HomeMy WebLinkAboutCity Council Ordinance 1995-02CITY OF PLYMOUTH
ORDINANCE NO. 95-2
AN ORDINANCE AMENDING THE ZONING ORDINANCE TO ESTABLISH
STANDARDS FOR THE PROTECTION OF WETLANDS
THE CITY COUNCIL OF THE CITY OF PLYMOUTH DOES HEREBY ORDAIN AS
FOLLOWS:
Section 1. Section 6 of the City's Zoning Ordinance is hereby amended by adding
Subdivision C as follows:
SUBDIVISION C - ESTABLISHING STANDARDS FOR THE PROTECTION OF
WETLANDS
1. Findings. Intent and Incorporation by Reference
The City has determined that wetlands serve to maintain water quality by filtering water that is
discharged into ground water aquifers and by retaining inorganic sediments, toxicants, and
nutrients. They also retain and reduce the discharge of phosphorus and transform nutrients from
their inorganic to organic forms, thereby, protecting streams and water bodies from
eutrophication and contamination. Wetlands also store runoff and reduce the velocity of and
magnitude of flood peaks. In addition, some wetlands receive the upward discharge of ground
water. These wetlands tend to support more stable biological communities since their water
temperatures and water levels tend to be more stable.
Wetland vegetation also reduces the energy of waves, currents, and other erosive forces and
serves to prevent the erosion of shoreline areas. In addition, aquatic vegetation provides food,
shelter, and special habitat for wildlife. All of these wetland characteristics provide valuable
recreation and education resources.
The City has also found that wetlands vary significantly in the degree that they have been
altered. Wetlands within the City exhibit great variations in their floral diversity, quality of
wildlife and fishery habitat, degree of fluctuation in response to storms, the extent to which
their shorelines have been altered or eroded, and their relative value in protecting water
quality. Therefore, the City has determined that it is necessary and beneficial to classify
wetlands based upon their functions and values. The City has also found that it is in the best
interest of the general health and welfare of the City to achieve no net loss of wetlands within
the community.
The City recognizes that a substantial amount of wetland degradation results from
sedimentation and nutrient loading related to construction projects. Therefore, the City finds it
necessary to require extraordinary measures to prevent such construction related degradation.
In addition to having regulations that affect the physical impacts within wetland areas the City
Ordinance, Wetland Protection
also finds that it is necessary to regulate the use of lands surrounding wetlands. Buffer strips
(as defined by this Subdivision), are necessary and beneficial to maintaining the health of
wetlands. These strips of land surrounding wetlands protect their shorelines from erosion,
while serving to filter sediment, chemicals and other nutrients before storm water discharges
into the wetland. Buffer strips are also beneficial in providing habitat for wildlife.
This ordinance hereby incorporates by reference the Wetlands Conservation Act of 1991
[Minn. Stat. 103G.221 et seq. (herein after referred to as the WCA)] and any future
amendments adopted by the legislature. Any activities exempted from the provisions of the
WCA are also exempted from the requirements of this ordinance, insofar as they relate to the
WCA. All wetlands, as defined in Section 4, Subdivision B of this ordinance, including those
governed by the Department of Natural Resources, are covered by the other provisions of this
Ordinance. Also, there are circumstances under which the strict enforcement of these
regulations may be unreasonable and in circumstances that meet the criteria established in
Section 11, Subdivision C of this code, departures from the strict application of these standards
may be permitted.
It is the intent of this ordinance to avoid the alteration and destruction of wetlands. When
wetlands are altered or destroyed, mitigation must be provided to recreate the functions and
values of the lost wetland.
2. Purpose and Implementation
Through the adoption and enforcement of this Subdivision, the City shall promote the general
health, safety, and welfare of its residents by both conserving and protecting wetlands and
requiring sound management practices and mitigation as provided for in the WCA when
development occurs in the vicinity of wetlands. Through the implementation of this subdivision,
the City seeks to accomplish the following purposes:
(a) To satisfy the requirements of the WCA as it may be amended and, thereby,
achieve no net loss of wetlands within the City;
(b) To balance the needs to preserve and protect natural resources and systems with
both the rights of private property owners and the need to support the efficient
use of developable land within the City;
(c) To preserve the natural character of the landscape through the maintenance of
wetland ecosystems;
(d) To promote water quality by maintaining the ability of wetlands to recharge
ground water and receive the discharge of ground water, to retain sediment and
toxicants and filter and strip nutrients from surface water runoff before it
discharges into community lakes and streams, thus avoiding the contamination and
eutrophication of these water features; and
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Ordinance, Wetland Protection
(e) To provide wildlife habitat and thereby support the maintenance of diversity of
both plant and animal species within the City.
To accomplish these purposes, the City will:
(a) Conduct an inventory of all wetlands within the City;
(b) Develop a system of classification for wetlands within the City and classify the
City's wetlands based upon their relative values related to floral diversity, wildlife
habitat, water quality protection, fishery habitat, flood storage, shoreline
protection, and aesthetic, recreational and education benefits.
(c) Prepare and maintain a comprehensive set of official maps identifying the location
and classification of all wetlands within the City.
(d) Establish wetland regulations that are coordinated with flood plain and shoreland
protection regulations.
(e) Require sound management practices to protect, conserve, maintain, enhance, and
improve the quality of wetlands within the community.
(I) Enforce standards for the alteration of wetlands when alteration is allowed,
including standards and procedures for the mitigation of the loss of wetland areas
and their functions and values, when alteration or destruction occurs.
(g) Obtain protective easements over or acquire fee title to wetlands as appropriate.
(h) Develop and maintain a program to educate the public about the numerous benefits
and features that wetlands provide and the adverse effects of improperly managed
urban development on wetlands.
3. General Provisions
(a) Identification and Delineation of Wetlands. This ordinance shall apply to all land
containing wetlands and land within the setback and buffer areas required by this
ordinance. Wetlands shall be subject to the requirements established herein, as
well as restrictions and requirements established by other applicable Federal, State,
and City ordinances and regulations. These wetland protection regulations shall
not be construed to allow anything otherwise prohibited in the zoning district
where the wetland area is located.
A wetland is land that meets the definition of "wetlands" set forth in this
Ordinance. Wetlands have been or will be identified and the wetland classification
as established by the officially adopted City maps shall be prima facie evidence of
the location and classification of a wetland. The official maps shall be developed
and maintained by the Community Development Department and are open to
inspection by the public. The presence or absence of a wetland on the official
maps does not represent a definitive determination as to whether a wetland
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Ordinance, Wetland Protection
covered by this ordinance is or is not present. Wetlands that are identified during
site specific delineation activities but do not appear on the official wetland maps
are still subject to the provisions of the Ordinance. It will be the responsibility of
an applicant to delineate the exact wetland boundary or to determine that no
wetland exists on a subject property. All delineations must be reviewed and
approved by the City. If an applicant questions whether a wetland exists or
disputes its classification, the applicant shall have the burden to supply detailed
information for review supporting the applicant's assertion, including but not
limited to, topographic, hydrologic, floristic and/or soil data deemed necessary by
the City to determine the jurisdictional status of the wetland, its exact boundary
and its classification. Wetland delineations supplied by applicants shall be certified
by a qualified wetland delineator. Wetland delineators must satisfy any
certification requirements that may be established by the U.S. Army Corps of
Engineers or the Minnesota Board of Water and Soil Resources.
This Subdivision establishes four wetland classifications as defined in the
Definitions section of this Ordinance; Exceptional Quality, High Quality, Medium
Quality, and Low Quality.
4. General Standards
The following standards apply to all lands within and/or abutting a wetland:
(a) Septic and soil absorption systems must be setback a minimum of 75 feet from the
City approved boundary of the wetland.
(b) The lowest ground floor elevation shall be two feet above the 100 -Year flood
elevation or three feet above the Ordinary High Water Mark of public waters
regulated by Section 6, Subdivision B of this ordinance, which ever is greater.
(c) Structures intended to provide access across a wetland shall be prohibited unless a
permit is obtained in conformance with State Regulations.
(d) The MPCAs Best Management Practices shall be followed to avoid erosion and
sedimentation during the construction process.
(e) City inspection schedules and fines for erosion control will double on projects
abutting wetlands.
(f) Before the City issues a building permit for a lot with a required wetland buffer,
the lot owner shall:
(1) record a notice of the wetland buffer requirement against the title to the lot
with the office of the Hennepin County Recorder or Registrar of Titles, and
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Ordinance, Wetland Protection
(2) install the wetland monumentation required by Section 6, Subdivision C7
of this ordinance.
5. Wetland Buffer Strips and Setbacks
For lots of record created after January 3, 1995, a buffer strip shall be maintained abutting all
wetlands. The setback and buffer provisions of this ordinance shall not apply to lots of record on
January 3, 1995, to developments for which conditional use permits, site plans, preliminary plats,
final plats or preliminary or final planned unit development plans have been approved by the City
within two (2) years prior to January 3, 1995, or to developments for which complete applications
for any of the above actions have been accepted by the City for review, but not yet acted upon,
prior to January 3, 1995, or to sites that have undergone substantial improvements or alterations
prior to January 3, 1995. The City does however, strongly encourage the use of a wetland buffer
and setback on all lots in the City.
Wetland buffer strips and structure setbacks shall apply to all parcels of land whether or not the
wetland is on the same parcel as a proposed development.
Buffer strip vegetation shall be established and maintained in accordance with the requirements
found in this Subdivision. During the first two years, any buffer vegetation that does not survive
must be replanted. After two years, if the condition of the buffer area changes through natural
processes not caused by the property owner, the owner shall not be required to reestablish the
buffer area to meet the standards contained in Section 6, Subdivision C, 8. Buffer strips shall be
identified within each lot by permanent monumentation approved by the City.
For roadways that must be aligned either adjacent to or across wetlands and are subject to WCA
replacement requirements, additional wetland filling to create a buffer strip shall not be required.
Trails that are intended to serve an interpretive function may also be exempted from the buffer
requirement. All other roadways and trails shall meet the setbacks and buffer standards
established in either Section 6, Subdivision C 5 or C 6 below.
If the area of the buffer has a preconstruction slope of 12 percent or greater, the buffer shall be at
the applicable maximum width for the wetland classification. The use of a meandering buffer strip
to maintain a natural appearance is encouraged but not required in areas of flat topography.
The required buffer widths and setbacks shall apply to structures, roadways and trails in all zoning
districts.
Ordinance, Wetland Protection
Wetland Buffer and Setback
Exceptional
Hiah
Medium
Low
Wetland Buffer Width (Min.):
50'
40'
20'
10'
Wetland Buffer Width (Max.):*
100'
60'
40'
20'
Wetland Buffer Average Width:
75'
50'
30'
15'
Structure Setback (from Buffer):**
15'
15'
15'
15'
Total (Average):
90'
65'
45'
30'
* Buffer widths in excess of the listed maximums shall not be used in calculating the average
buffer width.
** These setbacks shall take precedence over other setbacks required in this ordinance.
6. Alternative Wetland Buffer Strips and Setbacks: With Extraordinary Management Measures
Recognizing that there are instances where because of the unique physical characteristics of a
specific parcel of land, narrower buffer strips may be necessary to allow for the reasonable use of
the land, the City has developed alternative buffer strip standards that may be applied in these
instances.
The City Council may approve alternative standards, based on an assessment of the following:
(a) size of the parcel
(b) existing roads and utilities
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Ordinance, Wetland Protection
(c) percentage of parcel impacted by wetlands
(d) configuration of wetlands on the parcel
(e) quality of the affected wetland(s)
The City Council will evaluate the appropriateness of using the alternative standards as part of its
review of a General Development Plan or in the case of a Planned Unit Development, a Concept
Plan. An applicant must receive Council approval through either of these review processes prior
to submitting a preliminary plan or plat application that applies the alternative buffer strip
standards.
In instances where the City Council approves alternative buffer standards, an applicant will be
required to apply extraordinary management measures to control erosion, sedimentation and
nutrient loading during and for two years after construction. The applicant must demonstrate that
the proposed measures will limit disolved phosphorus concentration to one milligram per liter
(mg/1) or less. Buffer strips and structure setbacks shall meet the following standards:
Alternative Wetland Buffers and Setbacks,
With Extraordinary
Measures
Exceptional
Hi¢h
Medium
Low
Wetland Buffer Width (Minimum)
25'
20'
10'
S'
Wetland Buffer Width (Maximum)*
50'
30'
20'
15'
Average Wetland Buffer Width
30'
25'
15'
10'
Structure Setback (from Buffer)* *
15'
15'
15'
15'
Total (Average):
45'
40'
30'
25'
*Buffer widths in excess of the fisted maximums shall not be used in calculating the average buffer
width.
**These setbacks shall take precedence over other setbacks required in this ordinance.
Extraordinary management measures that may be permitted in conjunction with and up-slope from
the above buffer strip and setback requirement include, but are not limited to measures that add
redundant protections to normal required Best Management Practices.
The applicant shall be responsible to submit all of the necessary information to document that the
proposed extraordinary construction and stormwater management practices (hereinafter referred
to as "Extraordinary Management Practices") will at least duplicate the performance of the
required buffers and setbacks, if not exceed it. The applicant shall also have the burden of
proving that the purpose and objectives of the ordinance will be met through the use of these
Extraordinary Management Practices.
The approval of any Extraordinary Management Practices shall be conditioned upon a site
improvement performance agreement (Section 11, Subdivision A, 11), that includes a binding
commitment to the maintenance of the proposed alternative treatments throughout their useful
life.
7. Monument Required
A monument is required at each lot fine where it crosses a wetland buffer with a maximum
spacing of 200 feet of wetland edge. If no buffer is required, the monument shall be at the edge
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Ordinance, Wetland Protection
of the wetland.
8. Buffer Strip Vegetation Performance Standards
(a) Where acceptable natural vegetation exists in buffer strip areas, the retention of such
vegetation in an undisturbed state is preferred. A buffer strip has acceptable natural
vegetation if it:
(1) has a continuous, dense layer of perennial grasses that have been uncultivated or
unbroken for at least 10 consecutive years, or
(2) has an overstory of trees and/or shrubs with at least 80 percent canopy closure that
have been uncultivated or unbroken for at least 10 consecutive years, or
(3) contains a mixture of the plant communities described in (1) and (2) above, that
have been uncultivated or unbroken for at least 10 consecutive years.
(b) Notwithstanding the above performance standards, the City may determine existing buffer
vegetation to be unacceptable if,
(1) it is composed of undesirable plant species (including, but not limited to reed
canary grass, common buckthorn, purple loosestrife, leafy spurge and noxious
weeds), or
(2) it is lacking a layer of organic thatch or duff, or
(3) has topography that tends to channelize the flow of surface runoff, or
(4) for some other reason it is unlikely to retain nutrients and sediment.
(c) Where buffer areas, or a portion thereof, are not vegetated or have been cultivated or
otherwise disturbed within 10 years of the permit application, such areas shall be re-
planted and maintained according to each of the following standards:
(1) Buffer zones shall be planted with a seed mix containing 100 percent perennial
native plant species, except for a one-time planting of an annual nurse or cover
crop such as oats or rye.
(2) The seed mix to be used shall consist of at least 12 pounds pure live seed (PLS)
per acre of native prairie grass seed and 5 pounds PLS per acre of native forbs.
Native prairie grass and native forb mixes shall contain no fewer than four (4) and
(5) species respectively.
(3) The annual nurse or cover crop shall be applied at a rate of 20 pounds per acre.
(4) Native shrubs may be substituted for forbs. Such shrubs may be bare root
seedlings and shall be planted at a rate of 60 plants per acre. Shrubs shall be
distributed so as to provide a natural appearance and shall not be planted in rows.
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Ordinance, Wetland Protection
(5) Any ground cover or shrub plantings installed in buffer areas are independent of
landscaping requirements set forth elsewhere in the City code and City policy.
(6) Native prairie grasses and forbs shall be planted by a qualified contractor using a
drill designed for native prairie grass seedings, such as a Truax or Nesbitt Native
Grass Drill or a John Deere 1550 Power -Till Seeder.
(7) No fertilizer shall be used in establishing new buffer zones, except on highly
disturbed sites when deemed necessary to establish acceptable buffer vegetation
and then limited to amounts indicated by an accredited soil testing laboratory.
(8) All seeded areas shall be mulched immediately with clean straw at a rate of 1.5
tons per acre. Mulch shall be anchored with a disk or tackifier.
(9) Buffer zones (both natural and created), shall be protected by silt fence during
construction and the fence shall remain in place until the area crop is established.
(10) Applicants may obtain from the City a set of standard seeding and planting
specifications for buffer zones which meet all the City requirements.
During the first two years, the developer shall replant any buffer vegetation that does not survive.
After two years, if the condition of the buffer area changes through natural processes not caused
by the property owner, the owner shall not be required to reestablish the buffer area to meet the
standards established in this section.
9. Encroachment in Required Setback and Buffer Areas
Patios and decks may encroach up to a maximum of 6 ft. into required structure setback areas.
Porches may not encroach into required setback areas. Buffer areas must be kept free of all
structures, including fences and play equipment.
10. Variances
(a) Requests for variances shall be made in accordance with the procedures and
requirements set forth in Section 11, Subdivision C of this Ordinance.
(b) Variances shall only be granted when the standards and criteria set forth in Section
11, Subdivision C of this Ordinance have been met. Variances shall not be granted
which would circumvent the intent and purposes of this subdivision.
Section 2. Repealer. Ordinance 94-08, an ordinance amending the Zoning Ordinance
Requirements for yard areas abutting wetlands, is hereby repealed.
Section 3. Section 4, Subdivision B (Definitions) of the City's Zoning Ordinance shall be
amended by revising the following definitions and adding others to read as follows:
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Ordinance, Wetland Protection
Buffer Strip An area of vegetated ground cover abutting a wetland that, either in its natural
condition or through intervention, has the characteristics identified in Subdivision B,
Section 6, Subdivision C, 8(a),(b), and (c).
Building Line Setback The distance between the building line and the property line or, in the
case of a shoreland yard, the ordinary high water level, or, in the case of a lot
containing or adjacent to all or a portion of a wetland, the nearest edge of the wetland
buffer.
Vegetation, Native The pre -settlement group of plant species native to the North American
continent that were not introduced as a result of European settlement.
Wetland Lands transitional between terrestrial and aquatics systems where the water table is
usually at or near the surface or the land is covered by shallow water. For purposes of this
definition, wetlands must have three of the following attributes:
(1) A predominance of hydric soils;
(2) Inundated or saturated by surface or ground water at a frequency and duration
sufficient to support a prevalence of hydrophytic vegetation typically adapted for
life in saturated soil conditions;
(3) Under normal circumstances support a prevalence of such vegetation.
Wetlands, Exceptional Quality Exceptional Quality wetlands contain an abundance of different
plant species with dominance evenly spread among several species. Such wetlands may
support some rare or unusual plant species. Invasive or exotic plant species are either
absent or limited to small areas where some disturbance has occurred. This higher level
of plant species diversity generally provides high wildlife habitat value and may also
support rare wildlife species. The shorelines of exceptional quality wetlands are natural
and unaffected by erosion. These wetlands exhibit no evidence of significant man induced
water level fluctuation. Exceptional Quality wetlands provide excellent water quality
protection, high aesthetic quality, and provide excellent opportunities for educational and
scientific activities within the community.
Wetlands, High Quality High quality wetlands are still generally in their natural state and tend
to show less evidence of adverse effects of surrounding land uses. Exotic and invasive
plant species may be present and species dominance may not be evenly distributed among
several species, however, a minimum of twenty different species can be found within the
basin. There tends to be little evidence of water level fluctuation due to storms and their
shorelines are stable with little evidence of erosion. The combination of these factors
result in these wetlands being judged as providing a greater level of water quality
protection and significantly better wildlife habitat. They show little if any evidence of
human influences and their greater levels of species diversity, wildlife habitat and
ecological stability results in higher aesthetic quality. These characteristics also offer
opportunities for educational or scientific value to the community.
Wetlands, Low Quality Wetlands included in this category have been substantially altered by
agricultural or urban development that caused over nitrification, soil erosion,
sedimentation and water quality degradation. As a result of these factors these wetlands
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Ordinance, Weiland Protection
exhibit low levels of plant species diversity and the overcrowding and dominance of such
invasive species as reed canary grass and a related reduction in the quality of wildlife
habitat. These wetlands may also tend to exhibit extreme water level fluctuations in
response to storms and show evidence of shoreline erosion. While these wetlands do
provide for water quality and serve an important role in protecting water quality
downstream, the combination of these characteristics cause these wetlands to provide low
levels of water quality protection and to have poor aesthetic quality. They often exhibit
evidence of significant human influences and they are deemed to be of little educational or
scientific value to the community.
Wetlands, Medium Quality Medium quality wetlands have a slightly higher number of plant
species present than Low Quality wetlands, often with small pockets of indigenous species
within larger areas dominated by invasive or exotic species. Their relatively greater
species diversity results in slightly better wildlife habitat. They exhibit evidence of
relatively less fluctuation in water level in response to storms and less evidence of
shoreline erosion. As a result of these characteristics, these wetlands provide somewhat
better water quality protection. They also exhibit relatively less evidence of human
influences and therefore, tend to be of a higher aesthetic quality. These wetlands are still
judged to be of limited educational or scientific value to the community.
Wildlife Habitat Plant Communities which support wildlife in a natural, undomesticated state.
Yard Any open space on the same lot with a building, unoccupied and unobstructed by any
portion of a structure from the ground upward, except as otherwise provided herein. In
measuring a yard for the purpose of determining the width of a side yard, the mean
horizontal distance between the lot line and the main building shall be used except in
the case of a lot containing or adjacent to all or a portion of a wetland, in which case
the distance between the nearest edge of the wetland buffer and the main building shall
be as provided by Section 6, Subdivision 5.
Yard, Front A yard extending across any street frontage of a lot between the side lot lines
and being the minimum horizontal distance between any street line and main building
or any projections thereof other than the projections of the unusual steps, entranceway,
unenclosed balconies or open porch. In the case of a lot containing or adjacent to all or
a portion of a wetland, the front yard shall be the minimum horizontal distance between
the nearest edge of the wetland buffer and the main building and the permitted
projections, as provided by Section 6, Subdivision 5.
Yard, Rear A yard extending across the rear of a lot, measured between the side lot lines,
and being the minimum horizontal distance between the rear lot line and the rear of the
main building or any projections other than steps, enclosed balconies or unenclosed
porches. On corner lots the rear yard shall be considered as parallel to the street upon
which the lot has its least dimension. On both corner lots and interior lots the rear yard
shall in all cases be at the opposite end of the lot from the front yard. On all lots
containing or adjacent to all or a portion of a wetland, the rear yard shall be the
minimum distance between the nearest edge of the wetland buffer and the main
building and the permitted projections, as provided by Section 6, Subdivision 5.
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Ordinance, Wetland Protection
Yard, Side A yard between the main building and the side line of the lot and extending from
the front yard line to the rear yard line, except in the case of a lot containing or
adjacent to all or a portion of a wetland, in which case the side yard is between the
nearest edge of the wetland buffer and the main building, as provided by Section 6,
Subdivision 5.
Section 4. Section 7, Subdivision D, of the City's Zoning Ordinance providing for minimum
front yard requriements in residential districts, is hereby amended by revising section 7 as
follows:
7. Minimum Front Yard in Feet
(Applies to Each Street Frontage)
a. Dwellings, abutting an Arterial Street
50
50
50
50
b. Other Uses
100
50
50
50
c. Dwellings, one family
50
25
25
25
d. Dwellings, two family
50
25
25
25
e. Dwellings, over two family
--
--
35
35
f. Adult Correctional Facility
200
200
200
200
50 50
50 50
25 25
35 35
200 200
Section 5. Effective Date. This Ordinance shall take effect upon its passage and publication.
Adopted by the City Council this 3rd day of January, 1995.
J ay
ATTEST
City Clerk
cc: File
cd\plan\codes\zoning\wetland2. doc
Published: Sun Sailor 1-25-95.
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