HomeMy WebLinkAbout#5 - PW Stormwater ordMEMO
To: Planning Commissioners
From: Tom Montgomery
Date: May 19, 2010
Re: New Storm Water Management Ordinance to Conform to VRWJPO
Rules
Enclosed for the Planning Commission consideration is a new Storm Water
Management Ordinance that conforms to the Vermillion River Watershed Joint
Powers Organization (VRWJPO) rules. The City is required to adopt the
VRWJPO rules in order to take over local development permit review from the
VRWJPO. The proposed new Storm Water Ordinance has few substantive
changes from the existing ordinance other than the following:
Design storms for determining runoff rates are clearly defined
Runoff volume control is required — improvements that create one acre
or more of additional impervious surface must hold any increase in
runoff volume from a 2 year /24 hr storm. Typically this runoff volume
increase would be controlled through the use of infiltration basins.
CHAPTER 152: STORM WATER MANAGEMENT
Section
152.01 Statutory authorization
152.02 Findings
152.03 Purpose
152.04 Definitions
152.05 Scope and effect
152.06 Storm water management plan approval procedures
152.07 Plan review procedure
152.08 Approval standards
152.09 Other controls
152.98 Violations
$ 152.01 STATUTORY AUTHORIZATION.
This chapter is adopted pursuant to M.S. §462.351, as it maybe amended from time to time.
(Prior Code, § 15.01)
$ 152.02 FINDINGS.
The City of Hastings hereby finds that uncontrolled and inadequately planned 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 the City of Hastings 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 the areas and in areas which may be
affected by unplanned land usage.
(Prior Code, § 15.02)
Hastings - Land Usage
$ 152.03 PURPOSE.
The purpose of this chapter is to promote, preserve, and enhance the natural resources within the
City of Hastings and protect them from adverse effects occasioned 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 the areas,
thereby achieving a balance between urban growth and development and protection of water quality
and natural areas.
(Prior Code, § 15.03)
$ 152.04 DEFINITIONS.
For the purpose of this chapter, the following definitions shall apply unless the context clearly
indicates or requires a different meaning.
APPLICANT. Any person who wishes to obtain a building permit, zoning or subdivision
approval.
CONTROL MEASURE. A practice or combination of practices to control erosion and attendant
pollution.
DETENTION FACILITY. A permanent natural or human -made structure, including wetlands, for
the temporary storage of runoff which has a storm water outlet and may have a permanent pool of
water.
DUAL PURPOSE POND. A detention facility without a permanent pool that functions as both a
storm water ponding basin and as a sedimentation basin. Sediment removal is accomplished through
the use of filter media surrounding a slotted outlet pipe, with an overflow outlet set at an elevation that
provides for minimum required run off volume and sediment storage.
FLOOD FRINGE. The portion of the flood plain outside of the floodway. FLOOD FRINGE is
synonymous with the term FLOODWAYFRINGE used in the Flood Insurance Study for the City of
Hastings.
FLOOD PLAIN. The beds proper and the areas adjoining a wetland, lake, or watercourse, which
have been or hereafter may be covered by the regional flood (The critical 100 -year storm).
FLOODWAY. The bed of a wetland or lake and the channel of the watercourse and those portions
of the adjoining flood plains which are reasonably required to carry or store the regional flood
discharge.
HYDRIC SOILS. Soils that are saturated, flooded, or ponded long enough during the growing
season to develop anaerobic conditions in the upper part.
HYDROPHYTIC VEGETATION. Macrophytic plant life growing in water, soil, or on a substrate
that is at least periodically deficient in oxygen as a result of excessive water content.
LAND DISTURBING OR DEVELOPMENT ACTIVITIES. Any change of the land surface
including removing vegetative cover, excavating, filling, grading, and the construction of any structure.
PERSON. Any individual, firm, corporation, partnership, franchisee, association, or governmental
entity.
PUBLIC WATERS. Waters of the state as defined in M.S. § 103G.005, Subdivision 15, as
amended.
REGIONAL FLOOD. A flood which is representative of large floods known to have occurred
generally in Minnesota and reasonably characteristic of what can be expected to occur on an average
frequency in the magnitude of the critical 100 -year recurrence interval. REGIONAL FLOOD is
synonymous with the term BASE FLOOD in the Flood Insurance Study.
RETENTION FACILITY. A permanent natural or man made structure that provides for the
storage of storm water runoff by means of a permanent pool of water.
SEDIMENT. Solid matter carried by water, sewage, or other liquids.
STRUCTURE. Anything constructed or erected on the ground or attached to the ground,
including, but not limited to, buildings, factories, sheds, cabins, mobile or manufactured homes, and
other similar items.
WETLANDS. Lands transitional between terrestrial and aquatic systems where the water table is
usually at or near the surface or the land is covered by shallow water no deeper than 6 feet. For
purposes of this definition, wetlands must have the following 3 attributes:
(1) Have a predominance of hydric soils;
(2) Are 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; and
(3) Under normal circumstances support a prevalence of the vegetation.
(Prior Code, § 15.04)
Hastings - Land Usage
$ 152.05 SCOPE AND EFFECT.
(A) Applicability. Every applicant for a building permit, subdivision approval, or a permit to
allow land disturbing activities must submit a storm water management plan to the Public Works
Department. 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
requirements has been obtained in strict conformance with the provisions of this chapter. The
provisions of § 152.09 apply to all land, public or private, located within the City of Hastings.
(B) Exemptions. The provisions of this chapter do not apply to:
(1) Any part of a subdivision if a plat for the subdivision has been approved by the City
Council on or before the effective date of this chapter;
(2) Any land disturbing activity for which plans have been approved by the watershed
management organization within 6 months prior to the effective date of this chapter;
chapter;
(3) A lot for which a building permit has been approved on or before the effective date of this
(4) Installation of fence, sign, telephone, and electric poles and other kinds of posts or poles
gardening, tree planting, deck construction, and other types of construction disturbing 1/3 acre or less;
or
(5) Emergency work to protect life, limb, or property.
(C) Waiver. The City Council may waive any requirement of this chapter upon making a finding
that compliance with the requirement will involve an unnecessary hardship and the waiver of the
requirement will not adversely affect the standards and requirements set forth in § 152.06. The City
Council may require as a condition of the waiver, the dedication or construction, or agreement to
dedicate or construct as may be necessary to adequately meet the standards and requirements.
(Prior Code, § 15.05)
$ 152.06 STORM WATER MANAGEMENT PLAN APPROVAL PROCEDURES.
(A) Application.
(1) A written application for storm water management plan approval, along with the
proposed storm water management plan, shall be filed with the Public Works Department 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
Storm Water Management
proposed use will conform to the standards set forth in this chapter. Prior to applying for approval of a
storm water management plan, an applicant may have the storm water management plans reviewed by
the appropriate departments of the city.
(2) Two sets of clearly legible blue or black lined copies of drawings and required
information shall be submitted to the Public Works Department and shall be accompanied by all
required fees for processing and approval as set forth in § 152.07(E), and a bond when required by
§ 152.07(D) in the amount to be calculated in accordance with that section. Drawings shall be
prepared to a scale appropriate to the site of the project and suitable for the review to be performed.
The drawing size shall be limited to a maximum of 22 inches by 34 inches and the drawing scale may
range from a maximum of 1 inch equals 20 feet to a minimum of 1 inch equals 100 feet.
(B) Storm water management plan. At a minimum, the storm water management plan shall
contain the following information:
(1) Existing site map. A map of existing site conditions showing the site and immediately
adjacent areas, including:
(a) The name and address of the applicant, the section, township and range, north
direction arrow, date and scale of drawing and number of sheets;
(b) Location of the tract by an insert map at a scale sufficient to clearly identify the
location of the property and giving the information as the names and numbers of adjoining roads,
utilities, subdivisions, towns and districts or other landmarks;
(c) 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;
(d) 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 and any classification given to the water body
or wetland by the Minnesota Department of Natural Resources, the Minnesota Pollution Control
Agency, the Dakota County Soil and Water Conservation District, Vermillion River Watershed Joint
Powers Organization, and /or the United States Army Corps of Engineers;
(e) Location and dimensions of existing storm water drainage systems and natural
drainage patterns on and immediately adjacent to the site delineating in which direction and at what
rate storm water is conveyed from the site, identifying the receiving stream, river, public water, or
wetland, and setting forth those areas of the unaltered site where storm water collects;
Hastings - Land Usage
(f) 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 including special rotations locating where
erosion soils exist on the site;
(g) Vegetative cover and clearly delineating any vegetation proposed for removal; and
(h) One hundred -year flood plain, flood fringes and floodways.
(2) Site construction plan. A site construction plan including:
(a) Locations and dimensions of all proposed land disturbing activities and any phasing
and phasing time frame of those activities;
(b) Locations and dimensions of all temporary soil or dirt stockpiles;
(c) Locations and dimensions of all construction site erosion control measures necessary
to meet the requirements of this chapter;
(d) Schedule of anticipated starting and completion date of each land disturbing activity
including the installation of construction site erosion control measures needed to meet the requirements
of this chapter (in general the erosion control measure shall be installed prior to any grading activity);
and
(e) Provisions for maintenance of the construction site erosion control measures during
construction.
(3) 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:
(a) Finished grading shown at contours at the same interval as provided above or as
required to clearly indicate the relationship of proposed changes to existing topography and remaining
features;
(b) A landscape plan, drawn to an appropriate scale, 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;
(c) 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;
Storm Water Management
(d) The proposed size, alignment, and intended use of any structures to be erected on the
site;
(e) 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
(f) Any other information pertinent to the particular project which in the opinion of the
applicant and /or the city is necessary for the review of the project.
(Prior Code, § 15.06)
$ 152.07 PLAN REVIEW PROCEDURE.
(A) Process. Applicant prepared storm water management plans meeting the requirements of
§ 152.06 shall be submitted to the Public Works Department for review in accordance with the
standards of § 152.08. City Council action on the storm management plan must be accomplished
within 120 days following the date the application for approval is filed with the Public Works
Department.
(B) Duration. Approval of a plan submitted under the provisions of this chapter shall expire 1
year after the 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 Public
Works Department for an extension of time to commence construction setting forth the reasons for the
requested extension, the Public Works Department may grant an extension of not greater than 1 single
year. Receipt of any request for extension shall be acknowledged by the Public Works Department
within 15 days. The Public Works Department shall make a decision on the extension within 30 days
of receipt. Any plan may be revised in the same manner as originally approved.
(C) 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 chapter are met.
The 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 placement 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 Hastings or other public entity of certain lands or interests herein.
(D) Performance bond. Prior to approval of any storm water management plan, the applicant shall
submit an agreement to construct the required physical improvements, to dedicate property or
easements, or to comply with the conditions as may have been agreed to. The agreement shall be
accompanied by a performance bond to cover the amount of the established cost of complying with the
agreement. The agreement and performance bond shall guarantee completion and compliance with
conditions within a specific time, which time may be extended in accordance with division (B) above.
The performance
Hastings - Land Usage
bond amount shall be determined by the Director of Public Works, and shall be set at 125% of the
estimated cost of the required improvement. The adequacy, conditions and acceptability of any
agreement and performance bond shall be determined by the Hastings City Council or any official of
the City of Hastings as may be designated by resolution of the City Council.
(E) Fees. All applications for storm water management plan approval shall be accompanied by a
processing and approval fee as required by ordinance.
(Prior Code, § 15.07)
$ 152.08 APPROVAL STANDARDS.
(A) Site dewatering. Water pumped from the site shall be treated by temporary sedimentation
basins, grit chambers, sand filters, upflow chambers, hydro - cyclones, 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.
(B) 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 off by runoff into a receiving channel or storm sewer system.
(C) Tracking. Each site shall have graveled roads, access drives, and parking areas of sufficient
width and a length providing a minimum of 50 feet of maintained graveled surface both from the edge
of the public or private roadway to 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 end of each workday. Failure to keep the public or private roadway clean may
result in the city ordering construction halted until the time as the roadways are properly clean.
(D) 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 included in the City's Builders Handbook and Public
Works Design Manual or otherwise approved by the City
(E) Site erosion control.
(1) Construction Erosion Control
(a) Erosion and sediment control measures shall be consistent with Best Management
Practices (BMPs), included in the City's Builders Handbook and Public Works Design Manual or
otherwise approved by the City, and shall be sufficient to retain sediment on site. The City may at its
discretion use turbidity measurements as an indicator of potential non - compliance with erosion and
sediment control measures taken. Turbidity measurements will be in accordance with VRWJPO
Standards.
(b) All temporary erosion and sediment controls shall be installed on all down
gradient perimeters before commencing the land disturbing activity, and left in place and maintained as
needed until removal is approved by the City after the site had been stabilized.. All permanent erosion
control measures shall be installed and operational per the design and as approved by the City.
(c) For projects disturbing more than 1 acre,
(1) Erosion and sediment controls, and final stabilization of the site, shall meet
the most current requirements of the General Permit Authorization to Discharge Storm Water
Associated With Construction Activity Under the National Pollutant Discharge Elimination
System /State Disposal System Permit Program Permit ( NPDES General Construction Permit) issued
by the Minnesota Pollutant Control Agency.
(2) All on -site stormwater conveyance channels shall be designed and
constructed to withstand the expected velocity of flow from a 10 -year frequency storm without erosion.
(3) If the activity is taking place on a site where soils are currently disturbed
(e.g., a tilled agricultural site that is being developed), areas that will not be graded as part of the
development and areas that will not be stabilized according to the timeframes specified in the NPDES
General Construction permit Part IV.B. S, shall be seeded with a temporary or permanent cover before
commencing the proposed land disturbing activity.
(d) All activities on the site shall be phased and /or conducted in a logical sequence to
minimize the area of bare soil exposed at any one time.
(e) All disturbed ground left inactive for 14 or more days shall be stabilized by seeding
and mulching, sodding, coverings, or other equivalent control measure. Straw, hay, or other vegetative
mulch shall be disc anchored. Geotextile or other approved covering shall be anchored in accordance
with the manufacturer's specifications.
(F) Storm water management criteria for permanent facilities as constructed for new development
in the absence of stormwater infrastructure.
(1) Post Construction Water Quality
(a) Post construction stormwater runoff quality measures shall meet the standard for
the General Permit Authorization to Discharge Storm Water Associated With Construction Activity
Under the National Pollutant Discharge Elimination System /State Disposal System Permit Program
Permit ( NPDES General Construction Permit) issued by the Minnesota Pollution Control Agency,
except where more specific requirements are provided below.
(b) Infiltration /filtration options are the preferred approach to satisfying the water
quality
treatment requirements of the NPDES General Construction Permit. Given the high vulnerability of
the Hastings municipal water supply acquifer, only filtration will be allowed to treat stormwater runoff
from roadways, parking lots, and large paved surfaces located within the one year travel zone of a City
municipal well as defined by the Hastings Wellhead Protection Plan..
(2) Peak Runoff Rate
(a) A hydrograph method based on sound hydrologic theory will be used to analyze
runoff for the design or analysis of flows and water levels.
(b) Runoff rates for proposed activities, and development shall:
(1) Existing conditions in runoff calculations shall be the land cover conditions
existing in the year 2005.
duration storm events.
(2) Not exceed existing runoff rates for the 1 -year, and 10 -year critical
(3) Be implemented such that the peak runoff rate for proposed activities and
development, shall not exceed the existing rate for the 100 -year, 4 day critical duration storm event, or
the 100 -year, 24 -hour storm event, whichever is greater.
(3) Volume Runoff Criteria
(a) Development that creates one acre or more of new impervious surface must
incorporate volume control practices into the design sufficient to prevent an increase in the runoff
volume for the 2 -year 24 -hour storm above pre- development conditions unless waived in accordance
with the Drainage Alternate Rule. Determination of the necessary control volume to achieve this
Standard can be completed by the City on a regional basis and included in an approved Local Water
Plan, or calculated on a site -by -site basis for each individual proposal.
(b) The water quality control volumes necessary to meet the NPDES General
Construction Permit that are satisfied using infiltration or filtration technologies within the City's
Drinking Water Surface Management Area (DWSMA) can count toward the Volume Control
requirements of these Rules
(c) Given the high vulnerability of the Hastings municipal water supply acquifer, only
filtration will be allowed to treat stormwater runoff from roadways, parking lots, and large paved
surfaces located within the one year travel zone of a City municipal well as defined by the Hastings
Wellhead Protection Plan. When permitted, infiltration for volume control shall meet the following
requirements;
(1) Infiltration volumes and facility sizes shall be calculated:
(a) Using the appropriate hydrological soil group classification and
saturated infiltration rate from the current VRWJPO rules.
(b) Using documented, site specific, infiltration or hydraulic conductivity
measurements completed by a licensed soil scientist or engineer, or
(c) Using the method provided in the current Minnesota Stormwater
Manual as published by the Minnesota Pollution Control Agency and,
(2) The design shall consider the infiltration rates of the least permeable
horizon within the first five feet below the bottom of the infiltration practice, and
(3) The system shall be capable of infiltrating the required volume in 72 hours.
(d) Constructed infiltration or filtration facilities, such as basins and trenches:
(1) Can only be used if there is pretreatment of stormwater runoff designed to
protect such systems from clogging with sediment and to protect groundwater quality;
(2) Cannot be used within the emergency response area as defined by the
Drinking Water Surface Management Area, within the one year travel zone of a municipal or other
community supply well as defined in the Hastings Well Head Protection Plan, or within 100 feet of a
private well unless specifically allowed by an approved wellhead protection plan;
(3) Cannot be used for runoff from fueling and vehicle maintenance areas and
industrial areas with exposed materials capable of leeching into the soil.;
(4) Cannot be used on areas with less than 3 feet vertical separation from the
bottom of the infiltration system and the seasonal high water table;
(5) Cannot be used in Type D soils.
(e) Infiltration and filtration areas must be fenced or otherwise protected from
disturbance before the land disturbing activity starts.
(f) Volume control amounts may be waived by the City for sites with predominately
Type C and D soils, shallow bedrock, or where a shallow water table prevents construction of
infiltration systems, provided the following are met in order of decreasing preference:
(1) Site design practices to minimize the creation of connected impervious
surfaces are used to the extent practical.
(2) Underdrains are used to promote filtration instead of infiltration.
(g) Vegetation used in conjunction with infiltration systems must be tolerant of urban
pollutants, and the range of soil moisture conditions anticipated.
(4) Drainage Alteration Rule
(a) Outlets from landlocked basins with a tributary drainage area of 100 acres or more
will be allowed, provided such outlets are consistent with other portions of these Rules, State and
Federal regulations, and the downstream impacts, riparian impacts, and habitat impacts of such outlets
have been analyzed and no detrimental impacts result. The analysis and determination of detrimental
impacts shall:
(1) Use a hydrograph method based on sound hydrologic theory to analyze
runoff for the design or analysis of flows and water levels;
(2) Ensure a hydrologic regime consistent with the Peak Runoff Rate Control
Criteria and the Runoff Volume Control Criteria of these Rules;
(3) Ensure the outlet does not create adverse downstream flooding or water
quality conditions, or materially affect stability of downstream major waterways;
(4) Maintain dead storage within the basin to the extent possible while
preventing damage to property adjacent to the basin;
(5) Ensure that the low floors of new structures adjacent to the basin are set
consistent with the Floodplain Alterations Rule; and,
(6) Ensure that proposed development tributary to the land - locked basin has
incorporated runoff volume control practices to the extent practical.
(b) Artificial drainage, flow obstruction, and diversions involving waterways, public
waters, public water wetland, wetlands with drainage areas of 640 acres or more will be allowed
provided such alterations or diversions are consistent with other portions of these Rules, State and
Federal regulations, and the downstream impacts, riparian impacts and habitat impacts of such
alterations or diversions have been analyzed and no detrimental impacts result. Proposals for drainage
alterations and diversions shall demonstrate that:
(1) There is a reasonable necessity for such drainage alteration or diversion to
improve or protect human health and safety, or to improve or protect aquatic resources;
and downstream land;
(2) Reasonable care has been taken to avoid unnecessary injury to upstream
(3) The utility or benefit accruing to the land on which the drainage will be
altered reasonably outweighs the gravity of the harm resulting to the land receiving the burden; and
(4) The drainage alteration or diversion is being accomplished by reasonably
improving and aiding the normal and natural system of drainage according to its reasonable carrying
capacity, or in the absence of a practicable natural drain, a reasonable and feasible artificial drainage
system is being adopted.
(c) Drainage alterations, diversions, and landlocked basin outlets shall be provided
with stable channels and outfall.
(G) Wetlands
(1) General Provisions
(a) Any drainage, filling, excavation, or other alteration of a public waters wetland or
wetland shall be conducted in compliance with Minnesota Statues, section 103G.245, Wetland
Conservation Act (WCA), Minnesota Rules 8420, and regulations adopted hereunder.
(b) In order to preserve WCA exemption or no loss determination, projects involving
excavation in Types 1, 2, 6, and 7 wetlands must demonstrate a beneficial purpose, such as habitat or
water quality improvements, and minimize loss of wetland function as determined by the City.
(c) A high quality (or equivalent value) public waters wetland or wetland (as determined
by methods acceptable to the VRWJPO for vegetative diversity) may not be used for stormwater
management and treatment unless the use will not adversely affect the function and public value of the
wetland and other alternatives do not exist. Runoff shall not be discharged directly into a high quality
public water wetlands or wetland (as determined by methods acceptable to the VRWJPO for vegetative
diversity) without pretreatment of the runoff.
(2) No Net Loss and Wetland Alteration
(a) No permits will be granted until the WCA replacement plan is approved or
exemption certificate is obtained. Wetland replacement/mitigation citing must follow the priority
order:
(1) Mitigation on -site
(2) Mitigation within the same minor subwatershed as established by the
Minnesota Department of Natural Resources for the "1979 Watershed Mapping Project" pursuant to
Minnesota Laws 1977, chapter 455, section33, subdivision 7, paragraph (a).
(3). Mitigation within the JPO boundary
(4) Mitigation within Dakota County
(b) Transportation projects shall pursue wetland mitigation projects to the extent
practical using the criteria above. However, this does not preclude the use of the BWSR Replacement
Program.
(3) Wetland Buffer Areas
(a) Application: Buffer areas abutting all rivers, streams, and wetlands as
identified in Figure 4 of City's Water Management Plan.
(b) Classification: A wetlands functional assessment for vegetative diversity will be
completed with each wetland and public waters wetland, delineated for a project and buffers
established according to the management classification in the following table. Figure 4 and 8 in the
Water Management Plan, as adopted in 2009, delineates three different quality standards for wetlands.
All wetlands shown on Figure 8 not shown on Figure 4 are considered Low Quality. Buffers on
wetlands begin at the delineated edge of the wetland; (the line where hydrology, vegetation, and soils
indicates a change between upland and wetland).
(1) Exceptional Quality Wetland:
(a) Average Buffer Width: 50ft
(b) Minimum Buffer Width: 30ft
(2) High Quality Wetland:
(a) Average Buffer Width: 40ft
(b) Minimum Buffer Width: 30ft
(3) Medium Quality Wetland:
(a) Average Buffer Width: 30ft
(b) Minimum Buffer Width: 25ft
(4) Low Quality Wetland:
(a) Average Buffer Width: 25ft
(b) Minimum Buffer Width: 16.5ft
(c) Buffer area requirements: Where acceptable natural vegetation exists in buffer
areas, the retention of such vegetation in an undisturbed state is required unless approval to replace
such vegetation is received. A buffer has acceptable vegetation if it:
(1) Has a continuous, dense layer of perennial grasses that has been uncultivated
or unbroken for at least 5 consecutive years; or,
(2) Has an overstory of trees and /or shrubs that has been uncultivated or
unbroken for at least 5 consecutive years; or,
(3) Contains a mixture of the plant communities in Criteria (c)(1) and (c)(2)
above that has been uncultivated or unbroken for at least 5 years.
(d) Maintenance of Buffer Areas: Buffers shall be staked and protected in the field
prior to construction unless the vegetation and the condition of the buffer are considered inadequate.
Existing conditions vegetation will be considered unacceptable if:
(1) Topography or sparse vegetation tends to channelize the flow of surface
water
(2) Some other reason the vegetation is unlikely to retain nutrients and sediment
(e) Requirements for Replanting: Where buffer vegetation and conditions are
unacceptable, or where approval has been obtained to replant, buffers shall be replanted and
maintained according to the following criteria:
(1) Buffers shall be planted with a native seed mix approved by MnDOT,
BWSR, NRCS or the Dakota County SWCD, with the exception of a one -time planting with an annual
nurse or cover crop. Plantings of native forbs and grasses may be substituted for seeding. All
substitutions must be approved by the City. Groupings /clusters of native trees and shrubs, of species
and at densities appropriate to site conditions, shall also be planted throughout the buffer area.
(2) The seed mix and planting shall be broadcast/installed according to MnDOT,
BWSR, NRCS or Dakota County SWCD specifications. The selected seed mixes and plantings for
permanent cover shall be appropriate for the soil site conditions and free of invasive species.
(3) Buffer vegetation (both natural and created) shall be protected by erosion and
sediment control measures during construction.
(4) During the first five full growing seasons, except where the City has
determined vegetation establishment is acceptable, the owner or applicant must replant buffer
vegetation where the vegetative cover is less than 90 %. The owner or applicant must assure
reseeding /or replanting if the buffer changes at any time through human intervention or activities.
(f) Conservation Easement: Where a buffer is required, the City shall require the
protection of the buffer under a conservation easement, or include the buffer in a dedicated outlot as
part of platting and subdivision approval, except where the buffer is located in a public transportation
right -of -way. Buffer shall also have monumentation to clearly designate the boundaries of all new
buffers within new residential subdivisions. A monument shall consist of a post and a buffer strip sign
approved by the City.
(g) Usage:
(1) Alterations, including building, storage, paving, routine mowing, burning,
plowing, introduction of noxious vegetation, cutting, dredging, filing, mining, dumping, grazing
livestock, agricultural production, yard waste disposal, or fertilizer application are prohibited within
any buffer. Periodic mowing or burning, or the use of fertilizers and pesticides for the purpose of
managing and maintaining native vegetation. may be allowed with approval of the City. Noxious
weeds may be removed and mechanical or spot herbicide treatments may be used to control noxious
weeds, but aerial or broadcast spraying is not acceptable. Prohibited alterations would not include
plantings that enhance the natural vegetation or selective clearing or pruning of trees or vegetation that
are dead, diseased or pose similar hazards, or as otherwise clarified in Criteria 3d.
(2) The following activities shall be permitted within any buffer, and shall not
constitute prohibited alterations:
(a) The following activities are allowed within both the minimum and
average buffer width areas:
(1) Use and maintenance of an unimproved access strip through
the buffer, not more than 10 feet in width, for recreational access to the major waterway or wetland and
the exercise of riparian rights;
(2) Structures that exist when the buffer is created;
(3) Placement, maintenance, repair, or replacement of public
roads and utility and drainage systems that exist on creation of the buffer or are required to comply
with any subdivision approval or building permit obtained from the City, so long as any adverse
impacts of public road, utility, or drainage systems on the function of the buffer have been avoided or
minimized to the extent practical;
(4) Clearing, grading, and seeding is allowed if part of an
approved Wetland Replacement Plan, or approved Stream Restoration Plan.
(5) Construction of a multipurpose trail, including boardwalks
and pedestrian bridges, provided it is constructed to minimize erosion and new impervious surface, and
has an undisturbed area of vegetative buffer at least ten (10) feet in width between the trail and the
wetland or public waters wetland edge, or the bank of the major waterway; or where needed to cross
the major waterway, the minimum impact alignment is used.
(6) The construction of underground utilities such as water,
stormwater, and sanitary sewers and pipelines provided the minimum impact alignment is used, the
area is stabilized in accordance with Criteria 3d above, and setbacks established in the Floodplain
Alterations Rule, are met.
(b) The following activities are allowed within those portions of the
average buffer width that exceed the minimum buffer width:
(1) Stormwater management facilities, provided the land areas
are stabilized in accordance with Criteria (e)(1 -4) above, and alterations prohibited in Criteria (g)(1)
above are upheld.
(2) The area of shallow vegetated infiltration and biofiltration
facilities, and water quality ponds not to exceed 50 percent of the pond area, adjacent to wetlands and
major waterways may be included in buffer averaging provided the facilities do not encroach into the
minimum buffer width, and the land areas are stabilized in accordance with Criteria 3d above, and
alterations prohibited in Criteria fl above are upheld.
$ 152.09 OTHER CONTROLS.
In the event of any conflict between the provisions of this chapter and the provisions of an erosion
control or shoreland protection ordinance adopted by the City Council, the more restrictive standard
prevails.
(Prior Code, § 15.09)
Storm Water Management
$ 152.98 VIOLATIONS.
Every person violates a section, subdivision, paragraph, or provision of this chapter when he or she
performs an act thereby prohibited or declared unlawful, or fails to act when the failure is thereby
prohibited or declared unlawful, and upon conviction thereof, shall be punished as for a misdemeanor
except as otherwise stated in specific provisions hereof.
(Prior Code, § 15.99) Penalty, see § 10.99
Hastings - Land Usage