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Home My WebLink AboutSW6180602_Low Density Supplement_20180613 Form SW401-Low Density-Rev.3-2/10/09 Page 1 of 5 Permit No. (to be provided by DEMLR) State of North Carolina Department of Environment and Natural Resources Division of Energy, Mineral and Land Resources STORMWATER MANAGEMENT PERMIT APPLICATION FORM LOW DENSITY SUPPLEMENT This form may be photocopied for use as an original A low density project is one that meets the appropriate criteria for built upon area and transports stormwater runoff primarily through vegetated conveyances. Low density projects should not have a discrete stormwater collection system as defined by 15A NCAC 2H .1002(18). Low density requirements and density factors can be found in Session Law 2008-211, 15A NCAC 2H .1000, Session Law 2006-246 and the State of North Carolina Stormwater Best Management Practice Manual. Curb and gutter systems are allowed provided they meet the requirements in 15A NCAC 2H .1008(g). I. PROJECT INFORMATION Project Name : Linden 230kV Substation Contact Person: Mr. Reuben Jones Phone Number: ( 919 )546-3459 Number of Lots:N/A Allowable Built Upon Area (BUA) Per Lot*:N/A Number of Dwelling Units Per Acre**:N/A Low Density Development (check one): without curb & gutter with curb & gutter, outlets to (check one): Swales Vegetated Area *If lot sizes are not uniform, attach a table indicating the number of lots, lot sizes and allowable built upon area for each lot. The attachment must include the project name, phase, page numbers and provide area subtotals and totals. BU A shall be shown in units of square feet. **(Phase II Post-Construction [non-SA] only) II. BUILT UPON AREA Refer to DEMLR’s forms and applications website for specific language that must be recorded in the deed restrictions for all subdivided projects. (http://portal.ncdenr.org/web/lr/state-stormwater-forms_docs) Complete the following calculation in the space provided below where: • SA Site Area - the total project area above Mean High Water. • DF Density Factor - the appropriate percent built upon area divided by 100. • RA Road Area - the total impervious surface occupied by roadways. • OA Other Area - the total area of impervious surfaces such as clubhouses, tennis courts, sidewalks, etc. • No. of Lots - the total number of lots in the subdivision. • BUA per Lot - the computed allowable built upon area for each lot including driveways and impervious surfaces located between the front lot line and the edge of pavement. • Total allowable lot BUA - the computed allowable built upon area for all lots combined. Form SW401-Low Density-Rev.3-2/10/09 Page 2 of 5 • Total BUA from lot listing - the sum of built upon area allocated for each lot on the list of non-uniform lots. Calculation: For uniform lot sizes: (SA: ft2 x DF: ) – (RA: ft2) – (OA: ft2) = BUA per Lot = ft2 (No of Lots: ) For non-uniform lot sizes: a. (SA: ft2 x DF: ) – (RA: ft2) – (OA: ft2) = Total allowable lot BUA = ft2 b. Total BUA from lot listing: sf. b must be ≤ a III. DESIGN INFORMATION Complete the following table. If additional space is needed the information should be provided in the same format as Table 1 and attached to this form. Rainfall intensity data can be found in Appendix 8.03 of the State of North Carolina Erosion and Sediment Control Planning and Design Manual or at http://hdsc.nws.noaa.gov/hdsc/pfds/ Table 1. Swale design information based on the 10-year storm. Swale No. Drainage Area (ac) Impervious Area (ac) Grassed Area (ac) C Q (cfs) Slope (%) Vallow (fps) Vactual (fps) Flow Depth (ft) 1 1.40 0.09 1.31 0.34 3.78 0.20 2.70 1.04 0.46 2 3.48 0.43 3.05 0.38 10.47 0.20 2.70 1.41 0.80 3 5.83 0.36 5.47 0.34 15.69 0.20 2.70 1.58 0.99 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Form SW401-Low Density-Rev.3-2/10/09 Page 3 of 5 IV. REQUIRED ITEMS CHECKLIST The following checklist outlines design requirements per the North Carolina Administrative Code Section 15A NCAC 2H .1000, NCDENR BMP Manual (2007), Session Law 2006-246, and Session Law 2008-211. Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate that the following requirements have been met and supporting documentation is provided as necessary. If the applicant has designated an agent on the Stormwater Management Permit Application Form, the agent may initial below. If any item is not met, then justification must be attached. Only complete items n through p for projects with curb outlets. Page/Plan Initials Sheet No. N/A a. † For projects in the 20 coastal counties: Per NCAC 2H.1005, a 50 foot wide vegetative buffer is provided adjacent to surface waters. For Redevelopment projects, a 30’ wide vegetative buffer adjacent surface waters is provided. N/A b. † For HQW or ORW projects outside the 20 coastal counties: A 30 foot wide vegetative buffer is provided adjacent to surface waters. N/A c. † For Phase II Post-Construction projects: All built upon area is located at least 30 feet landward of all perennial and intermittent surface waters. N/A d. Deed restriction language as required on form SWU-101 shall be recorded as a restrictive covenant. A copy of the recorded document shall be provided to DWQ within 30 days of platting and prior to the sale of any lots. Stormwater Management Permit Application e. Built upon area calculations are provided for the overall project and all lots. N/A f. Project conforms to low density requirements within the ORW AEC. (if applicable per 15A NCAC 2H .1007) SHT 6 g. Side slopes of swales are no steeper than 3:1; or no steeper than 5:1 for curb outlet swales. SHT 6, SHT 13, Calcs h. Longitudinal slope of swales is no greater than 5%; for non-curb outlet projects, calculations for shear stress and velocity are provided if slope is greater than 5%. Calcs i. At a minimum, swales are designed to carry the 10 year storm velocity at a non-erosive rate. N/A j. Swales discharging to wetlands are designed to flow into and through the wetlands at a non- erosive velocity (for this flow requirement into wetlands, non-erosive is velocity ≤ 2 ft/s). SHT 13, SHT 15 k. Swale detail and permanent vegetation is specified on the plans. SHT 13, SHT 15 l. Swale detail provided on plans; includes grass type(s) for permanent vegetative cover. N/A m. Swales are located in recorded drainage easements. N/A n.†† Length of swale or vegetated area is at least 100 feet for each curb outlet. Form SW401-Low Density-Rev.3-2/10/09 Page 4 of 5 N/A o.†† The system takes into account the run-off at ultimate built-out potential from all surfaces draining to the system (delineate drainage area for each swale). N/A p.†† Curb outlets direct flow to a swale or vegetated area. † Projects in the Neuse, Tar-Pamlico, Catawba River basins, and Randleman Lake may require additional buffers. †† Only complete these items for projects with curb outlets.