Forsyth County › Unified Development Code
Chapter 18 — Subdivisions and Land Development, Article 13 — OPEN SPACE AND LOW-IMPACT STORMWATER DESIGN
§ 18-13.1
Purpose and Intent.
The provisions of this Article are intended to incentivize aesthetically-enhanced, natural looking stormwater management facilities designed to function as accessible community amenities and runoff reduction measures that incorporate enhanced landscape design for community benefit.
§ 18-13.2
Applicability.
The provisions of this Article shall apply to open space requirements associated with any zoning district, but shall not pertain to conservation subdivisions as regulated by Chapter 19.
§ 18-13.3
Incentive Requirements.
(A)Approved design features noted below may be applied towards minimum open space requirements at two times the amount of square footage for non-residential zoning districts to include the Master Planned District (MPD) and one and a half times the amount of square footage for residential districts. Square footage calculations shall include those areas serving as a low-impact stormwater control feature and may also include community amenity features such as pedestrian paths and seating located within and around such features.
(B)Developments in any zoning district may incorporate the following low-impact stormwater design options within required open space upon county review and approval. Approval shall be granted provided the design satisfies the requirements of this Article.
(1)Stormwater ponds that have a minimum permanent pool of water as long as all of the following elements are incorporated:
(a)Naturalized landscaping along gentle pond side slopes;
(b)Fountain for aeration to maintain water quality;
(c)No physical barriers around the pond perimeter;
(d)Pedestrian, pervious path with seating is located around pond perimeter. Path system must provide safe and convenient connectivity from pond area to either a residential subdivision amenity area or non-residential, primary building entrance(s) and then to the public street network. Connections to amenity areas and building entrances may be impervious when part of a sidewalk or multi-use trail network within the development.
(2)Incorporation of grass filter strips subject to the following:
(a)Turf grass or similar groundcover is provided to filter out sediments and other pollutants from runoff;
(b)Design shall be in accordance with the Georgia Stormwater Management Manual;
(c)Routine mowing of filter strip shall be required for proper maintenance;
(d)Filter strips may be located in required landscape strips.
(3)Parking lot bioretention applications which may include the following:
(a)Lot grading that is designed for sheet flow towards linear landscape areas and parking islands;
(b)Curb-less pavement edges used to convey water into depressed parking islands or other landscape areas;
(c)Parking lots that are graded so that flows reach a curb-less pavement edge or curb cut before reaching catch basins or storm drain inlets;
(d)Turf grass at the edge of parking lots to serve as a grass filter strip when the depression for bioretention is located within a pervious area that is adjacent to the parking lot.
(4)Courtyards utilized for collecting runoff from a storm drain system or roof leaders that may be directed to these areas or other pervious locations on site where bioretention may be installed.
(C)Planting plans sealed by a registered landscape architect must be submitted for each bioretention area and shall include the following:
(1)Delineation of planting areas including the size and species of all plant material;
(2)Plant material shall be based on the goal of simulating a terrestrial, forested community of native species including grass and herbaceous ground covers, shrubs, and trees, which shall achieve surface area coverage of at least 75% within two (2) years;
(3)The proper selection and installation of plant materials is critical to the performance and function of bioretention areas and shall be based on guidelines found in Appendix D, Georgia Stormwater Management Manual.
(D)The Engineering Director may administratively approve an alternate low impact stormwater design where the proposed design satisfies the intent of this Article at least as well as the designs identified in this Article and the public health, safety and welfare is protected.