In order to balance growth needs with environmental protection, reduce municipal infrastructure and utility maintenance costs (streets, curbs, gutters, sidewalks, storm sewer), reduce storm water management costs, preserve the integrity of ecological and biological systems, protect water quality by reducing sediment, nutrient, and toxic loads to water bodies, and to preserve trees and natural vegetation, low impact design is required for all nonresidential projects and all residential projects containing more than ten dwelling units. All projects shall meet the following criteria.
(A) Post-development discharge rates shall not exceed pre-development discharge rates from any development site. Engineering detail and documentation including a stormwater plan for the site shall be required at the time of application as specified in § 157.211(D)- Permits, which provides evidence that this requirement has been met.
(B) Site design shall minimize impervious surface and alteration of natural vegetation and topography.
(1) Clearing and re-grading on a development site shall be minimized.
(2) Clearing shall be done in phases to minimize the amount of bare ground at any one time.
(3) New streets, whether dedicated to the public or private internal drives serving multiple tenants on a single parcel, shall be designed in such a way as to minimize the total amount of impervious surface.
(4) Curb and guttering that directs the first inch of rainfall to an offsite stormwater conveyance shall be prohibited unless such conveyance is designed to discharge to an adjacent bioretention island or detention pond that has been approved by the city.
(5) Shared parking shall be used whenever possible.
(6) Open space areas set aside in residential cluster developments may be used for onsite treatment of stormwater.
(C) Landscape design shall integrate natural features into the footprint of each parcel under development and ensure that water resources are protected.
(1) Riparian buffer required. A minimum of 50 foot undisturbed vegetated buffer is required along all perennial streams and around all other water bodies as follows.
(a) Exceptions. Ephemeral streams, ditches, and manmade ponds and lakes located outside of natural drainage ways shall not be subject to the provisions of this division.
(b) Measurement. The buffer shall be measured landward from the top of bank of streams and the mean high water line of all other water bodies.
(c) Permitted uses. The following uses shall be permitted by right in all riparian buffers.
1. Natural or pervious footpaths no more than four feet in width providing a homeowner direct access to the stream or water body.
2. Passive recreational and educational uses that require limited areas of disturbance and minimal impervious surfaces including non-motorized recreational and greenway trails constructed of natural or pervious surfaces located no closer than 25 feet from the stream or water body within existing or planned public or private easements, approved as part of a site specific development plan.
3. Buffer planting that does not require grubbing or grading of more than 100 square feet or the removal of natural cover for more than 48 hours.
4. Streambank stabilization including live staking and other natural planting techniques to control erosion.
(d) Prohibited uses. Any use not expressly permitted by division (C)(1)(c) of this section shall be prohibited.
(2) No stormwater shall be directly discharged into a jurisdictional wetland without onsite pretreatment.
(D) To the maximum extent practicable, natural and vegetated stormwater management systems such as swales, rain gardens, constructed wetlands, and bioretention cells shall be used to manage stormwater and comply with federal and local stormwater regulations.
(1) Low impact development design guidelines created by and available through SCDHEC shall serve as the minimum design standards for the city.
(2) Roof top runoff shall be directed to rain gardens, bioretention areas, or cisterns, or may be allowed to sheet flow to any acceptable onsite stormwater treatment area.
(3) Onsite curb and guttering shall be designed to direct stormwater to acceptable onsite treatment areas and shall not allow stormwater to sheet flow off of the site.
(E) The type and design of low impact techniques proposed and built shall be approved by the City Planner and meet the intent and standards of the South Carolina Department of Health and Environmental Control best management practices as detailed in the latest edition of the Best Management Practices Handbook.
(Ord. 15-002, passed 2-24-15)