SW6240705_Design Calculations_20241029

Harnett County Northwest Convenience Center I Stormwater Permit Application—October 2024 r)�
Attachment C—Precipitation
Frequency Data
C
Attachment C —
Precipitation Frequency
Data

Harnett County Northwest Convenience Center I Stormwater Permit Application—October 2024 r)�
Attachment C—Precipitation
Frequency Data
This page intentionally left blank.

Point precipitation frequency estimates(inches)
NOAA Atlas 14 Volume 2 Version 3
Data type: Precipitation depth
Time series type: Partial duration
Project area: Ohio River Basin
Location n< North Carr USA
Station Name: DUNN 4 NW
Latitude: 35.3247°
Longitude:-78.6881°
Elevation (USGS):200 ft
PRECIPITATION FREQUENCY ESTIMATES
by duratior 1 2 5 10 25 50 100 200 500 1000
5-min: 0.437 0.513 0.594 0.659 0.734 0.791 0.844 0.894 0.954 1.01
10-min: 0.697 0.821 0.951 1.06 1.17 1.26 1.34 1.42 1.51 1.58
15-min: 0.872 1.03 1.2 1.33 1.48 1.59 1.7 1.79 1.9 1.99
30-min: 1.2 1.43 1.71 1.93 2.2 2.4 2.6 2.78 3.02 3.22
60-min: 1.49 1.79 2.19 2.52 2.93 3.25 3.58 3.9 4.34 4.69
2-hr: 1.75 2.12 2.63 3.06 3.63 4.09 4.56 5.06 5.72 6.29
3-hr: 1.86 2.25 2.81 3.29 3.94 4.49 5.07 5.68 6.53 7.28
6-hr: 2.22 2.68 3.35 3.94 4.73 5.41 6.13 6.89 7.97 8.91
12-hr: 2.61 3.15 3.96 4.68 5.67 6.52 7.42 8.41 9.82 11.1
24-hr: 3.05 3.7 4.74 5.58 6.75 7.72 8.73 9.8 11.3 12.5
2-day: 3.57 4.32 5.49 6.42 7.73 8.81 9.93 11.1 12.8 14.2
3-day: 3.8 4.59 5.79 6.76 8.1 9.19 10.3 11.5 13.2 14.6
4-day: 4.03 4.86 6.1 7.09 8.47 9.58 10.7 12 13.7 15.1
7-day: 4.67 5.6 6.95 8.02 9.49 10.7 11.9 13.2 15 16.4
10-day: 5.33 6.38 7.78 8.87 10.4 11.5 12.7 14 15.6 17
20-day: 7.18 8.53 10.2 11.6 13.4 14.8 16.2 17.7 19.7 21.3
30-day: 8.95 10.6 12.5 13.9 15.9 17.3 18.8 20.3 22.3 23.8
45-day: 11.4 13.4 15.5 17.2 19.3 20.9 22.5 24.1 26.2 27.8
60-day: 13.6 16 18.4 20.2 22.5 24.3 26 27.7 29.9 31.6
Date/time(GMT): Thu May 30 12:52:27 2019
pyRunTime: 0.0106019973755

Harnett County Northwest Convenience Center I Stormwater Permit Application—October 2024 r)�
Attachment C—Precipitation
Frequency Data
This page intentionally left blank.

Harnett County Northwest Convenience Center I Stormwater Permit Application—October 2024 r)�
Attachment D—Stormwater Flow
D
Aachment D —
Stormwatett r Flow

Harnett County Northwest Convenience Center I Stormwater Permit Application—October 2024 r)�
Attachment D—Stormwater Flow
This page intentionally left blank.

Harnett County Solid Waste Department I Stormwater Permit Application—October 2024 r)�
Attachment D.1 —Pre-Development Calculations
D . 1
Attachment D. 1 — Pre-
Development Calculations

Harnett County Solid Waste Department I Stormwater Permit Application—October 2024 r)�
Attachment D.1 —Pre-Development Calculations
This page intentionally left blank.

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CHANNELS IN DRAWS AND INTO ADVENT CREEK N
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NOTES:
�, 25‘/))),\))
i� 255605280 i /re 1. EXISTING TOPOGRAPHY AND PROPERTY LINES OBTAINED FROM
2Sp275 ' / HARNETT COUNTY GIS.
250 ya 270 /`ti° 330 2. PROPERTY BOUNDARY SURVEY COMPLETED BY BENTON W.
g5 .� t // DEWARE AND ASSOCIATES,APRIL 30,2019.
N ryyy ryN°,yby,�y0 25y Z6 25`— ` ,210��,1-g0 2854. 32S i 3. CONDITIONAL USE PERMIT#BA-CU-18-18 APPROVED 6/11/18.
0 Harnett
PROJECT MANAGER J.MURRAY,PE H a Y n ett
'q HDREngineering,Inc.oftheCarolinas PROJECT ENGINEER A.MCGREW,PE -m 0 U N T Y HYDROCAD MODEL
EXISTING CONDITIONS
DRAWN BY A.MCGREW,PE ` -
§
N.C.B.E.L.S.License Number:F-0116 NORTH CAROLINA KEY
strong roots new growth
Q Rae gheNte2760treet,Suite900 C 05/2024 ISSUED FOR BIDDING HARNETT COUNTY
II F)/ 919.232.6600 B 01/2023 REVISED BASED ON REVIEWER COMMENTS NORTHWEST CONVENIENCE CENTER 0 1" 2" FILENAME OOG-02 dwg SHEET
A 10/2022 ISSUED FOR PERMITTING OOG-01
ISSUE DATE DESCRIPTION PROJECT NUMBER 10354679 HARNETT COUNTY NORTH CAROLINA SCALE 1"=75'

4 D DO
Area 4 NCDOT Load Ditch
0
C B1
Existing ulvert
Area 1
0
2 D4
D1
Area 2 Arla 3 Di Next to Road
D w
D2 D3
D5 Draw Dr w
Draw
D6
D7 Draw
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4ubca) Reach 'On• MI Routing Diagram for 20221019_Harnett County_NW CC_Existing Conditions
Prepared by HDR, Inc, Printed 10/19/2022
HydroCAD®10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC

20221019_Harnett County_NW CC_Existing Conditions
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 2
Area Listing (all nodes)
Area CN Description
(acres) (subcatchment-numbers)
15.192 61 >75% Grass cover, Good, HSG B (1, 2, 4)
11.258 55 Woods, Good, HSG B (1, 2, 3)
26.450 58 TOTAL AREA

20221019_Harnett County_NW CC_Existing Conditions
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 3
Soil Listing (all nodes)
Area Soil Subcatchment
(acres) Group Numbers
0.000 HSG A
26.450 HSG B 1, 2, 3, 4
0.000 HSG C
0.000 HSG D
0.000 Other
26.450 TOTAL AREA

20221019_Harnett County_NW CC_Existing Conditions
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 4
Ground Covers (all nodes)
HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment
(acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers
0.000 15.192 0.000 0.000 0.000 15.192 >75% Grass cover, Good 1, 2, 4
0.000 11.258 0.000 0.000 0.000 11.258 Woods, Good 1, 2, 3
0.000 26.450 0.000 0.000 0.000 26.450 TOTAL AREA

20221019_Harnett County_NW CC_Existing Conditions
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 5
Pipe Listing (all nodes)
Line# Node In-Invert Out-Invert Length Slope n Diam/Width Height Inside-Fill
Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches)
1 C 1 354.50 351.00 137.0 0.0255 0.012 12.0 0.0 0.0

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 6
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1: Area 1 Runoff Area=11.609 ac 0.00% Impervious Runoff Depth>0.24"
Flow Length=1,164' Tc=28.9 min CN=58 Runoff=1.39 cfs 0.230 af
Subcatchment 2: Area 2 Runoff Area=5.131 ac 0.00% Impervious Runoff Depth>0.21"
Flow Length=700' Tc=22.2 min CN=57 Runoff=0.59 cfs 0.091 af
Subcatchment 3: Area 3 Runoff Area=1.231 ac 0.00% Impervious Runoff Depth>0.17"
Flow Length=326' Tc=22.4 min CN=55 Runoff=0.08 cfs 0.017 af
Subcatchment 4: Area 4 Runoff Area=8.479 ac 0.00% Impervious Runoff Depth>0.33"
Flow Length=606' Tc=13.1 min CN=61 Runoff=2.92 cfs 0.231 af
Reach DO: NCDOT Road Ditch Avg. Flow Depth=0.42' Max Vel=2.10 fps Inflow=2.92 cfs 0.231 af
n=0.035 L=1,130.0' S=0.0146 '/' Capacity=201.86 cfs Outflow=2.01 cfs 0.226 af
Reach D1: Draw Avg. Flow Depth=0.12' Max Vel=0.22 fps Inflow=1.39 cfs 0.230 af
n=0.400 L=500.0' S=0.0620 '/' Capacity=252.99 cfs Outflow=0.76 cfs 0.206 af
Reach D2: Draw Avg. Flow Depth=0.10' Max Vel=0.24 fps Inflow=0.59 cfs 0.091 af
n=0.400 L=430.0' S=0.0977 '/' Capacity=211.86 cfs Outflow=0.33 cfs 0.084 af
Reach D3: Draw Avg. Flow Depth=0.02' Max Vel=0.14 fps Inflow=0.08 cfs 0.017 af
n=0.400 L=228.0' S=0.1667 '/' Capacity=432.67 cfs Outflow=0.05 cfs 0.016 af
Reach D4: Ditch Next to Road Avg. Flow Depth=0.54' Max Vel=0.53 fps Inflow=2.01 cfs 0.226 af
n=0.400 L=500.0' S=0.0720 '/' Capacity=49.87 cfs Outflow=1.31 cfs 0.216 af
Reach D5: Draw Avg. Flow Depth=0.22' Max Vel=0.29 fps Inflow=1.05 cfs 0.290 af
n=0.400 L=982.0' S=0.0570 '/' Capacity=120.90 cfs Outflow=0.73 cfs 0.237 af
Reach D6: Draw Avg. Flow Depth=0.10' Max Vel=0.18 fps Inflow=1.35 cfs 0.232 af
n=0.400 L=1,720.0' S=0.0500 '/' Capacity=198.54 cfs Outflow=0.38 cfs 0.119 af
Reach D7: Outfall to Avent Creek Avg. Flow Depth=0.20' Max Vel=0.24 fps Inflow=0.90 cfs 0.356 af
n=0.400 L=130.0' S=0.0385 '/' Capacity=132.42 cfs Outflow=0.90 cfs 0.339 af
Pond C 1: Existing Culvert Peak Elev=355.29' Inflow=2.01 cfs 0.226 af
Primary=2.01 cfs 0.226 af Secondary=0.00 cfs 0.000 af Outflow=2.01 cfs 0.226 af
Total Runoff Area = 26.450 ac Runoff Volume = 0.570 af Average Runoff Depth = 0.26"
100.00% Pervious = 26.450 ac 0.00% Impervious = 0.000 ac

20221019_Harnett County_NW CC_Existing Conditions Type II 24-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment 1: Area 1
Runoff = 1.39 cfs @ 12.35 hrs, Volume= 0.230 af, Depth> 0.24"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1y 24h Rainfall=3.05"
Area (ac) CN Description
5.230 61 >75% Grass cover, Good, HSG B
6.379 55 Woods, Good, HSG B
11.609 58 Weighted Average
11.609 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
13.3 100 0.0200 0.13 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.70"
15.6 1,064 0.0520 1.14 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
28.9 1,164 Total
Subcatchment 1: Area 1
Hydrograph
D Runoff
1 1.39 cfs I
j Type 1124-h r
_ 0 ly 24h Rainfall=3.05"
Runoff Area=11.609 ac
'" lillir Runoff Volume=0.230 af
0 Runoff Depth>0.24"
LL �j Flow Length=1,164'
/% Tc=28.9 min
�� CN=58
i x
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type II 24-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 2: Area 2
Runoff = 0.59 cfs @ 12.26 hrs, Volume= 0.091 af, Depth> 0.21"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1y 24h Rainfall=3.05"
Area (ac) CN Description
1.483 61 >75% Grass cover, Good, HSG B
3.648 55 Woods, Good, HSG B
5.131 57 Weighted Average
5.131 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
13.1 600 0.0233 0.76 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.2 700 Total
Subcatchment 2: Area 2
Hydrograph
0.65- 1 1 Runoff
l 0.59 cfs l
0°5- : '
244h r
..._....24h Rain'faIi 3.05"___.
11
0.45
Runoff Area=5. 131..ac...
Runoff''':Volume=0.091 of
0.35 Runoff Depth>0.21"
LL 0.3 Flow Length=700'
�
/�_.... ..... To22.2_.min__.
0.2
1111 N--
7......
0.05-
0-/ A
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type II 24-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment 3: Area 3
Runoff = 0.08 cfs @ 12.29 hrs, Volume= 0.017 af, Depth> 0.17"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1y 24h Rainfall=3.05"
Area (ac) CN Description
1.231 55 Woods, Good, HSG B
1.231 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.0 100 0.0200 0.08 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.70"
2.4 226 0.0973 1.56 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.4 326 Total
Subcatchment 3: Area 3
Hydrograph
0.09_ ........ ■Runoff
0.085= .os
I
0 fs
0.08 i
;.. r
Type
0.075
ly 24h RainfaN=3.05" _.
0.07
0.065 i / Runoff Area=1 .231 ac.........
Runoff folume—O q.1. ..af..
0.055
Runoff_ Depth>0.17"
0.05=
•
3 0.045 ......................:........................................._......................... 2��
LL 0.04_ Flow Length=3
0.035
i -�- ;_Tc 224
0.03
0.025 I I __ ' CN=6S........
0.015
0.005
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type II 24-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment 4: Area 4
Runoff = 2.92 cfs @ 12.09 hrs, Volume= 0.231 af, Depth> 0.33"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 1y 24h Rainfall=3.05"
Area (ac) CN Description
8.479 61 >75% Grass cover, Good, HSG B
8.479 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
4.0 506 0.0198 2.11 Shallow Concentrated Flow,
Grassed Waterway Kv= 15.0 fps
13.1 606 Total
Subcatchment 4: Area 4
Hydrograph
.................................................... ❑Runoff
3 12.92 cfs i ::
Type 1124-h r
ly 24h Rainfall=3.05"
Runoff Area=8.479 ac
2- Runoff Volume=02311af_._..
Runoff Depth>0.33"
2 Flow Length=6Q6'
T 1 c� 3�1 min
1- I� cN=61
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 11
Summary for Reach DO: NCDOT Road Ditch
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 0.33" for 1y 24h event
Inflow = 2.92 cfs @ 12.09 hrs, Volume= 0.231 af
Outflow = 2.01 cfs @ 12.35 hrs, Volume= 0.226 af, Atten= 31%, Lag= 15.4 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 2.10 fps, Min. Travel Time= 9.0 min
Avg. Velocity= 1.20 fps, Avg. Travel Time= 15.7 min
Peak Storage= 1,084 cf @ 12.20 hrs
Average Depth at Peak Storage= 0.42'
Bank-Full Depth= 3.00' Flow Area= 30.0 sf, Capacity= 201.86 cfs
1.00' x 3.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.0 '/' Top Width= 19.00'
Length= 1,130.0' Slope= 0.0146 '/'
Inlet Invert= 372.00', Outlet Invert= 355.50'
Reach DO: NCDOT Road Ditch
Hydrograph
❑Inflow
; i
Izsz.ts ❑Outflo w
Inflow Area=8.479 ac
Avg. Flow Depth=0.42'
Max Vel=2.10 fps
1201. fs n=0.035
2—
L=1130.0'
LL _ 1 1 S=0.0146 '/'
iLitY2o1M6cft
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 12
Summary for Reach D1: Draw
Inflow Area = 11.609 ac, 0.00% Impervious, Inflow Depth > 0.24" for 1y 24h event
Inflow = 1.39 cfs @ 12.35 hrs, Volume= 0.230 af
Outflow = 0.76 cfs @ 13.47 hrs, Volume= 0.206 af, Atten= 45%, Lag= 67.2 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.22 fps, Min. Travel Time= 38.1 min
Avg. Velocity= 0.15 fps, Avg. Travel Time= 54.4 min
Peak Storage= 1,745 cf @ 12.84 hrs
Average Depth at Peak Storage= 0.12'
Bank-Full Depth= 3.00' Flow Area= 174.0 sf, Capacity= 252.99 cfs
28.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 10.0 '/' Top Width= 88.00'
Length= 500.0' Slope= 0.0620 '/'
Inlet Invert= 316.00', Outlet Invert= 285.00'
Reach D1: Draw
Hydrograph
/ ❑Inflow
I1.39cfs ❑Outflow
Inflow Area=11 .609 ac
Avg. Flow Depth=0.12'
Ad Max Vel 0.22 fps
n=0.400
1076cfs , L=500.0'
S=0.0620 '/'
��,��j < •acity=252.99 cfs
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 13
Summary for Reach D2: Draw
Inflow Area = 5.131 ac, 0.00% Impervious, Inflow Depth > 0.21" for 1y 24h event
Inflow = 0.59 cfs @ 12.26 hrs, Volume= 0.091 af
Outflow = 0.33 cfs @ 13.15 hrs, Volume= 0.084 af, Atten= 44%, Lag= 53.7 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.24 fps, Min. Travel Time= 29.3 min
Avg. Velocity= 0.17 fps, Avg. Travel Time= 42.1 min
Peak Storage= 576 cf @ 12.66 hrs
Average Depth at Peak Storage= 0.10'
Bank-Full Depth= 3.00' Flow Area= 126.0 sf, Capacity= 211.86 cfs
12.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 10.0 '/' Top Width= 72.00'
Length= 430.0' Slope= 0.0977 '/'
Inlet Invert= 327.00', Outlet Invert= 285.00'
Reach D2: Draw
Hydrograph
Inflow
0.65-" ss cts ❑Outflow
0.6
Inflow Area=5.131 ac
r
Avg. Flow Depth=0.10'
0.5.'
Vel=0.24 fps
_` n-0.400
Vl - .•
V - .................._.....................:......................................._:................. ............ .......... 033 cfs _......... ............. ............ ......... __._.
0.35= .
Q
0 0.3_' ;,, i C 7 '''
i
i 0
�•!•/ apacity=211 .86 cfs
. ' i ! Z
0.05
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 14
Summary for Reach D3: Draw
Inflow Area = 1.231 ac, 0.00% Impervious, Inflow Depth > 0.17" for 1y 24h event
Inflow = 0.08 cfs @ 12.29 hrs, Volume= 0.017 af
Outflow = 0.05 cfs @ 13.21 hrs, Volume= 0.016 af, Atten= 38%, Lag= 55.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.14 fps, Min. Travel Time= 26.3 min
Avg. Velocity= 0.14 fps, Avg. Travel Time= 26.3 min
Peak Storage= 82 cf @ 12.77 hrs
Average Depth at Peak Storage= 0.02'
Bank-Full Depth= 3.00' Flow Area= 195.0 sf, Capacity= 432.67 cfs
20.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 15.0 '/' Top Width= 110.00'
Length= 228.0' Slope= 0.1667 '/'
Inlet Invert= 353.00', Outlet Invert= 315.00'
Reach D3: Draw
Hydrograph
....................»................ ❑Outflow
0.085=' Inflow Area=1 .231 ac
0.08 ''
i..... i t Avg. Flow Depth=0.02'
0.075=' /
...................._ Max
ax a - . fps
0.06= _n 0 400
0.055 " .. 0.05 cf
v 0.05_" 1 %, =L 228 0
c 0.045 � % —
a 0.04 *#� —
...................,...........----....,.....----...........t---...........---- ------........... --............ ....
i .... S 0 1667 '/'
��
0.03= �`��'..
�
0.025 ,, : 1.4:0,0I....
/i"
.._.. II
•
0.01 i
0
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 15
Summary for Reach D4: Ditch Next to Road
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 0.32" for 1y 24h event
Inflow = 2.01 cfs @ 12.35 hrs, Volume= 0.226 af
Outflow = 1.31 cfs @ 12.83 hrs, Volume= 0.216 af, Atten= 35%, Lag= 29.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.53 fps, Min. Travel Time= 15.7 min
Avg. Velocity= 0.33 fps, Avg. Travel Time= 25.4 min
Peak Storage= 1,241 cf @ 12.57 hrs
Average Depth at Peak Storage= 0.54'
Bank-Full Depth= 3.00' Flow Area= 36.0 sf, Capacity= 49.87 cfs
3.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 3.0 '/' Top Width= 21.00'
Length= 500.0' Slope= 0.0720 '/'
Inlet Invert= 351.00', Outlet Invert= 315.00'
Reach D4: Ditch Next to Road
Hydrograph
-/ ❑Inflow
IDOutflo;........--....:..--...........! i.....--.....-'--........ - ____ �2.01 ors
w
Inflow Area=8.479 ac
Avg. Flow Depth=0.54'
Max Vel=0.53 fps
i 1.31 crs n=0.400
N _
0 0'
S=0.0720 '/'
Capacity=49.87 cfs
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 16
Summary for Reach D5: Draw
Inflow Area = 16.740 ac, 0.00% Impervious, Inflow Depth > 0.21" for 1y 24h event
Inflow = 1.05 cfs @ 13.41 hrs, Volume= 0.290 af
Outflow = 0.73 cfs @ 15.24 hrs, Volume= 0.237 af, Atten= 31%, Lag= 109.8 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.29 fps, Min. Travel Time= 55.7 min
Avg. Velocity= 0.23 fps, Avg. Travel Time= 70.5 min
Peak Storage= 2,436 cf @ 14.31 hrs
Average Depth at Peak Storage= 0.22'
Bank-Full Depth= 3.00' Flow Area= 93.0 sf, Capacity= 120.90 cfs
10.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 7.0 '/' Top Width= 52.00'
Length= 982.0' Slope= 0.0570 '/'
Inlet Invert= 285.00', Outlet Invert= 229.00'
Reach D5: Draw
Hydrograph
/ ■Inflow
i.os 11111 ■Outflow
Inflow Area=16.740 ac / _ ..-..-.. ._.-..
Avg. Flow Depth=0.22'
Max Vel=0.29 fps
0 73 cfs .
n=0.400 . '�j,
L=982.0' %j
S=0.0570 'I'
Capacity-120.90 cfs i
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 17
Summary for Reach D6: Draw
Inflow Area = 9.710 ac, 0.00% Impervious, Inflow Depth > 0.29" for 1y 24h event
Inflow = 1.35 cfs @ 12.84 hrs, Volume= 0.232 of
Outflow = 0.38 cfs @ 17.31 hrs, Volume= 0.119 af, Atten= 72%, Lag= 268.1 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.18 fps, Min. Travel Time= 162.2 min
Avg. Velocity= 0.15 fps, Avg. Travel Time= 186.0 min
Peak Storage= 3,696 cf @ 14.60 hrs
Average Depth at Peak Storage= 0.10'
Bank-Full Depth= 3.00' Flow Area= 159.0 sf, Capacity= 198.54 cfs
20.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 11.0 '/' Top Width= 86.00'
Length= 1,720.0' Slope= 0.0500 '/'
Inlet Invert= 315.00', Outlet Invert= 229.00'
Reach D6: Draw
Hydrograph
/ ■Inflow
I 1.35 cfs •Outflow
Inflow Area=9.710 ac
Avg. Flow Depth=0.10' P
MaxVet=0.18 fps / ...................._1......................................._................... ............
1 n=0.400
L=1 ,720.0'
I
Capacity=198.54 cfs ����
0.38 cfs
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 18
Summary for Reach D7: Outfall to Avent Creek
Inflow Area = 26.450 ac, 0.00% Impervious, Inflow Depth > 0.16" for 1y 24h event
Inflow = 0.90 cfs @ 16.45 hrs, Volume= 0.356 af
Outflow = 0.90 cfs @ 16.70 hrs, Volume= 0.339 af, Atten= 0%, Lag= 14.9 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.24 fps, Min. Travel Time= 9.2 min
Avg. Velocity= 0.20 fps, Avg. Travel Time= 10.9 min
Peak Storage= 495 cf @ 16.55 hrs
Average Depth at Peak Storage= 0.20'
Bank-Full Depth= 3.00' Flow Area= 117.0 sf, Capacity= 132.42 cfs
18.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 7.0 '/' Top Width= 60.00'
Length= 130.0' Slope= 0.0385 '/'
Inlet Invert= 229.00', Outlet Invert= 224.00'
Reach D7: Outfall to Avent Creek
Hydrograph
` ❑Inflow
1
I oso crs ❑Outflow
Inflow Area=26.450 ac 0.90
;���i���
Avg. Flow Depth=0.20'
Max Vel=0.24 fps
n=0.400
L=130.0
S=0.0385 '/'
Capacity=132.42 cfs
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Conditions Type 1124-hr 1y24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 19
Summary for Pond C 1: Existing Culvert
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 0.32" for 1y 24h event
Inflow = 2.01 cfs @ 12.35 hrs, Volume= 0.226 af
Outflow = 2.01 cfs @ 12.35 hrs, Volume= 0.226 af, Atten= 0%, Lag= 0.0 min
Primary = 2.01 cfs @ 12.35 hrs, Volume= 0.226 af
Secondary= 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 355.29' @ 12.35 hrs
Flood Elev= 357.00'
Device Routing Invert Outlet Devices _
#1 Primary 354.50' 12.0" Round Culvert
L= 137.0' RCP, end-section conforming to fill, Ke= 0.500
Inlet/Outlet Invert= 354.50' /351.00' S= 0.0255 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf
#2 Secondary 357.00' 50.0' long x 100.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=2.01 cfs @ 12.35 hrs HW=355.29' (Free Discharge)
L1=Culvert (Inlet Controls 2.01 cfs @ 3.02 fps)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=354.50' (Free Discharge)
L2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Pond C 1: Existing Culvert
Hydrograph
❑Inflow
. . . . . . .2.01 cfs l- El Outflow
z.o1cfs'' Inflow Area=8.479 ac ❑Primary
z..cfs ❑Secondary
2- / I
Peak Elev=355.29'
IN ,r
LL 1
•
0 „
0 }'(C��tS �lSsf44% ItSS�tSS ����
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 20
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1: Area 1 Runoff Area=11.609 ac 0.00% Impervious Runoff Depth>2.00"
Flow Length=1,164' Tc=28.9 min CN=58 Runoff=21.62 cfs 1.937 af
Subcatchment 2: Area 2 Runoff Area=5.131 ac 0.00% Impervious Runoff Depth>1.92"
Flow Length=700' Tc=22.2 min CN=57 Runoff=10.82 cfs 0.822 af
Subcatchment 3: Area 3 Runoff Area=1.231 ac 0.00% Impervious Runoff Depth>1.75"
Flow Length=326' Tc=22.4 min CN=55 Runoff=2.31 cfs 0.180 af
Subcatchment 4: Area 4 Runoff Area=8.479 ac 0.00% Impervious Runoff Depth>2.28"
Flow Length=606' Tc=13.1 min CN=61 Runoff=28.83 cfs 1.614 af
Reach DO: NCDOT Road Ditch Avg. Flow Depth=1.30' Max Vel=4.01 fps Inflow=28.83 cfs 1.614 af
n=0.035 L=1,130.0' S=0.0146 '/' Capacity=201.86 cfs Outflow=25.05 cfs 1.601 af
Reach D1: Draw Avg. Flow Depth=0.74' Max Vel=0.67 fps Inflow=21.62 cfs 1.937 af
n=0.400 L=500.0' S=0.0620 '/' Capacity=252.99 cfs Outflow=17.57 cfs 1.884 af
Reach D2: Draw Avg. Flow Depth=0.66' Max Vel=0.72 fps Inflow=10.82 cfs 0.822 af
n=0.400 L=430.0' S=0.0977 '/' Capacity=211.86 cfs Outflow=8.69 cfs 0.804 af
Reach D3: Draw Avg. Flow Depth=0.19' Max Vel=0.46 fps Inflow=2.31 cfs 0.180 af
n=0.400 L=228.0' S=0.1667 '/' Capacity=432.67 cfs Outflow=1.98 cfs 0.176 af
Reach D4: Ditch Next to Road Avg. Flow Depth=2.05' Max Vel=1.11 fps Inflow=25.05 cfs 1.601 af
n=0.400 L=500.0' S=0.0720 '/' Capacity=49.87 cfs Outflow=20.51 cfs 1.579 af
Reach D5: Draw Avg. Flow Depth=1.23' Max Vel=0.79 fps Inflow=24.94 cfs 2.688 af
n=0.400 L=982.0' S=0.0570 '/' Capacity=120.90 cfs Outflow=17.88 cfs 2.575 af
Reach D6: Draw Avg. Flow Depth=0.59' Max Vel=0.50 fps Inflow=22.48 cfs 1.755 af
n=0.400 L=1,720.0' S=0.0500 '/' Capacity=198.54 cfs Outflow=7.83 cfs 1.549 af
Reach D7: Outfall to Avent Creek Avg. Flow Depth=1.15' Max Vel=0.67 fps Inflow=19.98 cfs 4.125 af
n=0.400 L=130.0' S=0.0385 '/' Capacity=132.42 cfs Outflow=19.92 cfs 4.094 af
Pond C 1: Existing Culvert Peak Elev=357.27' Inflow=25.05 cfs 1.601 af
Primary=5.70 cfs 1.128 af Secondary=19.35 cfs 0.473 af Outflow=25.05 cfs 1.601 af
Total Runoff Area = 26.450 ac Runoff Volume =4.553 af Average Runoff Depth = 2.07"
100.00% Pervious = 26.450 ac 0.00% Impervious = 0.000 ac

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 21
Summary for Subcatchment 1: Area 1
Runoff = 21.62 cfs @ 12.25 hrs, Volume= 1.937 af, Depth> 2.00"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
5.230 61 >75% Grass cover, Good, HSG B
6.379 55 Woods, Good, HSG B
11.609 58 Weighted Average
11.609 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
13.3 100 0.0200 0.13 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.70"
15.6 1,064 0.0520 1.14 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
28.9 1,164 Total
Subcatchment 1: Area 1
Hydrograph
24=' :.............................................................................................................I.........................................
........ ..._i.
:............
■Runoff
22=' :........
21_ ; . ......_........_..._.............._............._............_.............._............_......_„...._........................ pe.....I1....24-O r
25y �4h �a�n#all-6 �'S
..._.............._1............_......_1....._............._i.........__
r
0
Ru ii noff Area �1.609 LI ;ac
15=' ,.......... I - Ru1noff..Volume=1.937 af.......
u 13- :.......... ........ ... ;.._._ .......__< ...._ .....;._--_........ ,.. ...... `
il 1 I 0
Runof# De th 2 QO
11 :
LT! FIQw.....Le.n. : th011 4'
TC 28 9 nitrt
O N=15
5 .......... ..... L....
q
! I f II 1 -E . 1- [ ! ; r
L
......... ....
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 22
Summary for Subcatchment 2: Area 2
Runoff = 10.82 cfs @ 12.17 hrs, Volume= 0.822 af, Depth> 1.92"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
1.483 61 >75% Grass cover, Good, HSG B
3.648 55 Woods, Good, HSG B
5.131 57 Weighted Average
5.131 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
13.1 600 0.0233 0.76 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.2 700 Total
Subcatchment 2: Area 2
Hydrograph
12
■Runoff
10.82 cfs_..-..-
11_
- - Type III 24-hr.
107 25y 24h Rainfall=6.75"
9_
..._.............._.,............_......_....._.............._.......... Runoff -
Area-5.131 ac
8_
Runoff Volume=0.822 af
N 7-
2 : 1, 1. I 0
Runoff Depth>1.92"_._..
3 6_ • Flow a rgt =700'
_ . Tc=22 2 m'rn.
4 I I •
3_
2-
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 23
Summary for Subcatchment 3: Area 3
Runoff = 2.31 cfs @ 12.17 hrs, Volume= 0.180 af, Depth> 1.75"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
1.231 55 Woods, Good, HSG B
1.231 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.0 100 0.0200 0.08 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.70"
2.4 226 0.0973 1.56 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.4 326 Total
Subcatchment 3: Area 3
Hydrograph
D Runoff
- 1 2.3l cfs I
i
Type 124-h r
2_ 025y 24h Rainfall=6.75
- Runoff Area=1 .231 ac
- Runoff Volume=0.180 of
'3 - / Runoff Depth>1.75"
F- , t ,' , 1low L.e_ngth=3261
1 Tc=22.4 min
. : . , : . : CN-55
0 ,iiiiiiiiiiiiiiiiiiiiiiiiiiiiiif ��
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 24
Summary for Subcatchment 4: Area 4
Runoff = 28.83 cfs @ 12.06 hrs, Volume= 1.614 af, Depth> 2.28"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
8.479 61 >75% Grass cover, Good, HSG B
8.479 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
4.0 506 0.0198 2.11 Shallow Concentrated Flow,
Grassed Waterway Kv= 15.0 fps
13.1 606 Total
Subcatchment 4: Area 4
Hydrograph
32="" 1 i I I I I ■Runoff
30 i iiii1J2883cfslii
28_ , 11111i01 Type II 24-hr
26= _ ��.........
2Sy 24h Rainfall-6.75
24
Runoff Area=8.479 ac.
22
20_ Runoff,Vol ume=1....fi1..._4.:._af...........
w 18=' .........iit [ ii _Runoff Depfh�2.2
8"
3 16_
o _
I
ow
� 14
................ ....en g... .......................... ..........
121 Tc=13..1......m.i.n0 .........
I
i
EN=61 .
8
iiii
4= .
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 25
Summary for Reach DO: NCDOT Road Ditch
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 2.28" for 25y 24h event
Inflow = 28.83 cfs @ 12.06 hrs, Volume= 1.614 af
Outflow = 25.05 cfs @ 12.19 hrs, Volume= 1.601 af, Atten= 13%, Lag= 8.1 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 4.01 fps, Min. Travel Time= 4.7 min
Avg. Velocity = 1.79 fps, Avg. Travel Time= 10.5 min
Peak Storage= 7,216 cf @ 12.11 hrs
Average Depth at Peak Storage= 1.30'
Bank-Full Depth= 3.00' Flow Area= 30.0 sf, Capacity= 201.86 cfs
1.00' x 3.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.0 '/' Top Width= 19.00'
Length= 1,130.0' Slope= 0.0146 '/'
Inlet Invert= 372.00', Outlet Invert= 355.50'
Reach DO: NCDOT Road Ditch
Hydrograph
32= /.. aas ❑Outflow
ill s
❑Inflow
......._:....
3 Inflow Area=8.479 ac
26 I I ir ,25.05 cfs vg.... Flo*..Dept 01
.301
2a Q1=4
Max = '-... a
22=
w 18 L='1,_'130 .0
. . . . . .
3 16 �a
- .0 ..a. a..
LL 14_' 1 4
81
12z. 4............ Ca.pmcity=.2U1... 6....cfs....
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 26
Summary for Reach D1: Draw
Inflow Area = 11.609 ac, 0.00% Impervious, Inflow Depth > 2.00" for 25y 24h event
Inflow = 21.62 cfs @ 12.25 hrs, Volume= 1.937 af
Outflow = 17.57 cfs @ 12.61 hrs, Volume= 1.884 af, Atten= 19%, Lag= 21.2 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.67 fps, Min. Travel Time= 12.5 min
Avg. Velocity = 0.29 fps, Avg. Travel Time= 28.7 min
Peak Storage= 13,185 cf© 12.40 hrs
Average Depth at Peak Storage= 0.74'
Bank-Full Depth= 3.00' Flow Area= 174.0 sf, Capacity= 252.99 cfs
28.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 10.0 '/' Top Width= 88.00'
Length= 500.0' Slope= 0.0620 '/'
Inlet Invert= 316.00', Outlet Invert= 285.00'
Reach D1: Draw
Hydrograph
24- t ......
I 21.62cfsI t
•Inflow
■Outflow
t
' t
22;';' <._.... .. �. 1. c w...-Area=- 1.$0 � ...
201 i l h*0 Avg Flow;Dept :1 '
1&. 0 757cf l~
1 s
Max
.67 fin
13= a....__ L=.
... 0.0I.O....
3121i /1IIIIII
..,.... :::: ::::::::: -........._...-._:.0620 'I'...._._.
1
ø *4
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 27
Summary for Reach D2: Draw
Inflow Area = 5.131 ac, 0.00% Impervious, Inflow Depth > 1.92" for 25y 24h event
Inflow = 10.82 cfs @ 12.17 hrs, Volume= 0.822 of
Outflow = 8.69 cfs @ 12.45 hrs, Volume= 0.804 af, Atten= 20%, Lag= 17.1 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.72 fps, Min. Travel Time= 10.0 min
Avg. Velocity= 0.32 fps, Avg. Travel Time= 22.6 min
Peak Storage= 5,253 cf @ 12.28 hrs
Average Depth at Peak Storage= 0.66'
Bank-Full Depth= 3.00' Flow Area= 126.0 sf, Capacity= 211.86 cfs
12.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 10.0 '/' Top Width= 72.00'
Length= 430.0' Slope= 0.0977 '/'
Inlet Invert= 327.00', Outlet Invert= 285.00'
Reach D2: Draw
Hydrograph
12= .........................................._.. , ❑
❑Inflow
....110.82 cfs : Outflow
11-'" ± Inflow Area=5.131 ac
,0= 'Avg. Flow Depth=0.66'
Max ,Vel=0.72 fps
n=0.400
S=0.0977 'I'
4=: ........._............._....................................._...................._........ i. •1' 1 _._.. Capacity=211.86 cfs
3- s
. i..... •,,I��
2
PI
0 �Sftf�
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 28
Summary for Reach D3: Draw
Inflow Area = 1.231 ac, 0.00% Impervious, Inflow Depth > 1.75" for 25y 24h event
Inflow = 2.31 cfs @ 12.17 hrs, Volume= 0.180 af
Outflow = 1.98 cfs @ 12.41 hrs, Volume= 0.176 af, Atten= 15%, Lag= 14.2 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.46 fps, Min. Travel Time= 8.2 min
Avg. Velocity= 0.19 fps, Avg. Travel Time= 19.7 min
Peak Storage= 982 cf @ 12.27 hrs
Average Depth at Peak Storage= 0.19'
Bank-Full Depth= 3.00' Flow Area= 195.0 sf, Capacity= 432.67 cfs
20.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 15.0 '/' Top Width= 110.00'
Length= 228.0' Slope= 0.1667 '/'
Inlet Invert= 353.00', Outlet Invert= 315.00'
Reach D3: Draw
Hydrograph
/ ❑Inflow
j 1 2.31 cfs I ❑Outflow
Inflow Area=1 .231 ac
198cfs i Avg. Flow Depth=0.19'
2 ' i
�� ' Max Vel=0.46 fps
I/ n=0.400
/�0 L=228.0
LL �� =0.1667 '/'
# ,
� Capacity=432.67 cfs
4.
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 29
Summary for Reach D4: Ditch Next to Road
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 2.27" for 25y 24h event
Inflow = 25.05 cfs @ 12.19 hrs, Volume= 1.601 af
Outflow = 20.51 cfs © 12.41 hrs, Volume= 1.579 af, Atten= 18%, Lag= 12.8 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 1.11 fps, Min. Travel Time= 7.5 min
Avg. Velocity = 0.50 fps, Avg. Travel Time= 16.7 min
Peak Storage= 9,343 cf @ 12.28 hrs
Average Depth at Peak Storage= 2.05'
Bank-Full Depth= 3.00' Flow Area= 36.0 sf, Capacity= 49.87 cfs
3.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 3.0 '/' Top Width= 21.00'
Length= 500.0' Slope= 0.0720 '/'
Inlet Invert= 351.00', Outlet Invert= 315.00'
Reach D4: Ditch Next to Road
Hydrograph
t......... ..-
28 I ❑Outflow
cfs I
D Inflow
26- 1n`flow A rea=8.479 ac
24-
22- .... 1 cfs I _
•
Avg Flow' Depth=2.05'
20- ,
Max Vel=1.11 fps
•
18- . ; 0 n=p.. ....__
.400
w 16-
3 14-
O0''I'
I 01 I a 12_
S�7 7
= i
10_:' t ._.
Da_ act_ C_ 149 7O#s•
s-'
•
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 30
Summary for Reach D5: Draw
Inflow Area = 16.740 ac, 0.00% Impervious, Inflow Depth > 1.93" for 25y 24h event
Inflow = 24.94 cfs @ 12.56 hrs, Volume= 2.688 af
Outflow = 17.88 cfs @ 13.17 hrs, Volume= 2.575 af, Atten= 28%, Lag= 36.2 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.79 fps, Min. Travel Time= 20.8 min
Avg. Velocity= 0.42 fps, Avg. Travel Time= 38.6 min
Peak Storage= 22,363 cf @ 12.82 hrs
Average Depth at Peak Storage= 1.23'
Bank-Full Depth= 3.00' Flow Area= 93.0 sf, Capacity= 120.90 cfs
10.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 7.0 '/' Top Width= 52.00'
Length= 982.0' Slope= 0.0570 '/'
Inlet Invert= 285.00', Outlet Invert= 229.00'
Reach D5: Draw
Hydrograph
..... ._.... + ..... 1
/ I ■Outflo
O Inflow
zasa�s I
w
26- In ow Area=16. 40` ac ,
24—'
vg....Flow.... .Qp
20=' ,,:
Max VeI 0.79 fps ,.
........ ? I zss of5
18
: 0 n .�0.0....._1....
N
.
C
LL 12 S00.0a77a._���.....-? ..... +..... ;� .......
i
Capacity 120.90 cfs oi I
ivipr
8 r I I I 1,
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 31
Summary for Reach D6: Draw
Inflow Area = 9.710 ac, 0.00% Impervious, Inflow Depth > 2.17" for 25y 24h event
Inflow = 22.48 cfs @ 12.41 hrs, Volume= 1.755 af
Outflow = 7.83 cfs © 13.76 hrs, Volume= 1.549 af, Atten= 65%, Lag= 81.3 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.50 fps, Min. Travel Time= 56.9 min
Avg. Velocity = 0.29 fps, Avg. Travel Time= 99.6 min
Peak Storage= 26,756 cf© 12.81 hrs
Average Depth at Peak Storage= 0.59'
Bank-Full Depth= 3.00' Flow Area= 159.0 sf, Capacity= 198.54 cfs
20.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 11.0 '/' Top Width= 86.00'
Length= 1,720.0' Slope= 0.0500 '/'
Inlet Invert= 315.00', Outlet Invert= 229.00'
7%.....................%%%%. **".....,
Reach D6: Draw
Hydrograph
•Inflow
ai
■Outflow
. :. .. ,.
:- � Inflow Area=910 ac
;
20=
i-.. ..-..-.. Avg:::::Flow`:Depth=O;59`:..
,8= 1 Max VeI=0 50 fps
n=!0
.400' ..-• ' I i : i 0 1 I
13=; .... ........ : ........... ;.-..-.. ..-..-.. ..-..-..-..-.._; : 4 1 =1,7
12=.
:
10 ?
I9- +..................._p....................3.............._ 17.83 cfs —
I i
21 7 ,,/..:1 , A
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 32
Summary for Reach D7: Outfall to Avent Creek
Inflow Area = 26.450 ac, 0.00% Impervious, Inflow Depth > 1.87" for 25y 24h event
Inflow = 19.98 cfs @ 13.49 hrs, Volume= 4.125 of
Outflow = 19.92 cfs © 13.58 hrs, Volume= 4.094 af, Atten= 0%, Lag= 5.5 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Max. Velocity= 0.67 fps, Min. Travel Time= 3.3 min
Avg. Velocity = 0.40 fps, Avg. Travel Time= 5.4 min
Peak Storage= 3,890 cf @ 13.53 hrs
Average Depth at Peak Storage= 1.15'
Bank-Full Depth= 3.00' Flow Area= 117.0 sf, Capacity= 132.42 cfs
18.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 7.0 '/' Top Width= 60.00'
Length= 130.0' Slope= 0.0385 '/'
Inlet Invert= 229.00', Outlet Invert= 224.00'
Reach D7: Outfall to Avent Creek
Hydrograph
/ 111rni 111 0 Inflow
22= ;' :......................................._;,...................._....................1..................._.................... .....................:..._.._.. 19.98 cfs ... ............. ............ ............. ............. ............ ............__. ❑Outflow
I
20° Inflow Area-426 450' ac )1992c,� :::::::: ::::::::::: ::::: :::::::::
19'_' f A
Avg. Flow Depth=1.15 /r/I
iiii
18'_' //�
MaxVel Q.6 f 's
15=' i
144 n0.400 1 ,
.13=
...... .-
12= L , 13o.0I 0 �j
1 1091:::.<.: St7-0.038$ 'I' I- I 1 NI
ir 320 8' iiii
Capscty12 4 cfsj��,i
�� �''0
10 /AV
1;14,'
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

20221019_Harnett County_NW CC_Existing Condition Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/19/2022
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 33
Summary for Pond C 1: Existing Culvert
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 2.27" for 25y 24h event
Inflow = 25.05 cfs @ 12.19 hrs, Volume= 1.601 af
Outflow = 25.05 cfs @ 12.19 hrs, Volume= 1.601 af, Atten= 0%, Lag= 0.0 min
Primary = 5.70 cfs @ 12.19 hrs, Volume= 1.128 af
Secondary= 19.35 cfs @ 12.19 hrs, Volume= 0.473 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 357.27' @ 12.19 hrs
Flood Elev= 357.00'
Device Routing Invert Outlet Devices _
#1 Primary 354.50' 12.0" Round Culvert
L= 137.0' RCP, end-section conforming to fill, Ke= 0.500
Inlet/Outlet Invert= 354.50' /351.00' S= 0.0255 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf
#2 Secondary 357.00' 50.0' long x 100.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=5.70 cfs @ 12.19 hrs HW=357.27' (Free Discharge)
L1=Culvert (Inlet Controls 5.70 cfs @ 7.26 fps)
Secondary OutFlow Max=19.13 cfs @ 12.19 hrs HW=357.27' (Free Discharge)
L2=Broad-Crested Rectangular Weir (Weir Controls 19.13 cfs @ 1.40 fps)
Pond C 1: Existing Culvert
Hydrograph
•Inflow
25.05////:
cfs I ❑Outflow
I s
28= :' 0s- Inflow;Area= .9...ac......... o se Secondary
26=: :. Pear v!e ~357 27'
24 -..
22_'..
20_. 19.35 cfs
18
w 16=
14_ :
r'
12='
10
8= _
6- �j��� ,i///////////Z
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

Harnett County Solid Waste Department I Stormwater Permit Application—October 2024 r)�
Attachment D.2—Post-Development Calculations
D . 2
Attachment D.2 — Post-
Development Calculations

Harnett County Solid Waste Department I Stormwater Permit Application—October 2024 01
Attachment D.2—Post-Development Calculations
This page intentionally left blank.

1 2 3 4 5 6 7 8
Y
irr".........r
N
Aji ill o syy D
m
LEGEND:
EXISTING CONTOURS
LOC LIMITS OF CONSTRUCTION
�yo
/36p BUFFER ZONE c
APPROXIMATE EDGE OF TREE LINE
ASS I =--- G911 T.WFR RADIUS
r 335f h 3SS M TOWER FENCG
ADJAC NT PUBLIC ROW
350�1 AREA 1:9.848 AC
"" 6"WAT RMAIN
50'BUFFE' - 3gs \ TIME TO CONCENTRATION
_ 100 LF SHEET FLOW
40111,4
AIII I � 1`?S� 827 LF SHALLOW CONC .440400
�46 ''',0N \
, 1:
E911 COMMUNICATIO_ �rtagolf
_�� 355�355
v ExisJl' NOF ce uE�N '—,L_vf� 8 t ONTBUFFS• fr„,,c,.„4,4„ r------
346
w w 30 DIVERSION DITCH(00) �/ PROPERTY LIN �
ail` 3 25V 24H MAX VELOCITY 517 FTIS y AREA 4 DRAINS TO EXISTING I �l
"2 - // h , '/ NCDOT ROW 6WALE NO — 3
O O / p / ,y IMPROVEMENTS TO BE MADE Sp
iiii
3p S 3j �� / n O 3S �� yo I TIME
SO* 7 60 CONCENTRATION 0 SHALLOW LOW ' IS `S
\I 295 p3 p s 50'BUFFS-1 �C/ � 2 I 100 LF SHEET FLOW
290 a % "<5. M��...,t(OVA, %'�i° c M .w
265 O 'iSL PROPERTY LINE AREA 1.1:1.761 A., K O
in M\ �/ � /' TIME TO CONCENTRATION t I W-
27528O 71(_?'
�ryh � 186100SHALLOW CO C V TIME TO CONCENTRAT AC ION ON M I ¢o
26 !I N '.alli��ll/ �O 1751LF SHALLOW FCONCLOW p
?gyp— �I.
S_ O CSWALE SiaSa�y.S�O ov'w ( I . �� I�k - ''‘ aD O \ 2ELOCITY611OdwSanOr�9� 320 0 \33US \ �O 25V 24H MAX VELOCITVACCESS DRIVE SWALE(599 FT/S ' 1t� � �ry4f 315 \ !STING 6-INCHNNN310 _ a M // �:..",_ �o.___ i WATER MAN `�"➢v �-
lii \ y, \� I J// ^ ,ASS T.... \ � :.-:7::. I 7. a�� \\ OV/
'..�li', I�o w �305 �E tit, .._.._. ..../ '-'._ / 1'�N 9 ;. 3'.1. AC ., \\\ Y\ ONTRION O,',�c5)°)\‘ 30p �, ' 100 LF SHEET FLOW\ '\ �� j&y- B
a N 9 2 290 ,�� I - 220 LF SHALLOW CONC f• a
a 'S ',• n `. \ PR\ \ it/iPLAUTLET CED FOR IMPRION TO BE
CULVERT Y� rv��ya�a� 28s � :2@5 ''�o ����,� �3�55 `���50
s 2T0 215 o "S / \340 —_3q3 "il
S AREA 4 AND 5 DRAIN TO U`
Al T.
M 3 �I EXISTING NCDOT ROW
N M "+ CSWALE(S2) 3 d `, SWALE NO IMPROVEMENTS
h N 265 ul '70 25Y 24H MAX VELOCITY 5.98 FT/S\� 3$ Q ` TO BE MADE/ p
ry � M 32s �� 325 dp �h �
, 3 320 �� 34��
i6 _ / �S�
423 N/1?
y
�SO� ry0 —310 ,51. <1 o
\ i1` N Nit, 06 "� 3s 1
aS N 305 b
D o w 315 �
a�N acyo � N i'3,5.
\ �'`,N N o �n
300 310 I�
N a�0 1
1
1t a:aSS o 295 305 Z'Itli
AVENTS CREEK h 2gS 2\ 29S3p0 0oMli
Flo A
— NTIRE SITE DRAINS THROUGH NATURAL 290
irit. CHANNELS IN DRAWS AND INTO ADVENT CREEK h
2>p �285 - N NOTES:
0.0:4 kitk
s \ p
a \ 2 25g 60
S 280 i�� /ry°0 II 1. EXISTING TOPOGRAPHY AND PROPERTY LINES OBTAINED FROM
S 275 ' HARNETT COUNTY GIs.
�) _250 270 rt.
33p 2. PROPERTY BOUNDARY SURVEY COMPLETED BY BENTON W.
e
ry 6 ��255 -- ^�ZgS� \ DEWARE AND ASSOCIATES,APRIL 30,2019.
cN T'S,�,do ph p ?- �60 /
'L ryy 65 Z60� / 0/2228 � 32S 3. CONDITIONAL USE PERMIT#BA-CU-18-18 APPROVED 6/11/18.
0.
PROJECT MANAGER J.MURRAY,PE
PROJECT ENGINEER A.MCGREW,PE Harnett PROPOSED CONDITIONS
$ HDR Engineering,Inc.of the Carolinas �/Th COUNTY HYDROCAD MODEL
DRAWN BY A.MCGREW,PE
N.C.B.E.L.S.License Number:F-0116 NORTH CAROLINA KEY
'';' IM) strong roots•new growth
555 Fayetteville Street,Suite 900 HARNETT COUNTY
919.32.6 00C 05/2024 ISSUED FOR BIDDING
Raleigh,NC 7601 B 01/2023 REVISED BASED ON REVIEWER COMMENTS 0 1" 2' FILENAME OOG-02.dwg
Z A 10/2022 ISSUED FOR PERMITTING NORTHWEST CONVENIENCE CENTER SHEET±
ISSUE DATE DESCRIPTION PROJECT NUMBER 10354670 SCALE 1"=125' oOV�01
HARNETT COUNTY NORTH CAROLINA

K 4 )
Area 4 DO
O
NCDOT Ro d Ditch
Area 4 SO
O
DD Area 10 Access Drive Swale CB1
c7
Diversi n Ditch 1 P Area 1.1 Area 0 Replaced C Ivert
CB
D1 Pond S1 < C2 Area 3 D3 D4
Dra D2 Swale Proposed Culvert S2 Draw 'ch Next to Road
/Draw CC Swale
D5
/ Draw
D6
Draw
D7 \`,,Q'. CA -n�
Outfall to Avent Creek co
� 0,,� ....EIS. r
/1L ''
rN •--
O4•OU54 •-
Cc.. .1
//('f.l\�`
(Subca) Reach 'on.
MI Routing Diagram for 20241024_Harnett County_NW CC_Construction Condition;
Prepared by HDR, Inc, Printed 10/28/2024
HydroCAD®10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC

20241024_Harnett County_NW CC_Construction Conditions
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 2
Area Listing (all nodes)
Area CN Description
(acres) (subcatchment-numbers)
18.218 61 >75% Grass cover, Good, HSG B (1, 1.1, 2, 3, 4, 5)
1.645 96 Gravel surface, HSG B (1.1, 2, 3, 5)
0.150 98 Paved parking, HSG B (5)
6.511 55 Woods, Good, HSG B (1, 1.1, 2)
26.524 62 TOTAL AREA

20241024_Harnett County_NW CC_Construction Conditions
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 3
Soil Listing (all nodes)
Area Soil Subcatchment
(acres) Group Numbers
0.000 HSG A
26.524 HSGB 1, 1.1, 2, 3, 4, 5
0.000 HSG C
0.000 HSG D
0.000 Other
26.524 TOTAL AREA

20241024_Harnett County_NW CC_Construction Conditions
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 4
Ground Covers (all nodes)
HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment
(acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers
0.000 18.218 0.000 0.000 0.000 18.218 >75% Grass cover, Good 1, 1.1, 2,
3, 4, 5
0.000 1.645 0.000 0.000 0.000 1.645 Gravel surface 1.1, 2, 3,
5
0.000 0.150 0.000 0.000 0.000 0.150 Paved parking 5
0.000 6.511 0.000 0.000 0.000 6.511 Woods, Good 1, 1.1, 2
0.000 26.524 0.000 0.000 0.000 26.524 TOTAL AREA

20241024_Harnett County_NW CC_Construction Conditions
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 5
Pipe Listing (all nodes)
Line# Node In-Invert Out-Invert Length Slope n Diam/Width Height Inside-Fill
Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches)
1 1P 318.00 317.00 66.0 0.0152 0.011 24.0 0.0 0.0
2 C 1 354.00 351.50 137.0 0.0182 0.012 30.0 0.0 0.0
3 C2 334.40 330.50 45.0 0.0867 0.012 30.0 0.0 0.0

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 6
Time span=0.00-180.00 hrs, dt=0.01 hrs, 18001 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Subcatchment 1: Area 1 Runoff Area=9.848 ac 0.00% Impervious Runoff Depth=0.29"
Flow Length=830' Tc=24.0 min CN=58 Runoff=1.33 cfs 0.238 af
Subcatchment 1.1: Area 1.1 Runoff Area=1.761 ac 0.00% Impervious Runoff Depth=0.35"
Flow Length=286' Tc=9.2 min CN=60 Runoff=0.65 cfs 0.052 af
Subcatchment2: Area 2 Runoff Area=5.131 ac 0.00% Impervious Runoff Depth=0.53"
Flow Length=500' Tc=11.8 min CN=65 Runoff=3.19 cfs 0.226 af
Subcatchment3: Area 3 Runoff Area=1.231 ac 0.00% Impervious Runoff Depth=0.99"
Flow Length=326' Tc=22.4 min CN=75 Runoff=1.21 cfs 0.102 af
Subcatchment4: Area 4 Runoff Area=6.257 ac 0.00% Impervious Runoff Depth=0.38"
Flow Length=606' Tc=13.1 min CN=61 Runoff=2.19 cfs 0.200 af
Subcatchment5: Area 4 Runoff Area=2.296 ac 6.53% Impervious Runoff Depth=0.61"
Flow Length=275' Tc=10.3 min CN=67 Runoff=1.87 cfs 0.117 af
Reach DO: NCDOT Road Ditch Avg. Flow Depth=0.36' Max Vel=1.99 fps Inflow=2.19 cfs 0.200 af
n=0.035 L=1,130.0' S=0.0159 '/' Capacity=210.84 cfs Outflow=1.46 cfs 0.200 af
Reach D1: Draw Avg. Flow Depth=0.11' Max Vet=0.21 fps Inflow=1.34 cfs 0.515 af
n=0.400 L=500.0' S=0.0620 '/' Capacity=252.99 cfs Outflow=0.65 cfs 0.513 af
Reach D2: Draw Avg. Flow Depth=0.00' Max Vet=0.00 fps
n=0.400 L=430.0' S=0.0977 'I Capacity=211.86 cfs Outflow=0.00 cfs 0.000 af
Reach D3: Draw Avg. Flow Depth=0.00' Max Vel=0.00 fps
n=0.400 L=228.0' S=0.1667 '/' Capacity=432.67 cfs Outflow=0.00 cfs 0.000 af
Reach D4: Ditch Next to Road Avg. Flow Depth=0.62' Max Vet=0.57 fps Inflow=2.65 cfs 0.317 af
n=0.400 L=500.0' S=0.0720 '/' Capacity=49.87 cfs Outflow=1.74 cfs 0.317 af
Reach D5: Draw Avg. Flow Depth=0.16' Max Vet=0.24 fps Inflow=0.65 cfs 0.513 af
n=0.400 L=982.0' S=0.0570 '/' Capacity=120.90 cfs Outflow=0.42 cfs 0.509 af
Reach D6: Draw Avg. Flow Depth=0.11' Max Vel=0.19 fps Inflow=1.74 cfs 0.317 af
n=0.400 L=1,720.0' S=0.0500 '/' Capacity=198.54 cfs Outflow=0.45 cfs 0.317 af
Reach D7: Outfall to Avent Creek Avg. Flow Depth=0.19' Max Vel=0.23 fps Inflow=0.87 cfs 0.826 af
n=0.400 L=130.0' S=0.0385 '/' Capacity=132.42 cfs Outflow=0.87 cfs 0.826 af
Reach DD: Diversion Ditch Avg. Flow Depth=0.05' Max Vet=1.82 fps Inflow=1.33 cfs 0.238 af
n=0.022 L=240.0' S=0.0375 'I Capacity=734.43 cfs Outflow=1.32 cfs 0.238 af
Reach SO: Access Drive Swale Avg. Flow Depth=0.24' Max Vet=1.05 fps Inflow=1.87 cfs 0.117 af
n=0.030 L=540.0' S=0.0037'/' Capacity=72.46 cfs Outflow=1.31 cfs 0.117 af

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 7
Reach S1: Swale Avg. Flow Depth=0.22' Max Vet=3.52 fps Inflow=4.01 cfs 0.328 af
n=0.022 L=390.0' S=0.0269 '/' Capacity=340.18 cfs Outflow=3.93 cfs 0.328 af
Reach S2: CC Swale Avg. Flow Depth=0.31' Max Vet=3.67 fps Inflow=4.13 cfs 0.328 af
n=0.022 L=455.0' S=0.0233'/' Capacity=49.84 cfs Outflow=4.01 cfs 0.328 af
Pond 1 P: Pond Peak EIev=323.80' Storage=29,966 cf Inflow=4.36 cfs 0.380 af
Primary=0.03 cfs 0.277 af Secondary=0.00 cfs 0.000 af Outflow=0.03 cfs 0.277 af
Pond C 1: Replaced Culvert Peak EIev=354.63' Inflow=2.65 cfs 0.317 af
Primary=2.65 cfs 0.317 af Secondary=0.00 cfs 0.000 af Outflow=2.65 cfs 0.317 af
Pond C2: Proposed Culvert Peak EIev=335.19' Inflow=4.01 cfs 0.328 af
30.0" Round Culvert n=0.012 L=45.0' S=0.0867 '/' Outflow=4.01 cfs 0.328 af
Total Runoff Area = 26.524 ac Runoff Volume = 0.935 af Average Runoff Depth = 0.42"
99.43% Pervious = 26.374 ac 0.57% Impervious = 0.150 ac

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 1: Area 1
Runoff = 1.33 cfs @ 12.27 hrs, Volume= 0.238 af, Depth= 0.29"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 1 y 24h Rainfall=3.05"
Area (ac) CN Description
5.230 61 >75% Grass cover, Good, HSG B
4.618 55 Woods, Good, HSG B
9.848 58 Weighted Average
9.848 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
13.3 100 0.0200 0.13 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.70"
10.7 730 0.0520 1.14 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
24.0 830 Total
Subcatchment 1: Area 1
Hydrograph
0 Runoff
1.33 cfs
T (pe� II 24-h r
jly 24h IRa1nfaII=3.05"
1 - j H Runoff Arela=9.848 ac
Runoff Volume=0.238 af
13, Runoff Depth=0.29"
LL j Flow Length=830'
Tc=24.d m i n
CN=58
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment 1.1: Area 1.1
Runoff = 0.65 cfs @ 12.04 hrs, Volume= 0.052 af, Depth= 0.35"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 1 y 24h Rainfall=3.05"
Area (ac) CN Description
1.314 61 >75% Grass cover, Good, HSG B
0.407 55 Woods, Good, HSG B
0.040 96 Gravel surface, HSG B
1.761 60 Weighted Average
1.761 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
8.0 100 0.0700 0.21 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.70"
1.2 186 0.2500 2.50 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
9.2 286 Total
Subcatchment 1.1: Area 1.1
Hydrograph
_ — — — I— t ❑Runoff
0 7E 0.65 cfs — — -
0.657v % IC�I L�F�
0.6
0.557 14 24h-kaiinfA= 0 "0.5-Y / Runoff ►re =L7611c
0.45 of o
% — — f�V �u rye .0 a2 pf
=9_3F
0 0.35-z j -Riclf! pep h
2 = / ow L-en h 86-,
05: c-7. m111
0.25-
0.2 j C VN--6O
0.15_ % 1-
0.1-
0 , . . . , . .. ..t
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment 2: Area 2
Runoff = 3.19 cfs @ 12.06 hrs, Volume= 0.226 af, Depth= 0.53"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 1 y 24h Rainfall=3.05"
Area (ac) CN Description
2.748 61 >75% Grass cover, Good, HSG B
1.486 55 Woods, Good, HSG B
0.897 96 Gravel surface, HSG B
5.131 65 Weighted Average
5.131 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
2.7 400 0.0233 2.46 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
11.8 500 Total
Subcatchment 2: Area 2
Hydrograph
/ D Runoff
- 3.19 cfs
3y' 0-- Type-I134-hr
- j I 1y 24h Rainfall=3.05"
I Runoff Area=5.131 ac
° 2- j _Fpunoffyo1unie=0.226 of
- Runoff Depth=O.53
° / Flow Length=500'
Tc=11.8 min
0 ,/
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment 3: Area 3
Runoff = 1.21 cfs @ 12.17 hrs, Volume= 0.102 af, Depth= 0.99"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 1 y 24h Rainfall=3.05"
Area (ac) CN Description
0.000 55 Woods, Good, HSG B
0.482 96 Gravel surface, HSG B
0.749 61 >75% Grass cover, Good, HSG B
1.231 75 Weighted Average
1.231 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.0 100 0.0200 0.08 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.70"
2.4 226 0.0973 1.56 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.4 326 Total
Subcatchment 3: Area 3
Hydrograph
D Runoff
1.21 cfs
Type II 24-hr
4y 24h Rainfall-.05"
I Runoff Area=1 .231 ac
I Zunoff Volume=0.102 af
Runoff Depth=0.99"
Flow Length=326'
Tc=22.4 m i n
CAI=75
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 12
Summary for Subcatchment 4: Area 4
Runoff = 2.19 cfs @ 12.09 hrs, Volume= 0.200 af, Depth= 0.38"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 1 y 24h Rainfall=3.05"
Area (ac) CN Description
6.257 61 >75% Grass cover, Good, HSG B
6.257 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
4.0 506 0.0198 2.11 Shallow Concentrated Flow,
Grassed Waterway Kv= 15.0 fps
13.1 606 Total
Subcatchment 4: Area 4
Hydrograph
/ ❑Runoff
2.19 cfs
j T�pell4
2-- / 1y 24h Rainfall=3.05"
Runoff Area=6.257 ac
Runoff Volume=0.200 af
Runoff Depth=9.38"
LL 1 j -Plow Length 6G6
Tc=13.1 min
CN=61
0 ,/
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 13
Summary for Subcatchment 5: Area 4
Runoff = 1.87 cfs @ 12.04 hrs, Volume= 0.117 af, Depth= 0.61"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 1 y 24h Rainfall=3.05"
Area (ac) CN Description
1.920 61 >75% Grass cover, Good, HSG B
0.226 96 Gravel surface, HSG B
0.150 98 Paved parking, HSG B
2.296 67 Weighted Average
2.146 93.47% Pervious Area
0.150 6.53% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
1.2 175 0.0285 2.53 Shallow Concentrated Flow,
Grassed Waterway Kv= 15.0 fps
10.3 275 Total
Subcatchment 5: Area 4
Hydrograph
❑Runoff
2- 1.87 cfs
Titpe II 14-hr
1y 24h Rainfall=3.05"
Runoff Area=2.296 ac
Runoff Volume=0.1117 af
Runoff Depth J.61"
° 1 Flow Length=275'
LL
Tc=10.3 min
CN=67
III/
o iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii/
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 14
Summary for Reach DO: NCDOT Road Ditch
Inflow Area = 6.257 ac, 0.00% Impervious, Inflow Depth = 0.38" for 1y 24h event
Inflow = 2.19 cfs @ 12.09 hrs, Volume= 0.200 af
Outflow = 1.46 cfs @ 12.19 hrs, Volume= 0.200 af, Atten= 33%, Lag= 6.2 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 1.99 fps, Min. Travel Time= 9.5 min
Avg. Velocity = 0.91 fps, Avg. Travel Time= 20.6 min
Peak Storage= 830 cf @ 12.19 hrs
Average Depth at Peak Storage= 0.36'
Bank-Full Depth= 3.00' Flow Area= 30.0 sf, Capacity= 210.84 cfs
1.00' x 3.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.0 '/' Top Width= 19.00'
Length= 1,130.0' Slope= 0.0159 '/'
Inlet Invert= 372.00', Outlet Invert= 354.00'
Reach DO: NCDOT Road Ditch
Hydrograph
❑Inflow
- 2.19 cfs ❑outflow)
Inflow Area=6.257 ac
2 Avg. Flow Depth=0.36'
Max Vel=1 .99 fps
1.46 cfs n=0.035
L=1 ,130.0'
S=0.0159 '/'
Capacity=210.84 cfs
•
•
j�I//%��VAVAVA fff��fff�fff��ff�fff�ff VA V
0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 15
Summary for Reach D1: Draw
[62] Hint: Exceeded Reach DD OUTLET depth by 0.08' @ 12.94 hrs
Inflow Area = 17.971 ac, 0.00% Impervious, Inflow Depth > 0.34" for 1y 24h event
Inflow = 1.34 cfs @ 12.30 hrs, Volume= 0.515 af
Outflow = 0.65 cfs @ 12.81 hrs, Volume= 0.513 af, Atten= 52%, Lag= 30.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.21 fps, Min. Travel Time= 40.4 min
Avg. Velocity = 0.09 fps, Avg. Travel Time= 90.2 min
Peak Storage= 1,565 cf @ 12.81 hrs
Average Depth at Peak Storage= 0.11'
Bank-Full Depth= 3.00' Flow Area= 174.0 sf, Capacity= 252.99 cfs
28.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 10.0 '/' Top Width= 88.00'
Length= 500.0' Slope= 0.0620 '/'
Inlet Invert= 316.00', Outlet Invert= 285.00'
Reach D1: Draw
Hydrograph
❑Inflow
1.34 cfs o Outflow
Inflow Area=17.971 ac
Avg. Flow Depth=0.11'
Max Vel=0.21 fps
n=0.400
L=500.0'
LL 0.65 cfs S=0.0620 '/'
Capacity=252.99 cfs
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 16
Summary for Reach D2: Draw
[43] Hint: Has no inflow (Outflow=Zero)
Bank-Full Depth= 3.00' Flow Area= 126.0 sf, Capacity= 211.86 cfs
12.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 10.0 '/' Top Width= 72.00'
Length= 430.0' Slope= 0.0977 '/'
Inlet Invert= 327.00', Outlet Invert= 285.00'
Reach D2: Draw
/ Hydrograph
1-
D Outflow
Avg. Flow Depth=0.00'
Max Vel=0.00 fps
n=0.400
L=430.0'
S=0.0977 '/'
Capacity=211 .86 cfs
0.00 cfs (
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 17
Summary for Reach D3: Draw
[43] Hint: Has no inflow (Outflow=Zero)
Bank-Full Depth= 3.00' Flow Area= 195.0 sf, Capacity= 432.67 cfs
20.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 15.0 '/' Top Width= 110.00'
Length= 228.0' Slope= 0.1667 '/'
Inlet Invert= 353.00', Outlet Invert= 315.00'
Reach D3: Draw
/ Hydrograph
1-
D Outflow
Avg. Flow Depth=0.00'
Max Vel=0.00 fps
n=0.400
L=228.0'
S=0.1667 '/'
Capacity=432.67 cfs
0.00 cfs (
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 18
Summary for Reach D4: Ditch Next to Road
Inflow Area = 8.553 ac, 1.75% Impervious, Inflow Depth = 0.44" for 1y 24h event
Inflow = 2.65 cfs @ 12.16 hrs, Volume= 0.317 of
Outflow = 1.74 cfs @ 12.35 hrs, Volume= 0.317 af, Atten= 34%, Lag= 11.8 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.57 fps, Min. Travel Time= 14.5 min
Avg. Velocity = 0.21 fps, Avg. Travel Time= 40.0 min
Peak Storage= 1,516 cf @ 12.35 hrs
Average Depth at Peak Storage= 0.62'
Bank-Full Depth= 3.00' Flow Area= 36.0 sf, Capacity= 49.87 cfs
3.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 3.0 '/' Top Width= 21.00'
Length= 500.0' Slope= 0.0720 '/'
Inlet Invert= 351.00', Outlet Invert= 315.00'
Reach D4: Ditch Next to Road
Hydrograph
❑Inflow
2.65 cfs ❑outflow)
Inflow Area=8.553 ac
Avg. Flow Depth=0.62'
Max Vel=0.57 fps
21 1.74 cfs n=0.400
L=500.0'
- S=0.0720 '/'
1— Capacity=49.87 cfs
0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 19
Summary for Reach D5: Draw
[62] Hint: Exceeded Reach D1 OUTLET depth by 0.08' @ 14.48 hrs
[61] Hint: Exceeded Reach D2 outlet invert by 0.16' @ 13.97 hrs
Inflow Area = 17.971 ac, 0.00% Impervious, Inflow Depth > 0.34" for 1y 24h event
Inflow = 0.65 cfs @ 12.81 hrs, Volume= 0.513 af
Outflow = 0.42 cfs @ 13.97 hrs, Volume= 0.509 af, Atten= 36%, Lag= 69.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.24 fps, Min. Travel Time= 67.8 min
Avg. Velocity = 0.09 fps, Avg. Travel Time= 174.9 min
Peak Storage= 1,693 cf @ 13.97 hrs
Average Depth at Peak Storage= 0.16'
Bank-Full Depth= 3.00' Flow Area= 93.0 sf, Capacity= 120.90 cfs
10.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 7.0 '/' Top Width= 52.00'
Length= 982.0' Slope= 0.0570 '/'
Inlet Invert= 285.00', Outlet Invert= 229.00'

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 20
Reach D5: Draw
Hydrograph
— H H I ❑Inflow
0.7 0.65 cfs A' �A 0 outflow
0.65 IIbfI lA- CQ= 11 .9 1 — C
00.6 —t + —H Aug�Fl10vu�Dpi h=b.16'
0.5 j IJVMax YeII O.24 fis
0.45 0.42 cfs I H H H A°
r I 3 0 35 A 1 _H L l— 1— 1 Z1—_
T324)1
o
0.25 z
— — + —H 129'9? S
0.1
0.05 ' /
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 21
Summary for Reach D6: Draw
[61] Hint: Exceeded Reach D3 outlet invert by 0.11' @ 13.84 hrs
[62] Hint: Exceeded Reach D4 OUTLET depth by 0.02' @ 29.06 hrs
Inflow Area = 8.553 ac, 1.75% Impervious, Inflow Depth = 0.44" for 1y 24h event
Inflow = 1.74 cfs @ 12.35 hrs, Volume= 0.317 af
Outflow = 0.45 cfs @ 13.84 hrs, Volume= 0.317 af, Atten= 74%, Lag= 89.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.19 fps, Min. Travel Time= 152.4 min
Avg. Velocity = 0.09 fps, Avg. Travel Time= 307.4 min
Peak Storage= 4,130 cf @ 13.84 hrs
Average Depth at Peak Storage= 0.11'
Bank-Full Depth= 3.00' Flow Area= 159.0 sf, Capacity= 198.54 cfs
20.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 11.0 '/' Top Width= 86.00'
Length= 1,720.0' Slope= 0.0500 '/'
Inlet Invert= 315.00', Outlet Invert= 229.00'

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 22
Reach D6: Draw
Hydrograph
/ 1 1 ❑Inflow
1.74 cfs 0 outflow
I nil ow Are =8.553 a c
I 1 1 Avg1. Flov' Depth=b.1 1'
I I Max VeI=0.19 fpls
1 0=0,.400
1- I I 1 ( =1,720.0'
o
A Cpci y=19".54 c s
0.45 cfs
o l l/
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 23
Summary for Reach D7: Outfall to Avent Creek
[62] Hint: Exceeded Reach D5 OUTLET depth by 0.04' @ 15.04 hrs
[62] Hint: Exceeded Reach D6 OUTLET depth by 0.08' @ 14.15 hrs
Inflow Area = 26.524 ac, 0.57% Impervious, Inflow Depth > 0.37" for 1y 24h event
Inflow = 0.87 cfs @ 13.92 hrs, Volume= 0.826 af
Outflow = 0.87 cfs @ 14.03 hrs, Volume= 0.826 af, Atten= 0%, Lag= 6.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.23 fps, Min. Travel Time= 9.3 min
Avg. Velocity = 0.08 fps, Avg. Travel Time= 27.1 min
Peak Storage= 484 cf @ 14.03 hrs
Average Depth at Peak Storage= 0.19'
Bank-Full Depth= 3.00' Flow Area= 117.0 sf, Capacity= 132.42 cfs
18.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 7.0 '/' Top Width= 60.00'
Length= 130.0' Slope= 0.0385 '/'
Inlet Invert= 229.00', Outlet Invert= 224.00'

20241024_Harnett County_NW CC_Construction CondType 1124-hr ly 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 24
Reach D7: Outfall to Avent Creek
Hydroggrraph
— ❑Inflow `
0.95=z fl R7 rfs _ _ ❑outflow)
09 0.87 cfs 1 -h t t I[#Idw Ar 2S.5 4Ic-
0.85
o 8 !j 1 —[ rt t t AVg 110W D p#i14. ' -
°o 7V j! 1 A T 1 riViax V-elI O.23 fps0.654/
Tii
0.6
0
0.5 ' 1 1 1 —L1 ” �
ay
/ E �� 19
025✓
0.2✓ z — 1— 1 1 1
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 25
Summary for Reach DD: Diversion Ditch
Inflow Area = 9.848 ac, 0.00% Impervious, Inflow Depth = 0.29" for ly 24h event
Inflow = 1.33 cfs @ 12.27 hrs, Volume= 0.238 af
Outflow = 1.32 cfs @ 12.30 hrs, Volume= 0.238 af, Atten= 1%, Lag= 1.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 1.82 fps, Min. Travel Time= 2.2 min
Avg. Velocity = 1.01 fps, Avg. Travel Time= 3.9 min
Peak Storage= 175 cf @ 12.30 hrs
Average Depth at Peak Storage= 0.05'
Bank-Full Depth= 2.00' Flow Area= 44.0 sf, Capacity= 734.43 cfs
14.00' x 2.00' deep channel, n= 0.022 Earth, clean & straight
Side Slope Z-value= 5.0 3.0 '/' Top Width= 30.00'
Length= 240.0' Slope= 0.0375 '/'
Inlet Invert= 325.00', Outlet Invert= 316.00'
7
Reach DD: Diversion Ditch
Hydrograph
/ ❑Inflow
1.33 r:fs I ❑Outflow
1.32 cfs Inflow Area=9.848 ac
Avg. Flow Depth=0.05'
j Max Vel=1 .82 fps
1-
n=0.022
L=240.0'
° S=0.0375 '/'
Capacity=734.43 cfs
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 26
Summary for Reach SO: Access Drive Swale
Inflow Area = 2.296 ac, 6.53% Impervious, Inflow Depth = 0.61" for 1y 24h event
Inflow = 1.87 cfs @ 12.04 hrs, Volume= 0.117 of
Outflow = 1.31 cfs @ 12.12 hrs, Volume= 0.117 af, Atten= 30%, Lag= 4.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 1.05 fps, Min. Travel Time= 8.5 min
Avg. Velocity = 0.34 fps, Avg. Travel Time= 26.4 min
Peak Storage= 672 cf @ 12.12 hrs
Average Depth at Peak Storage= 0.24'
Bank-Full Depth= 2.00' Flow Area= 21.0 sf, Capacity= 72.46 cfs
4.50' x 2.00' deep channel, n= 0.030 Short grass
Side Slope Z-value= 3.0 '/' Top Width= 16.50'
Length= 540.0' Slope= 0.0037 '/'
Inlet Invert= 358.00', Outlet Invert= 356.00'
Reach SO: Access Drive Swale
Hydrograph
❑Inflow
1.87 cfs ❑Outflow
2 Inflow Area=2.296 ac
Avg. Flow Depth=0.24'
Max Vet=1 .05 fps
1.31 cfs
n=0.030
L=540.0'
° S=0.0037 '/'
Capacity=72.46 cfs
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 27
Summary for Reach S1: Swale
Inflow Area = 6.362 ac, 0.00% Impervious, Inflow Depth = 0.62" for ly 24h event
Inflow = 4.01 cfs @ 12.10 hrs, Volume= 0.328 af
Outflow = 3.93 cfs @ 12.12 hrs, Volume= 0.328 af, Atten= 2%, Lag= 1.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 3.52 fps, Min. Travel Time= 1.8 min
Avg. Velocity = 1.23 fps, Avg. Travel Time= 5.3 min
Peak Storage= 435 cf @ 12.12 hrs
Average Depth at Peak Storage= 0.22'
Bank-Full Depth= 2.00' Flow Area= 28.0 sf, Capacity= 340.18 cfs
4.00' x 2.00' deep channel, n= 0.022 Earth, clean & straight
Side Slope Z-value= 5.0 '/' Top Width= 24.00'
Length= 390.0' Slope= 0.0269 '/'
Inlet Invert= 330.50', Outlet Invert= 320.00'
Reach S1: Swale
Hydrograph
❑Inflow
4.01 cfs ❑Outflow
3.93 cfs Inflow Area=6.362 ac
4 Avg. Flow Depth=0.22'
Maxl= 2 e 3 5 fps
3 n=0.022
j� L=390.0'
2 S=0.0269 '/'
Capacity=340.18 cfs
jj
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 28
Summary for Reach S2: CC Swale
Inflow Area = 6.362 ac, 0.00% Impervious, Inflow Depth = 0.62" for ly 24h event
Inflow = 4.13 cfs @ 12.07 hrs, Volume= 0.328 af
Outflow = 4.01 cfs @ 12.10 hrs, Volume= 0.328 af, Atten= 3%, Lag= 1.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 3.67 fps, Min. Travel Time= 2.1 min
Avg. Velocity = 1.33 fps, Avg. Travel Time= 5.7 min
Peak Storage= 497 cf @ 12.10 hrs
Average Depth at Peak Storage= 0.31'
Bank-Full Depth= 1.00' Flow Area= 7.0 sf, Capacity= 49.84 cfs
2.00' x 1.00' deep channel, n= 0.022 Earth, clean & straight
Side Slope Z-value= 5.0 '/' Top Width= 12.00'
Length= 455.0' Slope= 0.0233 '/'
Inlet Invert= 345.00', Outlet Invert= 334.40'
Reach S2: CC Swale
Hydrograph
❑Inflow
4.13 cfs ❑Outflow
4.01 cfs Inflow Area=6.362 ac
4 Avg. Flow Depth=0.31'
Max Vel=3.67 fps
3- n=0.022
3 _ L=455.0'
2- j S=0.0233 '/'
Capacity=49.84 cfs
1-
•
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 29
Summary for Pond 1 P: Pond
[62] Hint: Exceeded Reach S1 OUTLET depth by 3.80' @ 24.94 hrs
Inflow Area = 8.123 ac, 0.00% Impervious, Inflow Depth = 0.56" for 1y 24h event
Inflow = 4.36 cfs @ 12.11 hrs, Volume= 0.380 af
Outflow = 0.03 cfs @ 24.57 hrs, Volume= 0.277 af, Atten= 99%, Lag= 747.7 min
Primary = 0.03 cfs @ 24.57 hrs, Volume= 0.277 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Starting Elev= 322.14' Surf.Area= 8,230 sf Storage= 14,450 cf
Peak Elev= 323.80' @ 24.57 hrs Surf.Area= 10,554 sf Storage= 29,966 cf (15,516 cf above start)
Flood Elev= 327.00' Surf.Area= 17,014 sf Storage= 73,645 cf (59,195 cf above start)
Plug-Flow detention time= (not calculated: initial storage exceeds outflow)
Center-of-Mass det. time= 4,408.1 min ( 5,314.0 - 905.9 )
Volume Invert Avail.Storage Storage Description _
#1 318.50' 73,645 cf Custom Stage Data (Prismatic)Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
318.50 1,496 0 0
319.00 1,770 817 817
320.00 2,590 2,180 2,997
321.00 4,996 3,793 6,790
322.00 8,046 6,521 13,311
323.00 9,363 8,705 22,015
324.00 10,855 10,109 32,124
325.00 12,730 11,793 43,917
326.00 14,856 13,793 57,710
327.00 17,014 15,935 73,645
Device Routing Invert Outlet Devices
#1 Primary 318.00' 24.0" Round Culvert
L= 66.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 318.00' / 317.00' S= 0.0152 '/' Cc= 0.900
n= 0.011 Concrete pipe, straight & clean, Flow Area= 3.14 sf
#2 Device 1 322.14' 0.5" Vert. Orifice/Grate X 3.00 C= 0.600
#3 Device 1 325.50' 48.0" x 48.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#4 Secondary 326.50' 25.0' long x 15.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 30
Primary OutFlow Max=0.03 cfs @ 24.57 hrs HW=323.80' TW=316.04' (Dynamic Tailwater)
L =Culvert (Passes 0.03 cfs of 33.14 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.03 cfs @ 6.16 fps)
3=Orifice/Grate ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=322.14' TW=325.00' (Dynamic Tailwater)
4-4=Broad-Crested Rectangular Weir( Controls 0.00 cfs)
Pond 1 P: Pond
Hydrograph
/36cfs ❑inflow
❑Outflow
- hiflow Area=8.123 ac ose ondary
j Peak EIev=323.80'
4 Storage=29,966 cf
3
2
o
3
0
LL 2
1— I I I
4 nn' rf
0.03 cfs
0.00 cfs �
o 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 31
Summary for Pond C 1: Replaced Culvert
[62] Hint: Exceeded Reach DO OUTLET depth by 0.29' @ 12.11 hrs
Inflow Area = 8.553 ac, 1.75% Impervious, Inflow Depth = 0.44" for 1y 24h event
Inflow = 2.65 cfs @ 12.16 hrs, Volume= 0.317 of
Outflow = 2.65 cfs @ 12.16 hrs, Volume= 0.317 af, Atten= 0%, Lag= 0.0 min
Primary = 2.65 cfs @ 12.16 hrs, Volume= 0.317 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Peak Elev= 354.63' @ 12.16 hrs
Flood Elev= 357.00'
Device Routing Invert Outlet Devices
#1 Primary 354.00' 30.0" Round Culvert
L= 137.0' RCP, end-section conforming to fill, Ke= 0.500
Inlet/ Outlet Invert= 354.00' / 351.50' S= 0.0182 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 4.91 sf
#2 Secondary 357.00' 50.0' long x 100.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=2.65 cfs @ 12.16 hrs HW=354.63' TW=351.45' (Dynamic Tailwater)
4-1=Culvert (Inlet Controls 2.65 cfs @ 2.71 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=354.00' TW=351.00' (Dynamic Tailwater)
4-2=Broad-Crested Rectangular Weir( Controls 0.00 cfs)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 32
Pond C 1: Replaced Culvert
Hydrograph
7 Aq rf� ❑Inflow
9 Rai rf E Outflow
2.65 cfs Inflow Area=8.553 ac o Primary
e Secondary
Peak Elev=354.63'
2 -
i
1
o
1
A
0.00 cfs ; /��/����/����/����/��
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction CondType 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 33
Summary for Pond C2: Proposed Culvert
[62] Hint: Exceeded Reach S2 OUTLET depth by 0.48' @ 12.10 hrs
Inflow Area = 6.362 ac, 0.00% Impervious, Inflow Depth = 0.62" for 1y 24h event
Inflow = 4.01 cfs @ 12.10 hrs, Volume= 0.328 af
Outflow = 4.01 cfs @ 12.10 hrs, Volume= 0.328 af, Atten= 0%, Lag= 0.0 min
Primary = 4.01 cfs @ 12.10 hrs, Volume= 0.328 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Peak Elev= 335.19' @ 12.10 hrs
Flood Elev= 337.00'
Device Routing Invert Outlet Devices
#1 Primary 334.40' 30.0" Round Culvert
L= 45.0' RCP, end-section conforming to fill, Ke= 0.500
Inlet/Outlet Invert= 334.40' / 330.50' S= 0.0867 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 4.91 sf
Primary OutFlow Max=4.01 cfs @ 12.10 hrs HW=335.19' TW=330.72' (Dynamic Tailwater)
4-1=Culvert (Inlet Controls 4.01 cfs @ 3.02 fps)
Pond C2: Proposed Culvert
Hydrograph
n1 rf ❑Inflow
❑Primary
4.01 cfs 4-
Inflow Area=6.362 ac
Peak Elev=335.19'
30.0"
3
_ /
Round Culvert
3 _ n=0.012
2 , L=45.0'
_ S=0.0867 '/'
1-
It
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 34
Time span=0.00-180.00 hrs, dt=0.01 hrs, 18001 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Subcatchment 1: Area 1 Runoff Area=9.848 ac 0.00% Impervious Runoff Depth=2.24"
Flow Length=830' Tc=24.0 min CN=58 Runoff=20.88 cfs 1.839 af
Subcatchment 1.1: Area 1.1 Runoff Area=1.761 ac 0.00% Impervious Runoff Depth=2.43"
Flow Length=286' Tc=9.2 min CN=60 Runoff=6.73 cfs 0.356 af
Subcatchment2: Area 2 Runoff Area=5.131 ac 0.00% Impervious Runoff Depth=2.91"
Flow Length=500' Tc=11.8 min CN=65 Runoff=21.52 cfs 1.244 af
Subcatchment3: Area 3 Runoff Area=1.231 ac 0.00% Impervious Runoff Depth=3.93"
Flow Length=326' Tc=22.4 min CN=75 Runoff=5.04 cfs 0.403 af
Subcatchment4: Area 4 Runoff Area=6.257 ac 0.00% Impervious Runoff Depth=2.52"
Flow Length=606' Tc=13.1 min CN=61 Runoff=21.47 cfs 1.316 af
Subcatchment5: Area 4 Runoff Area=2.296 ac 6.53% Impervious Runoff Depth=3.11"
Flow Length=275' Tc=10.3 min CN=67 Runoff=10.89 cfs 0.595 af
Reach DO: NCDOT Road Ditch Avg. Flow Depth=1.13' Max Vel=3.84 fps Inflow=21.47 cfs 1.316 af
n=0.035 L=1,130.0' S=0.0159 '/' Capacity=210.84 cfs Outflow=18.97 cfs 1.316 af
Reach D1: Draw Avg. Flow Depth=0.77' Max Vel=0.68 fps Inflow=21.27 cfs 3.419 af
n=0.400 L=500.0' S=0.0620 '/' Capacity=252.99 cfs Outflow=18.65 cfs 3.416 af
Reach D2: Draw Avg. Flow Depth=0.00' Max Vet=0.00 fps
n=0.400 L=430.0' S=0.0977 'I Capacity=211.86 cfs Outflow=0.00 cfs 0.000 af
Reach D3: Draw Avg. Flow Depth=0.00' Max Vel=0.00 fps
n=0.400 L=228.0' S=0.1667 'I Capacity=432.67 cfs Outflow=0.00 cfs 0.000 af
Reach D4: Ditch Next to Road Avg. Flow Depth=2.15' Max Vel=1.14 fps Inflow=28.18 cfs 1.910 af
n=0.400 L=500.0' S=0.0720 '/' Capacity=49.87 cfs Outflow=23.15 cfs 1.910 af
Reach D5: Draw Avg. Flow Depth=1.07' Max Vel=0.73 fps Inflow=18.65 cfs 3.416 af
n=0.400 L=982.0' S=0.0570 '/' Capacity=120.90 cfs Outflow=13.62 cfs 3.409 af
Reach D6: Draw Avg. Flow Depth=0.58' Max Vet=0.50 fps Inflow=23.15 cfs 1.910 af
n=0.400 L=1,720.0' S=0.0500 '/' Capacity=198.54 cfs Outflow=7.76 cfs 1.910 af
Reach D7: Outfall to Avent Creek Avg. Flow Depth=1.18' Max Vel=0.68 fps Inflow=21.17 cfs 5.319 af
n=0.400 L=130.0' S=0.0385 '/' Capacity=132.42 cfs Outflow=21.09 cfs 5.318 af
Reach DD: Diversion Ditch Avg. Flow Depth=0.27' Max Vet=5.17 fps Inflow=20.88 cfs 1.839 af
n=0.022 L=240.0' S=0.0375 '/' Capacity=734.43 cfs Outflow=20.83 cfs 1.839 af
Reach SO: Access Drive Swale Avg. Flow Depth=0.73' Max Vel=1.99 fps Inflow=10.89 cfs 0.595 af
n=0.030 L=540.0' S=0.0037'/' Capacity=72.46 cfs Outflow=9.71 cfs 0.595 af

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 35
Reach S1: Swale Avg. Flow Depth=0.59' Max Vel=6.11 fps Inflow=25.18 cfs 1.648 af
n=0.022 L=390.0' S=0.0269 '/' Capacity=340.18 cfs Outflow=25.00 cfs 1.648 af
Reach S2: CC Swale Avg. Flow Depth=0.74' Max Vel=5.98 fps Inflow=25.47 cfs 1.648 af
n=0.022 L=455.0' S=0.0233 '/' Capacity=49.84 cfs Outflow=25.18 cfs 1.648 af
Pond 1 P: Pond Peak Elev=325.76' Storage=54,258 cf Inflow=30.53 cfs 2.004 af
Primary=7.12 cfs 1.580 af Secondary=0.00 cfs 0.000 af Outflow=7.12 cfs 1.580 af
Pond C 1: Replaced Culvert Peak Elev=356.67' Inflow=28.18 cfs 1.910 af
Primary=28.18 cfs 1.910 af Secondary=0.00 cfs 0.000 af Outflow=28.18 cfs 1.910 af
Pond C2: Proposed Culvert Peak Elev=336.77' Inflow=25.18 cfs 1.648 af
30.0" Round Culvert n=0.012 L=45.0' S=0.0867 '/' Outflow=25.18 cfs 1.648 af
Total Runoff Area = 26.524 ac Runoff Volume = 5.753 af Average Runoff Depth = 2.60"
99.43% Pervious = 26.374 ac 0.57% Impervious = 0.150 ac

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 36
Summary for Subcatchment 1: Area 1
Runoff = 20.88 cfs @ 12.19 hrs, Volume= 1.839 af, Depth= 2.24"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
5.230 61 >75% Grass cover, Good, HSG B
4.618 55 Woods, Good, HSG B
9.848 58 Weighted Average
9.848 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
13.3 100 0.0200 0.13 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.70"
10.7 730 0.0520 1.14 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
24.0 830 Total
Subcatchment 1: Area 1
Hydrograph
23 ■Runoff
22. 20.88 cfs
2 0 T�yp� i iE a. r
18/
17 ilunbffiAria 19.848 c
15
14V % 11 unlog Vflume 8. 9 of
12V_ F�no -fep "
Li10V —Plow Len th=830'
— 1�c 4 min —_
6 % H CiV---6-B
24/-17
— -
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 37
Summary for Subcatchment 1.1: Area 1.1
Runoff = 6.73 cfs @ 12.01 hrs, Volume= 0.356 af, Depth= 2.43"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
1.314 61 >75% Grass cover, Good, HSG B
0.407 55 Woods, Good, HSG B
0.040 96 Gravel surface, HSG B
1.761 60 Weighted Average
1.761 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
8.0 100 0.0700 0.21 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.70"
1.2 186 0.2500 2.50 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
9.2 286 Total
Subcatchment 1.1: Area 1.1
Hydrograph
❑Runoff
7- 6.73 cfs
e Type II 14-hr
61/ j 25y 24h Rainfall=6.75"
% —I Run-bff Area=1 .761 ac
/ F�uI1off Vo,Iume=0.356 oaf
Runoff Depth=2.43"
= % _Plow Length=286'
3
i-c=9.2 m i n
2 C14=6O
1
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 38
Summary for Subcatchment 2: Area 2
Runoff = 21.52 cfs @ 12.04 hrs, Volume= 1.244 af, Depth= 2.91"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
2.748 61 >75% Grass cover, Good, HSG B
1.486 55 Woods, Good, HSG B
0.897 96 Gravel surface, HSG B
5.131 65 Weighted Average
5.131 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
2.7 400 0.0233 2.46 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
11.8 500 Total
Subcatchment 2: Area 2
Hydrograph
241/1 — — —1 — — — •Runoff
23 21.5e-fsi
22_ / — —
21
20_'
19_ 2y4h Rnfl=�.7 "
18-
17= — — — —I -Run-off-Area=5.1-31 c -
;4= i i _ upo#1 V lu e 1.2144 f =
12= i Rer4-h2.91"
0 1101V, / I Length=500'
Li owLe 500
$4/ i c=i1$ min
7 r eiV=65
4 0 rt
2 o � J
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 39
Summary for Subcatchment 3: Area 3
Runoff = 5.04 cfs @ 12.15 hrs, Volume= 0.403 af, Depth= 3.93"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
0.000 55 Woods, Good, HSG B
0.482 96 Gravel surface, HSG B
0.749 61 >75% Grass cover, Good, HSG B
1.231 75 Weighted Average
1.231 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
20.0 100 0.0200 0.08 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.70"
2.4 226 0.0973 1.56 Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.4 326 Total
Subcatchment 3: Area 3
Hydrograph
0 Runoff
5.04 cfs
5 Type II 24-hr
1 2y 24h Rainfall=6.75"
4 j Runoff Arela=1.231 do
F�uI1off Vo,Iume70.403 oaf
3� % Rulnoff Depth=3.93"
_ Flow Length=326'
2- Tic==12.4 mein
CN='5
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 40
Summary for Subcatchment 4: Area 4
Runoff = 21.47 cfs @ 12.06 hrs, Volume= 1.316 af, Depth= 2.52"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
6.257 61 >75% Grass cover, Good, HSG B
6.257 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
4.0 506 0.0198 2.11 Shallow Concentrated Flow,
Grassed Waterway Kv= 15.0 fps
13.1 606 Total
Subcatchment 4: Area 4
Hydrograph
24 - •Runoff
23- 21.47 cfs _
22211 % —
— H
114 r
20_
19_% - 2y4h Ranfill4.7 " -
— — —
17_ -Run-off-Ar4a=6.257
15=� off Vol ui a 1 -
1 ='
w4=
13_ not Beph '5?n,
312 lowh-
666
0 1110
1
LL '9� L—e t
ic3. mnm
7=-
4
3
2 I
0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 41
Summary for Subcatchment 5: Area 4
Runoff = 10.89 cfs @ 12.02 hrs, Volume= 0.595 af, Depth= 3.11"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Type II 24-hr 25y 24h Rainfall=6.75"
Area (ac) CN Description
1.920 61 >75% Grass cover, Good, HSG B
0.226 96 Gravel surface, HSG B
0.150 98 Paved parking, HSG B
2.296 67 Weighted Average
2.146 93.47% Pervious Area
0.150 6.53% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.1 100 0.0200 0.18 Sheet Flow,
Grass: Short n= 0.150 P2= 3.70"
1.2 175 0.0285 2.53 Shallow Concentrated Flow,
Grassed Waterway Kv= 15.0 fps
10.3 275 Total
Subcatchment 5: Area 4
Hydrograph
12
■Runoff
10.89 cfs
11 pi 11_ 4 r -
y-24hiRai nfal l= .75"
I -Runoff-Area=2.2-96 ac -
$_ j -u+noff V-gIuie=0.5 5-af -
w pepth= .11"
6_ ;
o
low Length=27-5'
/
41/- i�c=10.3 min -
C-V==7 —
3
2_/
0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 42
Summary for Reach DO: NCDOT Road Ditch
Inflow Area = 6.257 ac, 0.00% Impervious, Inflow Depth = 2.52" for 25y 24h event
Inflow = 21.47 cfs @ 12.06 hrs, Volume= 1.316 af
Outflow = 18.97 cfs @ 12.11 hrs, Volume= 1.316 af, Atten= 12%, Lag= 3.2 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 3.84 fps, Min. Travel Time= 4.9 min
Avg. Velocity = 1.34 fps, Avg. Travel Time= 14.1 min
Peak Storage= 5,577 cf @ 12.11 hrs
Average Depth at Peak Storage= 1.13'
Bank-Full Depth= 3.00' Flow Area= 30.0 sf, Capacity= 210.84 cfs
1.00' x 3.00' deep channel, n= 0.035 Earth, dense weeds
Side Slope Z-value= 3.0 '/' Top Width= 19.00'
Length= 1,130.0' Slope= 0.0159 '/'
Inlet Invert= 372.00', Outlet Invert= 354.00'
Reach DO: NCDOT Road Ditch
Hydrograph
I I I
rl Inflow
241121.47 cfs 1 — — ❑outflow
22H — n 131 Are 6.2-67 ac
20 18.97 cfs —I 4 4 Avc Fio Dipth=�l:9!3'
19_ I /
18= I I —I I I RbxA/463A34.
1716
15= , —I I 11=9'05—
w 14- I / 1 i1
13
12 / I P_ 1
_ ,1,
a 11= IH V p.�1
_ /% I �p�ci =�a l 4 c
a %/ — — I t - t — —
3=
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 43
Summary for Reach D1: Draw
[62] Hint: Exceeded Reach DD OUTLET depth by 0.59' © 12.49 hrs
Inflow Area = 17.971 ac, 0.00% Impervious, Inflow Depth > 2.28" for 25y 24h event
Inflow = 21.27 cfs @ 12.32 hrs, Volume= 3.419 of
Outflow = 18.65 cfs @ 12.43 hrs, Volume= 3.416 af, Atten= 12%, Lag= 6.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.68 fps, Min. Travel Time= 12.2 min
Avg. Velocity = 0.11 fps, Avg. Travel Time= 78.2 min
Peak Storage= 13,700 cf @ 12.43 hrs
Average Depth at Peak Storage= 0.77'
Bank-Full Depth= 3.00' Flow Area= 174.0 sf, Capacity= 252.99 cfs
28.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 10.0 '/' Top Width= 88.00'
Length= 500.0' Slope= 0.0620 '/'
Inlet Invert= 316.00', Outlet Invert= 285.00'
7%.*%.%*%%%-%%*%%%%%%%* ***•••..
Reach D1: Draw
Hydrograph
H
■Inflow
23lz 21.27 cfs ■outflow
22 I 11i�nflwLAre�a147� 7�'I a`�
21=
20- 18.65 cfs 4 Av Fio th=V./ 17'
19
;; x1/4 OX8 Ts
16 15t H 0I
H n11— .400—
a 1413
' I %%
11
P"ci!"Y=12 ?' ?-' s7
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 44
Summary for Reach D2: Draw
[43] Hint: Has no inflow (Outflow=Zero)
Bank-Full Depth= 3.00' Flow Area= 126.0 sf, Capacity= 211.86 cfs
12.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 10.0 '/' Top Width= 72.00'
Length= 430.0' Slope= 0.0977 '/'
Inlet Invert= 327.00', Outlet Invert= 285.00'
Reach D2: Draw
/ Hydrograph
1-
D Outflow
Avg. Flow Depth=0.00'
Max Vel=0.00 fps
n=0.400
L=430.0'
S=0.0977 '/'
Capacity=211 .86 cfs
0.00 cfs (
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 45
Summary for Reach D3: Draw
[43] Hint: Has no inflow (Outflow=Zero)
Bank-Full Depth= 3.00' Flow Area= 195.0 sf, Capacity= 432.67 cfs
20.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 15.0 '/' Top Width= 110.00'
Length= 228.0' Slope= 0.1667 '/'
Inlet Invert= 353.00', Outlet Invert= 315.00'
Reach D3: Draw
/ Hydrograph
1-
D Outflow
Avg. Flow Depth=0.00'
Max Vel=0.00 fps
n=0.400
L=228.0'
S=0.1667 '/'
Capacity=432.67 cfs
0.00 cfs (
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 46
Summary for Reach D4: Ditch Next to Road
Inflow Area = 8.553 ac, 1.75% Impervious, Inflow Depth = 2.68" for 25y 24h event
Inflow = 28.18 cfs @ 12.09 hrs, Volume= 1.910 of
Outflow = 23.15 cfs @ 12.17 hrs, Volume= 1.910 af, Atten= 18%, Lag= 4.8 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 1.14 fps, Min. Travel Time= 7.3 min
Avg. Velocity = 0.30 fps, Avg. Travel Time= 28.2 min
Peak Storage= 10,151 cf @ 12.17 hrs
Average Depth at Peak Storage= 2.15'
Bank-Full Depth= 3.00' Flow Area= 36.0 sf, Capacity= 49.87 cfs
3.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 3.0 '/' Top Width= 21.00'
Length= 500.0' Slope= 0.0720 '/'
Inlet Invert= 351.00', Outlet Invert= 315.00'
Reach D4: Ditch Next to Road
Hydrograph
_I _L Inflow
30 28.18 cfs f ❑outflow
28
4 n4Iol Ar-e =8.-5 3--a c-
_
26 — — H -� Avd
24� 23.15 cfs
22Lax V =1 pl�
20= 0 _I 1 1 r T rn Q.4g0
18,
16
LLo
14= ØØ =000
'/12
a ' y=4g.817-cfs-
t -
2= %�,�I//
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 47
Summary for Reach D5: Draw
[62] Hint: Exceeded Reach D1 OUTLET depth by 0.49' @ 12.96 hrs
[61] Hint: Exceeded Reach D2 outlet invert by 1.07' @ 12.71 hrs
Inflow Area = 17.971 ac, 0.00% Impervious, Inflow Depth > 2.28" for 25y 24h event
Inflow = 18.65 cfs @ 12.43 hrs, Volume= 3.416 af
Outflow = 13.62 cfs @ 12.71 hrs, Volume= 3.409 af, Atten= 27%, Lag= 17.1 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.73 fps, Min. Travel Time= 22.5 min
Avg. Velocity = 0.12 fps, Avg. Travel Time= 135.7 min
Peak Storage= 18,360 cf @ 12.71 hrs
Average Depth at Peak Storage= 1.07'
Bank-Full Depth= 3.00' Flow Area= 93.0 sf, Capacity= 120.90 cfs
10.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 7.0 '/' Top Width= 52.00'
Length= 982.0' Slope= 0.0570 '/'
Inlet Invert= 285.00', Outlet Invert= 229.00'

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 48
Reach D5: Draw
Hydrograph
+ - 0 Inflow
� 18.65 cfs 1 _❑outflow
20i9 — lnfl w4r 371 °c_
1s
18= /'�V FkovO*t&lA y r
16/ I -r T Mx f ei OI73If s 15i 13.62 cfs
4 13 -/ ��/% 1— — 1 1 —1 — — -L H H H H Il -O.4OOI
11 - — — — - 44 - I— 1-1 $2.Q—
° 1 I j -0 CE57 11—
$V I �pci =fit cfs
Lt I j t _L H H H H — 1— 1 - 1
0 _. (._. ��
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 49
Summary for Reach D6: Draw
[61] Hint: Exceeded Reach D3 outlet invert by 0.58' @ 12.57 hrs
[62] Hint: Exceeded Reach D4 OUTLET depth by 0.03' @ 27.59 hrs
Inflow Area = 8.553 ac, 1.75% Impervious, Inflow Depth = 2.68" for 25y 24h event
Inflow = 23.15 cfs @ 12.17 hrs, Volume= 1.910 of
Outflow = 7.76 cfs @ 12.57 hrs, Volume= 1.910 af, Atten= 66%, Lag= 23.7 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.50 fps, Min. Travel Time= 57.1 min
Avg. Velocity = 0.12 fps, Avg. Travel Time= 244.8 min
Peak Storage= 26,581 cf @ 12.57 hrs
Average Depth at Peak Storage= 0.58'
Bank-Full Depth= 3.00' Flow Area= 159.0 sf, Capacity= 198.54 cfs
20.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 11.0 '/' Top Width= 86.00'
Length= 1,720.0' Slope= 0.0500 '/'
Inlet Invert= 315.00', Outlet Invert= 229.00'

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 50
Reach D6: Draw
Hydrograph
I
0 Inflow
24� 23.15 cfs 0 Outflow
l
-InftoAlre =8 s58--alc--
20 , —t kv6 Ftov�D6pt1�--b5i3T-
18:/ 1 1 1 1 I Maxl VeI=0.5O fills
16" - 1 -1 4 4 I- 11=9.400-
314� j 1 1 -1 17 T I- r1 ?G.
10 — I I A A A L i_ 'c'ta351°►ciV'
7.76 cfs —1 CapaaCiy=19,.54 C!s
8 - I
6L. ,
1 1 1 1 1 1 1 1 1 1
4�
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 51
Summary for Reach D7: Outfall to Avent Creek
[62] Hint: Exceeded Reach D5 OUTLET depth by 0.12' @ 12.96 hrs
[62] Hint: Exceeded Reach D6 OUTLET depth by 0.62' @ 12.78 hrs
Inflow Area = 26.524 ac, 0.57% Impervious, Inflow Depth > 2.41" for 25y 24h event
Inflow = 21.17 cfs @ 12.68 hrs, Volume= 5.319 of
Outflow = 21.09 cfs @ 12.72 hrs, Volume= 5.318 af, Atten= 0%, Lag= 2.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.68 fps, Min. Travel Time= 3.2 min
Avg. Velocity = 0.10 fps, Avg. Travel Time= 22.3 min
Peak Storage= 4,048 cf @ 12.72 hrs
Average Depth at Peak Storage= 1.18'
Bank-Full Depth= 3.00' Flow Area= 117.0 sf, Capacity= 132.42 cfs
18.00' x 3.00' deep channel, n= 0.400 Sheet flow: Woods+light brush
Side Slope Z-value= 7.0 '/' Top Width= 60.00'
Length= 130.0' Slope= 0.0385 '/'
Inlet Invert= 229.00', Outlet Invert= 224.00'

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 52
Reach D7: Outfall to Avent Creek
Hydrograph
1 I —1 ± T
4117r Outflow
h
2221_ 21.09 cfs ❑Inflow 1 1 1 — 1�iifIiW kr =261-i4 . C-
1204 9 I % — 1 1 —I H 4 4 kv Fkov ►dDJ tI CIA ill'
17 1 1 1 Nf x1A/ dX8Tpls-
161
15 % — 1 1 H H H- + H- H H — fl=OI.400-
° 11.1 0. I % 0 1
11
94
81 — — 1 —1 —1 —1 4 4 9Pci =1-3?-4?-,-
64
3
2✓ ' %/ i //
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 53
Summary for Reach DD: Diversion Ditch
Inflow Area = 9.848 ac, 0.00% Impervious, Inflow Depth = 2.24" for 25y 24h event
Inflow = 20.88 cfs @ 12.19 hrs, Volume= 1.839 of
Outflow = 20.83 cfs @ 12.20 hrs, Volume= 1.839 af, Atten= 0%, Lag= 0.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 5.17 fps, Min. Travel Time= 0.8 min
Avg. Velocity = 1.64 fps, Avg. Travel Time= 2.4 min
Peak Storage= 966 cf @ 12.20 hrs
Average Depth at Peak Storage= 0.27'
Bank-Full Depth= 2.00' Flow Area= 44.0 sf, Capacity= 734.43 cfs
14.00' x 2.00' deep channel, n= 0.022 Earth, clean & straight
Side Slope Z-value= 5.0 3.0 '/' Top Width= 30.00'
Length= 240.0' Slope= 0.0375 '/'
Inlet Invert= 325.00', Outlet Invert= 316.00'
Reach DD: Diversion Ditch
Hydrograph
r,Inflow
22- 20.83 cfs f� � 4 4 � ❑outflo23 An RR w
21 n to �1C@a=9.&48ac
19_ I %� H ,Svc, Fkno pth=b.2tr'
18_
17= % I I —I - MaXI-/e=54 74 s-
16
15 I —I rt fi fi 111=9.$22-
14
13
gr-
" 10_ %� _ rt fi � t )I-J
8_ ØØ,
I I 4 4 d— l 1
I1rtrtrtfi
0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 54
Summary for Reach SO: Access Drive Swale
Inflow Area = 2.296 ac, 6.53% Impervious, Inflow Depth = 3.11" for 25y 24h event
Inflow = 10.89 cfs @ 12.02 hrs, Volume= 0.595 af
Outflow = 9.71 cfs @ 12.07 hrs, Volume= 0.595 af, Atten= 11%, Lag= 2.6 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 1.99 fps, Min. Travel Time= 4.5 min
Avg. Velocity = 0.51 fps, Avg. Travel Time= 17.8 min
Peak Storage= 2,638 cf @ 12.07 hrs
Average Depth at Peak Storage= 0.73'
Bank-Full Depth= 2.00' Flow Area= 21.0 sf, Capacity= 72.46 cfs
4.50' x 2.00' deep channel, n= 0.030 Short grass
Side Slope Z-value= 3.0 '/' Top Width= 16.50'
Length= 540.0' Slope= 0.0037 '/'
Inlet Invert= 358.00', Outlet Invert= 356.00'
Reach SO: Access Drive Swale
Hydrograph
❑Inflow
12- 10.89 cfs - Eloutflow
ni o lRtL Are 2 2.76_ c_
10
j
9.71 cfs Svc, . F�ev�p�Erptl�= 7�i'
I I - H H H MaxWet=199-f s
$- I /
I � _ I I I I I I I I m=Q•�I�
3 6
_ /' I I IAA H L 1-1=54o.9'
5- I I - H H 5=0.0037 '/'
4- I I —I 7 Ca�acity=72.46 cfs
3-
2-
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 55
Summary for Reach S1: Swale
Inflow Area = 6.362 ac, 0.00% Impervious, Inflow Depth = 3.11" for 25y 24h event
Inflow = 25.18 cfs @ 12.06 hrs, Volume= 1.648 of
Outflow = 25.00 cfs @ 12.08 hrs, Volume= 1.648 af, Atten= 1%, Lag= 0.8 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 6.11 fps, Min. Travel Time= 1.1 min
Avg. Velocity = 1.77 fps, Avg. Travel Time= 3.7 min
Peak Storage= 1,596 cf @ 12.08 hrs
Average Depth at Peak Storage= 0.59'
Bank-Full Depth= 2.00' Flow Area= 28.0 sf, Capacity= 340.18 cfs
4.00' x 2.00' deep channel, n= 0.022 Earth, clean & straight
Side Slope Z-value= 5.0 '/' Top Width= 24.00'
Length= 390.0' Slope= 0.0269 '/'
Inlet Invert= 330.50', Outlet Invert= 320.00'
7%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\
Reach S1: Swale
Hydrograph
F
rl Inflow
28A.18 cfS 0 outflow
26, 25.00 cfs
24= I AV FrovIrDpth=b.5b'
22_ I //��
20= /�/ — —L 4 + T MxWA 1 4 s-
18_ T T T T T T T O.O 2
14 �-
14- tH=390.Q'
a 12- T T�=CitCf2 ,/,
appci =34�1 c s
6= T T T
4-
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type 1124-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 56
Summary for Reach S2: CC Swale
Inflow Area = 6.362 ac, 0.00% Impervious, Inflow Depth = 3.11" for 25y 24h event
Inflow = 25.47 cfs @ 12.05 hrs, Volume= 1.648 af
Outflow = 25.18 cfs @ 12.06 hrs, Volume= 1.648 af, Atten= 1%, Lag= 0.9 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Max. Velocity= 5.98 fps, Min. Travel Time= 1.3 min
Avg. Velocity = 1.88 fps, Avg. Travel Time= 4.0 min
Peak Storage= 1,916 cf @ 12.06 hrs
Average Depth at Peak Storage= 0.74'
Bank-Full Depth= 1.00' Flow Area= 7.0 sf, Capacity= 49.84 cfs
2.00' x 1.00' deep channel, n= 0.022 Earth, clean & straight
Side Slope Z-value= 5.0 '/' Top Width= 12.00'
Length= 455.0' Slope= 0.0233 '/'
Inlet Invert= 345.00', Outlet Invert= 334.40'
7%%%%%%%%%%%%%%%* *%%-%%%%%%%\
Reach S2: CC Swale
Hydrograph
r,Inflow
28 / 25.47 cfs ❑outflow
26. 25.18 cfs
24_ H Avgt Ft Dpth=b.7V'
22= I —I 7 MaxN 5 98 s
20- //
18= / 7 7 r =0.$22-
14 H =45.9'
o
12 7 7 `OtO
10_ — Ea9484cf�
8-
7 7 7
4-
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 57
Summary for Pond 1 P: Pond
[62] Hint: Exceeded Reach S1 OUTLET depth by 5.51' @ 24.76 hrs
Inflow Area = 8.123 ac, 0.00% Impervious, Inflow Depth = 2.96" for 25y 24h event
Inflow = 30.53 cfs @ 12.06 hrs, Volume= 2.004 af
Outflow = 7.12 cfs @ 12.44 hrs, Volume= 1.580 af, Atten= 77%, Lag= 22.8 min
Primary = 7.12 cfs @ 12.44 hrs, Volume= 1.580 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Starting Elev= 322.14' Surf.Area= 8,230 sf Storage= 14,450 cf
Peak Elev= 325.76' @ 12.44 hrs Surf.Area= 14,354 sf Storage= 54,258 cf (39,808 cf above start)
Flood Elev= 327.00' Surf.Area= 17,014 sf Storage= 73,645 cf (59,195 cf above start)
Plug-Flow detention time= 1,901.9 min calculated for 1.249 af(62% of inflow)
Center-of-Mass det. time= 1,389.8 min ( 2,238.7 - 848.9 )
Volume Invert Avail.Storage Storage Description
#1 318.50' 73,645 cf Custom Stage Data (Prismatic)Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
318.50 1,496 0 0
319.00 1,770 817 817
320.00 2,590 2,180 2,997
321.00 4,996 3,793 6,790
322.00 8,046 6,521 13,311
323.00 9,363 8,705 22,015
324.00 10,855 10,109 32,124
325.00 12,730 11,793 43,917
326.00 14,856 13,793 57,710
327.00 17,014 15,935 73,645
Device Routing Invert Outlet Devices
#1 Primary 318.00' 24.0" Round Culvert
L= 66.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 318.00' / 317.00' S= 0.0152 '/' Cc= 0.900
n= 0.011 Concrete pipe, straight & clean, Flow Area= 3.14 sf
#2 Device 1 322.14' 0.5" Vert. Orifice/Grate X 3.00 C= 0.600
#3 Device 1 325.50' 48.0" x 48.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#4 Secondary 326.50' 25.0' long x 15.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 58
Primary OutFlow Max=7.12 cfs @ 12.44 hrs HW=325.76' TW=316.77' (Dynamic Tailwater)
L =Culvert (Passes 7.12 cfs of 39.34 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.04 cfs @ 9.14 fps)
3=Orifice/Grate (Weir Controls 7.08 cfs @ 1.68 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=322.14' TW=325.00' (Dynamic Tailwater)
4-4=Broad-Crested Rectangular Weir( Controls 0.00 cfs)
Pond 1 P: Pond
Hydrograph
AI I F T I
30.53 cfs •OutflowInflow
_G' / 7 7 — ❑
Inflow Area&.1123 a�C ❑Primary
34_ z / ❑Secondary
30 / /- F F Peak Elev=325.76'
28= / /I I F F 1 1 Storage=54,258 cf
26 / ,
22V / � - I T IT T
20;/ / % I I T T 17 1 17 T F 1 1T
.!, 18
0 16_ / /— I T T 17 17 71 7 T F 71717
"' 14: / —
1210v1v 7.1 219 cfs rf 1- 1 71 T T 1F 17 71 7 T F 71717
8 / /
61
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 59
Summary for Pond C 1: Replaced Culvert
[62] Hint: Exceeded Reach DO OUTLET depth by 1.55' @ 12.09 hrs
[61] Hint: Exceeded Reach SO outlet invert by 0.67' @ 12.09 hrs
Inflow Area = 8.553 ac, 1.75% Impervious, Inflow Depth = 2.68" for 25y 24h event
Inflow = 28.18 cfs @ 12.09 hrs, Volume= 1.910 af
Outflow = 28.18 cfs @ 12.09 hrs, Volume= 1.910 af, Atten= 0%, Lag= 0.0 min
Primary = 28.18 cfs @ 12.09 hrs, Volume= 1.910 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Peak Elev= 356.67' @ 12.09 hrs
Flood Elev= 357.00'
Device Routing Invert Outlet Devices
#1 Primary 354.00' 30.0" Round Culvert
L= 137.0' RCP, end-section conforming to fill, Ke= 0.500
Inlet/Outlet Invert= 354.00' / 351.50' S= 0.0182 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 4.91 sf
#2 Secondary 357.00' 50.0' long x 100.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=28.15 cfs @ 12.09 hrs HW=356.67' TW=352.98' (Dynamic Tailwater)
4-1=Culvert (Inlet Controls 28.15 cfs @ 5.73 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=354.00' TW=351.00' (Dynamic Tailwater)
2=Broad-Crested Rectangular Weir( Controls 0.00 cfs)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 60
Pond C 1: Replaced Culvert
Hydrograph
A _L _L _L - _H -
/1 7R 1 R rfg E Inflow
A 751 1 R rf r - E Outflow
Nrfli4m Area=8.553 arc - ❑Primary
28.18 cfs ❑Secondary
30 %
28 I 7 I ea7k EIev=356.67'
26
24 I rt fi 1 —h fi fi I I H rt -
-
20;
i18 -/ + ]— + I —I —
16� —
014� / I —L ] -[ - 1 -1 —14
8 -/
6 -
4 - '/ / / / / /
0.00 cfs G / / / / / /rir//
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

20241024_Harnett County_NW CC_Construction Con Type II 24-hr 25y 24h Rainfall=6.75"
Prepared by HDR, Inc Printed 10/28/2024
HydroCAD® 10.00-20 s/n 11397 ©2017 HydroCAD Software Solutions LLC Page 61
Summary for Pond C2: Proposed Culvert
[62] Hint: Exceeded Reach S2 OUTLET depth by 1.63' @ 12.06 hrs
Inflow Area = 6.362 ac, 0.00% Impervious, Inflow Depth = 3.11" for 25y 24h event
Inflow = 25.18 cfs @ 12.06 hrs, Volume= 1.648 af
Outflow = 25.18 cfs @ 12.06 hrs, Volume= 1.648 af, Atten= 0%, Lag= 0.0 min
Primary = 25.18 cfs @ 12.06 hrs, Volume= 1.648 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-180.00 hrs, dt= 0.01 hrs
Peak Elev= 336.77' @ 12.06 hrs
Flood Elev= 337.00'
Device Routing Invert Outlet Devices
#1 Primary 334.40' 30.0" Round Culvert
L= 45.0' RCP, end-section conforming to fill, Ke= 0.500
Inlet/Outlet Invert= 334.40' / 330.50' S= 0.0867 '/' Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 4.91 sf
Primary OutFlow Max=25.15 cfs @ 12.06 hrs HW=336.76' TW=331.09' (Dynamic Tailwater)
4-1=Culvert (Inlet Controls 25.15 cfs @ 5.23 fps)
Pond C2: Proposed Culvert
Hydrograph
❑Inflow
28 7ri 1 R rf ❑Primary
26 25.18 cfs (' Inflow Area=6.362 ac
24 I Peak Elev=336.77'
22- I
20= I 30.0"
18- Round Culvert
w 16-
o
14- / n=0.012
IL 12- L=45.0'
$- S=0.O867 /
4- •
s
f 7Z/r
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Time (hours)

Harnett County Solid Waste Department I Stormwater Permit Application—October 2024 I.)
Attachment E—Wet Pond Calculations J
Attachment E — Wet Pond
Calculations

Harnett County Solid Waste Department I Stormwater Permit Application—October 2024 I.)
Attachment E—Wet Pond Calculations J
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Harnett County Solid Waste Department I Stormwater Permit Application—October 2024 I.)
E.1 J
■
Attachment E.1 — Wet Pond
Design Calculations

Harnett County Solid Waste Department I Stormwater Permit Application-October 2024 Fn
Attachment E.1-Wet Pond Design Calculations
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Harnett County Solid Waste Convenience Center Wet Pond Calculations
Using Simple Run-off Calcuation to determine Design Volume
Simple Method for Runoff Volume
Rv = 0.05 + 0.9 * IA
Where: Rv = Runoff coefficient(unitless)
In = Impervious fraction(unitless)
DV = 3630 * RD * Rv * A
Where: DV = Design volume(cu ft)
RD = Design storm depth(in)
A = Drainage area(ac) \O(i I I j J /1
C
Where IA is 1.379/8.123 `C •0`i • X ''
Rv=0.05+0.9* la or 0.05 +0.9*(1.379/8.123) Q� J ;3r
Rv= 0.2027884 �•,�� �<`
`//
Then determine the design volume (Dv) •// • , •
�,
)02,02
Where RD is 1 inch
Dv=3630*Rd*Rv*A or 3630*1*0.203*8.123
Dv= 5,980
From Equation 1 in the NCDEQ stormwater Design Manual the main pool volume was determined using
Equation 1: Main Pool Volume, VMP
Vmp = 0.87 * T T * DV
Where: 0.87 = Factor to adjust for the volume in the forebay
VMP = Main pool volume,not including the forebay(cubic feet)
HRT = Required hydraulic residence time(14 days)
Ts = Average time between storm events(5 days)
DV = Design volume(cubic feet)
Vmp=0.87*(Hrt/Ts)*Dv or 0.87*(14/5)*5,980
Vmp= 14,566
The Average Depth is found using Equation 3

Equation 3. Average depth when the shelf is partially or fully submerged and
the shelf is being excluded from the average depth calculation
Vrr—Vshelf
Davg=
A hntttn,of chvlf
Where: Davy = Average depth(feet)
Vpp = Main pool volume at permanent pool elevation(feet3)
Vahelf = Volume over the shelf only(feet3)—see below
Abottom of snelf = Area of main pool at the bottom of the shelf(feet2)
Vsholf= 0.5'Depthmaa over shelf*Perimeterp.,m pool*Wldthwbm.,p.d part of shelf
Where: Depth., overanetl = Depth of water at the deep side of the shelf as
measured from the permanent pool(feet)
Perimeteroe,,,,pod = Perimeter of main pool at the bottom of the
shelf(feet)
Widthsphmemed pal of shelf = Width from the deep side to the dry side of the
shelf as measured at permanent pool(feet)
Where Vpp is= 14,581 CF
Vshelf is 0.5 x 1.0 X 235 If* 6 ft= 705
Area of Bottom of Shelf is 3003 sf
Davg= 4.62 ft
Sediment Storage is from EL 318.5 to 319.0
Sediment Storage=738 CF
Forebay Storage to be 15 to 20%of Wet Pond Storage
Wet Pond Storage = 14566 CF
Forebay Vol = 2184.9 to 2913.2 CF
Measured Forebay Volume= 2214 CF
Drawdown Time
(3) 1/2-inch Orifices at EL 322.14
Orifice Equation for Outlet Flow
An orifice is simply a hole. In the design of SCMs, orifices are often used for drawing down the
design volume. It is important to determine the size an orifice correctly so that the appropriate
detention time provided.
The basic equation for discharge from an orifice is:
Q = CD A (2 g Ho)o.5
Where: Q = Discharge(cfs)
CD = Coefficient of discharge per Table 6(unitless)
A = Cross-sectional area of orifice entrance(sq ft)
g = Acceleration of gravity(32.2 ft/sec2)
Ho = Driving head from water surface to centroid
orifice (ft) *usually use Hd3 to compute
drawdown through an orifice to reflect the fact
that head is decreasing as drawdown occurs*

Table 6: Values of Coefficient of Discharge for Orifices, CD
(Malcom 1989)
Entrance Condition CD
Typical default value 0.60
Square-edged entrance 0.59
Concrete pipe,grooved end 0.65
Corrugated metal pipe,mitred to slope 0.52
Corrugated metal pipe,projecting from fill 1.00
Figure 6: Schematic of Orifice Flow
(Malcom 1989)
Hu
Where Cd =0.60 and Ho is 2.11'
Q= 3x(0.60*(0.5/12)*(0.5/12)*3.14/4)*(2g*2.11/3)^0.5
Q= 0.0165099 cfs
Dv= 5,980 cf
Drawdown Time= 362178.7 sec
100.6052 HR
4.191883 days

SUPPLEMENT-EZ COVER PAGE
FORMS LOADED
PROJECT INFORMATION
1 Project Name Harnett County Northwest Convenience Center
2 Project Area(ac) 28.26
3 Coastal Wetland Area(ac) 0
4 Surface Water Area(ac) 0
5 Is this project High or Low Density? High
6 Does this project use an off-site SCM? No
COMPLIANCE WITH 02H.1003(4)
7 Width of vegetated setbacks provided(feet) 30
8 Will the vegetated setback remain vegetated? Yes
9 If BUA is proposed in the setback,does it meet NCAC 02H.1003(4)(c-d)? N/A
10 Is streambank stabilization proposed on this project? No
NUMBER AND TYPE OF SCMs:
11 Infiltration System
12 Bioretention Cell
13 Wet Pond 1
14 Stormwater Wetland
15 Permeable Pavement
16 Sand Filter
17 Rainwater Harvesting(RWH)
18 Green Roof
19 Level Spreader-Filter Strip(LS-FS)
20 Disconnected Impervious Surface(DIS)
21 Treatment Swale
22 Dry Pond
23 StormFilter
24 Silva Cell
25 Bayfilter
26 Filterra
FORMS LOADED
DESIGNER CERTIFICATION
27 Name and Title: Jeffrey S.Murray,Vice President
28 Organization: HDR Engineering,Inc.of the Carolinas
29 Street address: 555 Fayetteville Street,Suite 900
30 City,State,Zip: Raleigh,NC 27601
31 Phone number(s): 919-232-6682
32 Email: [e-mail]
Certification Statement:
I certify,under penalty of law that this Supplement-EZ form and all supporting information were prepared under my direction or supervision;that the
information provided in the form is,to the best of my knowledge and belief,true,accurate,and complete;and that the engineering plans,
specifications,operation and maintenance agreements and other supporting information are consistent with the information provided here.
Designer
��\\,\1 i( 1jr)f•/f`f
0,7 .i ' , Sig ue f ner
�hyr
16/47ZT
Seal Date

DRAINAGE AREAS
1 Is this a high density project? Yes
2 If so,number of drainage areas/SCMs _ 0
3 Does this project have low density areas? _ No
4 If so,number of low density drainage areas _ 1
Is all/part of this project subject to previous rule
5 versions? No
CLICK TO LOAD FORM
DRAINAGE AREA INFORMATION Entire Site LD 1
4 Type of SCM NA Wet Pond
5 Total drainage area(sq ft) 1231005 _ 353846
6 Onsite drainage area(sq ft) 1231005 353846
7 Offsite drainage area(sq ft) 0 0
8 Total BUA in project(sq ft) 78190 sf 78190 sf
New BUA on subdivided lots(subject to
9 permitting)(sq ft)
New BUA not on subdivided lots(subject to
10 permitting)(sf) 78190 sf 78190 sf
11 Offsite BUA(sq ft) sf sf
12 Breakdown of new BUA not on subdivided lots:
-Parking(sq ft) 43300 sf 43300 sf
-Sidewalk(sq ft)
-Roof(sq ft) 100 sf 10 sf
-Roadway(sq ft) 34790 sf 34790 sf
-Future(sq ft)
-Other,please specify in the comment box
below(sq ft)
New infiltrating permeable pavement on
13 subdivided lots(sq ft) sf sf
New infiltrating permeable pavement not on
14 subdivided lots(sq ft) sf sf
Existing BUA that will remain(not subject to
15 permitting)(sq ft) sf sf
16 Existing BUA that is already permitted(sq ft) sf sf
17 Existing BUA that will be removed(sq ft) sf sf
18 Percent BUA 6% 22%
19 Design storm(inches) 1.0 in 1.0 in
20 Design volume of SCM(cu ft) 5980 cf
21 Calculation method for design volume 3630*Rd*Rv*A
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
22 drainage area(s):
A single drainage area is connected to the Wet Pond. Subareas were
delineated in the HydroCAD analysis for purposes of sizing conveyance
channels and piping for the 25-year,24-hour storm.

Disturbed Drainage Area Built Upon
Site Area Area to SCM1 Area
SF 1,231,006 256,133 353,846 78,190
AC 28.26 5.88 8.12 1.79
1 Drainage Area 1.1, 2, and 3

WET POND
1 Drainage area number A
2 Minimum required treatment volume(cu ft)
GENERAL MDC FROM 02H.1050
3 Is the SCM sized to treat the SW from all surfaces at build-out? Yes
4 Is the SCM located away from contaminated soils? Yes
5 What are the side slopes of the SCM(H:V)? 3:1
Does the SCM have retaining walls,gabion walls or other
6 No
engineered side slopes?
Are the inlets,outlets,and receiving stream protected from erosion
7 Yes
(10-year storm)?
8 Is there an overflow or bypass for inflow volume in excess of the Yes
design volume?
9 What is the method for dewatering the SCM for maintenance? Drawdown Orifice
10 If applicable,will the SCM be cleaned out after construction? Yes
11 Does the maintenance access comply with General MDC(8)? Yes
12 Does the drainage easement comply with General MDC(9)? _ N/A
If the SCM is on a single family lot,does(will?)the plat comply with
13 N/A
General MDC(10)?
14 Is there an O&M Agreement that complies with General MDC(11)? Yes
15 Is there an O&M Plan that complies with General MDC(12)? Yes
16 Does the SCM follow the device specific MDC? Yes
17 Was the SCM designed by an NC licensed professional? Yes
WET POND MDC FROM 02H.1053
18 Sizing method used SA/DA
19 Has a stage/storage table been provided in the calculations? _ Yes
20 Elevation of the excavated main pool depth(bottom of sediment 318.50
removal)(fmsl)
21 Elevation of the main pool bottom(top of sediment removal)(fmsl) 319.00
22 Elevation of the bottom of the vegetated shelf(fmsl) 321.00
23 Elevation of the permanent pool(fmsl) _ 322.14
24 Elevation of the top of the vegetated shelf(fmsl) 322.00
25 Elevation of the temporary pool(fmsl) 324.25
26 Surface area of the main permanent pool(square feet) 4066
27 Volume of the main permanent pool(cubic feet) 14581 cf
28 Average depth of the main pool(feet) 4.62 ft
29 Average depth equation used Equation 3
30 If using equation 3,main pool perimeter(feet) 235.0 ft
31 If using equation 3,width of submerged veg.shelf(feet) 6.0 ft
32 Volume of the forebay(cubic feet) 2214 cf
33 Is this 15-20%of the volume in the main pool? Yes
34 Clean-out depth for forebay(inches) 24 in
35 Design volume of SCM(cu ft) 5980 cf
36 Is the outlet an orifice or a weir? Orifice
37 If orifice,orifice diameter(inches) (3)0.5 Inch Orifices
38 If weir,weir height(inches)
39 If weir,weir length(inches)
40 Drawdown time for the temporary pool(days) 4
41 Are the inlet(s)and outlet located in a manner that avoids short- Yes
circuiting?
42 Are berms or baffles provided to improve the flow path? Yes
43 Depth of forebay at entrance(inches) 24 in
44 Depth of forebay at exit(inches) _ 12 in
45 Does water flow out of the forebay in a non-erosive manner? Yes
46 Width of the vegetated shelf(feet) 6 ft
47 Slope of vegetated shelf(H:V) 6:1
48 Does the orifice drawdown from below the top surface of the No
permanent pool?
49 Does the pond minimize impacts to the receiving channel from the 1- Yes
yr,24-hr storm?
50 Are fountains proposed?(If Y,please provide documentation that No
MDC(9)is met.)
51 Is a trash rack or other device provided to protect the outlet system? Yes
52 Are the dam and embankment planted in non-clumping turf grass? Yes
53 Species of turf that will be used on the dam and embankment Fescue/Bermuda
54,Has a planting plan been provided for the vegetated shelf? Yes
ADDITIONAL INFORMATION
Please use this space to provide any additional information about
55 the wet pond(s):
2

Harnett County Solid Waste Department I Stormwater Permit Application-October 2024 Fn
Attachment E.1-Wet Pond Design Calculations
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