SW4240503_Design Calculations_20240823

STORMWATER CALCULATIONS
BY
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LAND RESOURCE
FOR
WILDERNESS RESERVE PHASE 3
Watauga County, NC ,
OWNER
ELEVATE LAND HOLDINGS, LLC
491 WILLIAMSON ROAD STE. 207
MOORESVILLE, NC 28815
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WILDERNESS RESERVE PHASE 3
PROJECT SUMMARY/NARRATIVE
This project will require a POST CONSTRUCTION stormwater permit for ORW
All drainage in the western direction drains to an ORW Watershed.
As such, all calculations are for the 25-year storm.
All drainage to the East drains to Wild Cat Creek which is not an ORW fed stream.
OWNER Elevate Land Holdings, LLC
MAILING ADDRESS 491 Williamson Road Ste. 207
CITY, STATE, ZIP Moorseville, NC 28117
NBHD 0804 -SOUTH ELK TOWNSHIP
LAT 36°12'36.5786" N
LONG -81°31'22.5178"W
RECEIVING STREAMS To West, Elk Creek, B;Tr,ORW;12-24-(1)
To East, Wildcat Creek
RIVER BASIN WATAUGA
acres percent
Soils BoE 8.6 15.8
BrF 32.3 59.3
CsE 0.1 0.2
WaD 13.5 24.8
The proposed project is located along a ridge line in Watuga County, NC
AREA= 54.5 ACRES
The property contains logging roads, but is overwise un-developed
Nature of Watersheds
The terrain for the property is very steep with short travel paths to the existing
receiving streams. As such, time of concentration for the site is very short
which produces higher discharge rates when compared to flatter terrain.
Although the Site has multiple sub-basin watersheds, it was determined that modeling
2 watersheds would result in the same discharge rate as modeling all sub-basins.
Proposed Development
The property is to be developed with infrastructure to support single family home development
which will have a density below the threshold for structural SCMs/BMPs consisting
of Road Construction. Each lot will have its own water and septic system.
Proposed Drainage
In accordance with the requirements for Low Density Development, Site Drainage will be

accomplished with road swales and culverts. Stormwater Runoff upstream of disturbed
areas will be diverted directly to the culverts using temporary diversions at the top of slopes.
Stream and Wetland Encroachment
No streams or wetlands will be encroached and will not require permitting.
EXISTING PEAK RATE TO ORW
AVERAGE Tc= 10
125= 5.52
C= 0.3
A= 54.5
PRE
TOTAL RUNOFF PRE(25Y)
TO ORW 90.252
IMPERVIOUS AREA
WATERSHED 1 AREA(SF) % C
HOUSE 86913.01 3.66 0.95
PAVEMENT 57749.74 2.43 0.95
DRIVEWAY 23106.72 0.97 0.95
GRASS 2205013 92.93 0.3
TOTAL= 2372783
TOTAL IMPERVIOUS AREA PERCENTAGE= 7.07 % IMPERVIOUS
PROPOSED PEAK RATE TO ORW
AVERAGE Tc= 10
125= 5.52
C= 0.345959
A= 54.5
POST
TOTAL RUNOFF PRE(25Y)
TO ORW 104.0782

Point precipitation frequency estimates(inches/hour)
NOAA Atlas 14 Volume 2 Version 3
Data type: Precipitation intensity
Project area: Ohio River Basin
Location na North Carc USA
Latitude: 36.2054 Degree
Longitude: -81.5186 Degree
Elevation (USGS): 2775 ft
PRECIPITATION FREQUENCY ESTIMATES
1 2 5 10 25 50 100 200 500
5-min: 5 4.4 5.24 6.16 6.9 7.9 8.66 9.47 10.3
10-min: 10 3.52 4.2 4.93 5.52 6.29 6.9 7.52 8.16
15-min: 15 2.94 3.52 4.16 4.66 5.32 5.82 6.34 6.86
30-min: 30 2.01 2.43 2.95 3.37 3.94 4.39 4.85 5.34
60-min: 60 1.25 1.52 1.89 2.2 2.62 2.97 3.34 3.75
2-hr: 120 0.734 0.896 1.12 1.31 1.59 1.82 2.07 2.35
3-hr: 180 0.529 0.643 0.805 0.939 1.14 1.31 1.49 1.7
6-hr: 360 0.339 0.411 0.509 0.59 0.708 0.808 0.915 1.03
12-hr: 720 0.217 0.262 0.322 0.368 0.432 0.484 0.538 0.596
24-hr: 1440 0.129 0.157 0.199 0.234 0.285 0.326 0.371 0.419

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PIPE-5 0.14 5 7.91 0.62 0.62 0 0.62 18 0.012 3233 3232.1 43.93 2.06 3233.0 0.35 0.01944 3233.3 2.4 4.44 0.3 12 10 12 2.4 2.4 3236 3232.1
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PIPE-7 1.22 5 7.91 4.33 4.33 0 4.33 18 0.012 3265.5 3264 71.4 2.56 3265.5 1.05 0.05833 3266.9 5.97 5.45 0.3 12 10 12 5.97 5.97 3269.9 3264
PIPE-1 0.64 5 7.91 2.49 2.49 0 2.49 18 0.012 3093.1 3059.1 46.97 5.42 3093.1 0.7 0.03889 3093.5 3.35 10.95 0.3 12 10 12 3.35 3.35 3096.1 3059.1
PIPE-6 0.71 5 7.91 2.51 2.51A7181
S 0.012 3266.3 3266 66.22 0.49 3266.3 0.7 0.03889 3267.0 6.96 3.95 0.3 12 10 12 6.96 6.96 3270.3 3266
PIPE-S 0.79 5 7.91 3.13 3.13S 0.012 3305.2 3304.5 55.07 6.15 3305.2 0.85 0.04722 3309.1 4.05 10.52 0.3 12 10 12 4.05 4.05 3313.2 3304.5
PIPE-10 0.47 5 7.91 1.92 1.92S 0.012 3392.9 3391.3 57.02 2.55 3392.9 0.6 0.03333 3393.5 3.54 6.94 0.3 12 10 12 3.54 3.54 3396.9 3391.3
PIPE-9 0.22 5 7.54 1.1 1.1 0.012 3355.E 33551 35.53 1.55 3355.E 0.75 0.04167 3356.3 5.43 6.23 0.3 12 10 12 5.43 5.43 3359.6 3355.1

SWALE CHART
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SWALE-1 5 0.64 0.49 2.49 SC-250 2 2 1 5.7 0.2 11.2 15.0 0.9 8.0 3.3 2.4
SWALE-2 5 0.68 0.29 1.56 SC-250 2 2 1 11.4 0.2 7.7 15.0 1.1 8.0 4.6 1.8
SWALE-5 5 1.11 0.32 2.80 SC-250 2 2 1 12.0 0.2 10.0 15.0 1.3 8.0 6.2 1.3
SWALE-6 5 0.51 0.45 1.81 SC-250 2 2 1 13.2 0.2 7.9 15.0 1.2 8.0 5.4 1.5
SWALE-7 5 0.08 0.25 0.17 SC-250 2 2 1 13.2 0.2 2.4 15.0 0.6 8.0 1.6 4.9
SWALE-8 5 0.14 0.56 0.62 SC-250 2 2 1 12.2 0.2 4.8 15.0 0.9 8.0 3.0 2.6
SWALE-9 5 0.71 0.45 2.51 SC-250 2 2 1 11.5 0.2 9.6 15.0 1.2 8.0 5.7 1.4
SWALE-10 5 1.22 0.45 4.33 SC-250 2 2 1 11.5 0.0 4.1 15.0 7.6 8.0 2.4 3.3
SWALE-11 5 0.27 0.25 0.53 SC-250 2 2 1 11.5 0.2 4.6 15.0 0.8 8.0 2.7 2.9
SWALE-12 5 0.79 0.50 3.13 SC-250 2 2 1 8.7 0.2 11.3 15.0 1.2 8.0 5.1 1.6
SWALE-13 5 0.12 0.67 0.63 SC-250 2 2 1 5.8 0.2 5.8 15.0 0.7 8.0 1.7 4.6
SWALE-14 5 0.06 0.66 0.30 SC-250 2 2 1 5.8 0.2 4.0 15.0 0.5 8.0 1.2 6.7
SWALE-16 5 0.22 0.63 1.10 SC-250 2 2 1 12.7 0.2 6.4 15.0 1.0 8.0 4.2 1.9
SWALE-17 1 5 1 0.42 0.52 1.72 SC-250 2 2 1 12.9 0.2 1 7.8 15.0 1.2 8.0 5.2 1.5
SWALE-18 1 5 1 0.47 1 0.51 1 1.92 SC-250 2 2 1 13.0 0.2 1 8.2 1 15.0 1.2 8.0 5.5 1.4