitting into practice after
the failures in two major developments that, although not in bluff areas, did con-
tain significant retaining wall failures and a challenging process for structural
correction (see attached example photos). The City Engineer will attend the May
2nd Planning Commission meeting to discuss the permitting process and answer
any questions with regards to engineering requirements.
Current Circumstances
To manage bluffs and slopes properly, communities use preventative controls
including structure setbacks, erosion control methods, and storm water regula-
tions to preserve the integrity of the steep slopes. These methods also minimize
visual impact of construction and preserve natural vegetation that stabilizes
slopes and preserves wildlife habitat.
The City of Prior Lake restricts development within bluff and steep slope areas
through setbacks and construction limitations. It is the current practice of the
City to bring any project within a bluff area (including existing nonconforming
properties) through a variance process on a case-by-case basis to determine the
authorization of the construction. In recent months, a large number of inquiries
and variance applications regarding construction in bluff areas has lead City Staff
to consider an alternative approach that would allow a defined amount of con-
struction within these areas in comparison to the existing impacts on each site.
As is the case when the variances are granted through several similar requests,
such amendments could possibly create a more efficient and clear process to
achieve necessary City approvals. The City has inquired with the local DNR
representative as to the possibility of creating such an ordinance amendment as
any change would need to be reviewed for approval by the environmental state
agency. The DNR has indicated that possible ordinance amendments could be
considered as long as it does not impede with State Statutes.
Conclusion
City Staff believes that the current ordinance has some subjective language that
could possibly be changed to present property owners with a more direct and
clear objective for the regulatory limits of the ordinance and the purpose of the
ordinance. Possible changes include a degree of change that is allowed to occur
within bluff areas, detailed information regarding the required engineering anal-
ysis of the steep slopes, and regulations to improve existing erosion and storm
water issues with construction in steep slope areas. The DNR has been con-
sulted on these amendments and has indicated general support for them, there-
fore City Staff recommends approval of the ordinance amendments.
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ISSUES: After reviewing area regulations, MN State Statutes, and DNR rules the City Staff
has identified three main areas of possible amendments within the ordinances
which regulate bluff and steep slope areas. These relate to engineering review
and analysis, stairway installation, and retaining walls and grade alterations.
Engineering Analysis (Subsection 1104.305) – The current ordinance requires
the submittal of an engineering report regarding the bluff stability and impact of
excavation, fill, or placement of structures on the site. This report shall accom-
pany the site survey and an as built survey shall be prepared following the con-
struction to verify the work was performed according to the plan. This Subsec-
tion allows for a waiver of the engineering report for smaller projects on sites that
do not indicate previous bluff failure or erosion control issues. The amendment
proposes to expand upon the allowance under the waiver requirement for stair-
ways, retaining walls, and structures.
Stairways, Lifts, and Landings (Subsection 1104.308(5)) – This section of the
ordinance closely resembles State Statute; however, the regulation of Prior lake
has been to restrict stairways that are constructed into the bluff slope rather than
above the slope on post footings. The amendment proposes to allow such stair-
ways that would be constructed into the bluff slope as long as drainage, erosion
control, and slope stability is achieved with the stairway design.
Topographic Alterations/Grading and Filling (Subsections 1104.402) – The cur-
rent City Ordinance in this subsection greatly restricted alterations of bluff areas
to the exact replacement of retaining walls and current grades. The City has
identified that this method may not allow for the flexibility to improve drainage
patterns, provide for enhanced erosion control design and slope stability, and
decrease impervious surface. While the State Statute is clear in regards to the
exclusion of importing or exporting of material into a bluff zone without a variance
consideration, the movement of grade and materials within the bluff slope is per-
mitted. The amendment to this section proposes a limit of grade movement and
retaining wall alterations to allow moderate changes to the current slope design
which could improve the overall drainage, erosion control, and slope stability.
ALTERNATIVES: 1. Motion and a second to recommend amendments to Section 1104
(Shoreland Regulations) regarding bluff and steep slope areas.
2. Motion and a second to deny recommending amendments to the City Code.
3. Motion and a second to table action and provide direction to staff and con-
tinue discussion at a future specified meeting.
RECOMMENDED
MOTION:
ATTACHMENTS:
Alternative #1
1. Photo examples of bluff failures
2. Proposed amendments to Section 1104 (Shoreland Regulations) of the
City Code.
3. Bluff Cross-section Exhibit
Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p1
SECTION 1104
SHORELAND REGULATIONS
SUBSECTIONS
1104.100: General Provisions
1104.200: Designation of Types of Land Use
1104.300: Zoning Provisions
1104.400: Shoreland Alterations
1104.500: Special Provisions for Commercial, Industrial, Public/Semi-Public,
Agricultural and Forestry
1104.600: Water Supply and Sewage Treatment
1104.700: Conditional Uses
1104.800: Planned Unit Developments (PUDs)
1104.900: Development on Nonconforming Lots
(Subsections in this exhibit were removed due to lack of significance to bluffs & steep slopes)
1104.303 Bluff Impact Zones: Structures and accessory facilities, excluding stairways,
lifts, and landings, shall not be placed in bluff impact zones.
1104.304 Bluff Setbacks: The required setback from the Top of Bluff is determined as
follows: as measured from the Top of Bluff, the upper end of a segment at least
25 feet in length having an average slope less than 18%.
1104.305 Engineering Reports Required: On properties for which construction is
proposed within a bluff impact zone or bluff setback, the applicant for a building
permit and the property owner shall provide the following:
25’
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Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p2
(1) The applicant for a building permit on that property shall provide a report and
calculations prepared and signed by a professional engineer registered by the
State of Minnesota on the bluff stability and the impact any excavation, fill or
placement of structures will have on the site and whether the excavation, fill, or
placement of structures will cause any slope to become unstable or will impose
loads that may affect the safety of structures or slopes. The report shall include
the following:
• The global failure plane determination of the slope substantiated by at least
one soil boring at an appropriate depth and location
• Analysis of the land influence zone and its intersection with the failure plane
based on the soil type
• The Engineer's recommendations for the proper design and maintenance
of a drainage system so the site development will not interfere with
adequate drainage for the site or adjacent properties, will not obstruct,
damage or adversely affect existing sewer or drainage facilities, will not
adversely affect the quality of stormwater runoff, will not adversely affect
downstream properties, wetlands or bodies of water and will not result in
erosion or sedimentation.
• If the initial determination indicates that the load influence zone intersects
or falls within the global failure plane, a global stability analysis of the bluff
shall be required.
(2) The owner of the property shall submit an as-built survey and post- construction
report completed by a professional engineer registered by the State of
Minnesota that the final grading of the site was completed in compliance with
an approved grading plan and that the recommendations contained in the
engineer's report have been adhered to.
(3) The Building Official, the Community Development & Natural Resources
Director and the City Engineer may waive the engineer's report requirement for
replacement decks, new decks or additions to existing decks, replacement
retaining walls, stairways, lifts and landings, water-oriented accessory
sturctures, and additions or new structures not exceeding 480 1000 square feet
in size under the following conditions:
a. An inspection of the site does not indicate any obvious erosion
conditions.
b. There is no history of bluff failure on the site or on the adjacent lots.
c. All required setbacks are met.
1104.308 Placement, Design, And Height Of Structures:
(1) Piers and Docks: Setback requirements from the ordinary high-water mark
shall not apply to piers and docks. Location of piers and docks shall be
controlled by applicable state and local regulations.
(2) Setback Requirements For Residential Structures: On shoreland lots that
have 2 adjacent lots with existing principal structures on both such adjacent
Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p3
lots, any new residential structure or any additions to an existing structure may
be set back the average setback of the adjacent structures from the ordinary
high-water mark or 50 feet, whichever is greater, provided all other provisions
of the Shoreland Overlay District are complied with. In cases where only one
of the two lots adjacent to an undeveloped shoreland lot has an existing
principal structure, the average setback of the adjacent structure and the next
structure within 150 feet may be utilized. Setback averaging may not be utilized
when an undeveloped shoreland lot is adjacent to two other undeveloped
shoreland lots. In no instance shall a principal structure be located in a shore
impact zone or a bluff impact zone.
a. The following shall not be considered encroachments into the lakeshore
or bluff setback:
1) Eaves, gutters and basement egress windows, provided they do not
extend more than 2 feet into a yard; and provided such encroachment
is no closer than 5 feet from any lot line.
2) Yard lights and nameplate signs for one and two family dwellings in
the R-1, R-2 and R-2 districts.
3) Floodlights or other sources of light illuminating authorized signs, or
illuminating parking areas, loading areas, or yards for safety and
security purposes if these meet the regulations of Subsection
1107.1800.
4) Flag poles, bird baths and other ornamental features detached from
the principal building which are a minimum of 5 feet from any lot line.
5) Canopies no more than 12 feet wide are permitted in the "R-3", "C-1",
"C-2", "C-3" and "I-1" Districts if they are open at the sides, comply with
provisions of Subsection 1101.506 and provide 14 feet of clearance if
located over any access roadway or fire lane.
b. The following recreational equipment shall not be encroachments on the
lakeshore or bluff setback requirements: boats, boat trailers, general
purpose trailers, fish houses, fire pits, utility trailers, jet skis,
snowmobiles and other lake-oriented items.
c. Additional regulations regarding encroachments allowed in front, rear,
and side yards are located in Subsection 1101.503.
d. Decks not meeting the required setbacks may be replaced if the following
criteria are met:
The deck existed on the date the structure setbacks were
established;
The replacement deck is in the same size, configuration, location
and elevation as the deck in existence at the time the structure
setbacks were established;
Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p4
The deck is not roofed or screened; and
The existing deck is not located within an easement, right-of-way,
or over a property line.
(3) High Water Elevations: Structures must be placed in accordance with any
flood plain regulations applicable to the site. Where these controls do not exist,
the elevation to which the lowest floor, including basement, is placed must be
determined as follows:
a. For lakes, by placing the lowest floor at a level at least 3 feet above the
highest known water level, or 3 feet above the ordinary high water level,
whichever is higher;
b. For rivers and streams, by placing the lowest floor at least 3 feet above
the flood of record, if data are available. If data are not available, by
placing the lowest floor at least 3 feet above the ordinary high-water
level, or by conducting a technical evaluation to determine effects of
proposed construction upon flood stages and flood flows and to
establish a flood protection elevation. Under all three approaches,
technical evaluations must be done by a qualified engineer or
hydrologist consistent with Parts 6120.5000 to 6120.6200 governing the
management of flood plain areas. If more than one approach is used,
the highest flood protection elevation determined must be used for
placing structures and other facilities; and
c. Water-oriented accessory structures may have the lowest floor placed
lower than the elevation determined in this subsection if the structure is
constructed of flood-resistance materials to the flood elevation; electrical
and mechanical equipment are placed above the elevation and, if long
duration flooding is anticipated, the structure is built to withstand ice
action and wind-driven waves and debris.
(4) Water-Oriented Accessory Structures: One water-oriented accessory
structure may be allowed per lot on General Development (GD) lakes that have
Municipal sewer and water; provided a building permit is obtained from the City
and the following criteria are met:
a. On riparian lots containing a slope equal to or greater than 20%
measured from the front of the principal structure to the ordinary high
water mark and verified by a certificate of survey prepared by a
registered surveyor, one water-oriented structure meeting the criteria
listed in this subsection is permitted with a setback of not less than 10
feet from the ordinary high water mark.
b. On riparian lots containing slopes less than 20%, one water-oriented
accessory structure meeting the criteria listed in this subsection is
permitted with a setback of not less than 50 feet from the Ordinary High
Water elevation.
Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p5
c. The structure shall not occupy an area greater than 120 square feet,
and the maximum height of the structure must not exceed 10 feet,
including the roof; and
d. The structure shall be located in the most visually inconspicuous portion
of the lot as viewed form the surface of the lake, assuming summer, leaf-
on conditions; and
e. The structure shall not be designed or used for human habitation and
shall not contain water supply or sewage treatment facilities. However,
the structure may contain electrical and mechanical systems; and
f. The structure shall be constructed of treated materials compatible with
the principle structure and designed to reduce visibility as viewed from
public waters and adjacent shorelands by vegetation, topography,
increased setbacks or color, assuming summer, leaf-on conditions; and
g. If the proposed structure will be located below the regulatory flood plain
elevation, the structure shall be built compliant with applicable flood-
proofing requirements of the Building Code and Section 1105 of this
Ordinance; and
h. Trees that are 4 inches in caliper or larger should not be removed for
the erection of a water-oriented accessory structure. If removal is
necessary, replacement with like trees shall be made with the approval
of the Zoning Administrator. Erosion control measures shall be
implemented and all disturbed vegetation replaced with sod or suitable
landscaping materials; and
i. The structure shall be attached to a permanent foundation so as to be
immovable from its approved location.
j. Water oriented accessory structures not meeting the lakeshore required
setbacks may be replaced if the following criteria are met:
The structure existed legally on June 1, 2009;
The replacement structure is the same size, configuration, location,
building material, and height as the structure in existence on June
1, 2009;
The existing structure is not located within an easement, right-of-
way, side yard setback, or over a property line.
(5) Stairways, Lifts, And Landings: Stairways and lifts are the preferred
alternative to major topographic alterations for achieving access up and down
bluffs and steep slopes to shore areas. Stairways and lifts shall meet the
following design requirements:
a. Stairways and lifts shall not exceed 4 feet in width on residential lots.
Wider stairways may be used for commercial properties, public open
space recreational properties and planned unit developments;
Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p6
b. Landings for stairways and lifts on residential lots shall not exceed 32
square feet in area. Landings larger than 32 square feet may be used
for commercial properties, Park/Recreation properties, and planned unit
developments. The required lakeshore setback for landings shall be 10
feet measured from the ordinary high-water mark of the public water.
Landings shall not project into any required side yard;
c. Canopies or roofs are not allowed on stairways, lifts, or landings;
d. Stairways, lifts and landings may be either constructed above the
ground on posts or pilings, or placed into the ground, provided they are
designed and built in a manner that ensures control of soil erosion, and
maintains or improves drainage patterns and slope stability;
e. Stairways, lifts and landings shall be located in the most visually
inconspicuous portions of lots, as viewed from the surface of the public
water assuming summer, leaf-on conditions, whenever practical; and
f. Facilities such as ramps, lifts or mobility paths for physically
handicapped persons are also allowed for achieving access to shore
areas, provided that the dimensional and performance standards of
Subsections 1104.308(1) through (5) are complied with in addition to the
requirements of Minnesota Regulations, chapter 1340.
(6) Significant Historic Sites: No structure may be placed on a significant historic
site as defined by Minnesota Statutes in a manner that affects the values of the
site unless adequate information about the site has been removed and
documented in a public repository.
(7) Steep Slopes: The City Engineer shall evaluate possible soil erosion impacts
and development visibility from public waters before issuing a permit for
construction of sewage treatment systems, roads, driveways, structures, or
other improvements on steep slopes. When necessary, conditions must be
attached to issued permits to prevent erosion and to preserve existing
vegetation screening of structures, vehicles, and other facilities as viewed from
the surface of public waters, assuming summer, leaf-on vegetation.
1104.400: SHORELAND ALTERATIONS: Alterations of vegetation and topography will
be regulated to prevent erosion into public waters, fix nutrients, preserve
shoreland aesthetics, preserve historic values, prevent bank slumping, and
protect fish and wildlife habitat.
1104.401 Vegetation Alterations:
(1) Vegetation alteration necessary for the construction of structures and sewage
treatment systems and the construction of roads and parking areas regulated
by Section 1104 are exempt from the vegetation alteration standards that follow.
Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p7
(2) Removal or alteration of vegetation, except for agricultural and forest
management uses as regulated by Section 1104 is allowed subject to the
following standards:
a. Intensive vegetation clearing within the shore and bluff impact zones
and on steep slopes is not allowed. Intensive vegetation clearing for
forest land conversion to another use outside of these areas is allowable
as a conditional use if an erosion control and sedimentation plan is
developed and approved by the City Engineer in which the property is
located.
b. In shore and bluff impact zones and on steep slopes, limited clearing of
trees and shrubs and cutting, pruning, and trimming of trees is allowed
to provide a view to the water from the principal dwelling site and to
accommodate the placement of stairways and landings, picnic areas,
access paths, beach and watercraft access and permitted water-
oriented accessory structures of facilities, provided that:
The screening of structures, vehicles, or other facilities as viewed
from the water, assuming summer, leaf-on conditions, is not
substantially reduced;
Along rivers, existing shading of water surfaces is preserved; and
The above provisions are not applicable to the removal of trees,
limbs, or branches that are dead, diseased or pose safety hazards.
1104.402 Topographic Alterations/Grading And Filling:
(1) The exact replacement of existing grade and retaining walls within a bluff impact
zone is permitted.
(2) Grading and filling and excavation, including the import or export of materials
within the bluff impact zone is not permitted. However, the movement or
grading of existing materials within the bluff impact zone may be permitted
subject to approval of a grading/building permit. This movement of existing
grade may involve the modification of existing retaining walls or placement of
retaining walls as long as the following conditions are met:
a. A maximum 10% grade alteration from the existing grade across a 20 foot
slope area is permitted (as long as the newly created slope area does not
exceed a 3:1 slope). Any new retaining walls cannot exceed 4 feet in
height.
b. Any additional height to existing walls cannot increase the height of the
wall above 4 feet.
c. Walls which exist over 4 feet in height may decrease in height but may not
increase in overall height.
d. Proposed drainage patterns and/or erosion control methods shall indicate
an improvement over the existing conditions on the site.
e. Grading, and filling, and excavations in all areas within the Shoreland
District necessary for the construction of structures, sewage treatment
systems and driveways under validly issued construction permits for these
facilities do not require the issuance of a separate grading and filling
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Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p8
permit. However, the grading and filling standards in this subsection must
be incorporated into the issuance of permits for construction of structures,
sewage treatment systems and driveways.
(2) Public roads and parking areas are regulated by Subsection 1104.403.
(3) Notwithstanding subsections (1) and (2) above, a grading and filling permit will
be required for:
a. The movement of more than 10 cubic yards of material on steep slopes
and within the shore impact zone; and
b. The movement of more than 50 cubic yards or 500 square feet.
(4) The following considerations and conditions must be adhered to during the
issuance of construction permits, conditional use permits, variances and
subdivision approvals:
a. Grading or filling in any wetland must be done in accordance with the
Wetland Conservation Act.
b. Alterations shall be designed and conducted in a manner that ensures
only the smallest amount of bare ground is exposed for the shortest time
possible;
c. Erosion control best management practices shall be used, where
necessary, for temporary bare soil coverage, and a permanent
vegetation cover shall be established as soon as possible:
d. Methods to minimize soil erosion and to trap sediments before they
reach any surface water feature shall be used.
e. Altered areas shall be stabilized to acceptable erosion control standards
consistent with the Public Works Design Manual.
f. Fill or excavated material shall not be placed in a manner that creates
an unstable slope;
g. Plans to place fill or excavated material on steep slopes shall be
reviewed by qualified professionals for continued slope stability and
shall not create finished slopes of 4:1 or greater:
h. Fill or excavated material shall not be placed in bluff impact zones:
i. Any alterations below the ordinary high water level of public waters shall
first be authorized by the Commissioner of Natural Resources under
Minnesota Statutes, Section 103G.241.
Zoning Ordinance
City of Prior Lake
June 1, 2009 1104/p9
j. Alterations of topography shall only be allowed if they are accessory to
permitted or conditional uses and do not adversely affect adjacent or
nearby properties; and
k. Placement of natural rock riprap, including associated grading of the
shoreline and placement of a filter blanket, is permitted if the finished
slope does not exceed 3 feet horizontal to 1 foot vertical, the landward
extent of the riprap is within 10 feet of the ordinary high-water level, and
the height of the riprap above the ordinary high-water level does not
exceed 3 feet.
Decrease in
slope angle
New wall
Existing wall
Increase slope angle,
3:1 maximum allowed
Remove existing wall
4 foot
maximum
20 foot
maximum
Bluff Slope
Cross-Section
Water body