SW6230903_As-Built - Calculations_20231102

Track & Field Renovations
®m MOORE COUNTY
SCHOOLS North Moore High School
ENGAGE•INSPIRE•SUCCEED
Moore County Schools
1504 N.Moore Rd.
Robbins, NC
State Stormwater Permit
Supporting Documents
Calculations
Revised Final Submittal
October 31, 2023
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Runoff Volume Match Calculation

RUNOFF VOLUME MATCH DATE
31-Oct-23
PROJECT NAME PROJECT NO ��u
North Moore HS Track Replacement 22-102
LOCATION BY
Robbins, NC SM
Pre Development
Area of Interest 2,159,496 sf (entire 49.57-ac campus)
Impervious Area c=0.95 596,267 sf (exist. prior to 2019 project)
Pervious Area c= 0.35 1,563,229 sf (exist. prior to 2019 project)
Cc = 0.52
% Impervious = 27.6
Runoff Coeff. Rv (0.05 + 0.009 (% Imperv.)) = 0.30
Fraction of Rainfall Events that Produce Runoff, Pj = 0.9
Ave. Annual Rainfall Amount, P = 47.33 in (Carthage, NC)
Average Runoff Volume(ARV)
ARV - Pj x Rv x A x (P/12) = 2,288,222 cf
Post Development
Area of Interest 2,159,496 sf
Impervious Area c=0.95 639,571 sf (addition of 43,304-sf)*
Pervious Area c= 0.35 1,519,925 sf
Cc = 0.53
% Impervious = 29.6
Runoff Coeff. Rv (0.05 + 0.009 (% Imperv.)) = 0.32
Fraction of Rainfall Events that Produce Runoff, Pj = 0.9
Ave. Annual Rainfall Amount, P = 47.33 in (Carthage, NC)
Average Runoff Volume(ARV)
ARV - Pj x Rv x A x (P/12) = 2,426,569 cf
% Increase: 6.0%
* Added impervious area includes 28,709-sf added in 2019 plus 14,595-sf added in 2023

'DEQ Average Annual Precipitation and Nutrient Management Strategy Watershe•
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Precipitation Stations
• Average Annual Precip(inches) 47.33
Staron Name Carthage
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