(A) Site plan review. The applicant of construction activity shall submit a copy of the site plan as part of the permit application for review and confirmation that chapter requirements have been met.
(1) If the permit application is denied, and the applicant would like to proceed with the project, the applicant must revise the permit application, including the site plan, and resubmit.
(2) Once a permit application has been issued/approved, the site plan becomes an enforceable document and the applicant must comply with all requirements identified in the site plan. The applicant is also responsible for keeping the storm water runoff control requirements identified in the site plan up-to-date.
(B) Site plan requirements.
(1) The site plan must include the following project information.
(a) Project name.
(b) A narrative describing the nature of the construction activity, including:
1. Project description. The nature and purpose of the land disturbing activity and the amount of grading, utilities, and building construction involved;
2. Schedule of anticipated starting and completion date of each land disturbing activity, including the installation of construction site erosion control measures needed to meet the requirements of this chapter;
(c) Location of the project.
(d) Total acreage to be disturbed.
(e) Names of the applicant responsible for the proposed construction activity including chain of command describing who is responsible for implementing the erosion and sediment control BMPs during construction.
(f) Description of soils on site.
(g) Receiving waters within one mile of project.
(2) The site plan must include the location, type, and narrative of the following best management practices (BMPs) consistent with standards identified in division (C) of this section (Best Management Practices (BMPs) Requirements).
(a) Down gradient sediment controls;
(b) Soil stabilization (temporary and permanent);
(c) Vehicle tracking;
(d) Inspection and maintenance schedules; and
(e) Other BMPs as applicable:
1. Areas that are not to be disturbed;
2. Phasing and stabilization BMPs for steep slopes;
3. Temporary or permanent ditches or swales being used as sediment containment systems;
4. Pipe outlet energy dissipation;
5. Buffer zones including but not limited to:
a. A minimum of a 50-foot natural buffer;
b. A minimum of 100 foot buffer zone from "other special waters", "prohibited waters", and "restricted waters" as defined;
6. Inlet protection BMPs;
7. Stockpile BMPs;
8. Dewatering and basin draining;
9. Temporary sedimentation basins consistent with design criteria for temporary sediment basins;
10. Pollution prevention management BMPs;
11. Permanent stormwater management BMPs.
(C) Best management practices (BMPs) requirements.
(1) Erosion prevention practices.
(a) All areas not to be disturbed must be delineated before work begins;
(b) All steep slopes must be identified in the site plan and disturbance of those steep slopes should be minimized. If steep slopes must be disturbed, techniques such as phasing and stabilization practices designed for steep slopes (e.g., slope draining and terracing) must be implemented;
(c) All exposed soil areas, including stockpiles must be stabilized.
1. Stabilization must be initiated immediately to limit soil erosion when construction activity has permanently or temporarily ceased on any portion of the site and will not resume for a period exceeding 14 calendar days (or 7 calendar days on a project that is within one mile (aerial radius measurement) of, and flows to, one or more of the following: "impaired waters", "other special waters", "prohibited waters", and/or "restricted waters" as defined);
2. Stabilization must be completed no later than 14 calendar days after the construction activity has ceased (or 7 calendar days on a project that is within 1 mile (aerial radius measurement) of, and flows to, one or more of the following: "impaired waters", "other special waters", "prohibited waters", and/or "restricted waters" as defined);
3. Stabilization is not required on constructed base components of roads, parking lots and similar surfaces;
4. Stabilization is not required on temporary stockpiles without significant silt, clay or organic components (e.g., clean aggregate stockpiles, demolition concrete stockpiles, sand stockpiles) but permittees must provide sediment controls at the base of the stockpile.
(d) All exposed soil areas within 200 feet of the water's edge, and that drain to Public Waters that the Minnesota DNR has promulgated "work in water restrictions" during specified fish spawning time frames, must be stabilized within 24 hours during the restriction period;
(e) The normal wetted perimeter of the last 200 linear feet of temporary or permanent drainage ditches or swales that drain water from the site must be stabilized within 24 hours after connecting to a surface water or property edge;
(f) Stabilization of remaining portions of temporary or permanent ditches or swales must be completed within 14 calendar days after connecting to a surface water or property edge and after construction in that portion of the ditch temporarily or permanently ceases;
(g) Temporary or permanent ditches or swales being used as a sediment containment system during construction (with properly designed rock ditch checks, bio rolls, silt dikes, and the like) do not need to be stabilized. Stabilization of these areas must be completed within 24 hours after their use as a sediment containment system ceases;
(h) Mulch, hydromulch, tackifier, polyacrylamide or similar erosion prevention practices must not be used within any portion of the normal wetted perimeter of a temporary or permanent drainage ditch or swale section with a continuous slope of greater than 2%;
(i) Temporary or permanent energy dissipation must be provided at all pipe outlets within 24 hours after connection to a surface water or permanent storm water treatment system; and
(j) No more land can be disturbed (i.e., phasing) than can be effectively inspected and maintained in accordance with inspection and maintenance requirements. Street sweeping must be used if vehicle tracking BMPs are not adequate to prevent sediment tracking onto the street;
(2) Sediment control practices.
(a) Sediment control BMPs must be established on all downgradient perimeters of the site and downgradient areas of the site that drain to any surface water, including curb and gutter systems;
(b) Sediment control practices must be located upgradient of any buffer zones;
(c) Sediment control practices must be installed before any upgradient land-disturbing activities begin and must be kept in place until permanent cover is established;
(d) If downgradient sediment controls are overloaded, based on frequent failure or excessive maintenance requirements, additional upgradient sediment control practices or redundant BMPs must be installed to eliminate the overloading. The site plan must be amended to identify these additional practices;
(e) Temporary or permanent drainage ditches and sediment basins designed as part of a sediment containment system (e.g., ditches with rock-check dams) require sediment control practices only as appropriate for site conditions;
(f) A floating silt curtain placed in the water is not a sediment control BMP to satisfy perimeter control in this part except when working on a shoreline or below the waterline. When applicable, after the short term construction activity (e.g., installation of rip rap along the shoreline) in that area is complete, upland perimeter control practices must immediately be installed if exposed soils still drain to a surface water;
(g) All sediment control practices adjusted or removed to accommodate short-term activities such as clearing or grubbing, or passage of vehicles, must be re-installed immediately after the short-term activity is completed. All sediment control practices must be re-installed before the next precipitation event even if the short-term activity is not complete;
(h) All storm drain inlets must be protected using appropriate BMPs during construction until permanent cover has been established on all areas with potential for discharging to the inlet;
(i) Inlet protection for a particular inlet may be removed if a specific safety concern (e.g., street flooding/freezing) is identified. The need for removal must be documented in the site plan;
(j) Silt fence or other effective sediment controls must be provided at the base of stockpiles on the downgradient perimeter;
(k) All stockpiles must be located outside of natural buffers or surface waters, including stormwater conveyances such as curb and gutter systems unless there is a bypass in place for the stormwater;
(l) Vehicle tracking BMPs must be located to minimize the track out of sediment from the construction site or onto paved roads within the site;
(m) Street sweeping must be used if vehicle tracking BMPs are not adequate to prevent sediment tracking onto the street;
(n) Temporary sediment basins must be installed consistent with standards identified in division (D) of this section (Design Criteria for Temporary Sediment Basins);
(o) In any areas of the site where final vegetative stabilization will occur, vehicle and equipment use must be restricted to minimize soil compaction;
(p) Topsoil must be preserved on the site;
(q) Discharges from BMPs must be directed to vegetated areas unless infeasible;
(r) A 50-foot natural buffer must be preserved or, if a buffer is infeasible on the site, redundant (double) perimeter sediment controls must be provided when a surface water is located within 50 feet of the project's earth disturbances and stormwater flows to the surface water;
1. Permittees must install perimeter sediment controls at least five feet apart unless limited by lack of available space;
2. Natural buffers are not required adjacent to road ditches, judicial ditches, county ditches, stormwater conveyance channels, storm drain inlets, and sediment basins;
3. If preserving the buffer is infeasible, the reasons must be documented in the site plan;
4. Sheet piling is a redundant perimeter control if installed in a manner that retains all storm water.
(s) An undisturbed buffer zone of not less than 100 linear feet must be included on a project that is within 1 mile (aerial radius measurement) of, and flows to "other special waters", "prohibited waters", and/or "restricted waters" as defined;
1. The buffer zone must be maintained at all times, both during construction and as a permanent feature post construction, except where a water crossing or other encroachment is necessary to complete the project;
2. If buffer encroachment is necessary, the circumstance, reasons, and restoration activities must be fully documented in the site plan;
3. All potential water quality, scenic and other environmental impacts of the encroachments must be minimized by the use of additional or redundant (double) BMPs. Additional or redundant BMPs must be documented in the site plan.
(t) Polymers, flocculants, or other sedimentation treatment chemicals must be used in accordance with accepted engineering practices, dosing specifications and sediment removal design specifications provided by the manufacturer or supplier.
(u) Conventional erosion and sediment controls must be used prior to chemical addition and must direct treated stormwater to a sediment control system for filtration or settlement of the floc prior to discharge.
(3) Dewatering and basin draining.
(a) Turbid or sediment-laden waters related to dewatering or basin draining (e.g., pumped discharges, trench/ditch cuts for drainage) must be discharged to a temporary or permanent sediment basin on the project site unless infeasible;
(b) Dewatering to surface waters may be conducted if visual checks are completed to ensure adequate treatment has been obtained and nuisance conditions (see Minn. Rules 7050.0210, subp. 2) will not result from the discharge;
(c) If turbid or sediment-laden water cannot be discharged to a sedimentation basin prior to entering a surface water, the discharge must be treated with appropriate BMPs such that the discharge does not adversely affect the surface water or downstream properties;
(d) An oil-water separator or suitable filtration device (e.g., cartridge filters, absorbents pads) must be used prior to discharge of water containing oil or grease;
(e) Water from dewatering or basin-draining activities must be discharged in a manner that does not cause erosion or scour in the immediate vicinity of discharge points;
(f) Dewatering or basin-draining activities cannot cause inundation of wetlands that causes significant adverse impact to the wetland in the immediate vicinity of discharge points;
(g) If filters with backwash water are used, all backwash must be hauled away for disposal, returned to the beginning of the treatment process, or incorporated into the site in a manner that does not cause erosion.
(4) Inspection and maintenance.
(a) A trained person must inspect the entire construction site at least once every 7 days during active construction, or every 3 calendar days on a project that is within 1 mile (aerial radius measurement) of, and flows to a "prohibited waters" as defined, and within 24 hours after a rainfall event greater than 1/2 inch in 24 hours;
(b) All permanent stormwater treatment BMPs must be inspected and maintained;
(c) All erosion prevention and sediment control BMPs and pollution prevention management measures must be inspected to ensure integrity and effectiveness.
(d) All nonfunctional BMPs must be repaired, replaced, or supplemented with functional BMPs by the end of the next business day after discovery unless another time frame is specified below. Additional time, infield conditions prevent access to the area, may be taken;
(e) Surface waters, including drainage ditches and conveyance systems, but not curb and gutter systems, must be inspected for evidence of erosion and sediment deposition.
1. All deltas and sediment deposited in surface waters, including drainage ways, catch basins, and other drainage systems must be removed;
2. All areas where sediment removal resulted in exposed soils must be restabilized. Removal and stabilization must be completed within 7 calendar days of discovery unless precluded by legal, regulatory, or physical access constraints;
3. All reasonable efforts to obtain access must be used;
4. If precluded, removal and stabilization must take place within 7 days of obtaining access; and
5. Contact all local, regional, state and federal authorities and receive any applicable permits, prior to conducting any work in surface waters;
(f) 1. Construction site vehicle exit locations, streets and curb and gutter systems within and adjacent to the project must be inspected for sedimentation from erosion or tracked sediment from vehicles.
2. Sediment must be removed from all paved surfaces within 1 calendar day of discovery or, if applicable, within a shorter time to avoid a safety hazard to users of public streets;
(g) Perimeter control devices must be repaired, replaced, or supplemented when they become nonfunctional or the sediment reaches 1/2 of the height of the device;
(h) Temporary and permanent sedimentation basins must be drained and sediment removed when the depth of sediment collected in the basin reaches 1/2 the storage volume;
(i) At least one individual present on the site (or available to the project site in 3 calendar days) must be trained in the job duties of overseeing the implementation of, revising and/or amending the site plans and performing inspections for the project;
(j) Inspection schedules may be adjusted as follows:
1. Inspections of areas with permanent cover can be reduced to once per month, even if construction activity continues on other portions of the site; or
2. Where sites have permanent cover on all exposed soil and no construction activity is occurring anywhere on the site, inspections can be reduced to once per month and, after 12 months, may be suspended completely until construction activity resumes. The city may require inspections to resume if conditions warrant; or
3. Where construction activity has been suspended due to frozen ground conditions, inspections may be suspended. Inspections must resume within 24 hours of runoff occurring, or upon resuming construction, whichever comes first.
(k) Inspections and maintenance activities must be recorded within 24 hours of being conducted and these records must be retained with the site plan. These records must include:
1. Date and time of inspections;
2. Name of person(s) conducting inspections;
3. Accurate findings of inspections, including the specific location where corrective actions are needed;
4. Corrective actions taken (including dates, times, and party completing maintenance activities);
5. Date of all rainfall events greater than 1/2 inches in 24 hours, and the amount of rainfall for each event. Rainfall amounts must be obtained by either a properly maintained rain gauge installed onsite, a weather station that is within one mile of the site's location, or a weather reporting system that provides site specific rainfall data from radar summaries;
6. Observed discharges must be recorded, discharges should be photographed and the location of the discharge described (i.e., color, odor, settled or suspended solids, oil sheen, and other obvious indicators of pollutants); and
7. Any amendments to the site plan proposed as a result of the inspection must be documented within seven calendar days.
(5) Pollution prevention management measures.
(a) Building products and landscape materials must be placed under cover (e.g., plastic sheeting or temporary roofs) or protected by similarly effective means as designed to minimize contact with storm water.
(b) Products which are either not a source of contamination to storm water or designed to be exposed to storm water are not required to be covered or protected;
(c) Pesticides, herbicides, fertilizers and treatment chemicals must be placed under cover (e.g., plastic sheeting or temporary roofs) or protected by similarly effective means designed to minimize contact with storm water.
(d) Hazardous materials and toxic waste (including oil, diesel fuel, gasoline, hydraulic fluids, paint solvents, petroleum-based products, wood preservatives, additives, curing compounds, and acids) must be stored in sealed containers to prevent spills, leaks or other discharge.
(e) Hazardous materials must be stored and disposed of in accordance with Minn. Rules Ch. 7045.
(f) Solid waste must be stored, collected, and disposed of in accordance with Minn. Rules Ch. 7035.
(g) Portable toilets must be positioned so that they are secure and will not tip or be knocked over.
(h) Sanitary waste from the portable toilets must be properly disposed in accordance with Minn. Rules Ch. 7041.
(i) Reasonable steps must be taken to prevent the discharge of spilled or leaked chemicals, including fuel, from any area where chemicals or fuel will be loaded or unloaded including the use of drip pans or absorbents unless infeasible.
1. Adequate supplies must be available at all times to clean up discharged materials and an appropriate disposal method must be available for recovered spilled materials;
2. Spills must be immediately reported and cleaned up as required by M.S. § 115.061, using dry clean up measures where possible.
(j) Limit vehicle exterior washing and equipment to a defined area of the site.
1. Runoff from the washing area must be contained in a sediment basin or other similarly effective controls;
2. Waste from the washing activity must be disposed of properly;
3. Soaps, detergents, and solvents must be properly used and stored.
(k) Liquid and solid wastes generated by washout operations (e.g., concrete, stucco, paint, form release oils, curing compounds and other construction materials) related to the construction activity must be contained and not contact the ground. A sign, indicating the location of a washout facility, must be installed.
(6) Termination conditions.
(a) All construction activity must be completed and permanent cover must be installed over all areas;
1. Permanent cover must consist of a uniform perennial vegetation with a density of 70% of its expected final growth;
2. Vegetation is not required where the function of a specific area dictates no vegetation, such as impervious surfaces or the base of a sand filter.
(b) 1. Permanent stormwater treatment system must be cleaned of any accumulated sediment;
2. The system must meet all applicable requirements and operate as designed.
(c) Sediment must be removed from conveyance system(s);
(d) Temporary synthetic erosion prevention and sediment control BMPs must be removed. BMPs designed to decompose on-site may be left in place;
(e) For residential construction only, permit coverage may be terminated on individual lots if:
1. The structure(s) are finished;
2. Temporary erosion prevention and downgradient perimeter controls are complete; and
3. The residence is sold to the homeowner.
(f) For construction projects on agricultural land (e.g., pipelines across cropland), the disturbed land must be returned to its preconstruction agricultural use.
(D) Design criteria for temporary sediment basins.
(1) Where 10 or more acres of disturbed soil drain to a common location or where 5 or more acres of undisturbed soil drain to a common location on the project that is within 1 mile (aerial radius measurement) of an "impaired waters", "other special waters", "prohibited waters", and/or "restricted waters" as defined, the applicant must provide a basin to provide treatment of the runoff before it leaves the construction site or enters surface waters.
(2) Temporary sediment basins may be converted to a permanent basin after construction is complete.
(3) Temporary basins may be removed when permanent cover has reduced the acreage of disturbed soils to less than 10 (or 5 when applicable) acres draining to a common location.
(4) Must provide live storage for a calculated volume of runoff from a two-year, 24-hour storm from each acre drained to the basin, except that in no case shall the basin provide less than 1,800 cubic feet of live storage per acre drained to the basin.
(5) Where the 2-year, 24-hour storm runoff amount is not calculated, the temporary sediment basin must provide 3,600 cubic feet of live storage per acre of the basin's drainage area.
(6) Outlets must be designed to prevent short-circuiting and the discharge of floating debris.
(7) The outlet structure must be designed to withdraw water from the surface to minimize the discharge of pollutants. The use of a surface withdrawal mechanism may be temporarily suspended during frozen conditions. The basin must include a stabilized emergency overflow to prevent failure of pond integrity.
(8) Energy dissipation must be provided for the basin outlet within 24 hours after connection to a surface water.
(9) Temporary sediment basins must be situated outside of surface waters and include a buffer zone not less than 100 linear feet from special waters.
(10) The temporary basins must be constructed and made operational prior to disturbing ten or more acres of soil draining to a common location.
(11) Where a temporary sediment basin meeting the above requirements is infeasible, effective sediment controls such as smaller sediment basins, and/or sediment traps, silt fences, vegetative buffer strips, or any appropriate combination of measures must be installed as dictated by individual site conditions, including all down-slope boundaries and side-slope boundaries. In determining whether installing a sediment basin is infeasible, the owner/operator(s) must consider public safety and may consider factors such as site soils, slope, and available area on site. The determination of infeasibility must be documented in the site plan.
(Ord. 712, passed 11-14-2022)