HomeMy WebLinkAbout0776 Ord (Storm Water Management)
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ORIDIl~ANCE NO. 776
BE IT RESOLVED, by the city council of the city of stillwater
that an ordinance amendment has been adopted by the city council
amending the stillwater city Code by adding Chapter 31, Subd. 29,
"Storm Water Management," and that the Council by four-fifths of
its members, does find that the attached Title and summary of the
ordinance as prepared by the City Attorney, does clearly inform the
public of intent and effect of the ordinance and the form of
publication is approved. This action is given as authorized by the
stillwater City Charter, Article V, Sf. The form that shall be
published is as set forth hereafter:
TITLE AND SUMMARY
ORDINANCE NO. 776
AN ORDINANCE AMENDING THE CITY OF STILLWATER
CITY CODE, BY ADDING CHAPTER 31, SUBD. 29
STORM WATER MANAGEMENT
1. The ordinance prohibits development within the City that
involves land disturbing activity unless a Storm Water Management
Plan is approved by the community Development Director.
2. This ordinance provides for the procedure to be used and
the standards to be applied when the Community Development Director
reviews a Storm Water Management Plan.
3. The ordinance requires that Storm Water Management plans
are consistent with Minnesota Statute S103B.231 and 103B.255, and
the Rules of the Minnesota Board of Water and Soil Resources.
4. A printed copy of the ordinance is available for
inspection by any person during the regular office hours of the
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City Clerk, and during regular office hours at the stillwater
Public Library.
5. Effective Date. This ordinance shall be in full force and
effect from and after its passage and publication according to law.
Adopted by the City Council of stillwater this 3rd day of
August , 1993.
Attest:
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4It Publish: October 21, 1993
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ORDINANCE NO. 776
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AN ORDINANCE PROMOTING THE HEALTH, SAFETY AND GENERAL WELFARE
OF THE CITIZENS OF STILLWA'1'ER, MINNESOTA, BY AMBNDllIG THE ZONING
ORDINANCE, ADOPTING NKW SECTIONS REQUIRING S'.L'ORM WATER ~ PRACTICES
The City Council of the City of Stillwater does ordain:
1. Amending the City Code of the City of Stillwater is amended by adding the
following section that shall hereafter read as follows:
"Subdivision 29.
1. Statutory Authorization. This ordinance is adopted pursuant to Minnesota
statutes Section 462.351.
2.
Findings. The City of Stillwater hereby finds that uncontrolled and
inadequately planning use of wetlands, woodlands, natural habitat areas,
areas subject to soil erosion and areas containing restrictive soils
adversely affects the public health, safety and general welfare by
impacting water quality and contributing to other environmental problems,
creating nuisances, impairing other beneficial uses of environmental
resources and hindering the ability of th City of Stillwater to provide
adequate water, sewage, flood control and other community services. In
addition, extraordinary public expenditures may be required for the
protection of persons and property in areas which may be affected by
unplanned land usage.
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3. Purpose. The purpose of this ordinance is to promote,. preserve and enhance
the natural resources within the City of Stillwater and protect them from
adverse effects caused by poorly sited development or incompatible
activities by regulating land disturbing or development activities that
would have an adverse and potentially irreversible impact on water quality
and unique and fragile environmentally sensitive land; by minimizing
conflicts and encouraging compatibility between land disturbing and
development activities and water quality and environmentally sensitive
lands; and by requiring detailed review standards and procedures for land
disturbing or development activities proposed for such areas, thereby
achieving a balance between urban growth and development.
4. Scope and Effect.
4.1 Applicability. Every applicant for subdivision Planned Unit Developemnt
or a permit to allow land disturbing activities must submit a storm water
management plan to the Department of Community Development. No building
permit, subdivision approval or permit to allow land disturbing activities
shall be issued until approval of the storm water management plan or a
waiver of the approval requirement has been obtained in strict conformance
with the provisions of this ordinance.
4.2 Exemptions. The provisions of this ordinance do not apply to:
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a.
Any part of a subdivision if a plat for the subdivision has been
approved by the City on or before the effective date of this
ordinance.
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b. Any land disturbing activity for which plans have been approved by
the watershed management organization within six months prior to the
effective date of this ordinance.
c. A lot for which a building permit has been approved on or before the
effective date of this ordinance.
d. Installation of fence, sign, telephone and electric poles and other
kinds of posts or poles.
e. Emergency work to protect life, limb or property.
5. storm Water Management Plan Approval Procedures.
5.1
Application. A written application for storm water management plan
approval, along with the proposed storm water management plan, shall be
filed with the Department of Community Development and shall include a
statement indicating the grounds upon which the approval is requested, that
the proposed use is permitted by right or as an exception in the underlying
zoning district, and adequate evidence showing that the proposed use will
conform to the standards set forth in this ordinance. Prior to applying
for approval of a storm water management plan, an applicant may have the
storm water management plans reviewed by the City Engineers.
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5.2 storm Water Management Plan. At a minimum, the storm water management plan
shall contain the following information:
a. Existing Site Map. A map of existing site conditions showing the
site and immediately adjacent areas including:
1. The name and address of the applicant, the section, township
and range, north point, date and scale of drawing and number
of sheet;
2. location of the tract by an insert map at a scale sufficient
to clearly identify the location of the property and giving
such information as the streets and numbers of adjoining roads,
railroads, utilities; subdivisions, towns and districts or
other landmarks;
3. Existing topography with a contour interval appropriate to the
topography of the land but in no case having a contour interval
greater than 2 feet; (Use urban sea level as a base).
4.
A delineation of all streams, rivers, public waters and
wetlands located on and immediately adjacent to the site,
including depth of water, a description of all vegetation which
may be found in the water, a statement of general water quality
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and any classification given to the water body or wetlands by
the Minnesota Department of Natural Resources, the Minnesota
Pollution Control Agency and/or United states Corp of
Engineers;
5.
location and dimensions of existing storm water drainage
systems and natural drainage patterns on and i1mnediately
adjacent to the site delineating in which direction and at what
rate storm water is conveyed from the site, identifying and
receiving stream, river, public water or wetland and setting
forth those areas of the unaltered site where storm water
collects;
6.
a description of the soils of the site, including a map
indicating soil types of areas to be disturbed as well as a
soil report containing information on the suitability of the
soils for the type of development proposed and for the type
of sewage disposal proposed and describing any remedial steps
to be taken by the developer to render the soils suitable;
7. vegetative cover and clearly delineating any vegetation
proposed for removal; and
8. 100 year floodplains, flood fringes and floodways.
b.
Site Construction Plan. A site construction plan shall contain the
following information:
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1. Locations and dimensions of all proposed land disturbing
activities and any phasing of those activities;
2. locations and dimensions of all temporary soils or dirt
stockpiles;
3. locations and dimensions of all constructions site erosion
control measures necessary to meet the requirements of this
ordinance.
4. schedule of anticipated starting and completion date or each
land disturbing activity including the installation of
construction site erosion control measures needed to meet the
requirements of this ordinance; and
5. provisions for maintenance of the construction site erosion
control measures during construction.
c. Plan of Final Site Conditions. A plan of final site conditions on
the same scale as the existing site map showing the site changes
including:
1.
Finished grading shown at contours at the same interval as
provided above or as required to clearly indicate the
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relationship of proposed changes to existing topography and
remain features;
2.
a landscape plan, drawn to an appropriate sca~e, including
dimensions and distances and the location, type, size and
description of all proposed landscape materials which will be
added to the site as part of the development.
3.
a drainage plan of the developed site delineating in which
direction and at what rate storm water will be conveyed from
the site and setting forth the areas of the site where storm
water will be allowed to collect;
4.
the proposed size, alignment and intended use of any structures
to be erected on the site;
5.
a clear delineation and tabulation of all areas which shall
be paved or surfaced, including a description of the surfacing
material to be used; and
6.
any other information pertinent to the particular project which
in the opinion of the applicant is necessary for the review
of the project.
6. Plan Review Procedure.
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6.1
Process. storm water management plans meeting the requirements of Section
5 shall be submitted by the Community Development Director to the Planning
Commission for review in accordance with the standards of Section 7.
6.2 Duration. Approval of a plan submitted under the provisions of this
ordinance shall expire one year after date of approval unless construction
has commenced in accordance with the plan. However, if prior to the
expiration of the approval, the applicant makes a written request to the
Community Development Director for an extension of time to commence
construction setting fort the reasons for the requested extension, the
Planning Department may grant one extension of not greater than one single
year. Receipt of any request for an extension shall be acknowledged by
the Department of Community Development within 15 days. The Department
of Community Development shall make a decision on the extension within 30
days of receipt. Any plan may be revised in the same manner as originally
approved.
Conditions. A storm water management plan may be approved subject to
compliance with conditions reasonable and necessary to insure that the
requirements contained in this ordinance are met. Such conditions may,
among other matters, limit the size, kind or character of the proposed
development, require the construction of structures, drainage facilities,
storage basins and other facilities, require replacement of vegetation,
establish required monitoring procedures, stage the work over time, require
alteration of the site design to insure buffering and require the
conveyance to the City of Stillwater or other public entity of certain
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lands or interest therein.
6.4
Performance Bond. Prior to approval of any storm water management plan,
the applicant may be required to submit an agreement to construct such
required physical improvements, to dedicate property or easements or to
comply with such conditions as may have been agreed to. Such agreement
shall be accompanied by a bond to cover the amount of the established cost
of complying with the agreement. The agreement and bond shall guarantee
completion and compliance with conditions within a specific time, which
time may be extended in accordance with Section 6.2.
6.5 Fees. All applications for a storm water management plan approval shall
be accompanied by a processing and approval fee of $50 and actual
engineering costs.
7 . Approval Standards.
7.1 No storm water management plan which fails to meet the standards contained
in this section shall be approved.
(COMMENTARY: Sections 7.2 through 7.16 are an example of how best
management practices for handling storm water runoff and design criteria
for detention ponds can be included within an ordinance. Additional best
management practices and design criteria can be found in the MPCA
publication "Protecting Water Quality in Urban Areas".
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7.2
Site Dewatering. 'Water pumped from the site shall be treated by temporary
sedimentation basins, grit chambers, sand filters, upflow chambers, hyro-
cycones, swirl concentrators or other appropriate controls as appropriate.
'Water may not be discharged in a manner that causes erosion or flooding
of the site or receiving channels or a wetland.
7.3 'Waste and Material Disposal. All waste and unused building materials
(including garbage, debris, cleaning wastes, wastewater, toxic materials
or hazardous materials) shall be properly disposed of off-site and not
allowed to be carried by runoff into a receiving channel or storm sewer
system.
7.4 Tracking. Each site shall be graveled roads, access drives and parking
areas of sufficient width and length or prevent sediment from being tracked
onto public or private roadways. Any sediment reaching a public or private
road shall be removed by street cleaning (not flushing) before the each
of each workday.
7.5 Drain Inlet Protection. All storm drain inlets shall be protected during
construction until control measures are in place with a straw bale, silt
fence or equivalent barrier meeting accepted design criteria, standards
and specifications contained in the MPCA publication "Protecting 'Water
Quality in Urban Areas".
7.6
Site Erosion Control. The following criteria (a through d) apply only to
construction activities that result in runoff leaving the site.
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a.
Channelized runoff from adjacent areas passing through the site shall
be diverted around disturbed areas, if practical. Otherwise, the
channel shall be protected as described below. Sheetflow runoff from
adjacent areas greater than 10,000 square feet in area shall also
be diverted around disturbed areas, unless shown to have resultant
runoff of less than 0.5 f e. 3/ see.. across the disturbed area for one
year storm. Diverted runoff shall be conveyed in a manner that will
not erode the conveyance and receiving channels.
b. All activities on the site shall be conducted in a logical. sequence
to minimize the area of bare soil at anyone time.
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c. Runoff from the entire disturbed area on the site shall be controlled
by meeting either subsections 1 and 2 or 1 and 3.
1. All disturbed ground left inactive for fourteen or more days
shall be stabilized by seeding or sodding (only available prior
to September 15) or by mulching or covering or other equivalent
control measures,
2.
For sites with more than ten acres disturbed at one time, or
if a channel originates in the disturbed area, one or more
temporary or permanent sedimentation basins shall be
constructed. Each sedimentation basin shall have a surface
area of at least one percent of the area draining to the basin
and at least three feet of depth and constructed in accordance
with accepted design specifications. Sediment shall be removed
to maintain a depth of three feet. The basin discharge rate
shall also be sufficiently low as to not cause erosion along
the discharge channel or the receiving wat,er.
3. For sites with less than ten acres disturbed at one time, silt
fences, straw bales or equivalent control measures shall be
placed along all sideslope and downslope sides of the site.
If a channel or area of concentrated runoff passes through the
site, silt fences shall be placed along the channel edges to
reduce sediment reaching the channel. The use of silt fences,
straw bales or equivalent control measures must included a
maintenance and inspection schedule.
d.
Any sailor dirt storage piles containing more than ten cubic yards
of material should not be located with a downslope drainaq-e length
of less than 25 feet from the toe of the pile to a roadway or
drainage channel. If remaining for more than seven days, they shall
be stabili by mulching, vegetative cover, tarps or other means.
Erosion from piles which will be in existence for less than seven
days shall be controlled by placing straw bales or silt barriers
around the pile. In-street utility repair or construction sailor
dirt storage piles located closer than 25 feet of a roadway or
drainage channel must be covered with tarps or suitable alternative
control, if exposed for more than seven days and the stormdrain
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inlets must be protected with straw bales or other appropriate
filtering barriers.
7.7
storm Water Management Criteria for Permanent Facilities.
a. An applicant shall install or construct, on or for the proposed land
disturbing or development activity, all storm water management
facilities necessary to manage increased runoff so that the two-
year, ten-year and lOO-year storm peak discharge rates existing
before the proposed development shall not be increased and
accelerated channel erosion will not occur as a resul t of the
proposed land disturbing or development activity. An applicant may
also make an inkind or monetary contribution to the development and
maintenance of community storm water management facilities designed
to serve multiple land disturbing and development activities
undertaken by one or more persons, including the applicant.
b. The applicant shall give consideration to reducing the need for storm
water management facilities by incorporating the use of natural
topography and land cover such as wetlands, ponds, natural swales
and depressions as they exist before development to the degree that
they can accommodate the additional flow of water with out
compromising the integrity or quality of the wetland or pond.
c.
The following storm water management practices shall be investigated
in developing a storm water management plan in the following
descending order of preference:
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1. Infiltration of runoff on-site, if suitable soil conditions
are available for use;
2. Flow attenuation by use of open vegetated swales and natural
depressions.
3. storm water retention facilities; and
4. storm water detention facilities.
d. A combination of successive practices may be used to achieve the
applicable minimum control requirements specified in subsection (a)
above. Justification shall be provided by the applicant for the
method selected.
7.8 Design Standards. storm water detention facilities constructed in the City
of Stillwater shall be designed according to the National Urban Runoff
Program (NURP), wet basin design criteria and the urban best management
practices as reflected in the MPCA publication "Protecting Water Quality
in Urban Areas", and shall contain, at a minimum, the following design
factors.
a.
A permanent pond surface area equal to two percent of the impervious
area draining to the pond or one percent of the entire draining to
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the pond, whichever amount is greater;
b.
an average permanent pool depth of four to ten feet;
(COMMENTARY: An alternative to subsections (a) and (b) would be to
require that the volume of permanent pool be equal to or greater than
the runoff from a 2.0 inch rainfall for the fully developed site.)
c. a permanent pool length-to-width ratio of 3:1 or greater;
d. a minimum protective shelf extending ten feet into the permanent pool
with a slop of 10:1 beyond which slopes should not exceed 3:1;
e. a protective buffer strip of vegetation surrounding the permanent
pool at a minimum width of one rod (16.5 feet).
f. all storm water detention facilities shall have a device to keep oil,
grease and other floatable material from moving downstream as a
result of normal operations;
g. storm water detention facilities for new development must be
sufficient to limit peak flows in each subwatershed to those that
existed before the development for the 10-year storm event. Also,
calculations and hydrologic models/information used in determining
peak flows shall be submitted along with storm water management plan;
h.
all storm water detention facilities must have a forebay to remove
coarse-grained particles prior to discharge into a watercourse or
storage basin.
7.9 Wetlands.
a. Runoff shall not be discharged directly into wetlands without
presettlement of the runoff.
b. A protective buffer strip of natural vegetation at least one rod
(16.5 feet) in width shall surround all wetlands.
c. Wetlands must not be drained or filled, wholely or partial.ly, unless
replaced by restoring or creating wetland areas of at least equal
public value. Replacement must be guided by the following principles
in descending order of priority:
1.
Avoiding the direct or indirect impact of the activity that
my destroy or diminish the wetland;
2.
minimizing the impact by limiting the degree or magnitude of
the wetland activity and its implementation;
3.
Rectifying the impact by repairing, rehabilitating or restoring
the affected wetland environment;
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4.
Reducing or eliminating the impact over time by preservation
and maintenance operations during the life of the activity;
and
5. Compensating for the impact by replacing or providing
substitute wetland resources or environments. (Compensation
including the replacement ratio and quality or replacement
should be consistent with the requirements outlined in the
rules which will be adopted by the Board of Water and Soil
Resources to implement the Wetland Conservation Act of 1991.)
7.10 steep Slopes. No land disturbing or development activities shall be
allowed on slopes of 18 percent or more.
7.11 Catch Basins. All newly installed and rehabilitated catch basins shall
be provided with a sump area for the collection of coarse-grained material.
Such basins shall be cleaned when they are half filled with material.
7.12 Drain Leaders. All newly constructed and reconstructed buildings will
route drain leaders to pervious areas wherein the runoff can be allowed to
infiltrate. The flow ratio of water exiting the leaders shall be controlled so
no erosion occurs in the pervious areas.
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7 . 13 Inspections and Maintenance. All storm water management facilities shall
be designed to minimize the need of maintenance, to provide access for
maintenance purposes and to be structurally sound. All storm water management
facilities shall have a plan of operation and maintenance that assures continued
effective removal of pollutants carried in storm water runoff. The director of
public works, or designated representative, shall inspect all storm water
management facilities during construction, during the first year of operation
and at least once every five years thereafter. The inspection records will be
kept on file at the public works department for a period of six years. It shall
be the responsibility of the applicant to obtain any necessary easements or other
property interests to allow access to the storm water management facilities for
inspection and maintenance purposes.
7.14 Models/Methodologies/Computations. Hydrologic models and design
methodologies used for the determination of runoff and analysis of storm water
management structures shall be approved by the director of public works. Plans,
specifications and computations for storm water management facilities submitted
for review shall be sealed and signed by a registered professional engineer.
All computations shall appear on the plans submitted for review, unless otherwise
approved by the director of public works.
7.15 Watershed Management Plans/Groundwater Management Plans. storm water
management plans shall be consistent with adopted watershed management plans and
groundwater management plans prepared in accordance with Minnesota Statues
Section 103B.231 and 103B.255 respectively and as approved by the Minnesota Board
of Water and Soil Resources in accordance with state law.
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7.16 Easements. If a storm water management plan involved direction fall
runoff of the site, it shall be the responsibility of the applicant to obtain
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from adjacent property owners any necessary easements or other property interests
concerning flowage of water.
9. Other Controls. In the event of any conflict between the provlslons of
this ordinance and other provisions of the Zoning Ordinance, the more
restrictive standard prevails.
10. Severability. The provisions of this ordinance are severable. If any
provision of this ordinance or the application thereof to any person or
circumstances is held invalid, such invalidity shall not affect other
provisions of applications of this ordinance which can be given effect
without the invalid provisions or application."
11. Saving. In all other ways the Stillwater City Code shall remain in full
force and effect.
12. Publication. This ordinance shall be in full force and effect from and
after its passage and publication according to law.
Adopted by the City Council this 3rd of August 1993.
Attest:
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,/1 .~
/~ity clerk .
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