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(1) The developer shall submit phased SWM plans that meet the design requirements of this chapter. The plans shall be accompanied by reports that include sufficient information to evaluate the environmental characteristics of affected areas, the potential impacts of the proposed development on water resources, and the effectiveness and acceptability of measures proposed for managing stormwater runoff. The developer or builder shall certify on the drawings that all clearing, grading, drainage, construction, and development shall be conducted in strict compliance with the plans. The developer shall obtain from adjacent property owners any easements or necessary property interests concerning flow of water. Approval of a SWM plan does not create or affect any right to direct runoff or create dam breach inundation areas that extend onto adjacent properties. Whenever easements are required for water flow directed onto a downstream property, they shall be obtained by the developer and recorded in the Land Records of Carroll County. Easements for water flow onto properties below publicly owned facilities shall be conveyed to the county. Easements for water flow below privately owned facilities shall be conveyed to the SWM facility owner. New residential, industrial, institutional, or commercial buildings may not be built within any dam breach inundation area on or off site unless the dam was designed and approved as a high hazard dam. Any proposed roadway that crosses a dam breach inundation area shall meet the requirements of MD 378 for hazard Class “A” dams unless the dam was approved as a high hazard dam. The applicant shall acquire protective easements on areas delineated outside of the property limits unless the dam was approved as a high hazard dam. The easements shall protect the inundation area from future development. Easements protecting dam breach inundation areas below publicly owned facilities shall be conveyed to the county. Easements protecting dam breach inundation areas below privately owned facilities shall be conveyed to the SWM facility owner. Dam breach inundation easements shall be recorded in the Land Records of Carroll County.
(2) The information required shall be submitted in accordance with the checklist found in the Supplement.
(1) The plans submitted for concept approval shall include:
(a) The environmental site delineation items in accordance with § 155.055 (G) and (H) of the Code;
(b) The anticipated location of all proposed impervious areas (buildings, roadways, parking, sidewalks, etc.), utilities, and other site improvements;
(c) The proposed limits of disturbance, erodible soils, steep slopes, and areas to be protected during construction;
(d) Preliminary estimates of SWM requirements, the selection and location and preliminary sizing of ESD planning techniques, treatment and microscale (nonstructural) practices, and the location of all points of discharge into buffers or from the site;
(e) A separate written narrative, not on the plan sheets, that supports the concept design and describes how ESD will be implemented to the MEP;
(f) The location, description, and evaluation of infiltratable areas using the soils testing procedures in the Supplement;
(g) All other items described in § 5.1 of the Manual and in the concept plan portion of the checklist.
(2) Once the concept plan is approved in accordance with this section, the developer shall submit a preliminary plan in accordance with this section. The plan submitted for preliminary approval shall include:
(a) All information provided during concept plan review and approval phases;
(b) Final site layout, exact impervious areas, locations and acreages, proposed topography (contours), delineated drainage areas at all points of discharge from the site, and stormwater volume computations for ESD planning techniques, treatment and microscale (nonstructural) and structural practices;
(c) A phased erosion and sediment control plan that contains:
1. An overlay plan showing the types and locations of and coordinating all temporary erosion and sediment control and permanent ESD and structural SWM measures;
2. The location and delineated drainage area to each sediment control practice during each phase;
3. Evaluation of the need to provide interim quantity control of stormwater runoff during each phase; and
4. An overall sequence of construction phased to match the plan. If SWM facilities are being used for sediment control, the sequence must reference but not duplicate the specific sequence of construction for that facility.
(d) Limitations on earth disturbance and impacts to natural resources;
(e) A separate written narrative, not on the plan sheets, that supports the preliminary design, describes how ESD has been used to meet the minimum control requirements to the MEP and justifies any proposed interim or permanent structural SWM measures;
(f) All other items described in § 5.1 of the Manual or in the preliminary plan portion of the checklist; and
(g) Any other information required by the county where downstream flooding problems, danger to public health and safety, damage to property or the environment exist or may be created by runoff from the development.
(3) Once the preliminary plan is approved in accordance with this section, the developer shall submit a final plan in accordance with this section. The plans submitted for final approval shall include:
(a) All information provided during preliminary review and approval;
(b) A separate written narrative, not on the plan sheets, that supports the final integrated SWM and sediment control designs with sufficient information to evaluate the effectiveness of the proposed runoff control;
(c) Final erosion and sediment control plans shall be submitted according to COMAR 26.17.01.05;
(d) Geotechnical investigations including soil maps, borings, site-specific recommendations, and any additional information necessary for the proposed SWM design;
(e) Descriptions of all watercourses, impoundments, and wetlands on or adjacent to the site or into which stormwater directly flows;
(f) Drainage area maps depicting predevelopment and postdevelopment runoff flow path segmentation and land use;
(g) Hydraulic computations of the applicable ESD and the unified sizing criteria according to the Design Manual for all points of discharge from the site;
(h) Hydraulic and structural computations for all ESD practices and conveyance systems and structural SWM measures to be used;
(i) Unified sizing criteria volume computations according to the Design Manual;
(j) Dam breach inundation areas that may extend onto the property shall be shown. The dam breach inundation area shall be delineated downslope from existing or proposed dams until the dam breach floodwave enters an adequate ultimate floodplain, is captured by a closed storm drain system, or is reduced to a depth less than six inches. Any off site area potentially inundated by the breach of a dam, constructed as part of the development, shall be delineated;
(k) All other items described in § 5.1 of the Manual or in the final plan portion of the checklist; and
(l) The county may require any other information where downstream flooding problems, danger to public health and safety or damage to property or the environment exist or may be created by runoff from the development.
(C) Construction drawings submitted for final SWM plan approval shall include the following:
(1) A vicinity map;
(2) Topography survey showing existing and proposed contours, including the area necessary to perform the 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 streams, watercourses, 100-year floodplains (FEMA and ultimate study), impoundments, dam breach inundation areas, 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 SWM facilities;
(8) All necessary construction specifications;
(9) A sequence of construction, including an overall sediment control sequence of construction and detailed individual sequence for each interim or permanent SWM structure;
(10) Data for total site area, disturbed area, new impervious area, and total impervious area;
(11) Tables and drainage area maps on the as-built certification sheet for each ESD and structural practice with the coordinates, drainage area, impervious area, and unified sizing criteria volumes for each practice listed;
(12) A table of materials to be used for SWM facility planting;
(13) All soil boring logs and locations;
(14) An inspection and maintenance schedule;
(15) Certification by the owner or developer that all SWM construction will be done according to this plan;
(16) An as-built certification signature block to be executed after project completion;
(17) An inspection certification chart indicating the stages of construction, when inspection is to occur, the date of inspection, and inspector’s signature;
(18) All other items described in § 5.1 of the Manual or in the final plan portion of the checklist; and
(19) Any other information required by the county where downstream flooding problems, danger to public health and safety, damage to property or the environment exist or may be created by runoff from the development.
(2004 Code, § 191-14) (Ord. 01-12, passed 9-27-2001; Ord. 04-07, passed 4-1-2004; Ord. 2010-05, passed 4-29-2010; Ord. 2018-11, passed 11-29-2018)