SW3230501_Design Calculations_20231005

57 Union Street South
DAY L I G H T�41,' Conc980.234.7 500
ENGINEERING
daylighteng.com
Smith Industrial Subdivision
Stormwater Narrative
Existing Conditions:
The project site is located at 12400 Old Camden Road in Midland, NC in Cabarrus County.The site is predominately wooded with
25% of the site being open space. A web soil survey found soils on the site to be made up of Tarrus silt loam — Hydrologic Soil
Group B, and Herndon silt loam—Hydrologic Soil Group C. There is no existing on-site impervious area.
Proposed Improvements:
The proposed project consists of the construction of a small public road that ends with a cul-de-sac.This road includes driveway
stubs to the 4 lots that will be subdivided when the project is finalized along with a sidewalk along the southern side of the road.
The construction of this public road is in the open space area of the site. The proposed sand filter will be used to treat the BUA
that is developed due to the construction of the road including the asphalt, sidewalks, and driveway cuts.
Stormwater Treatment:
To provide treatment and attenuation for the site, a sand filter stormwater control measure (SCM) is proposed. Stormwater will
be collected by storm drainage systems and will drain into the sand filter to be treated.All other runoff will sheet flow or naturally
flow into the sand filter.
Required treatment volume was calculated using the discrete NRCS Curve Number Method for Runoff Depth.
August 23, 2023 I

Pre Development Nodal Diagram
PRE DA-A
/ LLFA
-W

Pre-Development Drainage Area A
Land use Condition Hydrologic Area(SF) Area(Acres) Cn Weighted Cn
Soil Group
Woods good C - - 70 0.0
Open Space good C 40,460 0.929 74 25.0
Impervious N/A C - 98 0.0
Woods good B - - 77 0.0
Open Space good B 79,487 1.825 80 53.0
Impervious N/A B - 98 0.0
119,947 2.754 78.0
tc Calculation L up down slope n pipe size(in) area(sf) perimeter
(ft)
Sheet Flow 100 694.00 691.82 2.18% 0.15 Grass:Short Praire
Shallow Concentrated 378 691.82 673.53 4.84% Un-Paved
CALCULATED TC= 10.80 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
TC USED IN CALCULATION= 10.80 MIN MINIMUM TC OF 10 MINUTES
Roughness Coefficients(Manning's N)for Sheet Flow
Smooth Surfaces(Concrete,asphalt,gravel,or bare soil) 0.011
Fallow(no residue) 0.05
Cultivated Soils,Residue<=20% 0.06
Cultivated Soils,Residue>20% 0.17
Grass:Short Praire 0.15 1-
Grass:Dense Grass _ 0.24
Grass:Bermuda Grass 0.41
Range:Natural 0.13
Woods:Light Underbrush 0.4
Woods:Dense Underbrush 0.8
Roughness Coefficients(Manning's N)for Channel Flow
Excavated Channels:Short Grass 0.027

TR55 Tc Worksheet
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024
Hyd. No. 1
Pre DA-A (Outfall 98-W)
Description A B C Totals
Sheet Flow
Manning's n-value = 0.150 0.011 0.011
Flow length (ft) = 100.0 0.0 0.0
Two-year 24-hr precip. (in) = 3.50 3.50 3.50
Land slope (%) = 2.18 0.00 0.00
Travel Time (min) = 9.05 + 0.00 + 0.00 = 9.05
Shallow Concentrated Flow
Flow length (ft) = 378.00 0.00 0.00
Watercourse slope (%) = 4.84 0.00 0.00
Surface description = Unpaved Paved Paved
Average velocity (ft/s) =3.55 0.00 0.00
Travel Time (min) = 1.77 + 0.00 + 0.00 = 1.77
Channel Flow
X sectional flow area (sqft) = 0.00 0.00 0.00
Wetted perimeter(ft) = 0.00 0.00 0.00
Channel slope (%) = 0.00 0.00 0.00
Manning's n-value = 0.015 0.015 0.015
Velocity (ft/s) =0.00
0.00
0.00
Flow length (ft) ({0})0.0 0.0 0.0
Travel Time (min) = 0.00 + 0.00 + 0.00 = 0.00
Total Travel Time, Tc 10.80 min

Post Development Nodal Diagram
Post DA-1
Post DA-2 Post DA-3
411,
OUTFALL
99-W

Sand Filter 1 Calculations
Discrete NRCS Curve Number Method for Runoff Depth
S = 1000 - J.
CN
Where: S = Maximum retention after rainfall begins(in)
CN = Curve number(unilless)
q* _ (P-0.2S)2
(P+0.8S)
Where: lY = Runoff depth(in)
P = Rainfall depth(in)
For DCIA:
P 1 Inch Non-coastal county
CN 98.0 DCIA-Impervious
A 33,621 sf Impervious Drainage Area in SF
S 0.20 Inches Maximum retention after rainfall begins
Q` 0.79 Inches Runoff Depth
Q" 2,216 cfs Runoff Volume
For Remainder:
P 1 Inch Non-coastal county
CN 78.2 CN for Remainder of the Drainage Area
A 55,378 sf Remainder of Drainage Area in SF
S 2.79 Inches Maximum retention after rainfall begins
Q* 0.06 Inches Runoff Depth
Q` 280 cfs Runoff Volume
Total Design Volume 2,496 cf
Discounted Design Volume 1,872 cf For Sand Filters apply 0.75 design volume
discount
Design Ponding Depth 1 2 3 4 5 6
Surface Area Required 1,872 936 624 468 374 312
Bottom of Sand Filter 678
Design Treatment Volume Elevation 680 minimum
Design Ponding Depth 2 (=Design Treatment Volume Elevation-
Bottom of Sand Filter)
Design Treatment Volume 7,163 Total Volume Provided at 679.00
Total Surface Area at Bottom 3,023 Surface Area Provided at 678.00 of Sand Filter&678.00 of Sediment Chamber
Minimum Surface Area Required 936 (=Discounted Design Volume divided by
Design Ponding Depth)
Minimum Design Draw Down 2 in/hr
Design Ponding Depth 24.00 in
Draw Down Time 12 hours
Minimum Flow 0.043 cfs (=Discounted Design Volume divided by
Draw Down Time in seconds)
Capacity of 6"underdrain at 5% 0.470 cfs Therefore meets required capacity

Forebay Chamber
Elevation Pond Area Depth Total Incremental Total Cumulative
Volume Volume
678.00 1,108.23 N/A N/A N/A
679.00 1,564.03 1.0 1,336.13 1,336.13
680.00 2,086.00 1.0 1,825.02 3,161.15
Sand Filter Chamber _
Elevation Pond Area Depth Total Incremental Total Cumulative
Volume Volume
678.00 1,458.51 N/A N/A N/A
679.00 1,983.93 1.0 1,721.22 1,721.22
680.00 2,577.22 1.0 2,280.58 2,280.58
_ Total Combined Treatment Storage
Elevation Pond Area Depth Total Incremental Total Cumulative
Volume _ Volume
678.00 2,566.74 N/A N/A _ N/A
679.00 3,547.96 1.0 3,057.35 3,057.35
680.00 4,663.22 1.0 4,105.59 7,162.94
681.00 5,725.75 1.0 5,194.48 12,357.43
682.00 6,681.29 1.0 6,203.52 18,560.95

Post-Development Drainage Area 2
Land use Condition Hydrologic Area(SF) Area(Acres) Cn Weighted Cn
Soil Group
Woods good C - - 70 0.0
Open Space good C 433 0.010 74 3.5
Impervious N/A C - 98 0.0
Woods good B - 77 0.0
Open Space good B 8,682 0.199 80 76.2
Impervious N/A B 1 - 98 0.0
9,115 0.209 79.7
TC USED IN CALCULATION= 10.00 MIN MINIMUM TC OF 10 MINUTES

Post-Development Drainage Area 3
Land use Condition Hydrologic Area(SF) Area(Acres) Cn Weighted Cn
Soil Group
Woods good C - - 70 0.0
Open Space good C 9,441 0.217 74 32.0
Impervious N/A C - 98 0.0
Woods good B - - 77 0.0
Open Space good B 12,392 0.284 80 45.4
Impervious N/A B - 98 0.0
21,833 0.501 77.4
TC USED IN CALCULATION= 10.00 MIN MINIMUM TC OF 10 MINUTES

SF DS1 Daylight Engineering
JOB NO.: P0001 BY: GAK P.O.Box 1804
DATE: 8/23/2023 P.M: KWU Concord,NC 28026
REVISED: FLOATATION CALCULATIONS
Calculations Given Data Standard Footing Assumptions
Density of Concrete 150 Ibs/ft^3 1.Footing base to be 1 ft.wider than structure
Density of Water 62.4 Ibs/ft^3 on all sides.
Safety Factor(S.F.) 2
-Equations used:
Outlet Structure Weight, W(s)= (w+2t)^2*h-w^2*(h-t)x D(c)
where, w= outlet box inside dimension,ft.
Displaced Water Weight, W(w)= (w+2t)^2 x D(w)x h t= structure wall thickness,ft.
h= height of structure,ft.
Required Base Weight,W(b)= (W(w)x S.F.)-W(s) D(c)= density of concrete,lbs/ft^3
D(w)= density of water,lbs/ft^3
Required Footing Volume, V(t)= W(b)/Dc-Dw S.F.= safety factor
WDP i Outlet Structure
Structure Dimensions Object Weights
Elevation at bottom of structure= 674.53
Elevation at top of structure= 680.50
Height of structure,h= 5.97 ft. Outlet Structure Weight, W(s)= 4778 lbs
Structure wall thickness,t= 6 in. Displaced Water Weight, W(w)= 3353 lbs
Average outlet box inside dimension, w= 2 ft. Req'd Base Weight, W(b)= 1928 lbs
Footing Size An
Required Footing Volume, V(fr)= 22 cf Standard Footing Length,L= 6.00 ft.
Provided Footing Volume, V(fp)= 24 cf Standard Footing Width, W= 6.00 ft.
Footing Check okay Minimum Footing Depth, D= 1.00 ft.
[1=
Footing Size to be used: Length= 3.00 ft.MI
Width= 4.00 ft.
Depth= 2.00 ft.

Hydraflow Results

Watershed Model Schematic HydraflowHydrographsExtensionforAutodesk®Civil3D®byAutodesk, Inc.v2024
1 2 3 4
501
V
.,.
6
Legend
Hyd. Origin Description
1 SCS Runoff Pre DA-A(Outfall 98-W)
2 SCS Runoff Post DA-1
3 SCS Runoff Post DA-2
4 SCS Runoff Post DA-3
5 Reservoir Post DA-A>SF1
6 Combine Outfall 99-W
Project: Z:\XXXXX Smith Industrial Subdivision\2-Engineering\2-Calculations\7-Water QLalityaddadteptOialaczo6sortoo Smith Indu;

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 1
Pre DA-A (Outfall 98-W)
Hydrograph type = SCS Runoff Peak discharge = 4.132 cfs
Storm frequency = 1 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 10,909 cuft
Drainage area = 2.754 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = TR55 Time of conc. (Tc) = 10.80 min
Total precip. = 2.90 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Pre DA-A (Outfall 98-W)
Q (cfs) Hyd. No. 1 -- 1 Year Q (cfs)
5.00 5.00
•
4.00 4.00
3.00 I 3.00
2.00 2.00
1.00 1.00
........7........._
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 3
Post DA-2
Hydrograph type = SCS Runoff Peak discharge = 0.345 cfs
Storm frequency = 1 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 906 cuft
Drainage area = 0.209 ac Curve number = 79.7
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 2.90 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-2
Q (cfs) Hyd. No. 3 -- 1 Year Q (cfs)
0.50 0.50
0.45 0.45
0.40 0.40
0.35 0.35
0.30 0.30
0.25 0.25
0.20 0.20
0.15 - 0.15
0.10 0.10
0.05 0.05
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 3 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 4
Post DA-3
Hydrograph type = SCS Runoff Peak discharge = 0.726 cfs
Storm frequency = 1 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 1,921 cuft
Drainage area = 0.501 ac Curve number = 77.4
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 2.90 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-3
Q (cfs) Hyd. No. 4 -- 1 Year Q (cfs)
1.00 - 1.00
0.90 0.90
0.80 0.80
0.70 0.70
0.60 0.60
0.50 0.50
0.40 - 0.40
0.30 - 0.30
0.20 0.20
0.10 0.10
0.00 ` - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 1
Pre DA-A (Outfall 98-W)
Hydrograph type = SCS Runoff Peak discharge = 11.12 cfs
Storm frequency = 10 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 28,833 cuft
Drainage area = 2.754 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = TR55 Time of conc. (Tc) = 10.80 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Pre DA-A (Outfall 98-W)
Q (cfs) Hyd. No. 1 -- 10 Year Q (cfs)
12.00 - 12.00
10.00 - 10.00
8.00 - 8.00
6.00 I - 6.00
4.00 4.00
2.00 2.00
0.00 "el ,- 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 3
Post DA-2
Hydrograph type = SCS Runoff Peak discharge = 0.890 cfs
Storm frequency = 10 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 2,310 cuft
Drainage area = 0.209 ac Curve number = 79.7
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-2
Q (cfs) Hyd. No. 3 -- 10 Year Q (cfs)
1.00 - 1.00
0.90 0.90
0.80 0.80
0.70 0.70
0.60 0.60
0.50 0.50
0.40 - 0.40
0.30 - 0.30
0.20 0.20
0.10 _ 0.10
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 3 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 4
Post DA-3
Hydrograph type = SCS Runoff Peak discharge = 1.984 cfs
Storm frequency = 10 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 5,144 cuft
Drainage area = 0.501 ac Curve number = 77.4
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-3
Q (cfs) Hyd. No. 4 -- 10 Year Q (cfs)
2.00 - 2.00
1.00 - 1.00
0.00 - - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 1
Pre DA-A (Outfall 98-W)
Hydrograph type = SCS Runoff Peak discharge = 14.19 cfs
Storm frequency = 25 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 36,897 cuft
Drainage area = 2.754 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = TR55 Time of conc. (Tc) = 10.80 min
Total precip. = 6.00 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Pre DA-A (Outfall 98-W)
Q (cfs) Hyd. No. 1 -- 25 Year Q (cfs)
15.00 15.00
12.00 — • 12.00
9.00 9.00
6.00 6.00
3.00 — - - 3.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 2
Post DA-1
Hydrograph type = SCS Runoff Peak discharge = 12.57 cfs
Storm frequency = 25 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 33,477 cuft
Drainage area = 2.043 ac Curve number = 85.7
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 6.00 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-1
Q (cfs) Hyd. No. 2 -- 25 Year Q (cfs)
14.00 14.00
12.00 12.00
10.00 10.00
8.00 8.00
6.00 6.00
4.00 - 4.00
2.00 - — 2.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 3
Post DA-2
Hydrograph type = SCS Runoff Peak discharge = 1.125 cfs
Storm frequency = 25 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 2,934 cuft
Drainage area = 0.209 ac Curve number = 79.7
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 6.00 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-2
Q (cfs) Hyd. No. 3 -- 25 Year Q (cfs)
2.00 - 2.00
1.00 - 1.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 3 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 4
Post DA-3
Hydrograph type = SCS Runoff Peak discharge = 2.541 cfs
Storm frequency = 25 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 6,600 cuft
Drainage area = 0.501 ac Curve number = 77.4
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 6.00 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-3
Q (cfs) Hyd. No. 4 -- 25 Year Q (cfs)
3.00 - 3.00
2.00 2.00
1.00 1.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024
Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph
No. type flow interval Peak volume hyd(s) elevation strge used Description
(origin) (cfs) (min) (min) (cuft) (ft) (cuft)
1 SCS Runoff 19.75 2 720 51,779 Pre DA-A(Outfall 98-W)
2 SCS Runoff 16.71 2 720 45,193 Post DA-1
3 SCS Runoff 1.549 2 720 4,081 Post DA-2
4 SCS Runoff 3.549 2 720 9,291 Post DA-3
5 Reservoir 12.98 2 726 45,183 2 681.37 12,371 Post DA-A>SF1
6 Combine 17.70 2 722 58,556 3,4,5 Outfall 99-W
Z:\XXXXX Smith Industrial Subdivision\2-Engiri img2eTiokdul thtf FWater QuffiitychrreatifD33,tati8dr22OCZOR13000 Smith Industrial WC

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 1
Pre DA-A (Outfall 98-W)
Hydrograph type = SCS Runoff Peak discharge = 19.75 cfs
Storm frequency = 100 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 51,779 cuft
Drainage area = 2.754 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = TR55 Time of conc. (Tc) = 10.80 min
Total precip. = 7.60 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Pre DA-A (Outfall 98-W)
Q (cfs) Hyd. No. 1 -- 100 Year Q (cfs)
21.00 21.00
18.00 18.00
15.00 15.00
12.00 12.00
9.00 9.00
6.00 6.00
3.00 3.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 3
Post DA-2
Hydrograph type = SCS Runoff Peak discharge = 1.549 cfs
Storm frequency = 100 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 4,081 cuft
Drainage area = 0.209 ac Curve number = 79.7
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 7.60 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-2
Q (cfs) Hyd. No. 3-- 100 Year Q (cfs)
2.00 - 2.00
1.00 - 1.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 3 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Hyd. No. 4
Post DA-3
Hydrograph type = SCS Runoff Peak discharge = 3.549 cfs
Storm frequency = 100 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 9,291 cuft
Drainage area = 0.501 ac Curve number = 77.4
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 7.60 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post DA-3
Q (cfs) Hyd. No. 4 -- 100 Year Q (cfs)
4.00 - 4.00
3.00 3.00
2.00 - 2.00
1.00 1.00
0.00 — 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
— Hyd No. 4

Hydraflow Rainfall Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2024 Wednesday,08/23/2023
Return Intensity-Duration-Frequency Equation Coefficients(FHA)
Period
(Yrs) B D E (N/A)
1 62.1764 12.7000 0.8901
2 69.8703 13.1000 0.8658
3 0.0000 0.0000 0.0000
5 79.2597 14.6000 0.8369
10 88.2351 15.5000 0.8279
25 102.6072 16.5000 0.8217
50 114.8193 17.2000 0.8199
100 127.1596 17.8000 0.8186
File name:Concord IDF Curve.IDF
Intensity= B/(Tc + D)AE
Return Intensity Values(in/hr)
Period
(Yrs) 5 min 10 15 20 25 30 35 40 I 45 50 55 60
1 4.82 3.86 3.23 2.79 2.46 2.20 1.99 1.82 1.68 1.56 1.46 1.37
2 5.69 4.61 3.89 3.38 2.99 2.69 2.44 2.24 2.07 1.93 1.81 1.70
3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
5 6.57 5.43 4.65 4.08 3.65 3.30 3.02 2.79 2.59 2.42 2.27 2.15
10 7.24 6.04 5.21 4.59 4.12 3.74 3.43 3.17 2.95 2.77 2.60 2.46
25 8.25 6.95 6.03 5.34 4.80 4.38 4.02 3.73 3.48 3.26 3.07 2.91
50 9.04 7.65 6.66 5.92 5.34 4.87 4.49 4.16 3.88 3.65 3.44 3.25
100 9.83 8.36 7.30 6.50 5.87 5.36 4.94 4.59 4.29 4.03 3.80 3.60
Tc=time in minutes.Values may exceed 60.
200114.000 Pitts School Flex Park Final Engineering\2-Engineering\2-Calculations\4-Erosion Control\Concord PCP.pcp
Rainfall Precipitation Table (in)
Storm
Distribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr
SCS 24-hour 2.90 3.50 0.00 4.40 5.10 6.00 6.80 7.60
SCS 6-Hr 2.06 2.48 0.00 3.09 3.57 4.21 4.72 5.23
Huff-1st 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Custom 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Riprap

DESIGN OF RIPRAP OUTLET PROTECTION
User Input Data
Calculated Value
Reference Data
Designed By: GAK Date: 8/23/2023
Checked By: KWU
Company: Daylight Engineering
Project Name: Smith Industrial
Site Location (City/Town) Midland, NC
Culvert Id. FES-1
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe. If the tailwater depth is less
than half the outlet pipe diameter,it is classified minimum tailwater condition.
If it is greater than half the pipe diameter. it is classified ma.xiimun condition.
Pipes that outlet onto wide Hat areas with no defined channel are assumed
to have a mininnun tailwater condition unless reliable Hood stage elevations
show otherwise.
Outlet pipe diameter, Do (in.) 18
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 6.16 See 25 year Hydraulic Gradeline Calculation
results
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b.and determine d.0 riprap size and minimum apron length
(L,). The d;c size is the median stone size in a well-graded riprap apron.
Step 3. Determine apron width at the pipe outlet. the apron shape, and the
apron width at the outlet end from the same figure used in Step 2.

Minimum TW Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 0.4
Minimum apron length, La (ft.) 10
Apron width at pipe outlet (ft.) 4.5 4.5
Apron shape Trapezoidal
Apron width at outlet end (ft.) 12 2
Step 4. Determine the maximum stone diameter:
drrax 1.5 x d50
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 0.6 0
Step 5. Determine the apron thickness:
Apron thickness = 1.5 x d,,_, Use class B riprap
Minimum TW Maximum TW
Apron Thickness(ft.) 0.9 0
RIP RAP CLASS MINIMUM MIDRANGE MAXIMUM
A 2 IN (0.17 FT) 4 IN (0.33 FT) 6 IN (0.5 FT)
B 5 IN (0.42 FT) 8 IN (0.67 FT) 12 IN (1 FT)
1 5 I N (0.42 FT) 10 IN (0.83 FT) 17 I N (1.42 FT)
2 9 IN (0.75 FT) 14 IN (1.17 FT) 23 IN (1.92 FT)
Step 6. Fit the riprap apron to the site by iinking it level for the i iluniuin
length. La. from Figure 8.06a or Figure 8.06b. Extend the apron farther
downstream and along channel banks until stability is assured. Keep the
apron as straight as possible and align it with the flow of the receiving stream.
Make any necessary alignment bends near the pipe outlet so that the entrance
into the receiving stream is straight.
Some locations may require lining of the entire channel cross section to assure
stability.
It may be necessary to increase the size of riprap where protection of the
channel side slopes is necessary (Appendix 8.05). Where overfills exist at
pipe outlets or flows are excessive. a plunge pool should be considered. see
page 8.06.8.

3 0
Outlet kJ • Do + La 90 'i f.
pipe .: ;; liiiili:; . .-..
II
! „ff ...
diameter (Do) ` �1 ..:. .
a 80
T i water 0.5DoP-C)‘' ..I :: ... • • • . : : : 1 1st 44/#: ,.... / ,
i`I. . .'...
0
,,,,, s : „
.....
v 0 1. .. . .
. ...
... . . . . .. .
,,,,
•
,,,, • ,,. .: .
: :::,..
41 _ ++ .7 r.0.i1 .'ml� ,� 4a
1. . 14- I . .. 4 ' 3 . .:_�1. i.. ØiI�
30 i z\a ' . . .._..._.
, „„„......_ , ' . . . • • • t il It - orrilerif
.404
.• •
_, fa0r.v14
0 _.... /�, .,� �. l�,144111 Iv MI ill:• ,it N_
1 I�II'1� 1'�Ir• illy 2
Ott!Iiiirlicl ;:; ' 0�. ' ,,;//��i''i r iitt"iit"� fl
a ; _ d V• ` 'i 'sun" co
» At 4; • .aiI.ilA1ii1uo1mlrnn
-4. ..
i 1111111111.1111111110
3 5 10 20 50 100 200 500 1000
9.92 cfs 1 Discharge(ft3/sec)
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full,minimum tailwater condition(Tw<0.5 diameter).
Rev.12'93 8.06.3

DESIGN OF RIPRAP OUTLET PROTECTION
User Input Data
Calculated Value
Reference Data
Designed By: GAK Date: 8/23/2023
Checked By: KWU
Company: Daylight Engineering
Project Name: Smith Industrial
Site Location (City/Town) Midland, NC
Culvert Id. FES-99
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe. If the tailwater depth is less
than half the outlet pipe diameter,it is classified minimum tailwater condition.
If it is greater than half the pipe diameter. it is classified nnaximuun condition.
Pipes that outlet onto wide fiat areas with no defined channel are assumed
to have a minimum tailwater condition unless reliable flood stage elevations
show otherwise.
Outlet pipe diameter, Do (in.) 15
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 6.27 See 10 year Water Quality results
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b.and determine d;,,riprap size and minimum apron length
(La). The d;c size is the median stone size in a well-graded'wrap apron.
Step 3. Determine apron width at the pipe outlet. the apron shape. and the
apron width at the outlet end from the same figure used in Step 2.

Minimum TW Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 0.3
Minimum apron length, La (ft.) 8
Apron width at pipe outlet (ft.) 3.75 3.75
Apron shape Trapezoidal
Apron width at outlet end (ft.) 9 1
Step 4. Determine the maximum stone diameter:
dmax 1.5 x d50
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 0.45 0
Step 5. Determine the apron thickness:
Apron thickness = 1.5 x d Use class B riprap
Minimum TW Maximum TW
Apron Thickness(ft.) 0.675 0
RIP RAP CLASS MINIMUM MIDRANGE MAXIMUM
A 2 IN (0.17 FT) 4 IN (0.33 FT) 6 IN (0.5 FT)
B 5 IN (0.42 FT) 8 IN (0.67 FT) 12 IN (1 FT)
1 5 IN (0.42 FT) 10 IN (0.83 FT) 17 IN (1.42 FT)
2 9 IN (0.75 FT) 14 IN (1.17 FT) 23 IN (1.92 FT)
Step 6. Fit the riprap apron to the site by making it level for the minimum
length, La. from Figure 8.06a or Figure 8.06b. Extend the apron farther
downstream and along channel banks until stability is assured. Keep the
apron as straight as possible and align it with the flow of the receiving stream.
Make any necessary alignment bends near the pipe outlet so that the entrance
into the receiving stream is straight.
Some locations may require lining of the entire channel cross section to assure
stability.
It may be necessary to increase the size of riprap where protection of the
channel side slopes is necessary (Appendix S.05). Where overfalls exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8.

3 a
Outlet W • Do + La 90
pipe
diameter (DO) /i
--La e1 80 �,15J'
i 1►vater < 0.5Do ""r: krifr
ar !!
v 8�9 !-: . ! i 1 ♦♦// •
r inii I
S pompom
g f . . ... 1ti • I11111111
,,,:i, :::_ ,...",,,,,,,,,,
:-,_. .. ,
,:. ,.,. :
• ,
la=8 L4:1415,10:1
_Led'
3C, �■ nl NO 2 dam;�i ������' ._ � �l�'
1: . N1 MIII= ■1 / r.. 0 ' r�I ... , I11I11111I'"„PloirAri,
N'i
•/f 11 1120± /■I i r �/• II I I fa�i�I.Ii1�Il3
t.
} ___ : . goo,,.
j ti.._w «. IiiIIY , Apir
10 -....L.:,IIII is ---
�;01 III Y Y ._......_.. ... _ ' .
�r 'Urn
T'
,• 1i1r"H!
t .... •i. ..;.....I'� O _" � 0I" 1 2"' . ,1 ��I■m••- .� _� /I � .. .P:aLI � 111 IIIII Inl n
. �-, t,,t , Blum gm • , ,, ,,V - dll'd 1 11II 1111f111111V
..... .. .........._l i. larI Ill . .; •�, P .IIIIIII IIIi
11111111111IIIIIIIIIIMIIIium I 1 �
• v= 15 : : /r I�� .I��r •. :. :: d50=0.30 .::.
J
3 5 10 20 50 100 200 500 1000
6.27 cfs Discharge(ft3/sec)
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full,minimum tailwater condition(T,.,<0.5 diameter)
Rev.12 93 8.06.3

Appendix

Table 4: HSGs for North Carolina Soil Types *
Urban areas runoff curve numbers fro SCS method (SCS 1986)
Cover Description Curve Number by HSG
A B f C D
Fully developed urban areas
Open Space (lawns, parks,golf courses, etc.)
Poor Condition (<50%Grass Cover) 68 79 86 89
Fair Condition (50%to 75%Grass Cover) 49 69 79 84
Good Condition (>75%Grass Cover) 39 61 74 80
Impervious areas:
Paved parking lots, roofs, driveways, etc.) 98 98 98 98
Streets and roads:
Paved; curbs and storm sewers 98 98 98 98
Paved; open ditches 83 89 98 98
Gravel 76 85 89 91
Dirt 72 82 85 88
Developing Urban Areas
Newly graded areas 77 86 91 94
_ Pasture (<50%ground cover or heavily grazed) 68 79 86 89
_ Pasture (50%to 75%ground cover or not heavily grazed) 49 69 79 84
_ Pasture (>75%ground cover or lightly) 39 61 74 80
Meadow-continuous grass, protected from grazing and
generally mowed for hay 30 58 71 78
_ Brush (<50%ground cover) 48 67 77 83
Brush (50%to 75% ground cover) 35 56 70 77
Brush (>75%ground cover) 30 48 65 73
Woods (forest liter,small trees, and brush destroyed by heavy
grazing or regular burning 45 66 77 83
Woods (Woods are grazed but not burned, and some forrest
litter covers the soil) 36 60 73 79
Woods (Woods are protected from grazing, and litter and brush
adequately cover the soil) 30 55 70 77
*Table taken from NCDEQ Sormwater Design Manual Part B: Calculations Guidance, revised 3/5/2017

DAYLIGHT
ENGINEERING
HGLE Calculations
For
Smith Industrial Subdivision
12400 Old Camden Road
Midland, NC 28107
Project No: P0001
Client: Robert J. Parks
Client Representitive: Billy Smith
12450 Grey Commercial Road
Midland, NC 28107
P: 704.361.4253
[e-mail]
Preparer's Name: Kate Underwood, PhD, PE
\owlI
Daylight Engineering PLLC \.\ C i 0�///''
NCBELS Corporate License Number P-2772 2�%%%% /1/%
57 Union Street South = SEAL
Concord, NC 28025 v 08 23/20223 o f
980.234.7500 ; y '•,HGINE,
[e-mail] '�,,, WI i 1U\vv\\\`\

Hydraflow Storm Sewers Extension for Autodesk® Civil 3D® Plan
Outfall
1
CB 3
2
3
CB 4
4
DCB 6
Project File: 200664.000 Smith Industrial HGLE v2.stm Number of lines:4 Date:7/28/2023
Storm Sewers v2021.00

Storm Sewer Tabulation Pagel
Station Len Drng Area Rnoff Area x C Tc Rain Total Cap Vel Pipe Invert Elev HGL Elev Grnd/Rim Elev Line ID
coeff (I) flow full
Line To Incr Total Incr Total Inlet Syst Size Slope Dn Up Dn Up Dn Up
Line
(ft) (ac) (ac) (C) (min) (min) (in/hr) (cfs) (cfs) (ft/s) (in) (%) (ft) (ft) (ft) (ft) (ft) (ft)
4 1 141.210 0.45 0.45 0.95 0.43 0.43 5.0 5.0 8.2 3.53 5.57 4.67 15 0.74 684.22 685.27 684.94 686.03 690.68 688.77 DCB 6>CB 2
3 2 37.016 0.14 0.14 0.95 0.13 0.13 5.0 5.0 8.2 1.10 6.54 3.53 15 1.03 688.56 688.94 688.91 689.35 692.24 692.23 CB 4>CB 3
2 1 122.866 0.15 0.29 0.95 0.14 0.28 5.0 5.7 8.0 2.21 11.70 5.59 15 3.28 684.22 688.25 684.59 688.84 690.68 692.24 CB 3>CB 2
1 End 131.904 0.10 0.84 0.95 0.10 0.80 5.0 6.8 7.7 6.16 15.60 5.16 18 2.21 680.44 683.35 681.40 684.31 682.23 690.68 CB 2>FES 1
Project File: 200664.000 Smith Industrial HGLE v2.stm Number of lines:4 Run Date: 7/28/2023
NOTES:Intensity=102.61 /(Inlet time+ 16.50)A 0.82; Return period=Yrs.25 ; c=cir e=ellip b=box
Storm Sewers v2021.00

Inlet Report Page 1
Line Inlet ID Q= Q Q Q Junc Curb Inlet Grate Inlet Gutter Inlet Byp
No CIA carry capt Byp Type Line
Ht L Area L W So W Sw Sx n Depth Spread Depth Spread Depr No
(cfs) (cfs) (cfs) (cfs) (in) (ft) (sqft) (ft) (ft) (ft/ft) (ft) (ft/ft) (ft/ft) (ft) (ft) (ft) (ft) (in)
4 DCB 6 3.53 0.00 3.53 0.00 Comb 4.0 2.00 12.00 2.00 6.00 Sag 2.00 0.050 0.020 0.000 0.24 9.09 0.24 9.09 0.0 Off
3 CB 4 1.10 0.00 1.10 0.00 Comb 4.0 3.00 6.00 3.00 2.00 Sag 2.00 0.050 0.020 0.000 0.19 6.49 0.19 6.49 0.0 Off
2 CB 3 1.18 0.00 1.18 0.00 Comb 4.0 3.00 6.00 3.00 2.00 Sag 2.00 0.050 0.020 0.000 0.20 6.82 0.20 6.82 0.0 Off
1 CB 2 0.78 0.00 0.78 0.00 Comb 4.0 3.00 6.00 3.00 2.00 Sag 2.00 0.050 0.020 0.000 0.16 5.09 0.16 5.09 0.0 Off
Project File: 200664.000 Smith Industrial HGLE v2.stm Number of lines:4 Run Date: 7/28/2023
NOTES: Inlet N-Values=0.016; Intensity= 102.61 /(Inlet time+16.50)A 0.82; Return period=25 Yrs. ; *Indicates Known Q added.All curb inlets are throat.
Storm Sewers v2021.00

Storm Sewer Profile Proj. file: 200664.000 Smith Industrial HGLE v2.stm
as
4-
5 5
M -J OE -J O
O — . co Lo CV
O O OC'7N M �N
O co O O) co V LC)
co
Elev. (ft) g w 2 M CO g co 2
+O -p W ,— iI N L.T. W
(6 ,E j c6 E j j co E j
co 0 E co ESE co ES
702.00 702.00
697.00 • • • • 697.00
692.00 692.00
687.00 [-687.00
ID.
682.00 682.00
13 .904Lf-18'
677.00 I I 677.00
0 25 50 75 100 125 150 175 200 225 250 275
HGL EGL Reach (ft)
Storm Sewers

Storm Sewer Profile Proj. file: 200664.000 Smith Industrial HGLE v2.stm
f6 — N CO
w-
C 5 5 C C 5
M J p C J OE J O
' co up CV
0)
O O . . . co N N co N .
O <0 0 0) H M V N- N W W I� o W
Elev. (ft) g w . M (0.g coo N.; (O
+O -6 W wWW N wWW N L.T.
(6 E j co j j co j j 6 E j
co 0 C co E C C co E C C co ES
706.00 706.00
700.00 700.00
694.00 —694.00
s
688.00 ___ - —688.00
. @328%
6Lf
37.016Lf-15"@ 1.03%
682.00 18" @ ° 682.00
•
676.00 I 676.00
0 25 50 75 100 125 150 175 200 225 250 275 300
HGL EGL Reach (ft)
Storm Sewers

Inlet Section (Line 1 - Combination Inlet) - CB 2 Page 1of1
All dimensions in feet
Line 1 - Combination Inlet in Sag - CE 2
.0..0...,___,...,,.,....,---0-1d'-'s- --. 17-.1_ .-
Q Inlet Gutter Depth Spread Byp
Line#
Catch Carry Capt Byp Length Depr Throat Width Slope Sw Sx Gutter Inlet Gutter Inlet Line
(cfs) (cfs) (cfs) (cfs) (ft) (in) (in) (ft) (ft/ft) (ft/ft) (ft/ft) (ft) (ft) (ft) (ft) (ft)
1 0.78 0.00 0.78 0.00 3.00 0.0 4.0 2.00 Sag 0.050 0.020 0.16 5.09 n/a n/a Sag
Project File: No. Lines. 4 Run Date: 7/28/2023
Storm Sewers

Inlet Section (Line 2 - Combination Inlet) - CB 3 Page 1of1
All dimensions in feet Line 2 - Combination Inlet in Sag - CB
/00_
_p,-0- ------ -- 00#:,:::117
0.2
4.82
ik
Q Inlet Gutter Depth Spread Byp
Line#
Catch Carry Capt Byp Length Depr Throat Width Slope Sw Sx Gutter Inlet Gutter Inlet Line
(cfs) (cfs) (cfs) (cfs) (ft) (in) (in) (ft) (ft/ft) (ft/ft) (ft/ft) (ft) (ft) (ft) (ft) (ft)
2 1.18 0.00 1.18 0.00 3.00 0.0 4.0 2.00 Sag 0.050 0.020 0.20 6.82 n/a n/a Sag
Project File: No. Lines: 4 Run Date: 7/28/2023
Storm Sewers

Inlet Section (Line 3 - Combination Inlet) - CB 4 Page 1of1
All dimensions in feet
Line - Combination Inlet in Sag - CB
lr
0.19
2 r 4.49 ,iii44\\
Q Inlet Gutter Depth Spread Byp
Line#
Catch Carry Capt Byp Length Depr Throat Width Slope Sw Sx Gutter Inlet Gutter Inlet Line
(cfs) (cfs) (cfs) (cfs) (ft) (in) (in) (ft) (ft/ft) (ft/ft) (ft/ft) (ft) (ft) (ft) (ft) (ft)
3 1.10 0.00 1.10 0.00 3.00 0.0 4.0 2.00 Sag 0.050 0.020 0.19 6.49 n/a n/a Sag
Project File: No. Lines. 4 Run Date: 7/28/2023
Storm Sewers

Inlet Section (Line 4 - Combination Inlet) - DCB 6 Page 1of1
All dimensions in feet Line 4 - Combination Inlet in Sag - DCB 6
—,------------l_---------'s--} ,. ,
Q Inlet Gutter Depth Spread Byp
Line#
Catch Carry Capt Byp Length Depr Throat Width Slope Sw Sx Gutter Inlet Gutter Inlet Line
(cfs) (cfs) (cfs) (cfs) (ft) (in) (in) (ft) (ft/ft) (ft/ft) (ft/ft) (ft) (ft) (ft) (ft) (ft)
4 3.53 0.00 3.53 0.00 2.00 0.0 4.0 2.00 Sag 0.050 0.020 0.24 9.09 n/a n/a Sag
Project File: No. Lines: 4 Run Date: 7/28/2023
Storm Sewers

31
Hydraflow Rainfall Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2021 Friday,07/28/2023
Return Intensity-Duration-Frequency Equation Coefficients(FHA)
Period
(Yrs) B D E (N/A)
1 62.1764 12.7000 0.8901
2 69.8703 13.1000 0.8658
3 0.0000 0.0000 0.0000
5 79.2597 14.6000 0.8369
10 88.2351 15.5000 0.8279
25 102.6072 16.5000 0.8217
50 114.8193 17.2000 0.8199
100 127.1596 17.8000 0.8186
File name:Concord IDF Curve.IDF
Intensity= B/(Tc+ D)^E
Return Intensity Values(in/hr)
Period
(Yrs) 5 min 10 15 20 25 30 35 40 45 50 55 60
1 4.82 3.86 3.23 2.79 2.46 2.20 1.99 1.82 1.68 1.56 1.46 1.37
2 5.69 4.61 3.89 3.38 2.99 2.69 2.44 2.24 2.07 1.93 1.81 1.70
3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
5 6.57 5.43 4.65 4.08 3.65 3.30 3.02 2.79 2.59 2.42 2.27 2.15
10 7.24 6.04 5.21 4.59 4.12 3.74 3.43 3.17 2.95 2.77 2.60 2.46
25 8.25 6.95 6.03 5.34 4.80 4.38 4.02 3.73 3.48 3.26 3.07 2.91
50 9.04 7.65 6.66 5.92 5.34 4.87 4.49 4.16 3.88 3.65 3.44 3.25
100 9.83 8.36 7.30 6.50 5.87 5.36 4.94 4.59 4.29 4.03 3.80 3.60
Tc=time in minutes.Values may exceed 60.
200114.000 Pitts School Flex Park Final Engineering\2-Engineering\2-Calculations\4-Erosion Control\Concord PCP.pcp
Rainfall Precipitation Table (in)
Storm
Distribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr
SCS 24-hour 2.90 3.50 0.00 4.40 5.10 6.00 6.80 7.60
SCS 6-Hr 2.06 2.48 0.00 3.09 3.57 4.21 4.72 5.23
Huff-1st 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Custom 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

RIPRAP

DESIGN OF RIPRAP OUTLET PROTECTION
User Input Data
Calculated Value
Reference Data
Designed By: GAK Date: 8/23/2023
Checked By: KWU
Company: Daylight Engineering
Project Name: Smith Industrial
Site Location (City/Town) Midland, NC
Culvert Id. FES-1
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe. If the tailwater depth is less
than half the outlet pipe diameter,it is classified minimum tailwater condition.
If it is greater than half the pipe diameter. it is classified ma.xiimun condition.
Pipes that outlet onto wide Hat areas with no defined channel are assumed
to have a mininnun tailwater condition unless reliable Hood stage elevations
show otherwise.
Outlet pipe diameter, Do (in.) 18
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 6.16 See 25 year Hydraulic Gradeline Calculation
results
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b.and determine d.0 riprap size and minimum apron length
(L,). The d;c size is the median stone size in a well-graded riprap apron.
Step 3. Determine apron width at the pipe outlet. the apron shape, and the
apron width at the outlet end from the same figure used in Step 2.

Minimum TW Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 0.4
Minimum apron length, La (ft.) 10
Apron width at pipe outlet (ft.) 4.5 4.5
Apron shape Trapezoidal
Apron width at outlet end (ft.) 12 2
Step 4. Determine the maximum stone diameter:
drrax 1.5 x d50
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 0.6 0
Step 5. Determine the apron thickness:
Apron thickness = 1.5 x d,,_, Use class B riprap
Minimum TW Maximum TW
Apron Thickness(ft.) 0.9 0
RIP RAP CLASS MINIMUM MIDRANGE MAXIMUM
A 2 IN (0.17 FT) 4 IN (0.33 FT) 6 IN (0.5 FT)
B 5 IN (0.42 FT) 8 IN (0.67 FT) 12 IN (1 FT)
1 5 I N (0.42 FT) 10 IN (0.83 FT) 17 I N (1.42 FT)
2 9 IN (0.75 FT) 14 IN (1.17 FT) 23 IN (1.92 FT)
Step 6. Fit the riprap apron to the site by iinking it level for the i iluniuin
length. La. from Figure 8.06a or Figure 8.06b. Extend the apron farther
downstream and along channel banks until stability is assured. Keep the
apron as straight as possible and align it with the flow of the receiving stream.
Make any necessary alignment bends near the pipe outlet so that the entrance
into the receiving stream is straight.
Some locations may require lining of the entire channel cross section to assure
stability.
It may be necessary to increase the size of riprap where protection of the
channel side slopes is necessary (Appendix 8.05). Where overfills exist at
pipe outlets or flows are excessive. a plunge pool should be considered. see
page 8.06.8.

3 0
Outlet kJ • Do + La 90 'i f.
pipe .: ;; liiiili:; . .-..
II
! „ff ...
diameter (Do) ` �1 ..:. .
a 80
T i water 0.5DoP-C)‘' ..I :: ... • • • . : : : 1 1st 44/#: ,.... / ,
i`I. . .'...
0
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3 5 10 20 50 100 200 500 1000
9.92 cfs 1 Discharge(ft3/sec)
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full,minimum tailwater condition(Tw<0.5 diameter).
Rev.12'93 8.06.3