The ESD planning techniques and practices and structural BMPs as established herein shall be used to develop stormwater management plans. A developer shall demonstrate that ESD has been implemented to the MEP before the use of a structural BMP is considered in developing the stormwater management plan.
(A) ESD planning techniques and practices.
(1) The following ESD planning techniques shall be applied according to the Design Manual (or as otherwise approved by the administration) to satisfy the applicable general requirements established in this chapter, and shall not conflict with existing state law or local ordinances, regulations, or policies:
(a) Preserving and protecting natural resources;
(b) Conserving natural drainage patterns;
(c) Minimizing impervious area;
(d) Reducing runoff volume;
(e) Using ESD practices to maintain 100 percent of the annual predevelopment groundwater recharge volume;
(f) Using green roofs, permeable pavement, reinforced turf, and other alternative surfaces;
(g) Limiting soil disturbance, mass grading, and compaction;
(h) Clustering development; and
(i) Any practices approved by the administration.
(2) The following ESD treatment practices shall be designed according to the Design Manual (or as otherwise approved by the administration) to satisfy the applicable general requirements established in this chapter, and shall not conflict with existing state law or local ordinances, regulations, or policies:
(a) Disconnection of rooftop runoff;
(b) Disconnection of non-rooftop runoff;
(c) Sheetflow to conservation areas;
(d) Rainwater harvesting;
(e) Submerged gravel wetlands;
(f) Landscape infiltration;
(g) Infiltration berms;
(h) Dry wells;
(i) Micro-bioretention;
(j) Rain gardens;
(k) Swales;
(l) Enhanced filters; and
(m) Any practices approved by the administration.
(B) Structural BMPs.
(1) Structural BMPs shall be designed in accordance with the Design Manual (or as otherwise approved by the administration) to satisfy the applicable general requirements established in this chapter:
(a) Stormwater management ponds;
(b) Stormwater management wetlands;
(c) Stormwater management infiltration;
(d) Stormwater management filtering systems; and
(e) Stormwater management open channel systems.
(2) The performance criteria specified in the Design Manual related to general feasibility, conveyance, pretreatment, treatment and geometry, environment and landscaping, and maintenance shall be considered when selecting structural stormwater management practices. Structural stormwater management practices shall be selected to accommodate the unique hydrologic or geologic features of Frederick County.
(C) Alternative ESD planning techniques and practices and structural BMPs. Alternative ESD planning techniques and practices and structural BMPs may be used if they meet the performance criteria established in the Design Manual and are approved by the administration. Practices used for redevelopment projects shall be approved by the Division.
(Ord. 10-09-544, 5-20-2010; Ord. 14-23-678, 11-13-2014)