A. 
The minimum control requirements established in this section and the Design Manual are as follows:
(1) 
The City of Havre de Grace shall require that the planning techniques, nonstructural practices, and design methods specified in the Design Manual be used to implement ESD to the MEP. The use of ESD planning techniques and treatment practices must be exhausted before any structural BMP is implemented. Stormwater management plans for development projects subject to this chapter shall be designed using ESD sizing criteria, recharge volume, water quality volume and channel protection storage volume sizing criteria according to the Design Manual. The MEP standard is met when channel stability is maintained, predevelopment groundwater recharge is replicated, nonpoint source pollution is minimized, and structural stormwater management practices are used only if determined to be absolutely necessary and agreed upon by the Department.
[Amended 11-15-2010 by Ord. No. 920]
(2) 
Control of the two-year- and ten-year-frequency storm event is required according to the Design Manual and all subsequent revisions if the Department determines that additional stormwater management is necessary because historical flooding problems exist and downstream floodplain development and conveyance system design cannot be controlled.
(3) 
The Department may require more than the minimum control requirements specified in this chapter if hydrologic or topographic conditions warrant or if flooding, stream channel erosion, or water quality problems exist downstream from a proposed project.
B. 
Alternate minimum control requirements may be adopted subject to Administration approval. The Administration shall require a demonstration that alternative requirements will implement ESD to the MEP and control flood damages, accelerated stream erosion, water quality, and sedimentation. Comprehensive watershed studies may also be required.
C. 
Stormwater management and development plans, where applicable, shall be consistent with adopted and approved watershed management plans or flood management plans as approved by the Maryland Department of the Environment in accordance with the Flood Hazard Management Act of 1976.
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 developing 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 Planning techniques and practices.
(1) 
The following planning techniques shall be applied according to the Design Manual to satisfy the applicable minimum control requirements established in § 169-16 of this chapter:
(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% 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 and the Department.
(2) 
The following ESD treatment practices shall be designed according to the Design Manual to satisfy the applicable minimum control requirements established in § 169-16 of this chapter:
(a) 
Disconnection of rooftop runoff;
(b) 
Disconnection of nonrooftop runoff;
(c) 
Sheetflow to conservation areas;
(d) 
Rainwater harvesting;
(e) 
Submerged gravel wetlands;
(f) 
Landscape infiltration;
(g) 
Infiltration berms;
(h) 
Dry wells;
(i) 
Microbioretention;
(j) 
Rain gardens;
(k) 
Swales;
(l) 
Enhanced filters; and
(m) 
Any practices approved by the Administration and the Department.
B. 
Structural stormwater management measures.
(1) 
The following structural stormwater management measures shall be designed according to the Design Manual to satisfy the applicable minimum control requirements established in § 169-16 of 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 and the rules and regulations with regard to general feasibility, conveyance, pretreatment, treatment and geometry, environment and landscaping, and maintenance shall be considered when selecting structural stormwater management practices.
(3) 
Structural stormwater management practices shall be selected to accommodate the unique hydrologic or geologic regions of the City and county.
C. 
Easements and maintenance agreements necessary for the ESD planning techniques and treatment practices and structural stormwater management measures used to satisfy the minimum requirements in § 169-16 of this chapter must be recorded in the land records of Harford County and remain unaltered by subsequent property owners. Prior written approval from the Department shall be obtained before any stormwater management practice is altered.
D. 
Alternative ESD planning techniques and treatment practices and structural stormwater measures may be used for new development runoff control if they meet the performance criteria established in the Design Manual and all subsequent revisions and are approved by the Administration. Practices used for redevelopment projects shall be approved by the Department.
E. 
For the purposes of modifying the minimum control requirements or design criteria, the owner/developer shall submit to the Department an analysis of the impacts of stormwater flows downstream in the watershed. The analysis shall include hydrologic and hydraulic calculations necessary to determine the impact of hydrograph timing modifications of the proposed development upon a dam, highway, structure, or natural point of restricted stream flow. The point of investigation is to be established with the concurrence of the City, downstream of the first downstream tributary whose drainage area equals or exceeds the contributing area to the project or stormwater management facility.
A. 
The basic design criteria, methodologies, and construction specifications, subject to the approval of the Department and the Administration, shall be those of the Design Manual.
B. 
The use of an off-site facility for channel protection storage volume (Cpv), overbank flood protection volume (Qp) and extreme flood volume (Qr) is acceptable, provided that the site has implemented ESD to the MEP according to the Design Manual and the runoff is conveyed to the off-site facility via a closed storm drain or similarly engineered system. It is not acceptable to subject natural stream systems to erosive conditions for conveying unmanaged stormwater runoff to downstream regional facilities. The engineer shall submit proof that the facility was designed to control runoff from the proposed development in question and that the facility has the capacity to control the additional runoff caused by the proposed development in question. An agreement allowing such use of an off-site facility shall be executed between the developer and the owner of the off-site facility and shall be recorded in the land records of Harford County.