(a) Concept plan. Before the Board may approve a preliminary plan of subdivision, an applicant must submit a stormwater management and sediment control concept plan to the Department for review and approval. Each plan submitted for concept approval must provide sufficient information for the Department to make an initial assessment of the proposed project and determine whether stormwater can be managed according to this Article and the Design Manual. Each concept plan is subject to the following conditions and requirements:
(1) A natural resources inventory must be reviewed and approved by the Department or the Planning Director before the applicant submits a concept plan under this Section.
(2) The plan must indicate how the stormwater management and sediment control criteria will be applied to each proposed development or redevelopment project. The Department may require a plan to analyze the downstream effects of any proposed development or redevelopment project. The basic design criteria, methodologies, and construction specifications used in developing the plan must be specified in the Design Manual and any other criteria established by regulation.
(3) The plan must describe how environmental site design practices will be implemented to the maximum extent practicable and allow use of any structural best management practice only where the applicant shows that environmental site design or another nonstructural best management practice is not a viable option.
(4) The plan must include:
(A) a map, at a scale specified by the Department, showing site location, existing natural features, water and other sensitive resources, topography, and natural drainage patterns;
(B) the anticipated location of each proposed impervious area, building, roadway, parking, sidewalk, utility, and other site improvement;
(C) the location of the proposed limit of disturbance, erodible soils, steep slopes, and any area to be protected during construction;
(D) preliminary estimates of stormwater management requirements, the location of each ESD practice to be used, and the location of each point of discharge from the site; and
(E) any other information the Director requires.
(5) Any stormwater management plan must be consistent with any watershed management plan that the Department of Environmental Protection has approved or any flood management plan that the Administration has approved involving the site of the proposed development or redevelopment project.
(6) The Department must refer the concept plan to the Department of Environmental Protection, the Department of Transportation, and the Board for comment before approving the plan.
(b) Site development stormwater management plan. Before the Board may approve a site plan, the applicant must submit a site development stormwater management plan to the Department for review and approval. The applicant may combine the site development stormwater management plans with the concept plan required under subsection (a) if the Director approves. Any site development stormwater management plan submitted for review and approval must include:
(1) all information provided during the concept plan review;
(2) final site layout, exact impervious area locations and acreages, proposed topography, a delineated drainage area at each point of discharge from the site, and stormwater volume computations for ESD practices and structural measures;
(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 type and location of each ESD and erosion and sediment control practice 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 the Director requires.
(c) Final stormwater management design plan
(1) Any person required under this Chapter to obtain a sediment control permit must include a final stormwater management design plan as part of the permit application. The final stormwater management design plan must conform to both the concept plan and site development stormwater management plan and serve as the basis for all later construction. The applicant must submit a final stormwater management design plan for approval in the form of construction drawings accompanied by a report that includes sufficient information to evaluate the effectiveness of the proposed runoff control design. The applicant must also submit a final erosion and sediment control plan under applicable State Regulations. Any plan submitted under this paragraph must meet all requirements of the Design Manual.
(2) Any report submitted for final stormwater management design plan approval must include:
(A) geotechnical investigations, including soil maps, borings, site-specific recommendations, and any additional information necessary for the final stormwater management design;
(B) a drainage area map depicting pre-development and post-development runoff flow path segmentation and land use;
(C) hydrologic computations of the applicable ESD and unified sizing criteria according to the Design Manual for each point of discharge from the site;
(D) hydraulic and structural computations for each ESD practice and structural stormwater management measure to be used; and
(E) a narrative that supports the final stormwater management design.
(3) Construction drawings submitted for final stormwater management design plan approval must include:
(A) a vicinity map;
(B) existing and proposed topography and any proposed drainage area, including any area necessary to determine downstream analysis for each proposed stormwater management facility;
(C) any proposed improvement, including the location of any building or other structure, impervious surface, storm drainage facility, and all grading;
(D) the location of any existing and proposed structure;
(E) any easement and right-of-way;
(F) the delineation, if applicable, of the 100-year floodplain and any on-site wetland;
(G) structural and construction details, including representative cross sections for each component of the proposed drainage system or systems and stormwater management facilities;
(H) all necessary construction specifications;
(I) a sequence of construction;
(J) data for total site area, disturbed area, new impervious area, and total impervious area;
(K) a table showing the ESD and unified sizing criteria volumes required in the Design Manual;
(L) a table of materials to be used for stormwater management facility planting;
(M) each soil boring log and location;
(N) an inspection and maintenance schedule;
(O) certification by the applicant that all stormwater management construction will be completed according to this plan; and
(P) an as-built certification signature block, to be executed after project completion.
(4) The maintenance schedule required under this Section must cover the life of any structural stormwater management facility or system of ESD practices and must specify the maintenance to be completed, the time period for completion, and the responsible party that will perform the maintenance. The maintenance schedule must be printed on the approved final stormwater management plan.
(d) Plan preparation. The Director may require the stormwater management concept, site development stormwater management, and final stormwater management and design plans to be prepared by a professional engineer, professional land surveyor, registered architect or landscape architect licensed in Maryland, or any other individual whose qualifications are acceptable to the Department. If a stormwater best management practice requires either a dam safety permit from the Administration or a small pond approval from the District, the Director must require the design plan to be prepared by a professional engineer licensed by the State of Maryland.
(e) Runoff. If a stormwater management plan involves direction of some or all runoff off site, the developer must obtain from any adjacent property owner any easement or other necessary property interest concerning water flow. Approval of a stormwater management plan does not create or imply any right to direct runoff onto any adjacent property without that property owners’s permission. (1980 L.M.C., ch. 60, § 3; 1985 L.M.C., ch. 27, § 1; 2001 L.M.C., ch. 27, § 1; 2002 L.M.C., ch. 3, § 1; 2006 L.M.C., ch. 37, § 1; 2010 L.M.C., ch. 34, § 1.)
Editor’s note — Former §§ 19-23, “Storm water management chapter,” and 19-25, “Storm water Management required for a development,” were repealed, re-enacted with amendments, renumbered § 19-23, and retitled pursuant to 2002 L.M.C., ch. 3, § 1.