(a)

This article establishes comprehensive erosion and sediment control regulations and permanent stormwater management regulations to meet the requirements of the Minnesota Pollution Control Agency's (MPCA's) general permit authorization to discharge stormwater associated with small municipal separate storm sewer systems under the National Pollutant Discharge Elimination System/State Disposal System (NPDES/SDS). This article is to safeguard persons, protect property, and prevent damage to the environment in the city. This article will also promote the public welfare by guiding, regulating, and controlling the design, construction, use and maintenance of any development or other activity that disturbs or breaks the topsoil or results in the movement of earth on land in the city.

(b)

This article is not to serve as a replacement for, nor is it intended to conflict with, the regulations set forth by the MPCA, the United States Environmental Protection Agency (USEPA), or the Shell Rock River Watershed District (SRRWD) regarding construction stormwater permitting and regulations. In the event that any regulation contained in this article conflicts with a corresponding MPCA, USEPA or SRRWD regulation, the more stringent or restrictive regulation will be upheld.

(c)

Generally, best management practices (BMPs) should be employed to first, reduce the risk of erosion through stabilization and minimal impact construction. Second, contaminated stormwater carrying pollutants shall be captured and treated to remove pollutants. Lastly, if these methods have yielded ineffective results or were not implemented correctly, any affected areas shall be cleaned and restored where stormwater discharges have caused nuisance, safety, or property impacts. In general, the simplest most effective practices will be preferred over more complicated methods yielding similar results. All BMPs and changes shall be included in the SWPPP document, as detailed herein.

(Code 1997, § 74-2021; Ord. No. 190, 5d, § 1, 3-9-2015)

The following words, terms and phrases, when used in this article, shall have the meanings ascribed to them in this section, except where the context clearly indicates a different meaning:

Active karst means geographic areas underlain by carbonate bedrock (or other forms of bedrock that can erode or dissolve) with less than fifty (50) feet of sediment cover.

Alum or ferric chloride phosphorus treatment system means the diversion of flowing stormwater, removal of phosphorus through the use a continuous feed of alum or ferric chloride additive, flocculation, and the discharge of the treated water off-site.

Applicable WLA means a waste load allocation assigned to the permittee and approved by the United States Environmental Protection Agency (USEPA).

Applicant means the owner of property applying to the city to complete a development, redevelopment, or other land-disturbing project. A contractor performing the work may also be an applicant.

Best management practices or BMPs means practices to prevent or reduce the pollution of the waters of the state, including schedules of activities, prohibitions of practices, and other management practices, and also includes treatment requirements, operating procedures and practices to control runoff, spillage or leaks, sludge, or waste disposal or drainage from raw material storage. Design and use of BMPs shall be consistent with the state stormwater manual or other design reference approved at the discretion of the city.

Clearing means any activity that removes the vegetative surface cover from a land area.

Common plan of development means a contiguous area where multiple separate and distinct land-disturbing activities may be taking place at different times, on different schedules, but under one (1) proposed published or submitted plan. A plan is broadly defined to include design, permit application, advertisement or physical demarcation indicating that land-disturbing activities may occur. Phasing the construction of similarly themed projects are considered common plans of development.

Construction activity means a disturbance to the land that results in a change in the topography, existing soil cover (both vegetative and non-vegetative), or the existing soil topography that may result in accelerated stormwater runoff, leading to soil erosion and movement of sediment into surface waters or drainage systems. Examples of construction activity may include clearing, grading, filling, and excavating.

Contractor means the individual, company, or other designee that is performing work for an owner. The owner and the contractor may be the same on some projects.

Drinking water supply management area or DWSMA means the surface and subsurface area surrounding a public water supply well that must be managed by the entity identified in a wellhead protection plan.

General permit authorization to discharge stormwater associated with construction activity means the most recently issued permit under Minnesota Rule by the MPCA to owners or contractors conducting construction activity.

Grading means excavation or placement of soil, base, and subbase materials.

Green infrastructure means a wide array of practices at multiple scales that manage wet weather and that maintains or restores natural hydrology by infiltrating, evapotranspiring, or harvesting and using stormwater. The term "green infrastructure" also includes the preservation or restoration of natural landscape features, such as forests, floodplains, and wetlands, coupled with policies, such as infill and redevelopment, that reduce overall imperviousness in a watershed. Neighborhood-specific practices, such as bioretention, trees, green roofs, permeable pavements, and cisterns, are also green infrastructure.

High flow bypass means a function of an inlet device that allows a certain flow of water through, but diverts any higher flows away. High flow bypasses are generally used for BMPs that can only treat a designed amount of flow and that would be negatively affected by higher flows.

Illicit discharge means any discharge to a municipal separate storm sewer that is not composed entirely of stormwater except discharges pursuant to section 44.093(n).

Impaired water means waters identified as impaired due to the presence of pollution by the MPCA, and approved by the USEPA, pursuant to the Clean Water Act.

Land disturbance permit is a permit issued for projects that involve greater than one (1) acre of land-disturbing activity that is not part of a project that would otherwise receive a permit from the city. A land disturbance permit may be issued to allow grading work on a project before final building permit approval is received or on grading projects where no building will be constructed.

Maximum extent practicable or MEP means the feasibility, effort, and execution of implementing BMPs. The pollutant reductions that represent MEP may be different for each project, given the unique local hydrologic and geologic concerns that may exist and the differing possible pollutant control strategies. Each project shall have BMPs employed to effectively manage stormwater runoff and reduce pollution. If BMPs are ineffective, other more advanced and aggressive BMPs will be required. This may include changing the construction method itself.

Nuisance condition means a condition caused by any discharge into waters of the state that cause significant amounts of floating solids, scum, visible oil film, excessive suspended solids, material discoloration, obnoxious odors, gas ebullition, deleterious sludge deposits, undesirable slimes or fungus growths, aquatic habitat degradation, excessive growths of aquatic plants or other offensive or harmful effects.

Owner means the person that owns the land where the project is located.

Perimeter control means a barrier that prevents sediment from leaving a site by filtering sediment laden runoff or diverting such flows to a sediment trap or basin. Perimeter control is placed down gradient of potential pollution sources.

Permanent stormwater management means the permanent BMPs contained in the SWPPP that remain after construction has finished. The BMPs shall form a functioning system to prevent stormwater pollution before it becomes polluted and treat stormwater that becomes polluted before it leaves the site. The term "permanent stormwater management" includes the maintenance requirements of the features constructed.

Pipe means a closed manmade conveyance device used to transport stormwater from location to location. The definition of the term "pipe" does not include foundation drain pipes, irrigation pipes, land drain tile pipes, culverts, and road sub-grade drain pipes.

Pollutant of concern means a pollutant specifically identified in a USEPA-approved TMDL report as causing a water quality impairment.

Pre-project conditions mean the pervious and impervious areas, the runoff characteristics, and the drainage area sizes (including subcatchments) that exist prior to commencing construction activity on the project.

Project means a site where permitted or unpermitted construction activity is proposed to occur, is occurring, or has occurred.

Receiving water means any lake, river, stream, or wetland that receives stormwater discharges.

Redevelopment means any construction activity where, prior to the start of construction, the areas to be disturbed have fifteen (15) percent or more of impervious surface.

Reduce means reduce to the maximum extent practicable (MEP) unless otherwise defined in the context in which it is used.

Saturated soil means the highest seasonal elevation in the soil that is in a reduced chemical state because of soil voids being filled with water. Saturated soil is evidenced by the presence of redoximorphic features or other information.

Site means a parcel of land or a contiguous combination thereof, where grading work is performed as a single unified operation.

Small construction site means a site where there exists construction activity that disturbs less than one (1) acre of land and is not a part of a larger common plan of development that would disturb over an acre of land.

Small municipal separate storm sewer system or small MS4 or MS4 means all separate storm sewers that are owned or operated by the city who has jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes.

Stormwater means stormwater runoff, snow melt runoff, and surface runoff and drainage.

Stormwater management means the acts used to prevent and reduce the pollution of stormwater and the detention/retention of stormwater to reduce the rate and volume of stormwater runoff.

Stormwater pollution prevention plan or SWPPP means a comprehensive plan for stormwater discharge that includes all required content of the MPCA's general permit authorization to discharge stormwater associated with construction activity and this article. The term "stormwater pollution prevention plan" describes the erosion prevention BMPs, sediment control BMPs and permanent stormwater management systems that, when implemented, will decrease soil erosion on a parcel of land and decrease off-site pollution. The term "stormwater pollution prevention plan" can include signed plans, specifications, design calculations or other accompanying documents designated for use as such.

Structural stormwater BMP means a stationary and permanent BMP that is designed, constructed, and operated to prevent or reduce the discharge of pollutants in stormwater.

Total maximum daily load or TMDL means the sum of the individual waste load allocations for point sources and load allocations for nonpoint sources and natural background established by the USEPA. A TMDL sets and allocates the maximum amount of a pollutant that may be introduced into a water of the state and still ensure attainment and maintenance of water quality standards.

Waste means any construction or demolition debris, concrete truck washout, chemicals, litter, mixed municipal solid waste, scrap metal, sanitary or hazardous waste or any other non-useable debris generated that may cause adverse impacts to water quality, the environment, or sight appearance.

Waste load allocation or WLA means the portion of a receiving water's loading capacity that is allocated to one (1) of its existing or future point sources of pollution. In the absence of a TMDL approved by USEPA, or an assessment and remediation plan, a WLA is the allocation for an individual point source that ensures that the level of water quality to be achieved by the point source is derived from and complies with all applicable water quality standards and criteria.

Water pollution means:

(1)

The discharge of any pollutant into any waters of the state or the contamination of any waters of the state so as to create a nuisance or render such waters unclean, or noxious, or impure so as to be actually or potentially harmful or detrimental or injurious to public health, safety or welfare, to domestic, agricultural, commercial, industrial, recreational or other legitimate uses, or to livestock, animals, birds, fish or other aquatic life; or

(2)

The alteration made or induced by human activity of the chemical, physical, biological, or radiological integrity of waters of the state.

Water quality standards mean those provisions established by the state for use in determining stormwater runoff pollution concentrations.

Waters of the state mean all streams, lakes, ponds, marshes, watercourses, waterways, wells, springs, reservoirs, aquifers, irrigation systems, drainage systems and all other bodies or accumulations of water, surface or underground, natural or artificial, public or private, which are contained within, flow through, or border upon the state or any portion thereof.

Wetlands mean those areas that are inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. Constructed wetlands designed for wastewater treatment are not waters of the state. Wetlands have the following attributes: A predominance of hydric soils, inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support a prevalence of hydrophytic vegetation typically adapted for life in a saturated soil condition, and under normal circumstances, support a prevalence of such vegetation. Other areas that meet the Wetland Conservation Act (WCA) definition of a wetland are also included.

(Code 1997, § 74-2022; Ord. No. 190, 5d, § 1, 3-9-2015)

(a)

All land-disturbing construction activities within the city corporate limits shall require a permit that meets the requirements of this article unless the project meets one (1) or more of the following exemptions:

(1)

Small construction sites. Projects disturbing less than one (1) acre of land must conform to section 50.1040. Small construction sites that are part of a larger common plan of development do not meet this exemption. Small construction sites that are responsible for causing nuisance conditions are still subject to enforcement action in this article.

(2)

Any emergency activity that is immediately necessary for the protection of life, property or natural resources.

(3)

Nursery and agricultural operations conducted as a permitted main or accessory use.

(4)

Sites that have stormwater treated by a completed regional stormwater management BMP that met the city's requirements at the time of construction are not subject to the permanent stormwater management requirements of this article when development conforming to the approved design of the regional stormwater management system is completed. The city will evaluate development and redevelopment in areas served by a completed regional stormwater management BMP and make a determination regarding the treatment level provided by the regional system. Supplemental stormwater treatment may be needed if the development or redevelopment does not conform to the original design for the completed regional stormwater management BMP.

(b)

Any permits issued by the city that involve the disturbance of land due to construction activity shall require conformance with this article.

(c)

Projects shall meet the minimum standards contained in this article by incorporating erosion and sediment control BMPs during construction and implementation of permanent stormwater management BMPs after construction as detailed in this article.

(Code 1997, § 74-2023; Ord. No. 190, 5d, § 1, 3-9-2015)

The city will review permit applications that include land-disturbing activity according to the following procedures:

(1)

Applying for permits. Permit application materials required to satisfy this article shall include:

a.

Stormwater pollution prevention plan. This document shall be incorporated into the final plans and specifications of the project. Any materials submitted apart from the plans and specifications for the project to meet the requirements of the SWPPP shall be under a separate cover and must be identified as SWPPP supporting documentation. Small construction sites are not required to submit a SWPPP for approval but must meet the requirements in section 50.1040. The requirements for the SWPPP are as follows:

1.

Description or plan of the proposed construction activity with potential pollutant discharges identified.

2.

Identification of a site representative with appropriate training in the application of erosion prevention and sediment control BMPs to oversee the implementation of the SWPPP.

3.

Identification of the long-term responsibility for operation and maintenance of the site after final completion.

4.

Training documentation for the site representative.

5.

Plan, design, calculations, and narrative detailing compliance with this article signed by a professional engineer licensed for practicing in the state for all permanent BMPs. Calculations and narrative do not have to be embedded in the plans and may be submitted as a separate document. The following information must be included in the application:

(i)

All existing and proposed drainage features including swales, ditches, culverts, storm sewer and tile.

(ii)

Plan locations and details of all existing and proposed stormwater management features. Normal water level, high water level, and emergency overflow elevations shall be included.

(iii)

Layout and elevations of site features including streets, parking surfaces, walks, buildings, and drainage features. Profile views may be required to illustrate change in grade and to clarify the design.

6.

Hydraulic calculations for total runoff volume and peak discharge rates by subwatershed for the NOAA Atlas 14 two (2) year; twenty-four (24) hour, ten (10) year, twenty-four (24) hour; and the one hundred (100) year, twenty-four (24) hour event frequencies. Include:

(i)

Assumed runoff curve numbers.

(ii)

Time of concentrations used in calculations.

(iii)

Existing total runoff volume and peak discharge rates.

(iv)

Delineation of all drainage areas.

(v)

Impervious surface acres created by the project for predevelopment and post development.

(vi)

Post-construction total runoff volume and peak discharge rates for predevelopment and post development conditions.

7.

Estimated quantities of erosion prevention and sediment control of BMPs.

8.

Site map with existing and final drainage areas, grades, and breaks. Steep slopes, impervious surfaces, on-site soil types, and potential pollutant generating locations or operations should also be included.

9.

Locations of buffer zones and other areas not to be disturbed.

10.

Location of concrete washout station, if applicable.

11.

Construction phasing details.

12.

Maps of surface waters and wetlands:

(i)

All surface waters, wetlands, and stormwater basins within one (1) mile from the project boundary that receive stormwater from the project site.

(ii)

Identify special and impaired surface waters.

13.

Final stabilization methods including timeline for stabilization after land-disturbing activity is finished in the area.

14.

BMP design criteria to assist in the type, location, and frequency of BMPs installed. Criteria should accommodate the amount frequency, intensity, and duration of precipitation expected on the site.

15.

Topsoil preservation and soil management methods to reduce compaction during construction of areas not designated as impervious areas after construction.

16.

Maintenance plan and accessible route for all permanent stormwater treatment systems. The plans must show an access to all permanent stormwater BMPs such that the responsible party is able to complete routine maintenance without the need to acquire easements or trespass on adjacent properties. Minimum access width shall be eight (8) feet and have a slope navigable by trucks and construction equipment.

17.

Chemical treatments needed to enhance the sedimentation process on the site, when applicable.

18.

BMPs and stormwater management to minimize erosion on the site

including

location and type.

19.

BMPs to minimize the discharge of sediment and other pollutants.

20.

BMPs for dewatering activities.

21.

Required for site inspections and records of rainfall events.

22.

BMP maintenance requirements during construction.

23.

Management of solid and hazardous wastes on each project site.

24.

Criteria for the use of temporary sediment basins.

b.

Two (2) hard copy sets of plans and specifications:

1.

One (1) plan set at full scale and having sheet sizes at least twenty-two (22) inches by thirty-four (34) inches; and

2.

One (1) plan set at half scale and having maximum sheet sizes of twelve (12) inches by eighteen (18) inches (only if project details are legible at that scale);

3.

Additional copies as requested.

c.

MPCA construction coverage card showing receipt of construction stormwater permit coverage.

d.

Letter of approval from Shell Rock River Watershed District.

(2)

Incomplete applications. Any applications that do not include all required information will be deemed incomplete. The city will notify the applicant in writing within fifteen (15) days after receiving an application that is incomplete. Once a complete application is in receipt, the city will begin its review.

(3)

Review and approval of applications.

a.

The city will review each application to determine its conformance with the provisions of this article. The city will also require conformance with the provisions of the current version of the Shell Rock River Watershed District rules approved by its board of managers on the date of the application before issuing city approval and the most recent MPCA general permit authorization to discharge stormwater related to construction activity. The application will be either approved, approved pending conditions, or denied within sixty (60) days of receipt of a complete application.

b.

Owners must amend the SWPPP within seven (7) days to include additional or modified BMP's whenever there is a change in design, construction, operation, maintenance, weather or seasonal conditions having a significant impact on the discharge of pollutants to surface waters or ground water.

c.

Owners must amend the SWPPP within seven (7) days to include additional or modified BMP's whenever inspections or investigations by the owner, operator, local, USEPA, or MPCA officials indicate the SWPPP is not effective in eliminating or significantly minimizing the discharge of pollutants to surface waters or ground water.

d.

All changes to the SWPPP and changes to the plans and specifications after receipt of approval that alters the final drainage areas or directions, permanent stormwater treatment capacity or methods, or impervious areas for the project shall require resubmittal to the city. Approval of the amended SWPPP and/or plans and specifications shall be required before constructing the changed portions of the project.

(Code 1997, § 74-2024; Ord. No. 190, 5d, § 1, 3-9-2015; Ord. No. 24-122, § 1,  7-22-2024)

All construction activity disturbing greater than one (1) acre of land within the city corporate limits shall require an MPCA general permit authorization for discharge of stormwater associated with construction activity and approval from the Shell Rock River Watershed District before commencing construction activity for any projects, or larger common plans of development, that will result in the disturbance of greater than one (1) acre of land. Proof of MPCA general permit coverage and Shell Rock River Watershed District approval is required prior to permit issuance.

(Code 1997, § 74-2025; Ord. No. 190, 5d, § 1, 3-9-2015)

This section establishes the requirements for permanent stormwater management for all sites discharging stormwater runoff to the city's MS4 (storm sewer system) and not meeting an exemption or limitation. The SWPPP document shall detail the design of post-construction stormwater management BMPs that will satisfy the following requirements:

(1)

Stormwater treatment requirements.

a.

Owners of construction activity must treat the water quality [on] any project where the sum of the new impervious surface and the fully reconstructed impervious surface equals one (1) or more acres.

b.

For construction activity (excluding linear projects), the water quality volume must be calculated as one (1) inch times the sum of the new and fully reconstructed impervious surface.

c.

For linear projects, the water quality volume must be calculated as larger of one (1) inch times the new impervious surface or one-half (½) inch times the sum of the new and the fully reconstructed impervious surface. Where the entire water quality volume cannot be treated within the existing right-of-way, a reasonable attempt to obtain additional right-of-way, easement, or other permission to treat the stormwater during the project planning process must be made. Volume reduction practices must be considered first, as described in item 20.8 of Minnesota Pollution Control Agency NPDES Permit MNR040000. Volume reduction practices are not required if the practices cannot be provided cost effectively. If additional right-of-way, easements, or other permission cannot be obtained, owners of construction activity must maximize the treatment of the water quality volume prior to discharge from the MS4.

d.

Projects not discharging stormwater runoff to the MS4 of the city that replace vegetation and/or other pervious surfaces with one (1) or more acres of cumulative impervious surface shall retain on-site one (1) inch of runoff from the new impervious surfaces (water quality volume) created by the project. This shall be provided using infiltration or other volume reducing practices when infiltration is not prohibited by a MPCA stormwater permit. If any of the water quality volume cannot be retained on-site, the remaining water quality volume shall be treated by a wet sedimentation basin, filtration system, regional pond, or equivalent methods prior to the discharge of stormwater from the site.

1.

All infiltration systems shall incorporate the following:

(i)

Infiltration systems shall include pretreatment to remove settleable solids, floating materials, and oils and grease from the runoff to the maximum extent practicable before runoff reaches the infiltration areas. Filtration should remove eighty (80) percent of total suspended solids. Infiltration systems shall not adversely affect the hydrology of adjacent wetlands.

(ii)

Infiltration systems shall not be excavated to final grade until the contributing drainage area has been constructed and fully stabilized unless rigorous erosion prevention and sediment controls are provided.

(iii)

Infiltration systems shall infiltrate and/or filter the water quality volume within forty-eight (48) hours and have a stabilized discharge channel to discharge any overflows.

(iv)

Infiltration systems shall provide three (3) feet of separation from seasonally saturated soils from the bottom of the infiltration system.

(v)

At least three (3) feet of the soil above the seasonally saturated soils or bedrock must consist of native undisturbed soils.

2.

All wet sedimentation basins shall incorporate the following:

(i)

Permanent volume of one thousand eight hundred (1,800) cubic feet of storage below the outlet pipe for each acre that drains to the basin. The basin's permanent volume must reach a minimum depth of at least three (3) feet and must have no depth greater than ten (10) feet. The basin shall be configured to avoid scour and short circuiting.

(ii)

Live storage shall be provided for the water quality volume (or the portion remaining after prior volume reduction achieved on-site) from the new impervious surfaces created by the project.

(iii)

Discharge rate shall be limited to five and sixty-six hundredths (5.66) cubic feet per second per acre of the surface of the pond.

(iv)

Ponds shall include a stabilized emergency overflow to accommodate storm events in access of the basin's hydraulic design.

(v)

Basins shall include a ten (10) foot-wide safety bench not steeper than ten to one (10:1) (V:H) or include other safety accommodations.

3.

Regional ponds will be reviewed by the city and may be allowed by special approval of the city. If approved, regional ponds may serve multiple parcels and must be designed to the same standards as on-site permanent stormwater management BMPs.

(2)

Stormwater management limitations and exceptions.

a.

Limitations.

1.

The use of infiltration techniques to achieve the conditions for post-construction stormwater management stated above is prohibited when the infiltration structural stormwater BMP will receive discharges from, or be constructed in areas:

(i)

That receive discharges from vehicle fueling and maintenance areas, regardless of the amount of new and fully reconstructed impervious surface.

(ii)

Where high levels of contaminants in soil or groundwater may be mobilized by the infiltrating stormwater. To make this determination, the owners and/or operators of construction activity must complete the agency's site screening assessment checklist, which is available in the Minnesota Stormwater Manual, or conduct their own assessment. The assessment must be retained with the site plans.

(iii)

Where soil infiltration rates are more than eight and three-tenths (8.3) inches per hour unless soils are amended to slow the infiltration rate below eight and three-tenths (8.3) inches per hour.

(iv)

With less than three (3) feet of separation distance from the bottom of the infiltration system to the elevation of the seasonally saturated soils or the top of bedrock.

(v)

Of predominately hydrologic soil group D (clay) soils.

(vi)

In an emergency response area (ERA) within a drinking water supply management area (DWSMA) as defined in Minn. R. 4720.5100, Subp. 13, classified as high or very high vulnerability as defined by the Minnesota Department of Health.

(vii)

In an ERA within a DWSMA classified as moderate vulnerability unless the permittee performs or approved a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater.

(viii)

Outside of an ERA within a DWSMA classified as high or very high vulnerability unless the permittee performs or approves a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater.

(ix)

Within one thousand (1,000) feet up-gradient or one hundred (100) feet down gradient of active karst features.

(x)

Where at least three (3) feet of soil above the seasonally saturated soils or bedrock does not consist of native undisturbed soils.

(xi)

That receive stormwater runoff from these types of entities regulated under NPDES for industrial stormwater: automobile salvage yards; scrap recycling and waste recycling facilities; hazardous waste treatment, storage, or disposal facilities; or air transportation facilities that conduct deicing activities.

(3)

Mitigation provisions.

a.

There may be circumstances where the project cannot feasibly or cost effectively meet the conditions for post-construction stormwater management for TSS and/or TP as required by this section on the site of the original construction activity. For this purpose, the city will evaluate proposals submitted by the applicant and at the applicant's expense that detail projects located off-site from the original construction site that can be used to mitigate the stormwater pollution resulting from development or redevelopment on the original construction site. Authorization to mitigate stormwater pollution resulting from development or redevelopment shall be at the discretion of the city. The following criteria shall be used to prioritize mitigation sites starting with the highest priority site:

1.

Locations that yield benefits to the same receiving water that receives runoff from the original construction activity.

2.

Locations within the same department of natural resource (DNR) catchment area as the original construction activity.

3.

Locations in the next adjacent DNR catchment area upstream.

4.

Locations anywhere within the permittee's jurisdiction.

b.

Mitigation projects must involve the creation of new structural stormwater BMPs or the retrofit of existing structural stormwater BMPs, or the use of a properly designed regional structural stormwater BMP.

c.

Routine maintenance of structural stormwater BMPs already required by this permit cannot be used to meet mitigation requirements of this section.

d.

Mitigation projects shall be completed within twenty-four (24) months after the start of the original construction activity.

e.

The responsible party for long-term maintenance on all mitigation projects proposed by the applicant will be subject to the approval of the city.

f.

If the city agrees to receive payment in lieu of the project meeting the conditions for post-construction stormwater management, the city will apply the funds to a public stormwater project that meets the same requirements of the needs at the mitigated project. The amount of the payment shall be negotiated between the city and the owner of the project. The amount of the payment should be approximately equal to the costs to construct the post-construction stormwater management BMPs on the site of the original project if site conditions allowed.

(4)

Long-term maintenance of structural stormwater BMPs. Long-term operation and maintenance of all structural stormwater BMPs shall be assigned to the owner of the parcel where the BMP is located. Owners who assign operation and maintenance tasks to other parties are still responsible for the proper function and condition of the BMPs on their parcels. Owners of structural stormwater BMPs installed after the effective date of this article shall:

a.

Allow the city to conduct inspections of structural stormwater BMPs not owned or operated by the city, perform necessary maintenance, and assess costs for those structural stormwater BMPs when the city determines that the owner and/or operator of that structural stormwater BMP has not conducted maintenance.

b.

The city reserves the right to ensure maintenance responsibilities are legally transferred to another party when parcels are transferred to other owners.

c.

The city may deny future permit requests that alter or eliminate structural stormwater BMPs and the site features that are implemented to comply with parts of this article if stormwater treatment effectiveness will be sacrificed. All structural stormwater BMPs shall be preserved, protected, and maintained unless being replaced or expanded with the written approval of the city.

(Code 1997, § 74-2026; Ord. No. 190, 5d, § 1, 3-9-2015; Ord. No. 22-077, 7-25-2022; Ord. No. 24-123, § 1,  7-22-2024)

All land-disturbing construction activity requirement a permit shall be performed using BMP's in a manner to reduce the likelihood of erosion from the site and deposition of sediment off-site. All activities shall be performed in conformance with this article and the MPCA's general permit authorization to discharge stormwater associated with construction activity. The following minimum requirements shall be detailed in the SWPPP (and amendments to the SWPPP after approval) as follows:

(1)

Erosion prevention practices.

a.

Plan and implement appropriate BMPs to minimize erosion of soil. All BMPs shall be maintained in a manner so as to provide the same level or protection as new installations following recommendations of the state stormwater manual.

b.

Provide stabilization for all exposed soil areas and stockpiled materials. Stabilization shall take place immediately after construction activity in an area stops permanently or temporarily and will not resume for fourteen (14) days. Any exposed soil must be stabilized if no work in the area has occurred in the last fourteen (14) days. The normal wetted perimeter of a drainage ditch or swale that drains water from any portion of the construction site shall be stabilized within twenty-four (24) hours within two hundred (200) feet of the property edge or outlet. Remaining portions of the ditch or swale shall be completed within fourteen (14) days. The use of mulch, hydro mulch, tackifier, polyacrylamide or similar item will not satisfy the stabilization requirements for the normal wetted perimeter of a ditch or swale. For projects located within one (1) mile (aerial radius of measurement) of a special or impaired water, the following requirements shall be met. Temporary stabilization shall be completed immediately after construction activity in an area of the project has halted permanently or temporarily.

c.

BMPs shall be provided to control erosion and dissipate velocity of stormwater runoff and shall be employed in all portions of construction whether permanent or temporary.

d.

Pipe outlets shall be provided with temporary or permanent energy dissipation within twenty-four (24) hours after installation.

e.

Unless unfeasible, discharges from BMPs should be directed towards vegetated areas of the site to further provide filtration before reaching surface waters.

(2)

Sediment control practices.

a.

Plan and implement sediment control practices appropriate to minimize sediment from reaching surface waters or leaving the project site including curb and gutter and storm sewer inlets. Care must be taken to reduce the sediment loading through the use of erosion prevention BMPs. Installation of additional up gradient sediment control practices and/or redundant BMPs will be required if sediment control practices are overloaded and become ineffective. The SWPPP must be amended to reflect these changes.

b.

Sediment control practices should be located down gradient of land-disturbing construction activity and up gradient of any buffer areas. Sediment control practices should be installed before any land-disturbing activity commences and shall remain installed and maintained until final stabilization. Silt curtains are not appropriate sediment perimeter control unless work on a shoreline below the normal waterline is taking place.

c.

Sediment control practices that need to be removed to allow access or construction activities shall be replaced immediately following the need for removal has ended.

d.

Storm drain inlet protection shall be provided during construction until final stabilization and potential sources for pollution have been eliminated. Inlet protection should be designed so that it does not create a flooding risk that causes a reduction in public safety or results in increased damage to private and public property. High flow bypasses shall be incorporated into the design of inlet protection when the possibility of backups would cause a safety concern or risk to property. When inlet protection causes or any nuisance conditions or safety concerns, the inlet protection may be removed temporarily or permanently to alleviate the nuisance or safety concern if approved by the city. These activities must be noted in the SWPPP.

e.

Temporary soil stockpiles shall have effective perimeter control in place prior to commencing stockpiling activities. Stockpiles shall not be placed in a manner that obstructs a drainageway, including curb and gutter.

f.

Sites with vehicles entering and exiting shall have a temporary construction access constructed or other suitable access BMP to minimize the sediment tracked onto local roads. Street sweeping shall be completed when the construction access BMP is not effective. Street sweeping is not an alternative to a suitable construction access BMP.

g.

Temporary sedimentation basins shall be required when ten (10) or more acres of disturbed area drain to a common point on a site. The basin shall provide treatment to runoff before it leaves the site. Temporary basins can be converted into permanent basins once the area draining to the basin has been permanently stabilized. Temporary sedimentation basins shall be sized according to the following minimum standards:

1.

The live volume shall be sized such that runoff from a two (2) year, twenty-four (24) hour storm event will be retained, but not less than one thousand eight hundred (1,800) cubic feet shall be provided per acre drained.

2.

Without engineering data to support a calculated live storage area, the basin shall be sized with a live volume of three thousand six hundred (3,600) cubic feet of storage per acre drained to the basin.

3.

Basins shall be designed to prevent short circuiting and the discharge of floating debris. The design shall allow basin draw down and sediment removal.

4.

Temporary sedimentation basins may not be located in or a part of an existing water body.

5.

Temporary sedimentation basins shall be operational prior to disturbing ten (10) or more acres that drain to a common point.

h.

Soil compaction shall be avoided to promote the natural infiltration of stormwater. Top soil shall be preserved whenever feasible.

i.

A fifty (50) foot natural buffer shall be preserved when land-disturbing activities occur near a water body. If construction activity occurs within fifty (50) feet of the edge of a water body, redundant perimeter control shall be provided. Natural buffers are not required along road ditches, judicial ditches, county ditches, stormwater conveyance channels, storm drain inlets, or sedimentation basins where leaving such a buffer is not feasible.

j.

Chemicals used to enhance the performance of sediment controls must be used after the implementation of conventional BMPs. Polymers and flocculants may only be added when stormwater is directed to a sediment control system where the sediment can settle and be captured before the water leaves the site or enters a water body. Chemicals may only be used at the manufacturer recommended doses for the recommended purposes and shall be environmentally friendly.

(3)

Dewatering and basin draining.

a.

All water from excavation dewatering activities or basin draining must be discharged in a manner that does not cause nuisance conditions, erosion in receiving channels, or on downslope properties or inundation in wetlands causing significant adverse impacts to the wetland.

b.

All sediment collected from dewatering and basin draining treatment processes, including any residual water remaining, shall be returned to the head of the treatment train, incorporated into the construction activity on-site, or hauled away for disposal at an alternate site by appropriate means.

c.

All dewatering discharges must be inspected and photographed at the beginning and once every four (4) hours during operations.

(4)

Inspections and maintenance.

a.

Trained personnel (according to the MPCA's construction stormwater permit) shall make regular inspections of the entire construction site and areas adjacent to the site at least once every seven (7) days during active construction and within twenty-four (24) hours after a rainfall event of one-half (½) inch or more in twenty-four (24) hours.

b.

All inspections shall be recorded in writing within twenty-four (24) hours of the inspection and shall be retained on-site and kept with the SWPPP. All Inspection records shall be made available to the city upon request. Inspection records shall include all of the following information:

1.

Date and time of inspections.

2.

Name of inspector.

3.

Findings of the inspection including location and detailed information for corrective action required.

4.

Documentation that corrective action was taken including date, time, and responsible party completing the action.

5.

Date and time of all rainfall events greater than one-half (½) inches in twenty-four (24) hours. Weather data shall be relevant to the specific construction site, not regional gauges.

6.

Inspections occurring during a rainfall event shall include locations on-site and adjacent to the site where discharge of stormwater occurs. The inspection should note the characteristics of the discharge and photographs.

7.

Any amendments to the SWPPP resulting from the required site inspections shall be documented in writing and within seven (7) days.

8.

All photographs of dewatering activities and documentation of nuisance conditions resulting from dewatering activities.

c.

Inspection frequency adjustment can occur when final stabilization of a portion of the site has occurred yet work remains on other portions of the site. Inspections may be reduced to once per month in areas that has received final stabilization. Where work has been suspended due to frozen ground conditions, inspection and maintenance may be suspended until twenty-four (24) hours after runoff occurs on the site.

d.

The inspection and maintenance requirements of this article will terminate once the requirements for final stabilization have been met and the MPCA has received and processed a notice of termination.

e.

All erosion prevention and sediment control BMPs must be inspected and maintained during all weekly and rainfall inspections. All nonfunctional BMPs must be repaired, replaced, or supplemented with functional BMPs by the next day after discovery. Minimum requirements are as follows:

1.

All perimeter control devices must be repaired, replaced, or supplemented when they become nonfunctional or the sediment reaches one-half (½) the height of the device.

2.

Temporary and permanent sedimentation basins must be drained and the sediment removed when the depth of sediment collected in the basin reaches one-half (½) the storage volume. Drainage and removal of the sediment must be completed within seventy-two (72) hours of discovery or as soon as field conditions allow.

3.

Drainage ditches, conveyance systems and other water bodies must be inspected for evidence of erosion and sediment deposition during each inspection. If deposits or erosion is observed, the condition must be corrected to eliminate additional erosion or sediment deposition. After any applicable local, state, or federal permits are acquired (as necessary) the erosion or sedimentation in the water body shall be removed.

4.

Construction site access BMPs shall be inspected for effectiveness. All tracked material shall be removed from the road surfaces within twenty-four (24) hours of the first occurrence, and by the end of each working day for subsequent occurrences. The construction access should be modified and improved if sediment continues to be tracked onto local roads to avoid the need for sediment removal from the roadway.

f.

Projects that include an infiltration BMP shall have the infiltration area inspected for evidence of sediment reaching the infiltration area before the site has final stabilization and the infiltration area is completed. Equipment shall not be driven in future infiltration areas. Soil compaction must be avoided.

(5)

Pollution prevention management measures.

a.

All sites where concrete washout will occur must have a concrete washout and disposal area designated on the plans and in the field with a sign. Concrete washout of delivery equipment, on-site mixers, and finishing and placement tools shall all be washed and have the rinse water contained in the concrete washout area. The washout area shall include an impervious sump or enclosure sized to suitably contain rinse water appropriate for the quantity of concrete anticipated for the type and size of the proposed project. Rinse water shall be evaporated or pumped back into delivery trucks. All accumulated solids remaining in the washout are shall be disposed of as solid waste.

b.

All construction products, materials and wastes shall be stored, handled, and disposed of in a manner that limits their exposure to stormwater and thus reduces the risk of pollution.

c.

Building products that have the potential to leach pollutants must be under cover to prevent contact with stormwater.

d.

Hazardous materials must be stored in sealed containers in restricted areas to prevent vandalism and accidental spills. All storage and disposal of hazardous materials shall be in accordance with Minnesota Rules.

e.

Solid waste must be stored in covered dumpsters to limit exposure to stormwater.

f.

On-site mobile toilet facilities shall be placed in a manner to reduce the risk of tipping over. All on-site personnel shall use appropriate sanitary facilities for restroom breaks.

g.

Fueling and maintenance activities shall be performed in a manner to avoid any mechanical fluids from contacting the soil or hard surfaces. Spills should be cleaned up immediately. Contaminated soil shall be removed and disposed of in accordance with state law. Absorbents shall be used on impervious surfaces and then swept up and removed. All spills shall be reported according to state law. Water may not be used to dilute or displace spilled materials.

h.

Vehicle washing to remove leaking fluids and contaminated debris from equipment shall not be permitted. Vehicle washing to allow removal of sediment from the vehicle's exterior will be permitted if runoff from the washing activity is appropriately removed from the runoff before discharging from the site.

(6)

Final stabilization. Final stabilization requirements shall be satisfied once each of the following has been completed:

a.

All soil disturbing activities at the site have been completed and all soils are stabilized by a uniform perennial vegetative cover with a minimum density of seventy (70) percent of final intended growth over the entire pervious surface or other equivalent means to prevent soil failure under erosive conditions.

b.

Permanent stormwater management system is constructed and meets design requirements. All accumulated silts must be removed from basins, swales, storm sewers and other stormwater features that may have been deposited during construction.

c.

All synthetic and structural erosion prevention and sediment control BMPs not meant for permanent installation shall be removed. BMPs designed to decompose or remain are not required to be removed.

d.

When individual lots in a residential or commercial development that were originally part of a larger development of an acre or more are sold, the new owners must comply with the requirements of small construction sites as detailed in section 50.1040 if an MPCA construction stormwater permit is not transferred with the property.

(Code 1997, § 74-2027; Ord. No. 190, 5d, § 1, 3-9-2015; Ord. No. 24-124, § 1,  7-22-2024)

(a)

All construction activities which disturb less than one (1) acre of land but more than two thousand five hundred (2,500) square feet are considered small construction sites and are required to have the following erosion and sediment control BMPs in place:

(1)

Perimeter control. Down gradient silt fence or other approved method.

(2)

Vehicle tracking control. Rock or wood mulch construction entrance measuring at least eight (8) feet wide and twenty (20) feet long. All construction access and egress shall be through this entrance.

(3)

Stockpile control. All soil stockpiles shall have effective perimeter control in place prior to commencing stockpiling activities. All soil stockpiles not being actively used shall be either covered with an impermeable sheet or protected by silt fence, no further than three (3) feet from the base of the stockpile.

(4)

Turf establishment. Upon completion of final topsoil grading and seeding, the soil shall be covered with straw mulch (disked in), liquid tackifier, erosion control blanket or sod. Perimeter controls shall remain in place until vegetation is established.

(5)

Good housekeeping. Any sediment that is transported off-site shall be cleaned up and replaced on the site within twenty-four (24) hours of discovery. This includes any sediment in the roadway or gutter.

(b)

A plan shall be submitted to the city development services department which addresses the details and locations of the items listed in this section.

(c)

Erosion and sediment control on small construction sites is the responsibility of the general contractor for the site. In the event that there is no general contractor for the site, the landowner becomes responsible.

(d)

Construction sites with activities disturbing less than two thousand five hundred (2,500) square feet of soil are exempt from the requirements set forth in this article.

(Code 1997, § 74-2028; Ord. No. 190, 5d, § 1, 3-9-2015; Ord. No. 24-125, § 1,  7-22-2024)

(a)

The city shall be allowed access upon written or verbal request and within a reasonable time to make compliance inspections at any point during the construction of the project before final turf is established and final stabilization of the site has been achieved. Specific inspections of the project may include start of construction, completion of clearing, completion of final grading and completion of final landscaping. The applicant shall notify the city a minimum of seventy-two (72) hours prior to these specific dates. Additional inspections as deemed necessary shall also occur.

(b)

The applicant shall allow the city and its assign agent to:

(1)

Enter the project site for the purpose of obtaining information, examining records, or conducting an investigation.

(2)

Bring such equipment on the site as is necessary to conduct such surveys and investigations.

(3)

Examine and copy any books, papers, or digital files pertaining to activities or records required to be kept under the terms and conditions of this article.

(4)

Inspect the stormwater BMPs.

(5)

Sample and monitor any items or activities pertaining to stormwater BMPs.

(6)

Make corrections in stormwater BMPs to meet the requirements of this article.

(c)

These inspections do not satisfy the weekly and rainfall inspections required of the applicant in this article.

(Code 1997, § 74-2029; Ord. No. 190, 5d, § 1, 3-9-2015)

(a)

Stop-work order; revocation of permit. In the event that any person holding a permit pursuant to this article or a landowner violates the terms of the permit or implements site development in such a manner as to materially adversely affect the health, welfare or safety of persons residing or working in the neighborhood, development site, or other area so as to be materially detrimental to the public welfare or injurious to property, nature, or improvements in the neighborhood, the city may suspend or revoke a permit. In addition, the city may enter the premises to perform correction work, following the revocation of the site development permit. The cost of said correction work shall be an assessment on the underlying property.

(b)

Violation and penalties. No person shall construct, enlarge, alter, repair, or maintain any grading, excavation, or fill, or cause the same to be done, contrary to or in violation of any terms of this article or the MPCA's general permit authorization for discharge of stormwater associated with construction activity. Any person violating any of the provisions of this article shall be deemed guilty of a misdemeanor. In addition to any other penalty authorized by this section, any person, partnership, or corporation convicted of violating any of the provisions of this article shall be required to bear the expense of such restoration.

(Code 1997, § 74-2030; Ord. No. 190, 5d, § 1, 3-9-2015)

Applicability. The following sections apply to all indoor and outdoor bulk deicer storage facilities (temporary and permanent) including salt piles, salt bag storage, sand piles and other storage of deicing materials. Bulk storage, as regulated by this chapter, is defined as storage of any material used for deicing and/or traction during winter conditions that is more than five (5) tons in solid form (or one thousand (1,000) gallons in liquid form).

General Requirements.

(1)

Indoor operations for the storage of deicing materials must be provided wherever possible in order to prevent such materials from being affected by rain, snow and melt water.

(2)

All salt, sand and other deicing materials stored outdoors must be covered at all times.

a.

When not using a permanent roof, a waterproof impermeable, flexible cover must be placed over all storage piles to protect against precipitation and surface water runoff. The cover must prevent runoff and leachate from being generated by the outdoor storage piles. The cover must be secured to prevent removal by wind or other storm events. Piles must be formed in a conical shape and covered as necessary to prevent leaching.

b.

Any roof leaks, tears or damage should be temporarily repaired during winter to reduce the entrance of precipitation. Permanent repairs must be completed prior to the next winter season.

Facility siting.

(1)

The facility must be in close proximity to the area in which the deicing materials are to be used, if practical.

(2)

Each facility must be located outside of floodplains and fifty (50) feet from lakes, rivers, streams, ditches, storm drains, manholes, catch basins, wetlands and any other areas likely to absorb runoff. A facility must not be located in close proximity to surface water features, water supplies, wells or drywells.

(3)

The facility must be located on impermeable surfaces.

(4)

The property slope must be away from the [facilities] salt, deicer, and sand storage area.

(5)

Salt vulnerable/intolerant natural areas should be avoided as storage facilities to the extent possible. Where they cannot be avoided, specific measures should be instituted to protect vulnerable areas. Salt vulnerable/intolerable natural areas include, but are not limited to:

a.

Areas with salt sensitive vegetation

b.

Areas serving as a source of drinking water (surface water and ground water)

c.

Areas with bodies of water with low dilution, low volume or salt sensitive species

d.

Areas associated with ground water recharge zones or shallow water table with medium to high permeable soils

Snow piles. Snow piles must be located downslope from salt and deicer storage areas to prevent the snow melt from flowing through storage areas and carrying material to the nearest drainage system or waterway.

Transfer of materials.

(1)

Practices must be implemented in order to reduce exposure (e.g., sweeping, diversions, and/or containment) when transferring salt or other deicing material.

(Ord. No. 22-077, 7-25-2022)