City of Hagerstown, MD Stormwater Management Plans

For any proposed development with a disturbed area greater than 15,000 square feet (i.e., any development that is not covered by a Standard Erosion and Sediment Control Plan issued by the Washington County Conservation District), the owner/developer shall submit phased stormwater management plans to the City for review and approval. At a minimum, plans shall be submitted for the concept, site development, and final stormwater management construction phases of project design. Each plan submittal shall include the minimum content specified in § 213-15 of this chapter and meet the requirements of the Design Manual and §§ 213-11 and 213-12 of this chapter.

For proposed developments with a disturbed area less than or equal to 15,000 square feet, the City's Zoning Administrator shall have the discretion to allow the owner/developer to submit a concept plan and a combined site development/final stormwater management construction plan. However, both the concept plan and the combined site development/final stormwater management plan must still meet the minimum content specified in § 213-15, and meet the requirements of the Design Manual and §§ 213-11 and 213-12 of this chapter.

The City shall perform a comprehensive review of the stormwater management plans for each phase of site design. Coordinated comments will be provided for each plan phase that reflect input from all appropriate agencies, including but not limited to the Soil Conservation District (SCD) and the departments of Planning, Engineering, Public Works, Utilities, and the Fire Marshal. All comments from the City and other appropriate agencies shall be addressed and approval received at each phase of project design before subsequent submissions.

The owner/developer shall submit a concept plan to the City Planning Department that provides sufficient information for an initial assessment of the proposed project and whether stormwater management can be provided according to § 213-11 of this chapter and the Design Manual. Plans submitted for concept approval shall include, but are not limited to:

(1)

A map at a scale specified by the City showing site location, existing natural features, water and other sensitive resources, surface rock outcroppings, topography, and natural drainage patterns;

(2)

The anticipated location of all proposed impervious areas, buildings, roadways, parking, sidewalks, utilities, and other site improvements;

(3)

The location of the proposed limit of disturbance, erodible soils, steep slopes, and areas to be protected during construction;

(4)

Preliminary estimates of stormwater management requirements, the selection and location of ESD practices to be used, and the location of all points of discharge from the site;

(5)

A narrative that supports the concept design and describes how ESD will be implemented to the MEP; and

(6)

Any other information required by the approving agency.

Following concept plan approval by the City, the owner/developer shall submit site development plans that reflect comments received during the previous review phase. Plans submitted for site development approval shall be of sufficient detail to allow site development to be reviewed and include but not be limited to:

(1)

All information provided during the concept plan review phase;

(2)

Final site layout, exact impervious area locations and acreages, proposed topography, delineated drainage areas at all points of discharge from the site, and stormwater volume computations for ESD practices and quantity control structures;

(3)

A proposed erosion and sediment control plan that contains the construction sequence, any phasing necessary to limit earth disturbances and impacts to natural resources and an overlay plan showing the types and locations of ESD and erosion and sediment control practices to be used;

(4)

A narrative that supports the site development design, describes how ESD will be used to meet the minimum control requirements, and justifies any proposed structural stormwater management measure; and

(5)

Any other information required by the approving agency.

Following site development approval by the City, the owner/developer shall submit final erosion and sediment control and stormwater management plans that reflect the comments received during the previous review phase. Plans submitted for final approval shall be of sufficient detail to allow all approvals and permits to be issued according to the following:

(1)

Final erosion and sediment control plans shall be submitted according to COMAR 26.17.01.05; and

(2)

Final stormwater management plans shall be submitted for approval in the form of construction drawings and be accompanied by a report that includes sufficient information to evaluate the effectiveness of the proposed runoff control design.

Reports submitted for final stormwater management plan approval shall include, but are not limited to:

(1)

Geotechnical investigations including soil maps, borings, site-specific recommendations, and any additional information necessary for the final stormwater management design;

(2)

Drainage area maps depicting predevelopment and post development runoff flow path segmentation and land use;

(3)

Hydrologic computations of the applicable ESD and unified sizing criteria according to the Design Manual for all points of discharge from the site;

(4)

Hydraulic and structural computations for all ESD practices and structural stormwater management measures to be used;

(5)

A narrative that supports the final stormwater management design;

(6)

The seal and signature of the professional engineer that prepared the report; and

(7)

Any other information required by the City.

Construction drawings submitted for final stormwater management plan approval shall include, but are not limited to:

(1)

A vicinity map;

(2)

Existing and proposed topography and proposed drainage areas, including areas necessary to determine downstream analysis for proposed stormwater management facilities;

(3)

Any proposed improvements including location of buildings or other structures, impervious surfaces, storm drainage facilities, and all grading;

(4)

The location of existing and proposed structures and utilities;

(5)

Any easements and rights-of-way;

(6)

The delineation, if applicable, of the one-hundred-year floodplain and any on-site wetlands;

(7)

Structural and construction details including representative cross sections for all components of the proposed drainage system or systems, and stormwater management facilities;

(8)

All necessary construction specifications;

(9)

A sequence of construction;

(10)

Data for total site area, disturbed area, new impervious area, and total impervious area;

(11)

A table showing the ESD and unified sizing criteria volumes required in the Design Manual;

(12)

A table of materials to be used for stormwater management facility planting;

(13)

All soil boring logs and locations;

(14)

An inspection and maintenance schedule, with specific maintenance instructions to be followed by the owner of the facilities;

(15)

Certification by the owner/developer that all stormwater management construction will be done according to this plan;

(16)

An as-built certification signature block to be executed by the certifying engineer after project completion; and

(17)

Any other information required by the City.

If a stormwater management plan involves direction of some or all runoff off of the site, it is the responsibility of the developer to obtain from adjacent property owners any easements or other necessary property interests concerning flowage of water. Approval of a stormwater management plan does not create or affect any right to direct runoff onto adjacent property without that property owner's permission.