Morrisville Administrative Manual_September 2023

Part 4. Appendices 4.5 Checklists

Construction Plan Approval for a Preliminary Subdivision Plat Approval (Type 1 or Type 2) Checklist (use this checklist for combined review applications) For each listed item, check (√) if provided, write “n/a” if the feature does not exist or is not proposed, and write “w” if a waiver from the requirement is justified because it is unnecessary in the particular case to determine compliance with applicable regulations. Staff Use Only √, n/a, or w Application Submittal Requirement √, n/a, or w • BMP drainage area map (include area of BMP itself) (on full-size plan sheet) • Inlet drainage area map (on full-size plan sheet) • USGS Quad map (identify site) • FIRM map (identify site) • Wake County Soil Survey (1970) map (identify site) 5 Runoff coefficient calculations 7 Analyze pre-development and post-development runoff conditions for each discharge point from the site 8 No net increase from pre-development peak flow for 1-yr, 2-yr, & 10-yr, 24-hr storm events 9 Roof drain & leader calculations (designed per the NC Plumbing Code) 10 Storm Drain System Design Calculations • Pipe material – RCP, minimum pipe diameter of 15 inches, minimum slope of 0.5% • Pipes carry the 2-yr storm at a velocity of at least 2 • 10-yr (contained in pipe) & 25-yr (contained in structures) HGL calculations & profiles • Swale calculations showing non-erosive flow for 10-yr storm • Gutter spread calculations for 4 in/hr storm (8ft max spread) • Culvert calculations (energy equation & nomographs) • Rip rap apron calculations/nomographs 12 Stormwater Quality (85% TSS removal)/Quantity Best Management Practices (BMPs) • Stormwater BMPs must be designed in accordance with the NCDENR Stormwater BMP Design Manual, or the Minimum Design Criteria (MDC), and any supplements to it issued by the Town of Morrisville including the Town of Morrisville EDCM and Policy or Technical Memorandums, • Stormwater BMP detention routing (1, 2, 10, 25, and 100-year storm events) • Provide 1 foot of freeboard from the top of any dam embankment during the 100-year storm event • Permanently stabilized emergency spillway must be provided • Water Quality Computations and BMP sizing/drawdown for the 1- inch (1”) runoff depth 13 Nutrient Calculations: Copy (of all tabs) & .xls file of completed J/F Nutrient Loading Accounting Tool 14 BMP Operation and Maintenance manual • Engineers estimate for BMP. Provide detailed, line-item bid summary with item/activity description, unit price, amounts of units, and total cost. • Maintenance surety calculation (30% cash payment) • Draft O&M agreement with site-specific data included for review prior to execution and recordation T Other 1 Keynotes are not permitted 2 3x5 vacant block for approval stamps • Rational Formula (up to 5 acres) • SCS Method (discrete CN method) 6 Time of concentration for pre/post development conditions

Morrisville, NC

August 7, 2023

Administrative Manual

Page 44