(A) General regulations.
(1) Minnesota Pollution Control Agency (MPCA) requirements. Every applicant for a building permit, subdivision approval, or a grading permit to allow land disturbing activities shall adhere to erosion control measure standards and specifications contained in the MPCA publication "Protecting Water Quality in Urban Areas," as may be amended, or as approved by the City Engineer and applicable city's storm water management requirements as stated in Chapter 93 of this code.
(2) Prohibited development. No land shall be developed, and no use shall be permitted that results in water runoff causing flooding, erosion, or deposit of sediment on adjacent properties. Such runoff shall be properly channeled into a storm drain, watercourse, ponding area, or other public facilities subject to the review and approval of the City Engineer.
(3) City approval. In the case of all single-family lots, multiple-family lots, business, industrial and institutional developments, the drainage and erosion control plans shall be subject to the City Engineer or Zoning Administrator's written approval. No modification in grade and drainage flow through fill, cuts, erection of retaining walls or other such actions shall be permitted until such plans have been reviewed and received written approval from the City Engineer.
(4) Approval of erosion control measures. Proposed erosion control measures may be approved by the City Engineer as part of grading plan review. Erosion control may be specified by the City Engineer as part of a site survey for individual building permits. Erosion control measures may also be specified by the City Engineer as needed and deemed appropriate during the construction and post-construction periods separate from the above.
(5) Storm sewer inlets. All storm sewer inlets which are functioning during construction shall be protected so that sediment laden water does not enter the conveyance system without first being filtered or otherwise treated to remove sediment.
(6) Storm water channels. All on-site storm water conveyance channels shall be designed and constructed to withstand the design volume of storm water with appropriate stabilization to prevent scour and erosion. Erosion controls shall be provided at the outlets of all storm sewer pipes.
(7) Sediment control practices. All temporary and permanent erosion and sediment control practices shall be maintained and repaired whenever necessary to assure the continued performance of their intended function.
(8) 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.
(9) Seeding. All disturbed ground left inactive for seven or more days shall be stabilized by seeding or sodding or by mulching or covering or other equivalent control measure.
(10) Sites one acre and more. For sites with more than one acre or more 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 1% 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.
(11) Sites under one acre. For sites with less than one acre disturbed at one time, silt fences, straw bales, or equivalent control measures shall be placed along all side slope and down slope 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.
(12) Removal. All temporary erosion control devices including silt fence, gravel, hay bales or other measures shall be removed from the construction site and properly disposed of or recycled. This removal and disposal shall occur within 30 days of the establishment of permanent vegetative cover on the disturbed area.
(13) 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 controls as appropriate. Water may not be discharged in a manner that causes erosion or flooding of the site or receiving channels of a wetland. All dewatering shall be in accordance with all applicable county, state, and federal rules and regulations.
(14) 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.
(15) Stop work order. The city's Building Official or City Engineer may issue stop work orders for any violation of this chapter. Where the topsoil is removed, sufficient topsoil shall be set aside for re-spreading over the developed area. The topsoil shall be restored to a depth of four inches and shall be of a quality at least equal to the soil quality prior to development.
(16) Public and private properties adjacent to the development site shall be protected from the effects of sedimentation. Any violation of this provision must be corrected by the owner to the satisfaction of the city within five days of receiving written notification from the city. If the violation is not remedied within the time period specified, the city may correct the problem and assess the costs incurred to the property owner.
(B) Exposed slopes. The following control measures shall be taken to control erosion during construction.
(1) Exposed slopes steeper in grade than five feet horizontal to one-foot vertical shall be contour plowed to direct runoff of water.
(2) At the foot of each exposed slope, a channel and berm shall be constructed to control runoff. The channeled water shall be diverted to a sedimentation basin (debris basin, silt basin or silt trap) before being allowed to enter the natural drainage system.
(3) Along the top of each exposed slope, a berm shall be constructed to prevent runoff from flowing over the edge of the slope. Where runoff collected behind the berm cannot be diverted elsewhere and must be directed down the slope, appropriate measures shall be taken to prevent erosion. The measures shall consist of either an asphalt paved flow apron and drop chute laid down the slope or a flexible slope drain. At the base of the slope drain or flow apron, a gravel energy dispatcher shall be installed to prevent erosion at the discharge end.
(4) Exposed slopes shall be protected by whatever means will effectively prevent erosion, considering the degree of slope, soil material and expected length of exposure. Slope protection shall consist of mulch, sheets of plastic, burlap or jute netting and blankets, fast-growing grasses or temporary seeding of annual grasses. Mulch consists of hay, straw, wood chips, corn stalks, bark or other protective material. Mulch shall be anchored to slopes with liquid asphalt, stakes and netting, or shall be worked into the soil to provide additional slope stability.
(5) Control measures other than those specifically stated above may be used in place of the above measures if it can be demonstrated that they will be as effective in protecting exposed slopes.
(Ord. 583, passed 8-26-2019)