§ 32-179. Stormwater Management Measures.

The ESD planning techniques, practices and structural stormwater management measures in this Division and the Maryland Design Manual and the Prince George's County Design Manual shall be used either alone or in combination in a stormwater management design plan. An 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 design plan.

(a)

ESD Planning Techniques and Practices.

(1)

The following planning techniques shall be applied to MEP according to the Maryland Design Manual and the Prince George's County Design Manual to satisfy the applicable minimum control requirements established in 32-178 of this Division:

(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 average 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 to MEP according to the Maryland Design Manual and the Prince George's County Design Manual to satisfy the applicable minimum control requirements established in 32-178 of this Division:

(A)

Disconnection of rooftop runoff;

(B)

Disconnection of non-rooftop runoff;

(C)

Sheet flow 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 practice approved by the Administration.

(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 County shall modify planning and zoning ordinances and public works codes to eliminate any impediments to implementing ESD to the MEP according to the Maryland Design Manual and the Prince George's County Design Manual.

(b)

Structural Stormwater Management Measures.

(1)

The following structural stormwater management practices shall be designed according to the Maryland Design Manual and the Prince George's County Design Manual to satisfy the applicable minimum control requirements established in 32-178 of this Division:

(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 Maryland Design Manual and the Prince George's County Design Manual 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 County.

(c)

ESD planning techniques, treatment practices and structural stormwater management measures used to satisfy the minimum requirements in 32-178 of this Division must be recorded in the land records of the County through the execution of a maintenance agreement by the permittee and remain unaltered by subsequent property owners. Prior approval from the Department shall be obtained before any stormwater management practice is altered.

(d)

Alternative ESD planning techniques, treatment practices and structural stormwater measures may be used for new development runoff control if they meet the performance criteria established in the Maryland Design Manual and the Prince George's County 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/applicant 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.

(CB-15-2011; CB-36-2015)