The ESD planning techniques and practices and structural stormwater management measures established in this chapter and the design manual shall be used, either alone or in combination in a stormwater management plan. The applicant 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 techniques and practices.
(a) Preserving and protecting natural resources;
(b) Conserving natural drainage patterns;
(c) Minimizing impervious areas;
(d) Reducing runoff volume;
(e) Using ESD practices to maintain 100% of the annual pre-development groundwater recharge volume.
(a) Disconnection of rooftop runoff;
(b) Disconnection of non-rooftop runoff;
(c) Sheetflow to conservation areas;
(d) Rainwater harvesting, including rain barrels, rainwater tanks, and cisterns.
(e) Submerged gravel wetlands;
(f) Landscape infiltration;
(g) Infiltration berms;
(h) Dry wells;
(i) Micro-bioretention;
(j) Rain gardens;
(k) Swales;
(l) Enhanced filters;
(m) Any practice approved by the Maryland Department of Environment.
(3) The use of ESD planning techniques and treatment practices specified in this section shall not conflict with existing state law or local ordinances, regulations, or policies. The town shall modify ordinances and codes to eliminate any impediments to implementing ESD to the MEP according to the design manual.
(B) Structural stormwater management measures.
(a) Stormwater management ponds;
(b) Stormwater management wetlands;
(c) Stormwater management infiltration;
(d) Stormwater management filtering systems;
(e) Stormwater management open channel systems.
(2) When selecting structural stormwater management practices, the applicant shall consider the performance criteria specified in the design manual with regard to general feasibility, conveyance, pretreatment, treatment and geometry, environment and landscaping, and maintenance.
(3) Structural stormwater management practices shall be selected to accommodate the unique hydrologic or geologic regions of the state.
(C) Alternative practices and measures. Alternative ESD planning techniques and treatment practices and structural stormwater measures may be used for new development runoff control if the practices and measures meet the performance criteria in the design manual and all subsequent revisions and are approved by the Maryland Department of Environment. Practices used for redevelopment projects shall be approved by the town.
(D) Recordation of practices and measures. ESD techniques and treatment practices and structural stormwater management measures used to satisfy the minimum requirements in Article V, § 142-11 of this chapter must be recorded in the land records of Kent County, and remain unaltered by subsequent property owners. Prior approval from the town shall be obtained before any stormwater management practice is altered.
(E) Modification. For purposes of modifying the minimum control requirements or design criteria, the applicant shall submit an analysis to the town of the impacts of stormwater flows downstream in the watershed. The analysis shall include hydrologic and hydraulic calculations necessary to determine the impact of hydrographic timing modifications of the proposed development upon a dam, highway, structure, or natural point of restricted stream flow. The point of investigation shall be established with the concurrence of the town downstream of the first downstream tributary whose drainage area equals or exceeds the contributing area to the project or stormwater management facility.
(F) Specific design criteria. The basic design criteria, methodologies, and construction specifications, subject to the approval of the town and the Maryland Department of Environment, shall be those of the design manual.
(Ord. 08-2010, passed 11-1-2010)