Section 317 Stormwater Management Ordinance
Section 317:00. General Provisions.
Subd. 1. Statutory Authorization. This ordinance shall be known as the Stormwater Management Ordinance and is adopted pursuant to Minnesota Statutes Section 462.351.
Subd. 2. Purpose. The purpose of this ordinance is to control or eliminate stormwater pollution along with soil erosion and sedimentation within the city. The ordinance establishes standards and specifications for conservation practices and planning activities, which minimize stormwater pollution, soil erosion and sedimentation; and prohibits illicit connections and illegal discharges.
Section 317:01. Definitions. Unless specifically defined below, the words or phrases used in this ordinance shall have the same meaning as they have in common usage. When not inconsistent with the context, words used in the present tense include the future tense, words in the plural number include the singular number, and words in the singular number include the plural number. The words 'shall" and 'must" are always mandatory and not merely directive.
Subd. 1. Applicant. Any person or entity that applies for a building permit, subdivision approval, or a permit to allow land disturbing activities. Applicant also means that person's agents, employees, and others acting under this person's direction.
Subd. 2. Best Management Practices (BMPs). Erosion and sediment control and water quality management practices that are the most effective and practicable means of controlling, preventing, and minimizing the degradation of surface water, including construction phasing, minimizing the length of time soil areas are exposed, prohibitions, and other management practices published by state or designated area-wide planning agencies. (Examples of BMPs can be found in the current versions of the Minnesota Pollution Control Agency's publications, 'Protecting Water Quality in Urban Areas," and 'Storm-Water and Wetlands: Planning and Evaluation Guidelines for Addressing Potential Impacts of Urban Storm-Water and Snow-Melt Runoff on Wetlands," the United States Environmental Protection Agency's 'Stormwater Management for Construction Activities: Developing Pollution Prevention Plans and Best Management Practices," (as a reference for BMPs) and the Minnesota Department of Transportation's 'Erosion Control Design Handbook for Local Roads.")
Subd. 3. Buffer. A protective vegetated zone located adjacent to a natural resource, such as a water of the state, that is subject to direct or indirect human alteration. Such a buffer strip is an integral part of protecting an aquatic ecosystem through filtering pollutants and providing adjacent habitat. Acceptable buffer vegetation includes preserving existing predevelopment vegetation and/or planting locally distributed native Minnesota trees, shrubs and grassy vegetation. Alteration of buffers is strictly limited. Buffer areas are designated with permanent markers.
Subd. 4. Developer. A person, firm, corporation, sole proprietorship, partnership, state agency, or political subdivision thereof engaged in a land disturbance activity.
Subd. 5. Discharge. The release, conveyance, channeling, runoff, or drainage, of stormwater, including snowmelt, from a construction site.
Subd. 6. Energy Dissipation. This refers to methods employed at pipe outlets to prevent erosion. Examples include, but are not limited to; aprons, riprap, splash pads, and gabions that are designed to prevent erosion.
Subd. 7. Erosion. Any process that wears away the surface of the land by the action of water, wind, ice, or gravity. Erosion can be accelerated by the activities of people and nature.
Subd. 8. Erosion Control. Refers to methods employed to prevent erosion. Examples include soil stabilization practices, horizontal slope grading, temporary or permanent cover, and construction phasing.
Subd. 9. Erosion and Sediment Practice Specifications or Practice. The management procedures, techniques, and methods to control soil erosion and sedimentation as officially adopted by either the state, county, city or local watershed group, whichever is more stringent.
Subd. 10. Exposed Soil Areas. All areas of the construction site where the vegetation (trees, shrubs, brush, grasses, etc.) or impervious surface has been removed, thus rendering the soil more prone to erosion. This includes topsoil stockpile areas, borrow areas and disposal areas within the construction site. It does not include stockpiles or surcharge areas of gravel, concrete or bituminous. Once soil is exposed it is considered 'exposed soil," until it meets the definition of 'final stabilization."
Subd. 11. Filter Strips. A vegetated section of land designed to treat runoff as overland sheet flow. They may be designed in any natural vegetated form from a grassy meadow to a small forest. Their dense vegetated cover facilitates pollutant removal and infiltration.
Subd. 12. Final Stabilization. Means that all soil disturbing activities at the site have been completed, and that a uniform perennial vegetative cover with a density of seventy (70) percent of the cover for unpaved areas and areas not covered by permanent structures has been established, or equivalent permanent stabilization measures have been employed. Simply sowing grass seed is not considered final stabilization. (Examples of vegetative cover practices can be found in the current version of the Minnesota Department of Transportation's publication, 'Standard Specifications for Construction" as supplemented and as amended from time to time.)
Subd. 13. Hydric Soils. Soils that are saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part.
Subd. 14. Hydrophytic Vegetation. Macrophytic (large enough to be observed by the naked eye) 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.
Subd. 15. Illegal Discharge. Any direct or indirect non-storm water discharge to the storm drain system, except as exempted in Section 317:06 of this ordinance.
Subd. 16. Illicit Connections. An illicit connection is defined as either of the following: Any drain or conveyance, whether on the surface or subsurface, which allows an illegal discharge to enter the storm drain system including but no limited to any conveyance which allows any non-storm water discharge including sewage, process wastewater, and wash water to enter the storm drain system and any connections to the storm drain system from indoor drains and sinks, regardless of whether said drain or connection has been previously allowed, permitted, or approved by an authorized enforcement agency or, any drain or conveyance connected from a commercial or industrial land use to the storm drain system which has not been documented in plans, maps, or equivalent records and approved by an authorized enforcement agency.
Subd. 17. Impervious Surface. A constructed hard surface that either prevents or retards the entry of water into the soil, and causes water to run off the surface in greater quantities and at an increased rate of flow than existed prior to development. Examples include rooftops, sidewalks, patios, driveways, parking lots, storage areas, and concrete, asphalt, or gravel roads.
Subd. 18. Land Disturbance Activity. Any land change that may result in soil erosion from water or wind and the movement of sediments into or upon waters or lands within this government's jurisdiction, including clearing and grubbing, grading, excavating, transporting and filling of land. Within the context of this rule, land disturbance activity does not mean:
a. Minor land disturbance activities such as home gardens and an individual's home landscaping, repairs, and maintenance work.
b. Any activity including construction, installation, and maintenance of fences, signs, posts, poles, and electric, telephone, cable television, utility lines or individual service connections to these utilities, which result in disturbing less than one acre of land.
c. Tilling, planting, or harvesting of agricultural, horticultural, or silvicultural (forestry) crops.
d. Emergency work to protect life, limb, or property and emergency repairs, unless the land disturbing activity would have otherwise required an approved erosion and sediment control plan, except for the emergency. If such a plan would have been required, then the disturbed land area shall be shaped and stabilized in accordance with the city's requirements as soon as possible.
Subd. 19. Native Vegetation. The presettlement group of plant species native to the local region that were not introduced as a result of European settlement or subsequent human introduction.
Subd. 20. Ordinary High Water Mark. This is generally the boundary elevation where the vegetation changes from predominately aquatic (where 'aquatic" broadly means that the vegetation can survive moist conditions) to terrestrial. This elevation delineates the highest water level, which has been maintained for a sufficient period of time to leave evidence upon the landscape, commonly that point where the natural vegetation changes from predominantly aquatic to predominantly terrestrial. Water often reaches this elevation in spring. For rivers and streams the ordinary high water mark is usually the top of the bank. It is less well defined for lakes and wetlands. The definition in Minnesota Statute 103G.005, subdivision 14 provides that the ". . . 'Ordinary high water level" means the boundary of water basins, watercourses, public waters, and public waters wetlands, and:
a. the ordinary high water level is an elevation delineating the highest water level that has been maintained for a sufficient period of time to leave evidence upon the landscape, commonly the point where the natural vegetation changes from predominantly aquatic to predominantly terrestrial;
b. for watercourses, the ordinary high water level is the elevation of the top of the bank of the channel; and
c. for reservoirs and flowages, the ordinary high water level is the operating elevation of the normal summer pool.
The term 'ordinary high water mark" is further defined in Minnesota Rule 6120.2500, subpart 11. Ordinary high water marks are determined by the Minnesota Department of Natural Resources' area hydrologist.
Subd. 21. Paved Surface. A constructed hard, smooth surface made of gravel, asphalt, concrete or other pavement material. Examples include, but are not limited to, roads, sidewalks, driveways and parking lots.
Subd. 22. Permanent Cover. Means 'final stabilization." Examples include grass, gravel, asphalt, and concrete. See also the definition of 'final stabilization."
Subd. 23. Runoff Coefficient. The fraction of total precipitation that is not infiltrated into or otherwise retained by the soil, concrete, asphalt or other surface upon which it falls, that will appear at the conveyance as runoff. This coefficient is usually estimated for an event or on an average annual basis.
Subd. 24. Sediment. The product of an erosion process; solid material both mineral and organic, that is in suspension, is being transported, or has been moved by water, wind, or ice, and has come to rest on the earth's surface either above or below water level.
Subd. 25. Sedimentation. The process or action of depositing sediment.
Subd. 26. Sediment Control. The methods employed to prevent sediment from leaving the development site. Sediment control practices include silt fences, sediment traps, earth dikes, drainage swales, check dams, subsurface drains, pipe slope drains, storm drain inlet protection, and temporary or permanent sedimentation basins.
Subd. 27. Soil. The unconsolidated mineral and organic material on the immediate surface of the earth. For the purposes of this document, stockpiles of gravel, aggregate, concrete or bituminous materials are not considered 'soil" stockpiles.
Subd. 28. Stabilized. The exposed ground surface after it has been covered by sod, erosion control blanket, riprap, or other material that prevents erosion. Simply sowing grass seed is not considered stabilization.
Subd. 29. Stormwater. Under Minnesota Rule 7077.0105, subpart 41b stormwater, 'means precipitation runoff, stormwater runoff, snow melt runoff, and any other surface runoff and drainage." (According to the Federal Code of Regulations under 40 CFR 122.26 [b], 'Stormwater means stormwater runoff, snow melt runoff and surface and drainage."). Stormwater does not include construction site dewatering.
Subd. 30. Stormwater Management Plan. A joint grading/erosion and sediment control plan that is a document containing the requirements of Section 317:03 of this Ordinance, that when implemented will decrease soil erosion on a parcel of land and off-site nonpoint pollution. It involves both temporary and permanent controls.
Subd. 31. Structure. Anything manufactured, constructed or erected which is normally attached to or positioned on land, including portable structures, earthen structures, roads, parking lots, and paved storage areas.
Subd. 32. Subdivision. Any tract of land divided into building lots for private, public, commercial, industrial, etc. development. Minnesota Rule 6120.2500, subpart 17 defines subdivision as, '. . . land that is divided for the purpose of sale, rent, or lease, including planned unit development."
Subd. 33. Temporary Protection. Short term methods employed to prevent erosion. Examples of such protection include: straw, mulch, erosion control blankets, wood chips, and erosion netting.
Subd. 34. Urban. Of, relating to, characteristic of, constituting a city.
Subd. 35. Vegetated or Grassy Swales. A vegetated earthen channel that conveys stormwater, while treating the stormwater by biofiltration. Such swales remove pollutants by both filtration and infiltration.
Subd. 36. Waters of the State. As defined in Minnesota Statutes section 115.01, subdivision 22 the term '. . . "waters of the state" means 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."
Subd. 37. Wet Detention Facility. A permanent man made structure, used for the temporary storage of runoff to control the peak discharge rates and provide gravity settling of pollutants.
Subd. 38. Wet Retention Facility. A permanent man-made structure, containing a permanent pool of water without release except by mean of evaporation, infiltration, or emergency bypass.
Subd. 39. Wetlands. As defined by the Wetland Conservation Act, as amended from time to time, and Steele County.
Section 317:02. Scope and Effect.
Subd. 1. Applicability. Every applicant for a building permit or subdivision approval must submit a stormwater management plan to the Department of Community Development. Every applicant for a permit for land disturbing activities that do not require a building permit or subdivision approval must submit a stormwater management plan to the Engineering Department. Each application shall be accompanied by a copy of the applicant's application to the Minnesota Pollution Control Agency (MPCA) for a National Pollutant Discharge Elimination System/State Disposal System (NPDES/SDS) construction stormwater permit, if applicable. No building permit, subdivision approval, or permit to allow land disturbing activities shall be issued until approval of the stormwater management plan or a waiver of the approval requirement has been obtained in strict conformance with the provisions of this ordinance.
Subd. 2. Exemptions. The provisions of this ordinance do not apply to:
a. 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 ordinance and was not required to have a NPDES/SDS construction stormwater permit;
b. Any land disturbing activity for which plans have been approved by other watershed management organizations within six months prior to the effective date of this ordinance;
c. A lot for which a building permit has been approved on or before the effective date of this ordinance;
d. Certain activities that disturb less than one acre of land, such as, the installation of fence, sign, telephone, and electric poles and other kinds of posts or poles; or other underground utilities;
e. Emergency work to protect life, limb, or property.
Subd. 3. The City Council may waive any requirement of this ordinance upon making finding that compliance with the requirement will involve an unnecessary hardship and the waiver of such requirement will not adversely affect the standards and requirements set forth in Section 317:05 and 317:06. The City Council may require as a condition of the waiver, such dedication or construction, or agreement to dedicate or construct as may be necessary to adequately meet said standards and requirements.
Section 317:03. Stormwater Management Plan Application Procedures.
Subd. 1. Application. A written application for stormwater management plan approval, along with the proposed stormwater management plan, shall be filed with the Department of Community Development or the Engineering Department when applicable and shall include a statement indicating the purpose for which the approval is requested and adequate evidence showing that the proposed use will conform to the standards set forth in this ordinance. Prior to applying for approval of a stormwater management plan, an applicant may have the stormwater management plans reviewed by the appropriate departments of the city.
Subd. 2. Two sets of clearly legible blue or black lined copies of drawings and required information (as noted in Subd. 3 of this section) shall be submitted to the Department of Community Development or the Engineering Department when applicable and shall be accompanied by all applicable fees. Drawings shall be prepared to a scale appropriate to the site of the project and suitable for the review to be performed. At a minimum the scale shall be 1 inch equals 100 feet.
Subd. 3. Stormwater Management Plan. At a minimum, the stormwater management plan shall contain the following information, except as determined otherwise by staff. Items identified with an asterix (*) in subsections a) through e) below may be omitted upon initial application if determined to be unnecessary by staff.
a. Identification and Description
1) Proposed name of development;
2) Legal description and address;
3) Names, addresses, and phone numbers of the primary contact, record owner, subdivider, land surveyor, engineer, designer of the plat, and any agent having control of the land;
4) Graphic scale not less than one inch to one hundred feet;
5) North arrow;
6) Location of the tract by an insert map at a scale sufficient to clearly identify the location of the property and giving such information as the names and numbers of adjoining roads, railroads, utilities, subdivisions, towns and districts or other landmarks; and
7) Date of preparation.
b. Existing Conditions
1) Boundary lines of proposed plan;
2) Location of all utility or drainage easements on said property;
3) Existing zoning classifications for land within and abutting the development;
4) Acreage and lot dimensions;
5) Location of roads, lots, structures, etc. as required by the city;
6) 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;
7) Location and dimensions of existing stormwater drainage systems and natural drainage patterns on and immediately adjacent to the site delineating in which direction and at what rate stormwater is conveyed from the site, identifying the receiving stream, river, public water, or wetland, and setting forth those areas of the unaltered site where stormwater collects;
8) 100-year floodplains, flood fringes and floodways.
9) *Wetland area (submit approval letter from the Steele County Soil and Water Conservation District Office stating that there are either no wetlands, or detailing construction requirements related to wetlands and any necessary wetlands mitigation);
10) *Steep slopes where areas of 18% or more exist over a distance for 50 feet or more;
11) *Bluff areas where the slope rises at least 25 feet above the toe of the bluff and the grade of the slope from the toe of the bluff to a point 25 feet or more above the toe of the bluff averages 30% or greater;
12) *Vegetative cover and clearly delineating any vegetation proposed for removal;
13) *Wooded area and tree survey;
14) *Agricultural land preservation area(s);
15) *Map of soil types and infiltration rates;
16) *Hydrologic calculations for volume runoff, velocities, and peak flow rates for the 2-year 24-hour rainfall event, 10-yr 24-hour storm event, and 100-yr 24-hour storm event;
17) *Bankfull discharge rate (1.5 year recurrence interval) of creek or stream if there is a waterway on the site or if the site discharges directly to a waterway; and
c. Site Construction Plan. A site construction plan including:
1) Locations and dimensions of all proposed land disturbing activities and any phasing of those activities;
2) Locations and dimensions of all temporary soil or dirt stockpiles;
3) Locations and dimensions of all construction site erosion control measures necessary to meet the requirements of this ordinance;
4) 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 ordinance; and
5) Provisions for maintenance of the construction site erosion control measures during construction.
6) NPDES/SDS construction stormwater permit.
d. Plan of Final Site Conditions. A plan of final site conditions on the same scale as the existing site map showing the site changes including:
1) Layout of proposed streets showing the proposed names, the right-of-way widths, centerline gradients and typical cross sections;
2) Location and width of proposed pedestrian ways and utility easements;
3) Lot sizes, layout, numbers and preliminary dimensions of lots and blocks;
4) Minimum building setback lines as required by the zoning ordinance;
5) Proposed elevations of lowest floor, top of foundation at center line of lot, elevation of lot corners, along with the structure type are indicated on the plan;
6) Areas and size of areas other than streets, alleys, pedestrian ways and utility easements, intended to be dedicated or reserved for public use;
7) Location of proposed public sewer and water mains;
8) 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;
9) A drainage plan of the developed site delineating in which direction and at what rate stormwater will be conveyed from the site and setting forth the areas of the site where stormwater will be allowed to collect;
10) Normal water level (NWL), high water level (HWL), and emergency overflow elevations for the site; and
11) A maintenance plan indicating the responsible party or parties charged with the long term maintenance, repair, or replacement of any privately owned stormwater conveyance and retention facilities. Such plan shall also include information on the intended final ownership of the properties containing such facilities and the means by which inspection, maintenance, repair, or replacement when necessary shall be funded and accomplished;
12) *A landscape plan, drawn to an appropriate scale, including dimensions and distances and the location, type, size and description of all proposed landscape materials and proposed ground cover (final stabilization) which will be added to the site as part of the development;
13) * Hydrologic calculations for volume runoff, velocities, and peak flow rates for the 1-year 24-hour event, 2-year 24-hour rainfall event, 10-yr 24-hour storm event, and 100-yr 24-hour storm event. All rainfall amounts shall be determined according to the United States Weather Bureau (USWB) TP40 report;
14) *Bankfull discharge rate (1.5 year recurrence interval) of creek or stream if there is a waterway on the site or if the site discharges directly to the waterway;
15) Any other information pertinent to the particular project that, in the opinion of the City is necessary for the review of the project.
e. *Models/Methodologies/Computations. Hydrologic models and design methodologies used for determining runoff characteristics and analyzing stormwater management structures shall be approved by the City Engineer. Plans, specifications and computations for stormwater management facilities submitted for review shall be sealed and signed by a registered professional engineer. All computations shall appear on the plans submitted for review, unless otherwise approved by the City Engineer.
Section 317:04. Stormwater Management Plan Review Procedure.
Subd. 1. Process.
a. Subdivisions. Stormwater management plans meeting the requirements of Section 317:03 shall be reviewed by both the Community Development Department and the Engineering Department and reviewed in accordance with the Standards of Section 317:05. Their findings shall be forwarded to the Planning Commission prior to its approval of the final plat of the subdivision. Staff findings shall include recommendation for approval; approval with conditions or modifications; or denial based on submission of incomplete plans, failure to meet ordinance provisions, or incompatibility with overall city drainage plans. Following Planning Commission approval, the final plat with the stormwater management plan shall be submitted with any recommendations and conditions to the City Council at its next regular meeting. City Council action on the final plat and stormwater management plan must be accomplished within 60 days following the date the application for approval is filed with and accepted by the Community Development Department, unless this time limit is extended as provided by State statue.
b. Building Permits. Stormwater management plans meeting the requirements of Section 317:03 shall be reviewed by both the Community Development Department and the Engineering Department for compliance with the standards of Section 317:05. Within 30 days of the filing of the plan, city staff shall contact the applicant or its agent on the review findings and indicate approval; approval with certain conditions or modifications; or denial based on submission of incomplete plans, failure to meet ordinance provisions, or incompatibility with overall city drainage plans. If the plan is denied by the city, the applicant or its agent shall have 45 days from this initial contact to resubmit plans for review under the original application and with no additional processing and review fee. Upon approval of the stormwater management plans, the applicant or its agent shall be notified of compliance. Building permits involving such non-exempted land disturbance activities shall not be issued until such notice of compliance is given. Construction of single family or two family dwellings must comply with in place BMPs and any existing permitted SWPPP for the subdivision, including NPDES/SDS construction stormwater permit requirements and Subdivision Registration.
c. Land Disturbing Activities Not Requiring a Building Permit. Stormwater management plans meeting the requirements of Section 317:03 shall be reviewed by the Engineering Department for compliance with the standards of Section 317:05. Within 30 days of the filing of the plan, city staff shall contact the applicant or its agent on the review findings and indicate approval; approval with certain conditions or modifications; or denial based on submission of incomplete plans, failure to meet ordinance provisions, or incompatibility with overall city drainage plans. If the plan is denied by the city, the applicant or its agent shall have 45 days from this initial contact to resubmit plans for review under the original application and with no additional processing and review fee. Upon approval by the Engineering Department of the stormwater management plan, the applicant or its agent shall be notified of compliance. Subject to any other applicable statutes, ordinances, rules and regulations, permits or other such approvals for such non-exempted land disturbing activities shall be issued.
Subd. 2. Duration. Approval of a plan submitted under the provisions of this ordinance shall expire one year after the date of approval unless construction has commenced in accordance with the plan. Prior to the date of expiration the applicant or its agent may submit to the Community Development Department or the Engineering Department, as applicable, a written request for an extension of time to commence construction activities. This request shall include the reasons for the requested extension and a projected timetable for construction and completion. An extension of not greater than one single year may be granted by the department. Receipt of any request for an extension shall be acknowledged by the department within 15 days and a final decision on the extension shall be made within 30 days of receipt.
Subd. 3. Conditions. A stormwater management plan may be approved subject to compliance with conditions reasonable and necessary to insure that the requirements contained in this ordinance are met. Such conditions may, among other matters, limit the size, kind or character of the proposed development, require the construction of structures, drainage facilities, storage basins and other facilities, require replacement of vegetation, establish required monitoring procedures, stage the work over time, require alteration of the site design to insure buffering, and require the conveyance to the City of Owatonna or other public entity of certain lands or interests therein.
Subd. 4. Fees. All applications for stormwater management plan approval shall be accompanied by a grading/erosion and sediment control permit application and the applicable fee. The fees shall be in the amount duly established by the Council from time to time. The permit fee schedule is listed in Section 550:00, subd. 20.
Section 317:05. Stormwater Management Plan Approval Standards.
Subd. 1. No stormwater management plan which fails to meet the standards contained in this section shall be approved.
Subd. 2. All stormwater management plans must be prepared in accordance with the City of Owatonna Stormwater Management Plan (SWMP), as amended from time to time.
Subd. 3. Site Dewatering. Water pumped from the site shall be treated by temporary sedimentation basins, grit chambers, sand filters, up flow chambers, hydro-cyclones, swirl concentrators or other appropriate controls. Water may not be discharged in a manner that causes erosion or flooding of the site or receiving channels or a wetland and shall not be discharged into the City Sanitary Sewer System.
Subd. 4. Waste and Material Disposal. All waste and unused building materials (including garbage, debris, cleaning wastes, wastewater, toxic materials or hazardous materials) shall be properly disposed of off-site and not allowed to be carried by runoff into a receiving channel or storm sewer system.
Subd. 5. Tracking. Each site shall have graveled roads, access drives and parking areas of sufficient width and length 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.
Subd. 6. Drain Inlet Protection. All storm drain inlets shall be protected during construction until control measures are in place with a straw bale, silt fence or equivalent barrier meeting accepted design criteria, standards and specifications contained in the MPCA publication 'Protecting Water Quality in Urban Areas."
Subd. 7. Site Erosion Control. The following criteria apply only to construction activities that result in runoff leaving the site.
a. Channelized runoff from adjacent areas passing through the site shall be diverted around disturbed areas, if practical. Otherwise, the channel shall be protected as described below. Sheetflow runoff from adjacent areas greater than 10,000 square feet in area shall also be diverted around disturbed areas, unless shown to have resultant runoff rates of less than 0.5 cubic feet per second across the disturbed area for the one-year storm. Diverted runoff shall be conveyed in a manner that will not erode the conveyance and receiving channels.
b. All activities on the site shall be conducted in a logical sequence to minimize the area of bare soil exposed at any one time.
c. Runoff from the entire disturbed area on the site shall be controlled by meeting either subsections 1) and 2) or 1) and 3) below:
1) All disturbed ground left inactive for fourteen or more days shall be stabilized by seeding or sodding (only available prior to September 15) or by mulching or covering or other equivalent control measure. All exposed soil areas or slopes draining to an impaired water shall be stabilized no later than seven (7) days after the construction activity in that portion of the site has temporarily or permanently ceased.
2) For sites with more than ten acres disturbed at one time, or if a channel originates in the disturbed area, one or more temporary or permanent sedimentation basins shall be constructed. Each sedimentation basin shall have a surface area of at least one percent of the area draining to the basin and at least three feet of depth and constructed in accordance with accepted design specifications. Sediment shall be removed to maintain a depth of three feet The basin discharge rate shall also be sufficiently low as to not cause erosion along the discharge channel or the receiving water.
3) For sites with less than ten acres disturbed at one time, silt fences, straw bales, or equivalent control measures shall be placed along all sideslope and downslope sides of the site. If a channel or area of concentrated runoff passes through the site, silt fences shall be placed along the channel edges to reduce sediment reaching the channel. The use of silt fences, straw bales, or equivalent control measures must include a maintenance and inspection schedule.
d. Any soil or dirt storage piles containing more than ten cubic yards of material should not be located with a downslope drainage length of less than 25 feet from the toe of the pile to a roadway or drainage channel. If remaining for more than seven days, they shall be stabilized by mulching, vegetative cover, tarps, or other means. Erosion from piles which will be in existence for less than seven days shall be controlled by placing straw bales or silt fence barriers around the pile and tarping. In-street utility repair or construction soil or dirt storage piles located closer than 25 feet of a roadway or drainage channel must be covered with tarps or suitable alternative control, if exposed for more than seven days, and the storm drain inlets must be protected with straw bale or other appropriate filtering barriers.
Subd. 8. Stormwater Management Criteria For Permanent Facilities.
a. An applicant shall install or construct, on or for the proposed land disturbing or development activity, all stormwater management facilities necessary to manage increased runoff so that the 2-year, 10-year, and 100-year 24 hour storm peak discharge rates existing before the proposed development shall not be increased unless otherwise approved by the City. Applicant shall also verify accelerated channel erosion will not occur as a result of the proposed land disturbing or development activity. The City may require, at its discretion, an applicant to make an in-kind or monetary contribution to the development and maintenance of community stormwater management facilities designed to serve multiple land disturbing and development activities undertaken by one or more persons, including the applicant.
b. The applicant shall give consideration to reducing the need for stormwater management facilities by incorporating the use of natural topography and land cover such as wetlands, ponds, natural swales and depressions as they exist before development to the degree that they can accommodate the additional flow of water without compromising the integrity or quality of the wetland or pond.
c. The following stormwater management practices shall be investigated in developing a stormwater management plan in the following descending order of preference:
1) Natural infiltration of precipitation on-site;
2) Flow attenuation by use of open vegetated swales and natural depressions; and
3) Stormwater detention and/or retention facilities. (Wet detention basins preferred method) or financial contribution for regional detention/retention facilities.
d. A combination of successive practices may be used to achieve the applicable minimum control requirements specified in subsection (a) above. Justification shall be provided by the applicant for the method selected.
Subd. 9. Wet Detention Basin Design Standards. Wet detention basins constructed in the City of Owatonna shall be designed according to the most current technology as reflected in the MPCA publication 'Protecting Water Quality in Urban Areas", and shall contain, at a minimum, the following design factors:
a. A permanent pond surface area equal to two percent of the impervious area draining to the pond or one percent of the entire area draining to the pond, whichever amount is greater;
b. An average permanent pool depth of three to ten feet;
c. A recommended permanent pool length to width ratio of 3:1 or greater;
d. A minimum protective shelf extending ten feet into the permanent pool with a slope of 10:1, beyond which slopes should not exceed 3:1, and above which slopes should not exceed 4:1;
e. A protective buffer strip of vegetation surrounding the permanent pool at a minimum width of one rod (16.5 feet);
f. All wet detention basins shall place the outlet at least 1' below the NWL and have a skimming device to keep oil, grease, and other floatable material from moving downstream during a 1-year 24 hour storm;
g. All stormwater detention/retention facilities must have a forebay to remove coarse-grained particles prior to discharge into a watercourse or storage basin;
h. Wet detention basins should have a dead storage volume equal or greater to the post-development runoff from a 1-year 24 hour rainfall;
i. Wet detention basins should have a 20-foot access easement if not located along a roadway;
j. Buildings should have a minimum setback of 30 feet from the Normal Water Level (NWL) of the wet detention basin;
k. Wet detention basins shall incorporate multi-staged outlets as necessary;
l. All wet detention basins designed should have the NWL, the 2-year HWL, 10-year HWL, and the 100-year HWL clearly indicated on all plans;
m. City approved vegetation which is consistent with the surrounding wetland vegetation should be proposed in the 10:1 bench area of the proposed ponds.
Subd. 10. Alternative Stormwater Detention and/or Retention Facilities. Alternative facilities are allowed and are subject to approval by the City Engineer. All alternative facilities shall be designed according to Section VII of the City's SWMP, the most current technology as reflected in the MPCA publication 'Protecting Water Quality in Urban Areas", and are subject to applicable wet detention basin design factors.
Subd. 11. Wetlands. All projects must meet the requirements of the Wetlands Conservation Act and the Steele County Technical Evaluation Panel, and a letter from the Local Government Unit (LGU) certifying impending approval is required.
Subd. 12. Steep Slopes. No land disturbing or development activities shall be allowed on slopes of 18 percent or more.
Subd. 13. Inspection and Maintenance. All stormwater management facilities shall be designed to minimize the need of maintenance, to provide access for maintenance purposes and to be structurally sound. All stormwater management facilities shall have a plan of operation and maintenance that assures continued effective removal of pollutants carried in stormwater runoff. The City Engineer, or designated representative, may inspect all stormwater management facilities during and after construction as deemed necessary by the City. The inspection records will be kept on file at the Engineering Department for a period of 6 years. It shall be the responsibility of the applicant to obtain any necessary easements or other property interests to allow access to the stormwater management facilities for inspection and maintenance purposes.
Subd. 14. Models/Methodologies/Computations. Hydrologic models and design methodologies used for the determination of runoff and analysis of stormwater management structures shall be approved by the City Engineer. Plans, specification and computations for stormwater management facilities submitted for review shall be sealed and signed by a registered professional engineer. All computations shall appear on the plans submitted for review, unless otherwise approved by the City Engineer.
Subd. 15. All hydrologic calculations submitted shall incorporate NRCS (formally known as SCS) methods. Show all calculations regarding curve numbers and time of concentration determinations.
Subd. 16. All hydrologic calculations submitted shall show existing soil maps of the site to verify existing soil conditions.
Subd. 17. All drainage maps submitted for the existing and proposed conditions shall show 2-foot contours, with drainage areas clearly labeled. Drainage area maps shall be scaled no less than 1:100.
Subd. 18. Watershed Management Plans/Groundwater Management Plans. Stormwater management plans shall be consistent with adopted watershed management plans and groundwater management plans prepared in accordance with Minnesota Statutes section 103B.231 and 103B.255 respectively, and as approved by the Minnesota Board of Water and Soil Resources in accordance with state law.
Subd. 19. Easements. If a stormwater management plan involves direction of some or all runoff off the site, it shall be the responsibility of the applicant to obtain from adjacent property owners any necessary easements or other property interests concerning flowage of water.
Section 317:06. Stormwater and Urban Runoff Pollution Control.
Subd. 1. Illegal Disposal.
a. No person shall throw, deposit, place, leave, maintain, keep or permit to be thrown, placed, left, maintained or kept, any refuse, rubbish, garbage, or any other discarded or abandoned objects, articles, or accumulations, in or upon any street, alley, sidewalk, storm drain, inlet, catch basin conduit or drainage structure, business place, or upon any public or private plot of land in the City, so that the same might be or become a pollutant, except in containers, recycling bags, or other lawfully established waste disposal facility.
b. No person shall intentionally dispose of leaves, dirt, or other landscape debris into a street, road, alley, catch basin, culvert, curb, gutter, inlet, ditch, natural watercourse, flood control channel, canal, storm drain or any fabricated natural conveyance.
Subd. 2. Illegal Discharges and Illicit Connections.
a. No person shall cause any illegal discharge to enter the municipal storm water system unless such discharge: (1) consists of non-storm water that is authorized by an NPDES/SDS construction stormwater permit obtained from the MPCA; or (2) is associated with fire fighting activities.
b. No person shall use an illicit connection to intentionally convey non-storm water to the City storm water system.
Subd. 3. Good Housekeeping Provisions. Any owner or occupant of property within the City shall comply with the following good housekeeping requirements:
a. No person shall leave, deposit, discharge, dump, or otherwise expose any chemical or septic waste in an area where discharge to streets or storm drain system may occur. This section shall apply to both actual and potential discharges.
b. Runoff of water from residential property shall be minimized to the maximum extent practicable. Runoff of water from the washing down of paved areas in commercial or industrial property is prohibited unless necessary for health or safety purposes and not in violation of any other provisions in the City's codes.
c. Storage of Materials, Machinery, and Equipment
1) Objects, such as motor vehicle parts, containing grease, oil or other hazardous substances, and unsealed receptacles containing hazardous materials, shall not be stored in areas susceptible to runoff.
2) Any machinery or equipment which is to be repaired or maintained in areas susceptible to runoff shall be placed in a confined area to contain leaks, spills, or discharges.
Subd. 3. Removal of Debris and Residue.
a. All motor vehicle parking lots located in areas susceptible to runoff shall be swept, every six (6) months at a minimum, to remove debris. Such debris shall be collected and properly disposed. However, lots are not required to be swept for one month following a day on which precipitation of one-half inch or more occurs.
b. Fuel and chemical residue or other types of potentially harmful material, such as animal waste, garbage or batteries, which is located in an area susceptible to runoff, shall be removed as soon as possible and disposed of properly. Household hazardous waste may be disposed of through the Steele County collection program or at any other appropriate disposal site and shall not be placed in a trash container.
Section 317:07. Enforcement. The city shall be responsible for enforcing this ordinance.
Subd. 1. Notification of Failure of the Stormwater Management Plan. The City shall notify the applicant of the failure of the stormwater pollution control plan's measures.
a. Notification by City. The initial contact will be by phone to the parties listed on the application and/or the stormwater pollution control plan. Forty-eight (48) hours after notification by the City or seventy-two (72) hours after the failure of erosion control measures, the City, at its discretion, may begin corrective work.
b. Erosion Off-Site. If erosion breaches the perimeter of the site, the applicant shall immediately develop a cleanup and restoration plan, obtain the right-of-entry from the adjoining property owner, and implement the cleanup and restoration plan within forty-eight (48) hours of obtaining the adjoining property owner's permission. In no case, unless written approval is received from the City, may more than seven (7) calendar days go by without corrective action being taken. If in the discretion of the City, the permit holder does not repair the damage caused by the erosion, the City may do the remedial work required.
c. Erosion into Streets, Wetlands, or Water Bodies. If eroded soils (including tracked soils from construction activities) enter or appear likely to enter streets, wetlands, or other water bodies, the applicant shall immediately undertake cleanup and repair. The applicant shall provide all traffic control and flagging required to protect the traveling public during the cleanup operations.
d. Failure to Do Corrective Work. When an applicant fails to conform to any provision of this policy within the time stipulated, the City may take the following actions.
1) Withhold the scheduling of inspections and/or the issuance of a Certificate of Occupancy.
2) Revoke any permit issued by the City to the applicant for the site in question or any other of the applicant's sites within the City's jurisdiction.
3) Direct the correction of the deficiency by the City staff or by a separate contract. The issuance of a permit constitutes a right-of-entry for the City or its contractor to enter upon the construction site for the purpose of correcting deficiencies in the erosion control.
4) All costs incurred by the City in correcting stormwater pollution control deficiencies shall be reimbursed by the applicant. If payment is not made within thirty (30) days after costs are incurred by the City, then the City may assess the remaining amount against the property. As a condition of the permit granted under this Ordinance, the owner shall waive notice of any assessment hearing to be conducted by the City, concur that the benefit to the property exceeds the amount of the proposed assessment, and waive all rights by virtue of Minnesota Statute 429.081 to challenge the amount or validity of assessment.
Subd. 2. Notification of Need for Maintenance, Repair, or Replacement of Existing Private Stormwater Facilities of a Non-Critical Nature. If upon inspection, the Engineering Department finds that any private stormwater management facilities require maintenance, repair, or replacement, but such deficiencies do not create a critical or imminent threat to adjacent properties, the environment, or other stormwater facilities, the party or parties responsible for the continued operation of the facilities shall be given written notice of the findings, what actions are required to correct the situation, and a timetable by which such activities must be completed. Such parties shall have 15 days to reply to the Engineering Department indicating their response to the notice. If the responsible party or parties do not complete the necessary activities stipulated by the Engineering Department, the City Council, after notice and public hearing, may order that such activities are completed by the city or its designated contractor and that all costs associated with such activities be certified by the City Engineer to the City Council. The amount so charged shall be a lien upon the properties benefiting from and utilizing the stormwater facilities maintained, repaired or replaced and shall be added to, and become, and form part of the taxes next to be assessed and levied upon such properties, and the Council shall, by appropriate resolution, assess the costs above mentioned against said properties, and certify the same to the County Auditor of Steele County, Minnesota. The same shall be collected and enforced in the same manner as the collection of real estate taxes.
Subd. 3. Nuisance. A violation of this Ordinance constitutes a public nuisance under Section 1090:00 of this Ordinance Code.
Subd. 4. Legal Remedies Nonexclusive. Nothing in this section shall be construed to limit the City's other available legal remedies for any violation of this Ordinance including criminal, civil, injunctive or other remedies.
Subd. 5. Penalties. Any person, firm, or corporation violating any provision of this ordinance shall be guilty of a penal offense and upon conviction thereof, subject to the penalties set forth in Chapter XI, Section 1100:00 subd. 1 of this Ordinance Code of Owatonna for each offense. A separate offense shall be deemed committed on each day during or on which a violation occurs or continues.
Section 317:08. Right of Entry and Inspection.
Subd. 1. Powers. The applicant shall allow the city and its authorized representatives, upon presentation of credentials to:
a. Enter upon the permitted site for the purpose of obtaining information, examination of records, conducting investigations or surveys.
b. Bring such equipment upon the permitted development as is necessary to conduct such surveys and investigations.
c. Examine and copy any books, papers, records, or memoranda pertaining to activities or records required to be kept under the terms and conditions of this permitted site.
d. Inspect the stormwater pollution control measures.
e. Sample and monitor any items or activities pertaining to stormwater pollution control measures.
Section 317:09. Abrogation and Greater Restrictions. This ordinance is not intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this ordinance imposes greater restrictions, the provisions of this ordinance shall prevail. All other ordinances inconsistent with this ordinance are hereby repealed to the extent of the inconsistency only.
Section 317:10. Severability. The provisions of this ordinance are severable, and if any provisions of this ordinance, or application of any provision of this ordinance to any circumstance, are held invalid, the application of such provision to other circumstances, and the remainder of this ordinance must not be affected thereby.