The following general and specific standards shall apply.
(A) General standards.
(1) When possible, existing natural drainage ways, wetlands, and vegetated soil surfaces must be used to convey, store, filter, and retain storm water runoff before discharge to public ditches.
(2) Development must be planned and conducted in a manner that will minimize the extent of disturbed areas, runoff velocities, erosion potential, and reduce and delay runoff volumes. Disturbed areas must be stabilized and protected as soon as possible and facilities or methods used to retain sediment on the site.
(3) When development density, topographic features, and soil and vegetation conditions are not sufficient to adequately handle storm water runoff using natural features and vegetation, various types of constructed facilities such as diversions, settling basins, skimming devices, dikes, waterways, and ponds may be used. Preference must be given to designs using surface drainage, vegetation, and infiltration rather than buried pipes and human-made materials and facilities.
(B) Specific standards.
(1) Impervious surface coverage of lots must not exceed 40% of the lot area or 25% of the lot area within the shoreland management area. Impervious surface is 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 prior to development. Examples include, but are not limited to, decks, rooftops, sidewalks, patios permeable pavers, storage areas, and concrete, asphalt, or gravel driveways.
(2) When constructed facilities are used for storm water management, they must be approved by the City Zoning Officer that they are designed and installed consistent with the field office technical guide of the local soil and water conservation districts.
(3) Minimum floor elevation for building shall be established at 1,339.38 feet.
(4) Surface area covered by permeable pavers must be included in the impervious surface calculation. Half of the area covered by professionally installed and properly maintained permeable pavers will be counted as impervious. Professionally installed means installed by an interlocking concrete pavement institute certified installer, and properly maintained means following the manufacturer’s suggested maintenance schedule.
(5) Surface area of a lot physically separated (i.e., public, private road right-of-way or easement) from itself or another, cannot be included for purposes of the impervious surface calculation.
(6) Unless otherwise provided by the property owner, a minimum 12-foot wide driveway, from the nearest road right-of-way to the proposed structure(s), must be included in the impervious calculation. This includes an accessory structure that has the ability to house a vehicle and requires a garage door.
(C) All land-disturbing activities must comply with these minimum requirements.
(1) Property and streets adjacent to the site of a land disturbance shall be protected from sediment deposition. This shall be accomplished by preserving a well-vegetated buffer strip around the lower perimeter of the land disturbance, by installing perimeter controls such as sediment barriers, filters, dikes, or sediment basins, by stockpiling soil in appropriate locations or by a combination of such measures.
(2) All storm sewer inlets which are functioning during construction shall be protected so that sediment-laden water will not enter the conveyance system without first being filtered or otherwise treated to remove sediment.
(3) Property and waterways downstream from development sites shall be protected from flooding and erosion due to increases in the volume, velocity, and peak water flow rate of storm water runoff. Concentrated storm runoff water leaving a development’s site must be discharged directly into a well-defined natural or human-made off-site receiving channel or pipe.
(4) A permanent vegetative cover shall be established in denuded areas not otherwise permanently stabilized forthwith after the land-disturbing activity is complete.
(5) Whenever construction vehicles access public roads, the provision shall be made to minimize the transport of sediment by runoff or vehicle tracking onto the paved surface. Where sediment is transported onto a public road surface, the roads shall be cleaned thoroughly at the end of each day.
(6) All temporary and permanent erosion and sediment control practices shall be maintained and repaired to assure the continued performance of their intended function.
(7) All temporary erosion and sediment control measures shall be removed within 30 days after final site stabilization is achieved or after the temporary measures are no longer needed.
(Ord. passed 5-9-2017; Ord. passed 4-13-2021; Ord. passed 8-16-2022) Penalty, see § 10.99