Dorchester County, MD Article V Stormwater Management Plans

§ 134-13 Review and approval of stormwater management plans.

A. For any proposed subdivision or land development, the owner/developer shall submit phased stormwater management plans to the Dorchester County Department of Public Works for review and approval. At a minimum, plans shall be submitted for the sketch, preliminary and final land development phases of project design. Each plan submittal shall include the minimum content specified in § 134-14 of this chapter and meet the requirements of the Design Manual and Article IV of this chapter.

B. The Dorchester County Department of Public Works 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), the Departments of Planning and Zoning, Public Works and Health. All comments from the Dorchester County Department of Public Works and other appropriate agencies shall be addressed and approval received at each phase of project design before subsequent submissions.

C. All plan submissions shall be made to the Dorchester County Planning and Zoning Department, which shall coordinate planning reviews with the appropriate reviewing agencies.

D. The applicant for submission of a minor residential subdivision may request a waiver of the requirement to submit a preliminary plan in accordance with § 134-14B if environmental site design practices have been fully utilized.

E. The subdivision and land development of a one-lot single-family residential unit utilizing the application of preapproved environmental site design features may utilize a standard stormwater management plan approved by the Dorchester County Department of Public Works as an alternative to the requirements of §§ 134-13 and 134-14.

F. Notification of approval or reasons for disapproval or modification shall be given to the applicant within 30 days after submission of a complete stormwater plan. If a decision is not made within 30 days, the applicant or designated representative shall be informed of the status of the review process and the anticipated completion date. The stormwater management plan shall not be considered approved without the inclusion of the signature and date of signature of the Director of the Dorchester County Department of Public Works on the plan.

§ 134-14 Contents and submission of stormwater management plans.

A. The owner/developer shall submit a sketch plan that provides sufficient information for an initial assessment of the proposed project and whether stormwater management can be provided according to § 134-11 of this chapter and the Design Manual. Plans submitted for sketch plan approval shall include but are not limited to:

(1) A location map, for the purpose of locating the project site to be developed, at a minimum scale of 2,000 feet to the inch, showing the relation of the tract to adjoining property and to all streets and municipal boundaries existing within 1,000 feet of any part of the tract of land on which the project site is proposed to be developed;

(2) The proposed name or identifying title of the project along with plan date, date of latest revision, North point, graphic scale and written scale. All plans shall be drawn at a common engineering scale;

(3) Total acreage of the project site and the tract of land on which the project site is located;

(4) The proposed land use, number of lots and dwelling units and the extent of commercial, industrial or other residential uses;

(5) The name and address of the landowner and developer of the project site;

(6) The names of all owners of all immediately adjacent land, the names of all proposed or existing developments immediately adjacent, and the locations and dimensions of any adjacent streets or easements;

(7) A site plan at a scale specified by the Dorchester County Department of Public Works showing development site location, existing natural features, water and other sensitive resources, topography, and natural drainage patterns;

(8) The location of any existing private and public drainage easements and culvert pipes, including the designation of state and federal regulated water bodies and streams;

(9) The anticipated location and area computation of all proposed impervious areas, buildings, roadways, parking, sidewalks, utilities, and other site improvements;

(10) The location of the proposed limit of disturbance (LOD), soil types as designated by the USDA Natural Resources Conservation Service for Dorchester County, wetlands, forest conservation areas, floodplain, steep slopes, and other areas to be protected during construction;

(11) The boundary and designation of any critical areas;

(12) Preliminary estimates of stormwater management requirements, the selection and location of environmental site design practices to be used, and the location of all proposed points of discharge from the site;

(13) A narrative that supports the sketch plan design and describes how environmental site design will be implemented to the maximum extent practicable;

(14) A certificate for review by the Dorchester County Department of Public Works;

(15) A certificate of approval by the Dorchester County Department of Public Works; and

(16) Any other information required by the Dorchester County Department of Public Works.

B. Following sketch plan approval by the Dorchester County Department of Public Works, the owner/developer shall submit preliminary land development plans that reflect comments received during the previous review phase. Plans submitted for preliminary land 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 sketch plan review phase;

(2) Final site layout, exact impervious area locations and acreages, proposed topography with contour lines at one-foot intervals for slopes of 5% or less or two-foot intervals for more steeply sloped land, delineated drainage areas at all points of discharge from the site;

(3) A written and bound hydrologic and hydraulic report including or prepared in accordance with the following:

(a) Stormwater runoff calculations for both pre-development and post-development conditions for peak discharge and pollutant removal;

(b) Stormwater volume computations for environmental site design practices and quantity control structure;

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

(d) Hydrologic computations of the applicable environmental site design and unified sizing criteria according to the Design Manual for all points of discharge from the site;

(e) Hydraulic and structural computations for all environmental site design practices and structural stormwater management measures to be used;

(f) For all proposed detention basins and retention basins, and temporary sedimentation basins, the documentation shall include a plotting or tabulations of storage volumes with corresponding water surface elevations and the outflow rates for those water surfaces;

(g) A plan showing the delineation of pre- and post-development drainage areas, including the path used to determine the time of concentration;

(h) An analysis of all existing and proposed drainage conveyance facilities capacity. The analysis shall include any off-site watercourses determined to be potentially impacted by the Dorchester County Department of Public Works;

(i) A narrative that supports the final stormwater management design; and

(j) Any other information required by the Dorchester County Department of Public Works.

(4) 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 environmental site design and erosion and sediment control practices to be used;

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

(6) Any other information required by the approving agency.

C. Following preliminary land development approval by the Dorchester County Department of Public Works, 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) All information provided during the preliminary plan review phase;

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

(3) 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;

(4) An engineer's cost opinion for construction of all stormwater management facilities and practices;

(5) A signed stormwater permit application;

(6) Payment of permit fees. Permit fees will be determined after review of the cost opinion; and

(7) Submittal of any required maintenance, conservation and development improvement agreements;

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

(1) A location map in accordance with § 134-14A(1);

(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) A note on the plan indicating the ownership and maintenance responsibilities for all stormwater management facilities;

(7) The delineation along with the signature and date of the person responsible, if applicable, of any on-site wetlands;

(8) The delineation and basis for determination of the one-hundred-year floodplain;

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

(10) All necessary construction specifications;

(11) A sequence of construction;

(12) Data for total site area, disturbed area, new impervious area, and total impervious area;

(13) A table showing the environmental site design and unified sizing criteria volumes required in the Design Manual;

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

(15) All soil boring logs and locations;

(16) An inspection and maintenance schedule;

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

(18) A note that record drawings will be provided within 90 days following completion of construction;

(19) A record drawing certification signature block to be executed after project completion;

(20) A certificate for review by the Dorchester County Department of Public Works;

(21) The plans need to identify the person responsible for preparation of the stormwater management plan; and

(22) Any other information required by the Dorchester County Department of Public Works.

§ 134-15 Preparation of stormwater management plans.

A. The design of stormwater management plans shall be prepared by any individual whose qualifications are acceptable to the Dorchester County Department of Public Works. The design shall be prepared by a professional engineer, professional land surveyor, or landscape architect licensed in the state, as necessary to protect the public or the environment.

B. If a stormwater best management practice requires either a dam safety permit from the Maryland Department of the Environment or small pond approval from the soil conservation district, the Dorchester County Department of Public Works shall require that the design be prepared by a professional engineer licensed in the state.