SW6240705_Design Calculations_20240927

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024
Wet Pond Design
Attachment C — Precipitation
Frequency Data

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024
Wet Pond Design
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 ni North Car( 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 Solid Waste Department I Stormwater Permit Application—May 2024
Wet Pond Design
This page intentionally left blank.

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024
Wet Pond Design
Attachment D — Stormwater
Flow

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024 �1J�
Wet Pond Design
This page intentionally left blank.

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024
Attachment D.1 —Pre-Development Calculations
■
Attachment D. 1 — Pre-
Development Calculations

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024 �1J�
Attachment D.1 —Pre-Development Calculations
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1 2 3 4 5 6 7 8
3
N
3
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3 LEGEND:
0
O h O M 3
EXISTING CONTOURS
O LOC LIMITS OF CONSTRUCTION
�h0 t-MUt-r-M i r UINIC
3 360 — — — — — — — — — — BUFFER ZONE
APPROXIMATE EDGE OF TREE LINE
6s - - - - - - - - - E911 TOWER RADIUS
TOWER FENCE
ADJACENT PUBLIC ROW
o W W W— 6"WATER MAIN
350 x AREA 1: 11.609 AC � 3
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x_ 100 LF SHEET FLOW l\
1068 LF SHALLOW CONC
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100 LF SHEET FLOW
600 LF SHALLOW CONC IMITS OF CONSTRUCTION O � Q a
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O N AREA 3: 1.231 AC�11- c�
.3 Lo�N C', 3p0 M TIME TO CONCENTRATION I )o B
100 LF SHEET FLOW 3
226 LF SHALLOW CONC I
APPROXIMATE LOCATION Q O�
OF THREE EXISTING TREES s O
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280 nj/ APPROXIMATE 3
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o N 275
N c�
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N 315
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N NTIRE SITE DRAINS THROUGH NATURAL M
� CHANNELS IN DRAWS AND INTO ADVENT CREEK 290
N2>U J 285 <V NOTES:
O� O O6 26S
a 255 60 280 c�°O 1. EXISTING TOPOGRAPHY AND PROPERTY LINES OBTAINED FROM
`�So 275 HARNETT COUNTY GIS.
250 270 ��`bh 330 2. PROPERTY BOUNDARY SURVEY COMPLETED BY BENTON W.
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255 DEWARE AND ASSOCIATES, APRIL 30, 2019.
CD
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CD ��h `L�o 255 60 ?6 65�2�Q 2�5 ,ZgQ 2S5 285 32S 3. CONDITIONAL USE PERMIT#BA-CU-18-18 APPROVED 6/11/18.
26Q 2
10
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J
PROJECT MANAGER J. MURRAY, PE Harnett
EXISTING CONDITIONS
PROJECT ENGINEER A. MCGREW, PE
CD
HDR Engineering, Inc. of the Carolinas C Q U N T Y HYDROCAD MODEL
DRAWN BY A. MCGREW, PE NORTH C A R O LI N A KEY
N.C.B.E.L.S. License Number: F-0116 strong roots a new growth
555 Fayetteville Street, Suite 900 HARNETT COUNTY
Raleigh, NC 27601 C 05/2024 ISSUED FOR BIDDING SHEET
919.232.6600 B 01/2023 REVISED BASED ON REVIEWER COMMENTS NORTHWEST CONVENIENCE CENTER 0 T. 2" FILENAME OOG-02.dwg
C) A 10/2022 ISSUED FOR PERMITTING OOG-01
ISSUE DATE DESCRIPTION PROJECT NUMBER 10354679 SCALE 1" = 75' v 1
HARNETT COUNTY NORTH CAROLINA

4 [DO]
Area 4 NCDOTtad Ditch
cB
1 C1
Existing Culvert
Area 1 i
2 3 D4
D1
Area 2 At 3 Dit Next to Road
D w
[D2] D3
v D5 Draw Dr w
Draw
D6
D7 Draw
Outfall to Avent Creek `��®���
a .A _
40654
SUbcat Reach On Link 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 DiamMidth 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 1 y 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 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 of
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 of
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 of
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 of
Reach DO: NCDOT Road Ditch Avg. Flow Depth=0.42' Max Vet=2.10 fps Inflow=2.92 cfs 0.231 of
n=0.035 L=1,130.0' S=0.0146 '/' Capacity=201.86 cfs Outflow=2.01 cfs 0.226 of
Reach D1: Draw Avg. Flow Depth=0.12' Max Vet=0.22 fps Inflow=1.39 cfs 0.230 of
n=0.400 L=500.0' S=0.0620 '/' Capacity=252.99 cfs Outflow=0.76 cfs 0.206 of
Reach D2: Draw Avg. Flow Depth=0.10' Max Vet=0.24 fps Inflow=0.59 cfs 0.091 of
n=0.400 L=430.0' S=0.0977 '/' Capacity=211.86 cfs Outflow=0.33 cfs 0.084 of
Reach D3: Draw Avg. Flow Depth=0.02' Max Vet=0.14 fps Inflow=0.08 cfs 0.017 of
n=0.400 L=228.0' S=0.1667 '/' Capacity=432.67 cfs Outflow=0.05 cfs 0.016 of
Reach D4: Ditch Next to Road Avg. Flow Depth=0.54' Max Vet=0.53 fps Inflow=2.01 cfs 0.226 of
n=0.400 L=500.0' S=0.0720 '/' Capacity=49.87 cfs Outflow=1.31 cfs 0.216 of
Reach D5: Draw Avg. Flow Depth=0.22' Max Vet=0.29 fps Inflow=1.05 cfs 0.290 of
n=0.400 L=982.0' S=0.0570 '/' Capacity=120.90 cfs Outflow=0.73 cfs 0.237 of
Reach D6: Draw Avg. Flow Depth=0.10' Max Vet=0.18 fps Inflow=1.35 cfs 0.232 of
n=0.400 L=1,720.0' S=0.0500 '/' Capacity=198.54 cfs Outflow=0.38 cfs 0.119 of
Reach D7: Outfall to Avent Creek Avg. Flow Depth=0.20' Max Vet=0.24 fps Inflow=0.90 cfs 0.356 of
n=0.400 L=130.0' S=0.0385 '/' Capacity=132.42 cfs Outflow=0.90 cfs 0.339 of
Pond C 1: Existing Culvert Peak Elev=355.29' Inflow=2.01 cfs 0.226 of
Primary=2.01 cfs 0.226 of Secondary=0.00 cfs 0.000 of Outflow=2.01 cfs 0.226 of
Total Runoff Area= 26.450 ac Runoff Volume = 0.570 of 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 1124-hr 1 y 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 ly 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
❑Runoff
,. 99 cfs
Type II 24hr
1y 2h Rainfall=3.a5"
....
R not Area=11. 09 ac
.................
1 Runoff:Volume=0.230 of
Runoff Depth>0.24"
FIOw Len : th=1,164'
Tc=28:9 min
CN=58
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 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 ly 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 ■Runoff
.............. ...
0.59 cfs
0.6
T 1.
2.4h r .
0.55
........ .....
yp� Ow
ly 24h f air
fall=3
0.505.11..........
................................................................. ............... ............... .........
0.45 F�..0 n off.... #re ........_5..._1..3._1.....ac.........
............. ...........................
0.4 RuMoff'Vol:m: =0.091 af.....
....... ............... ..
......................
....................
R
0.35 u:noff De:pth>0.21"
0.3 Flow Len th=700'
LL ......................._......................._ ....... _........................._ ............... _........................_ .. ........................._ ...............
0.25 Tv:
.................................................:......................................................................................... .. .....22 min
0.2 _
CN 47
0.15
0.1
0.05
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 1 y 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 ly 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
o.oa as
.........................................,..................................................;..........................................................................
0.08 Ty. e..._1_..._24' _r.........
0.075
............... ........
1 24h Rainfall: 3.45
0.07
y
n ff Ar 1. 1_
0.065 R.I.I............o.................................e.s�_...................... ..............xa.C..........
0.06
0.055 R.u.":off Vol: M :0 017 of
_ ...........................................
0.05 ........................ ...................................................................................................................... ............................Runoff....Q..ep: th>..O.....1.7'
3-LL 0.045
..........................,.........................;.................... _ ............... ................ ....... .........o
oWLen
0.04 Ff t1 =326
......
0.035
Tc
...................................................:.........................,....................................................................... ............ ..............
22:4 in
0.03
0.02
0.02 ............. ............... ................ ..............
0.015
0.01
0.005
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 1 y 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 ly 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 2.92 cfs
Type 11 24-h r
"ly 24h Rainfall: 3.05"
............................................ Run : ff Area=8.�79 ac
2 Runoff Volume=0 231af .
Runoff Depth>0.33"
Flow Length=606'
T 13.1 min c. .
1
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 1 y 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 11
Summary for Reach DO: NCDOT Road Ditch
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 0.33" for ly 24h event
Inflow = 2.92 cfs @ 12.09 hrs, Volume= 0.231 of
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 7' Top Width= 19.00'
Length= 1,130.0' Slope= 0.0146 7'
Inlet Invert= 372.00', Outlet Invert= 355.50'
Reach DO: NCDOT Road Ditch
Hydrograph
...................................................................................................................... _ ............... .......... ............... ............... ............... ............... ............... ............... ...............
Inflow
2.92 cfs
❑Outflow
3 Inflow Area::8.479 ac
Avg. Flow: Depth:0.42'
Max Vel: 2.10 fps
.............. ............
2- 2.01°`S n^0.035
L=11130:0'
S=0.0'146 T
...................................................................................................
Cap : city=201 .86 cfs
1
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 1 y 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 12
Summary for Reach D1: Draw
Inflow Area = 11.609 ac, 0.00% Impervious, Inflow Depth > 0.24" for ly 24h event
Inflow = 1.39 cfs @ 12.35 hrs, Volume= 0.230 of
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 7' Top Width= 88.00'
Length= 500.0' Slope= 0.0620 7'
Inlet Invert= 316.00', Outlet Invert= 285.00'
Reach D1: Draw
Hydrograph
Inflow
1.39cfs ❑outflow
Inflow Area=11 .609 ac
Avg. Flow; Depth=0.12'
Max ps .
e
1 n^0.400
tV 0.76 cfs L=VOOi O'
LL S=0.0620 '/'
acity=262.99 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 1 y 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 13
Summary for Reach D2: Draw
Inflow Area = 5.131 ac, 0.00% Impervious, Inflow Depth > 0.21" for ly 24h event
Inflow = 0.59 cfs @ 12.26 hrs, Volume= 0.091 of
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 7' Top Width= 72.00'
Length= 430.0' Slope= 0.0977 7'
Inlet Invert= 327.00', Outlet Invert= 285.00'
Reach D2: Draw
Hydrograph
Inflow
0.65
0.59 cfs ❑oUtfIOW
0.6 tnftor r.....Area�5 131 ae
... ..........:.. ............... . ..........
_ ,
0.55 ............................................................................................................................................................... ................ .............................. ...... ......... ........ ,..........
r4vg. Flow Depth-0.10
0.5
Max Vel l 0.24 f s
0.45
....................... ...... .............. .......................... ............. ............... _ ............. .............. ..............p
....................... ............................. .............. ........................._ ..... _ .
d
0.4 .......... .......... ......n.........0...""" ". .�.........
0.35 0.33 cfs .............. 0 0 .........i..... ..........
3 ............................................ ` �/
0 0.3 =
LL
S 0.0977 1
0.25 .................................................I..............................................................................................
a.pcty=21.1 �_ 6 _cs
0.2
0.15 ................................................................................................................................................................ ... .............. ............... ..............
0.1 ............................................................................................................................................................ ................................ _ ............... ...........
0.05
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 1 y 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 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 of
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 7' Top Width= 110.00'
Length= 228.0' Slope= 0.1667 7'
Inlet Invert= 353.00', Outlet Invert= 315.00'
Reach D3: Draw
Hydrograph
...................................................................................................................................................... ..................................._ .............. .............. ............... ........................_ .............. ..............
[ Inflow
0.09 0.08 cfs
'""""" Outflow
.............................................................................
0.085
Inflow area= 2 a
................................................................................................................................................. ............................. ... .............. ............. _ ............. ..............
0.08 ,....
............................................................................................................................................................... ...... ►vg Fl......................... ................................................ _.......................
0.07
......................:........................:........................;............. ............. ...... ..... ..
Maxel: ._ 4 _#�5
0.065
......................................................................:.........................:................................................................ .............. _ .............. _ .............. ............... ........................_ ..
0.06
...................... n4 Q
0.055 o.os cfs
0.05
L
.............. ..
2....................
8.
3 0.045
..................................................................... S= 6.6.7 ,1.
0
.. ..... .. ..
LL 0.04
......................,........................,.........................................................................,........................,................ .......... ......... ...............
0.035
tty=432 67 Oft
0.03
......................,........................,..................................................,................... ....... .............. ..............
0.025
........................................................................,.........................:................... .............. ..... ........ .............. ..............
0.02
..........
0.015 ..............
.........................................................................,.........................:................... .............. ... ........... .............. .............. .............. ............... .............. ..............
0.01
0.005
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 1 y 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 15
Summary for Reach D4: Ditch Next to Road
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 0.32" for ly 24h event
Inflow = 2.01 cfs @ 12.35 hrs, Volume= 0.226 of
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 7' Top Width= 21.00'
Length= 500.0' Slope= 0.0720 7'
Inlet Invert= 351.00', Outlet Invert= 315.00'
Reach D4: Ditch Next to Road
Hydrograph
Inflow
...................................................................................................................... ... .................................................. ............... ...............20
_..... ❑Outflow
2 Inflow Area:8.479 ac
Avg. Flow: Depth:0.54'
Max Vel: 0.53 fps
1.31 cfs n^0.400
H � 1
L- 000
1 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 1 y 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 16
Summary for Reach D& Draw
Inflow Area = 16.740 ac, 0.00% Impervious, Inflow Depth > 0.21" for ly 24h event
Inflow = 1.05 cfs @ 13.41 hrs, Volume= 0.290 of
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 7' Top Width= 52.00'
Length= 982.0' Slope= 0.0570 7'
Inlet Invert= 285.00', Outlet Invert= 229.00'
Reach D& Draw
Hydrograph
Inflow
os as ❑Outflow
Inflow.Area=16740.
a _
1 Avg. Flow Depth=022'
Max Vet:0.29 fps
n=0.400 0735
L=98Z.0'
LL S=O.Q570 T
Capacity=120.90 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 1 y 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 17
Summary for Reach D6: Draw
Inflow Area = 9.710 ac, 0.00% Impervious, Inflow Depth > 0.29" for ly 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 7' Top Width= 86.00'
Length= 1,720.0' Slope= 0.0500 7'
Inlet Invert= 315.00', Outlet Invert= 229.00'
Reach D6: Draw
Hydrograph
Inflow
1.35 cfs ❑outflow
Inflow Area=9.710 aC
Avg. Flow Depth=010'
K 1=01 fps
1 n=0.400
L=11720.0'
LL S=0.0500 T
Capacity=198.54 cfs
0.38 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 1 y 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 18
Summary for Reach D7: Outfall to Avent Creek
Inflow Area = 26.450 ac, 0.00% Impervious, Inflow Depth > 0.16" for ly 24h event
Inflow = 0.90 cfs @ 16.45 hrs, Volume= 0.356 of
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 7' Top Width= 60.00'
Length= 130.0' Slope= 0.0385 7'
Inlet Invert= 229.00', Outlet Invert= 224.00'
Reach D7: Outfall to Avent Creek
Hydrograph
1 Inflow
0.90 cfs ❑outflow
In 'low Area=26.�450 ac °�S
Avg. Flow Depth=020'
Max Vet:0.24 fps
n=0.400
L=130.0'
LL S=0.0385) '/'
C pa city=13E2.42 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 1 y 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 19
Summary for Pond C 1: Existing Culvert
Inflow Area = 8.479 ac, 0.00% Impervious, Inflow Depth > 0.32" for ly 24h event
Inflow = 2.01 cfs @ 12.35 hrs, Volume= 0.226 of
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 of
Secondary= 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
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
.................................................................................................................. 0 . .................................................. ............. ............. ............................................. Outflow
20 o PrimaryInfow:Area=8.4j9a: c 0 Second a ry1 cfs2.
2 Peak Elev=355.29
N
U
3
0 1
LL
0.00 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 Condition Type 1124-hr 25y24h 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 of
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 of
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 of
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 of
Reach DO: NCDOT Road Ditch Avg. Flow Depth=1.30' Max Vet=4.01 fps Inflow=28.83 cfs 1.614 of
n=0.035 L=1,130.0' S=0.0146 '/' Capacity=201.86 cfs Outflow=25.05 cfs 1.601 of
Reach D1: Draw Avg. Flow Depth=0.74' Max Vet=0.67 fps Inflow=21.62 cfs 1.937 of
n=0.400 L=500.0' S=0.0620 '/' Capacity=252.99 cfs Outflow=17.57 cfs 1.884 of
Reach D2: Draw Avg. Flow Depth=0.66' Max Vet=0.72 fps Inflow=10.82 cfs 0.822 of
n=0.400 L=430.0' S=0.0977 '/' Capacity=211.86 cfs Outflow=8.69 cfs 0.804 of
Reach D3: Draw Avg. Flow Depth=0.19' Max Vet=0.46 fps Inflow=2.31 cfs 0.180 of
n=0.400 L=228.0' S=0.1667 '/' Capacity=432.67 cfs Outflow=1.98 cfs 0.176 of
Reach D4: Ditch Next to Road Avg. Flow Depth=2.05' Max Vet=1.11 fps Inflow=25.05 cfs 1.601 of
n=0.400 L=500.0' S=0.0720 '/' Capacity=49.87 cfs Outflow=20.51 cfs 1.579 of
Reach D5: Draw Avg. Flow Depth=1.23' Max Vet=0.79 fps Inflow=24.94 cfs 2.688 of
n=0.400 L=982.0' S=0.0570 '/' Capacity=120.90 cfs Outflow=17.88 cfs 2.575 of
Reach D6: Draw Avg. Flow Depth=0.59' Max Vet=0.50 fps Inflow=22.48 cfs 1.755 of
n=0.400 L=1,720.0' S=0.0500 '/' Capacity=198.54 cfs Outflow=7.83 cfs 1.549 of
Reach D7: Outfall to Avent Creek Avg. Flow Depth=1.15' Max Vet=0.67 fps Inflow=19.98 cfs 4.125 of
n=0.400 L=130.0' S=0.0385 '/' Capacity=132.42 cfs Outflow=19.92 cfs 4.094 of
Pond C 1: Existing Culvert Peak Elev=357.27' Inflow=25.05 cfs 1.601 of
Primary=5.70 cfs 1.128 of Secondary=19.35 cfs 0.473 of Outflow=25.05 cfs 1.601 of
Total Runoff Area= 26.450 ac Runoff Volume =4.553 of 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 25y24h 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
23
■Runoff
22 21.62 cfs
_ « . .............
21 ......................... Type i�. 24.11r........
20 ..........:...........................:..........................«.........................«..........................;...........................;............... ...... ........ ....
19
18
17 .........................;..........................;...........................;..................
Runvf Area=1809e
16 ......................._................................................................................................... ... ... ........ ................
15
....................._.....................................................................................
Rang#f Voame-1,g7 e .
14 ................................................................................................... ................. .. ................ .................
13 .................. ..............................Ru.n.O.f ....De:pth+`� { 0'�..........
3 12 ......................................................................................................;...................................................................... .................................................................................... _....................................................._.........................._ ...............
0 11 ......................._..................................................................... h. ..
LL FI6w Lengt �64'
10 ......................._ ......................... ........................................... .. ............................ ..........................._........................._ ................ ................ _.........................._ ...............
g ......................._.............................................................................................................................. ...... ................ ................. ...............
TG=2-8: 9 m: in
.......................................................... ..... ........................ ................ .............. _ ............... ............... ............... _ ...............
...................._ ............. ..................7 _
g ......................._ .........................
Chl-�5.8
5 ................................................................................................................................................... .. ........... ................. ............... ................ ................ ................ ...............
q ........................................................................................................................................................................ .. ................. ................ ................ .........................._ ...............
3 ................................................................................................................................................................ .......... ............... ................ ................ ................ ...............
2 .................................................................................................................................................................. ..... ..........
1
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 25y24h 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
Ty 24�h r .
pa i
10
..
26y 24h Rair�#a1l=67 .....
9
Ru nbff,4rea=5, 31 Oc..........
8
.......................................................................................................................................................................... ............... Ra -
noff Volume-O. 22 of .
R
_ uno f Dpth1
3 6
.....:..... .....:.....
Flow Lein th-700'
LL 5
Tq#22G................ ....
4
............................................................................................ ................ .................
3
2
1
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 25y24h 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
❑Runoff
2.31 cfs
Type 11 24 :hr
2 5y 2�4h Rainfall=6.7
Runoff Area=1. 31 ac
Runoff:Volume=0.180 of
Runoff Depth>1.75"
FI L h= '
p
LL . . _vw _e�gt , _3�fi
1 Tc=22 4 min
CN=55
.
OL
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 25y24h 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
.............................................................................................................................................................................................................................................................. ............... ................ ................ ................ ............... ■Runoff
30 28.as as
.............. ................
28 ell 24-h r
T.
... ...... ............. _ ................ _ ..................................._: .....' Yp
26
........................ .............. .......................1 26V 24h Rain fall=6 75"
24
......................._,...........................,.............................................. ................................... ..... ......... a�....
22 Runoff .7.t3..... .........
...................._.
20 ......................... .............. ................
..._....R.u..lip.. ?.ff._V. ?. .u..m. ...=_'I...G._'1..4.._af.........
w 18 p n
................................................................:................................ D
,......................... Runoff p�pth�2
3 16 ............. ................ ................. ... .......... ................ ..............
o
Flow' Le'ngth_606
FL: 14
....................................................................................................................................................................... ................................................................................................._....................................................._..........................:.........................
12
TG _13�� min
..................... ........ ................ .................
10
................................................................................................. ................ ................. ....... ................ CN-
8
6
4
2
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 25y24h 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 of
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 7' Top Width= 19.00'
Length= 1,130.0' Slope= 0.0146 7'
Inlet Invert= 372.00', Outlet Invert= 355.50'
Reach DO: NCDOT Road Ditch
Hydrograph
.................................................................................................._j................................................_....................
Inflow
32
Outflow
28.83 cfs
30 Inflow Area:8.4�79 ac
........... .............. .............. ...............
28
25.05 cfs
26
Avg. Flo pe �th=10
........................i..................................................i........................_i....... ...............
24
........... ............... ........... ... ......ax e , s ps
zz
20
.......... ............... .......
ti 18
,.., ..................................................................................................._..................................................I...... .......... ............... ............... ............... ............ �.... _ ... .... ..........
3 16
LL 14 S�V.© 6: /
........................:.........................;.........................;................................................................................ ....................................................................................................................;.........................:....................
12
...........................................................................; ........................
CaPOcit�=201.$_6 dfs
10
........................:.........................:.........................;........................_..........................:......................._.... ...... ............... ............... ...............
8
........................:.........................:.........................;........................_..........................;.................
6
............................................ ............... ............... ............... ............... ............... ...............
4
2
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 25y24h 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 of
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 7' Top Width= 88.00'
Length= 500.0' Slope= 0.0620 7'
Inlet Invert= 316.00', Outlet Invert= 285.00'
Reach D1: Draw
Hydrograph
C Inflow
24
i ......................... . .....
❑oUtfIOW
23 ........... ...........................................................i i................................................_ - .............. - ..............: ::: :::: -
: ::::: ...............:::::oflow: a-�� 6dgac22
21 .................................................i................................................._I.........................
20 ........... ,qV .........F...o ... .�, .. .i} .0.. .4�..........
19 ...... _ ............... ............... _ ............... ...............
1
17
8 ............................................ JV
................... .... ....................:............ ..e.11
15 n- .��.fl...........
14 ............................................
w
3 12
.2 1
u10 .................................................................................................._.........................
9 .................................................................................................._j................................................_............. ....
apci / 2a2. 9 ifs
7 .............. .............. _ .............. ............... _ .............. ...............
6 .................................................................................................._............................................. .......... ............... ...............
5 .......... ...............
4 .......................................................................... ................ ............... _ ............... ............... _ ............... ...............
3 .............................................................................................................................................
2
1
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 25y24h 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 7' Top Width= 72.00'
Length= 430.0' Slope= 0.0977 7'
Inlet Invert= 327.00', Outlet Invert= 285.00'
Reach D2: Draw
Hydrograph
12 ................................................................................................................................................
Inflow
10.82 cfs
'......................... ❑Outflow
11 .................................................:................................................._I................................................_............. Inflow Area 5
31 a
10 .................................................................................................._ ....... ..........._..AV ...Q ... .e *. .(�.�.( .(�.�..........
v vv
9 at-0
.......... ..._;... 8.69 cfs ..... ..._,.....
Max V - 72 f s
8
n^0.00
7 .........................................................................................
L 43 00'.
6
LL S-0.0977 T
5 .................. ..
4 .......................................................................... ..................................................I..........
apcit =211.$_6 ifs
3 .................................................................................................._..........................................
2 ......................................................................... ......................................................... ......... ............... _ ............... ............... _ ............... ...............
1
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 25y24h 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 of
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 7' Top Width= 110.00'
Length= 228.0' Slope= 0.1667 7'
Inlet Invert= 353.00', Outlet Invert= 315.00'
Reach D3: Draw
Hydrograph
Inflow
2.31 cfs ❑outflow
Inflow Area:1 .231 ac
98 5 Avg. Fiow Depth-0.1
2
Max Vel: 0.46 fps
n^0.400
L=2280'
0
S=O.fi677,
LL
1
Capacity=432.67 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 Condition Type 1124-hr 25y24h 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 of
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 7' Top Width= 21.00'
Length= 500.0' Slope= 0.0720 7'
Inlet Invert= 351.00', Outlet Invert= 315.00'
Reach D4: Ditch Next to Road
Hydrograph
.................................................._..............................................................................._..................................................._...................................................._..................................................._..................................................._..................................................
................................................ .................................................................................. ......................... ............... ............... ............... ...............
❑Inflow
28 25.05 cfs Outflow
........................:.........................:.........................;.............................................. ............... ......... .......... ... t_Hfito Area=8 47.9 .........................
26
24
Av . Flow! De th:_ 2.05
........... ............... . ............... ...............
22
20.51 cfs
Maxyel=1 1.1 fp
20e
_ . _ . , n^04.0.0
H 16 U
L-_
00 0
3 14
.2 12 ...............
.........:..................................................:...................................................,....................................
S 0 0720
10
.................................................................................
Capac y ' 9 $7 cfs
......... .............. ..............
6 ............................................................................................................................................................ ......... ............... ............... ............... ............... _ ............... ...............
4 ......................................................................................................
2
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 25y24h 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 D& 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 of
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 7' Top Width= 52.00'
Length= 982.0' Slope= 0.0570 7'
Inlet Invert= 285.00', Outlet Invert= 229.00'
Reach D& Draw
Hydrograph
.................................................................................................._................................................_....................
Inflow
24.94 as ❑Outflow
Inflow Area=fi6.70 aC
24 �,
Av ........FI_ow D_e th.=.1 23 ...............
22
J p
n 07.g. fps.....................M ........................................ _ ............... ........................._ ............... ........................._ ....................:......
...................20 c. e0 7
18 =0.40 16 L=98 .0'
3 14 .............................................._................................................_................ ........... ...............
- 12 ........ .................................._;................................................_;.......................
10 C paucity='I0.9 cfs
s ........................:.........................;.........................;.....................
6 ...................................................................................................1.................................................I................ ......... ............... ............... ............... _ ............... ...............
4 ............................................ ............... ...............
2
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 25y24h 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 of
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 7' Top Width= 86.00'
Length= 1,720.0' Slope= 0.0500 7'
Inlet Invert= 315.00', Outlet Invert= 229.00'
Reach D6: Draw
Hydrograph
.......................................................................... ..................................................................... _ ............... _ ............... ............... _ ............... ............... _ ............... ...............
25 ............................................ ............... ...............
C Inflow
24 ,..
22.48 cfs
Outflow
.......................:.........................i................................................._I................................................_.......
23 :.............f #fo�iv.....Ares+.9...7. ..{�.....a. ..........
22 .................................................................................................._.......................................... .. ............... ............... ...............
..........................................
21 ....._. V.* .........F... W...D. �I-O..... .. ..............
20
18 ...................................................................................................I.................................................I....................... .........I.......................................... C7..x...�f�.�.�.�..���.....r�.s..........
16 ........................._ ............... �0......A
n, 00
15 ............... ............... ............... ............... ............... ............... ...............
w14 ............................................................................................... ............... ............... ........... ............... ............... ...............
V — .s. ..�..........
13 ...7.
3 12 .................................................................................................._.............................................
S0000 /
10 ........................................................................................................................................................................ .. ....................... ............... ............... ............... ............... _ ...............
9
7.83 cfs _a.p_ .cat t..-1 4.... :8... ....�fs...........
7 .......................................................................... ..................................................I................... ...... ............... _ ............... ............... _ ............... ...............
6 .................................................................................................._.......................................... ......... ............... ............... ............... ............... ...............
5 ............................................ .. ............... ............... ...............
4 ............................................ ........ ............... ............... ............... ...............
3
uwu
2
1
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 25y24h 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 7' Top Width= 60.00'
Length= 130.0' Slope= 0.0385 7'
Inlet Invert= 229.00', Outlet Invert= 224.00'
Reach D7: Outfall to Avent Creek
Hydrograph
.................................................................................................................................................................................................. ............... ............... ............... ............... ............... _ ............... ...............
C-Inflow
22 Outflow
19.98 cfs .....«..... .....i.....
21 II flV YM....�I�i��L V...�.5 ....�.�........ 19.92 cfs
20 ............................:.........................
19 �............... ............... ............... ............... ............... ............... ...............
18
Avg. I_ovx Q�pth �1 15
17 ............... ...............
..........Max el_# .67 fps ........
16 ........................:..................................................:...................................................:.........................
15 .................................................................................................._.................... .......... ...............
14 ...T.. ........i.........................i.........................:.
13
12 -0 ..
0 10 ........... '. .Q.. .8. ..._.��......._................................................_..........................
9 .......... ............... ............... ............... .................... .....
8 ............... ............... _ ............... ..............._.....
Ctipa ity _1_32 A�2 _Cfs
7 ........................:.................... ....... ...............
6 ............................................................................................................................................. ...............
5 .................................................................................................._................................................_......................... ............... ............... ...............
q .............................................
....................................................._..........................................
3 ............................................................................................................................................................................. ......................... ............... ............... ..
2
1'
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 25y24h 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 of
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 of
Secondary= 19.35 cfs @ 12.19 hrs, Volume= 0.473 of
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
......................:......................................................................,......................,......................,.......................:........................:..............................................,......................,.......................:........................:..............................................
......................I......................................................................................................................................... .............. ............. ............. ............ ............. .............. ............. .............
- -- _Inflow
25.05 cfs L oUtflow
............................................................................................................. _ ..... .......
zs.os ofs �Primary
Inflow Area=8 y7_wC Secondary 28 4 y
............................................................................................r.................................................. ............................................................... ............a.............
26 V3
. Peak 1e : 57 7
24
22
..........................................................................................
.....:............
19.
2035 cfs
18
H 16
....................................................................................................................... .. .....................................................
3 14 ............. ............. ............ _ ............. .............. ............. .............
0
LL 12
10
8 s
6
4
2
0
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—May 2024
Attachment D.2—Post-Development Calculations
D2
■
Attachment D.2 — Post-
Development Calculations

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024 �1J�
Attachment D.2—Post-Development Calculations
This page intentionally left blank.

1 2 3 4 5 6 7 8
3
N
3
6� I
Q 3
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3 LEGEND:
0
M
3 EXISTING CONTOURS
LOC LIMITS OF CONSTRUCTION
41- t-MUt-r-M I T UIVC
3 360 - - - - - - - - - - BUFFER ZONE
APPROXIMATE EDGE OF TREE LINE
�s
— — — — — — — — — — E911 TOWER RADIUS
�� 3ss 3 —xxxxx TOWER FENCE
ADJACENT PUBLIC ROW
o W W W— 6" WATER MAIN
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3SS TIME TO CONCENTRATION
z_ 100 LF SHEET FLOW
827 LF SHALLOW CONC
_ i 3gs � coo
m
ME911 COMMUNICATIO _^-� TOWER _ _ 355—355
M
345 EXISTING FENCE LINE I X � � — 3 NCS
35'FRONT BUFFER (6U pVF�SR42�
p �' �k/C °qo 3�ss
ROw j,
O — /ON DITCH(D PROPERTY
w rJ0 (DID)
�cS 3 ' 25Y 24H MAX VELOCITY 5.17 FT/S �. AREA 4 DRAINS TO EXISTING
NCDOT ROW SWALE NO 3S0
AREA 4:4.518 AC IMPROVEMENTS TO BE MADE
i
�jO c�� 32ro v c�2 O TIME TO CONCENTRATION
100 LF SHEET FLOW
S 30 506 LF SHALLOW CONC �s
w�°'
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285 � �� �-- TIME TO CONCENTRATION � �-�
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275 0 / 186 LF SHALLOW CONC U, TIME TO CONCENTRATION o
100 LF SHEET FLOW `� Q
175 LF SHALLOW ONC I O
�ss\O N M Mw0 C SWALE(S1) r I
24H MAX VELOCITY 6.11 FT/S ACCESS DRIVE SWALE(SO)
25Y 24H MAX VELOCITY 1.99 FT/S\ o
N �h 315 0 i XISTING 6-INCH
Nry o M p i 3 WATER MAIN
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O N AREA 3: 1.231 AC w
N IM TIME TO CONCENTRATION �O
100 LF SHEET FLOW 3 B
220 LF SHALLOW CONC \ r
O N UTLET PROTECTION TO BE 4j
PROPERTY LIN PLACED FOR IMPROVED CULVERT
\�LIN
�3 29p 285 O M \355 s
N2�5 34S AREA 4 AND 5 DRAIN TO 345 P
O N N N `L7 o M 33S 3 EXISTING NCDOT ROW
SWALE NO IMPROVEMENTS
CDEst M 3 C SWALE(S2) \ 3 0 TO BE MADE o
N 265 0 30 25Y 24H MAX VELOCITY 5.98 FT/S 3 3S / w
345 s'�s
N 15
Aso 310 � 320 M o^0
315 N M 32S o
000
AVENTS CREEK
M
� N NTIRE SITE DRAINS THROUGH NATURAL 290 S MO M;;
� CHANNELS IN DRAWS AND INTO ADVENT CREEK �
N 2�p 285 N� NOTES:
Q� O O6 26S
rr
255 60 280 ��0 1. EXISTING TOPOGRAPHY AND PROPERTY LINES OBTAINED FROM
`So 275 HARNETT COUNTY GIS.
330 2. PROPERTY BOUNDARY SURVEY COMPLETED BY BENTON W.
40 DEWARE AND ASSOCIATES, APRIL 30, 2019.
CD
`L�� 23h2��' h 2to0 255 60 60 265� �7p 2�5 2g0 285 2$ 32S 3. CONDITIONAL USE PERMIT#BA-CU-18-18 APPROVED 6/11/18.
2
0
J
a
PROJECT MANAGER J. MURRAY, PE Harnett
PROJECT ENGINEER A. MCGREW, PE PROPOSED CONDITIONS
CD
0 C o U N T Y HYDROCAD MODEL
HDR Engineering, Inc. of the Carolinas DRAWN BY A. MCGREW, PE NORTH C A R O LI N A KEY
N.C.B.E.L.S. License Number: F-0116
strong roots a new growth
N
7
555 Fayetteville Street, Suite 900 HARNETT COUNTY
co Raleigh, NC 27601 C 0 /202 ISSUED FOR BIDDING NORTHWEST CONVENIENCE CENTER SHEET
919.232.6600 B 01/2023 0 T. 2�� FILENAME OOG-02.dwg REVISED BASED ON REVIEWER COMMENTS
A 10/2022 ISSUED FOR PERMITTING 00019 OOG-01
s ISSUE DATE DESCRIPTION PROJECT NUMBER 10354679 SCALE 1" = 125' 1
HARNETT COUNTY NORTH CAROLINA

O
Area 4 [DO]
ONCDOT Ro d Ditch
Area 4 � ISO]
1
O
❑
Area 1
Access Drive Swale ce
D D � 1.1 2 O O
Diversi n Ditch 1 P Area 1.1 Area 3 Replaced C Ivert
� O �
❑ �B
D 1 Pond C2rea 3❑ [si] [D3] [D:4]
Dra [D2] Swale Proposed Culvert [S2] Draw ch Next to Road
Draw CC Swale
[D5]
Draw
[D6]
[D7] Draw
Outfall to Avent Creek
a A _
40654 Z7
GINS
I1 11k1�\\\��
�/� 7 6
Subcat Reach on Link Routing Diagram for 20220116_Harnett County_NW CC—Construction Conditions
Prepared by HDR, Inc, Printed 1/17/2023
HydroCAD®10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC

20220116_Harnett County_NW CC—Construction Conditions
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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

20220116_Harnett County_NW CC—Construction Conditions
Prepared by HDR, Inc Printed 1/17/2023
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
26.524 HSG B 1, 1.1, 2, 3, 4, 5
0.000 HSG C
0.000 HSG D
0.000 Other
26.524 TOTAL AREA

20220116_Harnett County_NW CC—Construction Conditions
Prepared by HDR, Inc Printed 1/17/2023
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 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

20220116_Harnett County_NW CC—Construction Conditions
Prepared by HDR, Inc Printed 1/17/2023
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 DiamMidth Height Inside-Fill
Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches)
1 1 P 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

20220116_Harnett County_NW CC-Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 6
Time span=0.00-120.00 hrs, dt=0.01 hrs, 12001 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 of
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 of
Subcatchment 2: 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 of
Subcatchment 3: 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 of
Subcatchment 4: 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 of
Subcatchment 5: 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 of
Reach DO: NCDOT Road Ditch Avg. Flow Depth=0.36' Max Vet=1.99 fps Inflow=2.19 cfs 0.200 of
n=0.035 L=1,130.0' S=0.0159 '/' Capacity=210.84 cfs Outflow=1.46 cfs 0.200 of
Reach D1: Draw Avg. Flow Depth=0.12' Max Vet=0.21 fps Inflow=1.42 cfs 0.620 of
n=0.400 L=500.0' S=0.0620 '/' Capacity=252.99 cfs Outflow=0.72 cfs 0.620 of
Reach D2: Draw Avg. Flow Depth=0.00' Max Vet=0.00 fps
n=0.400 L=430.0' S=0.0977 '/' Capacity=211.86 cfs Outflow=0.00 cfs 0.000 of
Reach D3: Draw Avg. Flow Depth=0.00' Max Vet=0.00 fps
n=0.400 L=228.0' S=0.1667 '/' Capacity=432.67 cfs Outflow=0.00 cfs 0.000 of
Reach D4: Ditch Next to Road Avg. Flow Depth=0.62' Max Vet=0.57 fps Inflow=2.65 cfs 0.317 of
n=0.400 L=500.0' S=0.0720 '/' Capacity=49.87 cfs Outflow=1.74 cfs 0.317 of
Reach D5: Draw Avg. Flow Depth=0.17' Max Vet=0.26 fps Inflow=0.72 cfs 0.620 of
n=0.400 L=982.0' S=0.0570 '/' Capacity=120.90 cfs Outflow=0.50 cfs 0.620 of
Reach D6: Draw Avg. Flow Depth=0.11' Max Vet=0.19 fps Inflow=1.74 cfs 0.317 of
n=0.400 L=1,720.0' S=0.0500 '/' Capacity=198.54 cfs Outflow=0.45 cfs 0.317 of
Reach D7: Outfall to Avent Creek Avg. Flow Depth=0.20' Max Vet=0.24 fps Inflow=0.95 cfs 0.937 of
n=0.400 L=130.0' S=0.0385 '/' Capacity=132.42 cfs Outflow=0.95 cfs 0.937 of
Reach DD: Diversion Ditch Avg. Flow Depth=0.05' Max Vet=1.82 fps Inflow=1.33 cfs 0.238 of
n=0.022 L=240.0' S=0.0375 '/' Capacity=734.43 cfs Outflow=1.32 cfs 0.238 of
Reach SO: Access Drive Swale Avg. Flow Depth=0.24' Max Vet=1.05 fps Inflow=1.87 cfs 0.117 of
n=0.030 L=540.0' S=0.0037 '/' Capacity=72.46 cfs Outflow=1.31 cfs 0.117 of

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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 of
n=0.022 L=390.0' S=0.0269 '/' Capacity=340.18 cfs Outflow=3.93 cfs 0.328 of
Reach S2: CC Swale Avg. Flow Depth=0.31' Max Vet=3.67 fps Inflow=4.13 cfs 0.328 of
n=0.022 L=455.0' S=0.0233 '/' Capacity=49.84 cfs Outflow=4.01 cfs 0.328 of
Pond 1P: Pond Peak Elev=323.32' Storage=25,085 cf Inflow=4.36 cfs 0.380 of
Primary=0.14 cfs 0.382 of Secondary=0.00 cfs 0.000 of Outflow=0.14 cfs 0.382 of
Pond C 1: Replaced Culvert Peak Elev=354.63' Inflow=2.65 cfs 0.317 of
Primary=2.65 cfs 0.317 of Secondary=0.00 cfs 0.000 of Outflow=2.65 cfs 0.317 of
Pond C2: Proposed Culvert Peak Elev=335.19' Inflow=4.01 cfs 0.328 of
30.0" Round Culvert n=0.012 L=45.0' S=0.0867 '/' Outflow=4.01 cfs 0.328 of
Total Runoff Area= 26.524 ac Runoff Volume = 0.935 of Average Runoff Depth = 0.42"
99.43% Pervious= 26.374 ac 0.57% Impervious = 0.150 ac

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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= 0.00-120.00 hrs, dt= 0.01 hrs
Type II 24-hr ly 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
❑Runoff
1.33 cfs
Type II 24-hr
1y 24h Rainfall=3.05`'
_ .Runo , Ate 48 air
1
RunpffVQlume0. 3$ of
Runoff Depth=0.29"'
FIaW Length=830'
Tc=24.0 m i n
CN=58
L W4.K44�04;�
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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= 0.00-120.00 hrs, dt= 0.01 hrs
Type II 24-hr ly 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
0.7 ■Runoff
.............. 0.65 cfs ...... _............................i........................................... ...... ...... ..... ..... ................................. ..... ..... ..... ...... ..... ..... ...... ...... .... .....
0.65
0.6
.............. .........................
.....:.....
fall=3 _5 ,
0.55
am
0.5 R..0 n off...Area..=.1.....7,.6._,�.....a .........
0.45 RunOffVplume= .05z af........
0.4 '
3 0.35
o
LL 0.3
0.25 TC-9.2......rn.1_n_........
.......................... .......:...............:............ .... ..... ..... .... .... ..... .... .... .... .... ..... .... .....
0.2 CN:60
0.15
0.1
0.05
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 160 165 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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= 0.00-120.00 hrs, dt= 0.01 hrs
Type II 24-hr ly 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
❑Runoff
3.19 cfs
.......................... .........................:................................................,................;................................. .... _ ..... _ ...... ...... .....
T
3
1y 24h Rainf6ll=3.05`'
Runoff Area=5.131 ac
Run_OffYQlume .0.�2.5 of .
H 2
Runoff:Depth=0.33 '
Flow Length=500'
T&11.8 min
......................... ............................................................................................................................... ..............._ .... _ ..... ..... ..............._ .... _................
..... .....
1 CN:65
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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= 0.00-120.00 hrs, dt= 0.01 hrs
Type II 24-hr ly 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
❑Runoff
1.21 cfs
Type II 24-hr
�y2�h Rai
1
Runoff Area=1.231 aC
Run : ff Volume 0.102 of
Runoff Depth=0.99"'
FIoW Length=326'
TC=22.4 m i n
CN:
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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= 0.00-120.00 hrs, dt= 0.01 hrs
Type II 24-hr ly 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
_ _ _ype r .
: . . : : . . . . . . . . . . . . : . . .
. . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .
2-1/
1y 24h Rainfall=3.05"
Runoff Area=6.257 ac
RunOff V: I : me=0.20b of
Runoff Depth=0.38"
LL Flow Len th=606
. .....:..... ....
1
Tc=13.1 14.
min
GN=6"I
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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= 0.00-120.00 hrs, dt= 0.01 hrs
Type II 24-hr ly 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
2
...........
❑Runoff
87 cfs
Type II 24-hr
1y 24h Rainfall
Runoff Area=2.296 aC
NU
RunfVlume0 , 17ofpQ 0.�Run_offDepth "
1 Flow Length=275'
LL
T&10.3 min
GN=67
0- ILL:
0 5 10 15 20 25 30 35 40 45 50 55 60 i5 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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 ly 24h event
Inflow = 2.19 cfs @ 12.09 hrs, Volume= 0.200 of
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= 0.00-120.00 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 7' Top Width= 19.00'
Length= 1,130.0' Slope= 0.0159 7'
Inlet Invert= 372.00', Outlet Invert= 354.00'
Reach DO: NCDOT Road Ditch
Hydrograph
Inflow
2.19 cfs ❑outflow
I pflow , rya. 5.2 7 a
2 r4vg. Flog Depth=0.3C'
Max Vet=1 .99 fps
.46 cfs n=0.035
L=1 ,130.0'
3 ...... .
.....
o
LL S-0 0159 T
1
Cap:city=210.94 cfs
---------------
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 15
Summary for Reach D1: Draw
Inflow Area = 17.971 ac, 0.00% Impervious, Inflow Depth = 0.41" for ly 24h event
Inflow = 1.42 cfs @ 12.30 hrs, Volume= 0.620 of
Outflow = 0.72 cfs @ 12.83 hrs, Volume= 0.620 af, Atten= 49%, Lag= 31.9 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.21 fps, Min. Travel Time= 38.8 min
Avg. Velocity = 0.11 fps, Avg. Travel Time= 78.1 min
Peak Storage= 1,685 cf @ 12.83 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 7' Top Width= 88.00'
Length= 500.0' Slope= 0.0620 7'
Inlet Invert= 316.00', Outlet Invert= 285.00'
Reach D1: Draw
Hydrograph
Inflow
1.42 cfs ❑outflow
In 'Iow Area=17.971 a
Avg.; Flog Depth : 0.12'
.....:..... .....:..... .....:..... .....:.....
Max: e p
1 n=0.400
U
L=500.0'
3 0.72 cfs
LL S=00620 7'
Cap:city=252.99 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 16
Summary for Reach D2: Draw
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 7' Top Width= 72.00'
Length= 430.0' Slope= 0.0977 7'
Inlet Invert= 327.00', Outlet Invert= 285.00'
Reach D2: Draw
Hydrograph
1 ❑Outflow
Avg. FlOW Depth=0.00'
Max Vet=0.00 fps
n=0.400
N
L=430.0'
V S 0.0977 T
LL
Capacity=211 .86 cfs
0.00 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 17
Summary for Reach D3: Draw
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 7' Top Width= 110.00'
Length= 228.0' Slope= 0.1667 7'
Inlet Invert= 353.00', Outlet Invert= 315.00'
Reach D3: Draw
Hydrograph
1 ❑Outflow
Avg. FlOW Depth=O. Q'
Max Vet=0.00 fps
n=0.400
N
L=228.0
V
S=0.1667 T
LL
Capacity=432.67 cfs
0.00 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 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 ly 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= 0.00-120.00 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 7' Top Width= 21.00'
Length= 500.0' Slope= 0.0720 7'
Inlet Invert= 351.00', Outlet Invert= 315.00'
Reach D4: Ditch Next to Road
Hydrograph
Inflow
2.65 cfs ❑outflow
I: flouv Area=8.553 ac
Avg. Flog Depth=0.6 '
. .......... .....
Max e
2 = .57 : ps
n= .400
1.7 cfs
U
L=500.0'
........................................................... 7 .. 0I.0 2.0.......................LL ..............:. ...._................:............._.............._:...............:............._.. ..._i.... ....i..... .......... ..._i....
1 Gapao:4=49.87 cf.43
0
]A 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC-Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 19
Summary for Reach D& Draw
Inflow Area = 17.971 ac, 0.00% Impervious, Inflow Depth = 0.41" for ly 24h event
Inflow = 0.72 cfs @ 12.83 hrs, Volume= 0.620 of
Outflow = 0.50 cfs @ 14.01 hrs, Volume= 0.620 af, Atten= 31%, Lag= 71.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.26 fps, Min. Travel Time= 63.5 min
Avg. Velocity = 0.13 fps, Avg. Travel Time= 130.1 min
Peak Storage= 1,906 cf @ 14.01 hrs
Average Depth at Peak Storage= 0.17'
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 7' Top Width= 52.00'
Length= 982.0' Slope= 0.0570 7'
Inlet Invert= 285.00', Outlet Invert= 229.00'
Reach D& Draw
Hydrograph
.............................................................................................................................................. ..... ..... ..... ..... ..... ..... .... .... .... ..... ..... ..... ..... ....
0.8 ❑Oultf ow
0.72 cfs
............_i............. ..._i...............i......................... .... ..... ..... ..... ..... ..... .....
0.75
n low Qea_ ............................. ..... ................ ....
0.7
I Flo.... ....
0.65
:
..... .. _ ....................
..
0.6 Va e.
................... .......... .....
........................ ..... ..... ..... ..... ..... ....0.55
0.50 cfs
..... ..... _ ..... .... _ ..... ..... _ ..... ..... ..... _ ..... ..... _ ..... ..... _.............._..............._........................ .� ..._ ..........
0.5 ..
00
............_..... ..............:............................_'.............................;...............................'...............;...............................;...............................'.............................._ .... .... _ _
0.45 �.........
3 0.4
O ............_... .............................._......... ..... ..... ..... ..... ..... ..... ..... ..... ..... .... ....
LL 0.35 ... 0570 .1. .. .... ...A...........
�* t
�.. f
.....:.....
................ ..;............................;..........................................................................;........................................ ..... .... _ .... .... _ ..... ..... _ ..... ..... ....
0.3 .................................................................... _ ..... Cy- .. ..,.a�u......�if��..........
0.25 .�. .
0.2
.... .... ..... ..... ..... ..............................._.............................._.............._..............._.............._................ ..... ..............................._..............
0.15
.............. ..........
................... ..... ..... ..... .... .... .... ..... ..... ..... ..... ....
0.1
0.05
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 20
Summary for Reach D6: Draw
Inflow Area = 8.553 ac, 1.75% Impervious, Inflow Depth = 0.44" for ly 24h event
Inflow = 1.74 cfs @ 12.35 hrs, Volume= 0.317 of
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= 0.00-120.00 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 7' Top Width= 86.00'
Length= 1,720.0' Slope= 0.0500 7'
Inlet Invert= 315.00', Outlet Invert= 229.00'
Reach D6: Draw
Hydrograph
Inflow
1.74 cfs ❑outflow
Inflouv Are a: ac
Avg. Flog Depth=0.11'
Max Vet=0.19 fps
n=0.400
1 4=1 ,720.0'
LL 0500 T
Ca:p:city=198.54 cfs
0.45 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 21
Summary for Reach D7: Outfall to Avent Creek
Inflow Area = 26.524 ac, 0.57% Impervious, Inflow Depth = 0.42" for ly 24h event
Inflow = 0.95 cfs @ 13.96 hrs, Volume= 0.937 of
Outflow = 0.95 cfs @ 14.06 hrs, Volume= 0.937 af, Atten= 0%, Lag= 6.5 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.24 fps, Min. Travel Time= 9.0 min
Avg. Velocity = 0.10 fps, Avg. Travel Time= 21.3 min
Peak Storage= 513 cf @ 14.06 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 7' Top Width= 60.00'
Length= 130.0' Slope= 0.0385 7'
Inlet Invert= 229.00', Outlet Invert= 224.00'
Reach D7: Outfall to Avent Creek
Hydrograph
................................................................................................................................................. _ _ ..... ..... ..... _ ..... ..... F Inflow
....:......................... ..... ..... ...... ..... ..... ..... .........
0.55 cfs ;
❑Outflow
1 095 ds Inflo�W Area=26.524 ae
r4vg. Flog Depth=0.2a'
Max Vel=0.24 fps
n=0.400
U
L=130.0'
.2 S=0:0385 7'
ap:city=132.42 cfs C .
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 22
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 of
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= 0.00-120.00 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 7' Top Width= 30.00'
Length= 240.0' Slope= 0.0375 7'
Inlet Invert= 325.00', Outlet Invert= 316.00'
Reach DD: Diversion Ditch
Hydrograph
Inflow
1.33 cfs ❑outflow
1.32 cfs I n 1b : Area=91.848 a
...........
Avg.; Flog Depth : 0.05�'
ax e: ps
1 n=0.022
N
L=240.0'
LL S=0:0375 7'
Cap:city=734.43 cfs
6 1
07
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 23
Summary for Reach SO: Access Drive Swale
Inflow Area = 2.296 ac, 6.53% Impervious, Inflow Depth = 0.61" for ly 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= 0.00-120.00 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 7' Top Width= 16.50'
Length= 540.0' Slope= 0.0037 7'
Inlet Invert= 358.00', Outlet Invert= 356.00'
Reach SO: Access Drive Swale
Hydrograph
1.87 cfs
2
Inflow
❑Outflow
1: flouv Area=Z.296 ad
Avg. Flog Depth=0.24'
Max Vel=1 .05 fps
1.31 cfs n=0.030
y .............. ...............i....................................................... ..... ...... ..... ..... ..... ..... ...... ..... ..... ..... ....
U
1 S w540-01 00037T
LL
Ca : a: 4=72.46 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 24
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 of
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= 0.00-120.00 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 7' Top Width= 24.00'
Length= 390.0' Slope= 0.0269 7'
Inlet Invert= 330.50', Outlet Invert= 320.00'
Reach S1: Swale
Hydrograph
Inflow
......................................... ..... ..... ..... ...... ..... ..... ..... ..... ...... ..... ..... ..... .... ..... ..... ..... ..... .....
4.01 cfs .......... .......... _ _ ❑Outflow
3.93 cfs 1: fl:ouv Area: .362:ad.
4
Avg. Flog Depth=0.2 '
M
_
. . ......_:......... ..: ..................... ..
ax a ps
3 n=0.022
N
w
.......... .......;...............«..............«............._i...............i......................
2 S=0 0269.T
Capac t034p.18 cfs
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 25
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 of
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= 0.00-120.00 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 7' Top Width= 12.00'
Length= 455.0' Slope= 0.0233 7'
Inlet Invert= 345.00', Outlet Invert= 334.40'
Reach S2: CC Swale
Hydrograph
Inflow
4.13 cfs ❑outflow
.............,........... ........«...............i...............«............._i...............
.... l an rea= 34.01 cfs ..4
Avg.; Flog Dept.h=0.31'
Max: -
. . .........
3 n=0.022
U _ '1
L............................ .... .... .... ..... .... - .....
LL 2 S=0 0 33 ' '
Capacity=49.84 cft
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC-Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 26
Summary for Pond 1 P: Pond
Inflow Area = 8.123 ac, 0.00% Impervious, Inflow Depth = 0.56" for ly 24h event
Inflow = 4.36 cfs @ 12.11 hrs, Volume= 0.380 of
Outflow = 0.14 cfs @ 22.49 hrs, Volume= 0.382 af, Atten= 97%, Lag= 622.6 min
Primary = 0.14 cfs @ 22.49 hrs, Volume= 0.382 of
Secondary= 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs
Starting Elev= 322.14' Surf.Area= 8,230 sf Storage= 14,450 cf
Peak Elev= 323.32' @ 22.49 hrs Surf.Area= 9,840 sf Storage= 25,085 cf (10,635 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= 2,363.5 min calculated for 0.050 of (13% of inflow)
Center-of-Mass det. time= 944.3 min ( 1,850.3 - 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 (Turned on 3 times)
#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 Primary 322.14' Tube/Siphon/Float Valve 2.500" Diameter, C= 0.600
20.0' Long Tube, Hazen-Williams C= 130
Inlet/ Outlet Elev. = 0.00' /322.00' Starts@322.14' Breaks@322.13'
#3 Device 1 324.25' 44.0"W x 6.0" H Vert. Orifice/Grate X 4.00 C= 0.600
#4 Device 1 325.50' 48.0" x 48.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5 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

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 27
Primary OutFlow Max=0.14 cfs @ 22.49 hrs HW=323.32' TW=316.06' (Dynamic Tailwater)
1=Culvert (Passes 0.00 cfs of 31.44 cfs potential flow)
L3=Orifice/Grate ( Controls 0.00 cfs)
4=Orifi ce/G rate
( Controls 0.00 cfs)
2=Tube/Siphon/Float Valve (Tube Controls 0.14 cfs @ 4.05 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=322.14' TW=325.00' (Dynamic Tailwater)
L5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Pond 1 P: Pond
Hydrograph
❑Inflow
4.36 cfs ❑oUtfIOW
_............... ............. ea�.8......'�...�.3...aC ❑Primary
_ I �c7 n# O�-'Ar �Secondary
Peak Elegy= 2 .32
4
drag
y
3
............;........ ......:..........................................;..............;..............;............................_ ... .... .... _.............._ .... .... .... .... _ ...
N
U
3
0
LL 2
1
0.14 cfs
0.14 cfs
0.00 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC-Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 28
Summary for Pond C 1: Replaced Culvert
Inflow Area = 8.553 ac, 1.75% Impervious, Inflow Depth = 0.44" for ly 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 of
Secondary= 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 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)
L1=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)
L2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Pond C 1: Replaced Culvert
Hydrograph
Inflow
2.65 cfs oUtfIOW
2.65 cfs I h W: rea-8.;553 ac Primary
z.ss as a Secondary
Peak EI: =354.63"
2
N
U
3
0
LL
-----------------
0.00 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Condit Type 1124-hr 1 y 24h Rainfall=3.05"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 29
Summary for Pond C2: Proposed Culvert
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 of
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 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 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)
L1=Culvert (Inlet Controls 4.01 cfs @ 3.02 fps)
Pond C2: Proposed Culvert
Hydrograph
❑Inflow
a.o�ots �..... ..._..... _ Primary
4 a°' s Inflow Area=6.362 ad
Ptak EIeev=33a.19'
............................................................ ........................ .... .... .... . ........................�.............
30:0
3
Round Culvert
N
3
n
Gf
0 2
" L=46.0'
.....:.....
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 165 110 115 120
Time (hours)

20220116_Harnett County_NW CC-Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 30
Time span=0.00-120.00 hrs, dt=0.01 hrs, 12001 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 of
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 of
Subcatchment 2: 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 of
Subcatchment 3: 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 of
Subcatchment 4: 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 of
Subcatchment 5: 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 of
Reach DO: NCDOT Road Ditch Avg. Flow Depth=1.13' Max Vet=3.84 fps Inflow=21.47 cfs 1.316 of
n=0.035 L=1,130.0' S=0.0159 '/' Capacity=210.84 cfs Outflow=18.97 cfs 1.316 of
Reach D1: Draw Avg. Flow Depth=0.99' Max Vet=0.79 fps Inflow=39.22 cfs 3.845 of
n=0.400 L=500.0' S=0.0620 '/' Capacity=252.99 cfs Outflow=29.66 cfs 3.845 of
Reach D2: Draw Avg. Flow Depth=0.00' Max Vet=0.00 fps
n=0.400 L=430.0' S=0.0977 '/' Capacity=211.86 cfs Outflow=0.00 cfs 0.000 of
Reach D3: Draw Avg. Flow Depth=0.00' Max Vet=0.00 fps
n=0.400 L=228.0' S=0.1667 '/' Capacity=432.67 cfs Outflow=0.00 cfs 0.000 of
Reach D4: Ditch Next to Road Avg. Flow Depth=2.15' Max Vet=1.14 fps Inflow=28.18 cfs 1.910 of
n=0.400 L=500.0' S=0.0720 '/' Capacity=49.87 cfs Outflow=23.15 cfs 1.910 of
Reach D5: Draw Avg. Flow Depth=1.28' Max Vet=0.80 fps Inflow=29.66 cfs 3.845 of
n=0.400 L=982.0' S=0.0570 '/' Capacity=120.90 cfs Outflow=19.45 cfs 3.845 of
Reach D6: Draw Avg. Flow Depth=0.58' Max Vet=0.50 fps Inflow=23.15 cfs 1.910 of
n=0.400 L=1,720.0' S=0.0500 '/' Capacity=198.54 cfs Outflow=7.76 cfs 1.910 of
Reach D7: Outfall to Avent Creek Avg. Flow Depth=1.35' Max Vet=0.73 fps Inflow=27.20 cfs 5.755 of
n=0.400 L=130.0' S=0.0385 '/' Capacity=132.42 cfs Outflow=27.06 cfs 5.755 of
Reach DID: Diversion Ditch Avg. Flow Depth=0.27' Max Vet=5.17 fps Inflow=20.88 cfs 1.839 of
n=0.022 L=240.0' S=0.0375 '/' Capacity=734.43 cfs Outflow=20.83 cfs 1.839 of
Reach SO: Access Drive Swale Avg. Flow Depth=0.73' Max Vet=1.99 fps Inflow=10.89 cfs 0.595 of
n=0.030 L=540.0' S=0.0037 '/' Capacity=72.46 cfs Outflow=9.71 cfs 0.595 of

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 31
Reach S1: Swale Avg. Flow Depth=0.59' Max Vet=6.11 fps Inflow=25.18 cfs 1.648 of
n=0.022 L=390.0' S=0.0269 '/' Capacity=340.18 cfs Outflow=25.00 cfs 1.648 of
Reach S2: CC Swale Avg. Flow Depth=0.74' Max Vet=5.98 fps Inflow=25.47 cfs 1.648 of
n=0.022 L=455.0' S=0.0233 '/' Capacity=49.84 cfs Outflow=25.18 cfs 1.648 of
Pond 1P: Pond Peak Elev=324.79' Storage=41,247 cf Inflow=30.53 cfs 2.004 of
Primary=18.39 cfs 2.006 of Secondary=0.00 cfs 0.000 of Outflow=18.39 cfs 2.006 of
Pond C 1: Replaced Culvert Peak Elev=356.67' Inflow=28.18 cfs 1.910 of
Primary=28.18 cfs 1.910 of Secondary=0.00 cfs 0.000 of Outflow=28.18 cfs 1.910 of
Pond C2: Proposed Culvert Peak Elev=336.77' Inflow=25.18 cfs 1.648 of
30.0" Round Culvert n=0.012 L=45.0' S=0.0867 '/' Outflow=25.18 cfs 1.648 of
Total Runoff Area= 26.524 ac Runoff Volume =5.753 of Average Runoff Depth = 2.60"
99.43% Pervious= 26.374 ac 0.57% Impervious = 0.150 ac

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 32
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= 0.00-120.00 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.aa cfs ..._..... .......... ..........
21 ..............._........... _............ .......:................,...............;.......... _ ........._:..... ...............
r .
19 ............................................................_................;............................................................_..............._............. .. fit.........
4 in. 11- .7
18 ...............................;...............;...............;................;................................ .J5.. ....... ......... ......R ................... .................�?.............5...............
17 .......................... ........:.....
R , n y�_f �1r _ _ �Q
16 ........................... .......................,...............,...............,................................................,...............,.............................................................................. ...........�/.........,...............,.....Qr_s..........17.....�..........5:7......f�t.........
. .
15
R n ff V 1 m ,1. f .
u...........�............. u..............e......................8 ....I ........
13
..................................................................._......... ......
ff ©_e th 2.24
12 Runo 3
11 - ILL
....... ...... ...... ...... ..... ..... ...... ... . ... ...........
9 ..... ...... ...... ...... .
2 0 .............................. ..................................................
7 ................ .
6 ............._....... .................................................................._........................................... _..............._ ......
CN-5S
5 ................................................... ...... ...... ..... _..............._ ...... ...... ...... ..... ..... _..............
4 ..... ...... ....... ...... ...... ...... ..... ..... ...... ...... ......
3 ...................................................................................................................... _ ...... ....... ...... ...... ...... _ ..... _................_ ...... ...... ...... _ ..... _ ..... _ .....
2 ......... ...... ..... ..... ...... ....... ...... ...... ...... ..... ..... ...... ...... ...... ..... ..... .....
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 33
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= 0.00-120.00 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
............................................................................................................................................................... ...... ...... ...... ..... ............... ...... ...... ..... ..... ...... ...... ...... ...... .....
:
uno
7 6.73 cfs
TYP II 24- r
..... .... _ .... _ .....e ..... ..... ..... _..........
5 24 Rain fall=6.75"y
# unof�F Ares-1 .6� a c
5
Ru n : ff V: I : me 0. 56 of
N ............._........... ........,.............._.............._;.............._...............,.............._.............._;.............._.............._!................;.............._.............._.............._........ ...... ..............._ ....
4 Runoff pth=2.43'
LL ..... ..._........... ............. .......... .... _ FIawLen NOW -286
g
3
Tc : 9.2 nin
.... .... .... ..... ..... .... ......
2
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 34
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= 0.00-120.00 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
24
❑Runoff
23 ..............................................._................_................. ...... ...... ..... ..... ................. ....... ...... ...... ..............................._................_................. ...... ...... ..... ..... ................
21.52 cfs
22 ................«...............«...............«........... ...... ...... ..... ..... ...... ....... ...... ...... ...... ..... ..... ...... .....
21 ...........
............._i............ .........i................«.... «.......
......... .
20
19 .... C
h
..C .........
18
1 ............... Ru nbf Ae =S,_ _
16 .......................... .........................................
15 er"1...to
,Rt�nQ#f �/olum 24�; _fit .
14 ..........................
w
......... ........... ........... ....:.....
V Runo#f-Depth 2.91"
3
12 .......................... ............................................................................................... ..... ..............._ ...... ....... ...... ...... ...... ..............._..............._ ...... .................................. ...............
0 11 ....
LLFfoWLength_ 00, .
10 ............._........... ............................................................................................... _ ..... _ ..... _ ...... ....... ...... ...... ...... - ..... _..............._ ...... ..............._ ..... _ .....
g
.....:.....
-rc_, .gmph
8 ......................... ............................................................................................... ..... _ ...... ....... ...... ...... ...... ..... _ ..... _ ...... ................................. .
7
CN:
6 ...........
5 ........... ............................................................................................... _ ..... _ ..... _ ...... ....... ...... ...... ...... _ ..... _ ..... _ ...... ...... ...... _ ..... _ ..... _ .....
q ......................... ............................................................................................. ..... ..... _ ...... ....... ...... ...... ...... ..... _ ..... _ ...... ...... ...... ..... ..... _ .....
3 ...... ........................................................... ...... ......
2 ............................. .......
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 35
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= 0.00-120.00 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
❑Runoff
s.oa as ............................................................................................................................ ...... ...... ..............._................_ ...... ...... ..... ..............._ ...... ...... ...... ...... .....
5 Type II 24-Ir
25 : 2�41 Rainfall :
...... ..... ..... .....
4 =
Runoft Area 1.231 ac
RunpffVQlume0.403 of
3 Ru:noff:Depth=3. 3''
_ _ FlowLenth=326'g
............._............ ................................. ........:......... ..... ..............._................ ..... ..... ..... ..... ............... ..... ................................ .....T .2 C min:CN
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 36
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= 0.00-120.00 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
23
■Runoff
22
21.47 cfs
21 ............ .........i............................................................_i................i...................................... ape �� �4
20 ........................................................................................................ _ ..... _ ...... ....... .........:.....
19 ........... 2.5 / 4I7 Fairlfa �,
18 ....................................................................................................................... _ ...... ....... ...... ...... ...... ...................._ ...... ...... ...... ..... ................._ .....
17 ......
F u nOf �4t�e -6 � �£
16 .....
15 R me=-1.... ._1..6.....a.f........
Unoff\ft�ltt
14 ............._............ ............................................................................................... ..... ..... _ ...... ....... ...... ...... ...... ..............._................_ ...... ...... ...... ..... ..............._ .....
w
u 13 .. ..
12 ............
RttnoffDept ��"
3
0 11 .......................... .......:...............................................................................................;........................................ �G+.O.��..........
LL Ffow Len ,th_
10 .......... ...................... .............. .... ..... ..... ......
. ..._:.....
g .......... ................................................................
.....
8 ......
7
...... ................................................ _ ...... ...... ...... _..............._..............._ ...... ....... ...... ...... ...... _ ..... _..............._................6 ........... .............................................................
GN: 61
5 /
......................... .............................................................................................. ..... ..... _ ...... ....... ...... ...... ...... ..... _ ..... _ ...... ...... ...... ..... ..... _ .....
4 .......... ............................................................
3 .......... ............................................................................................................. _ ..... _ ...... ....... ...... ...... ...... _ ..... _................_ ...... ...... ...... _ ..... _ ..... _ .....
2 .....
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 37
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= 0.00-120.00 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
ape
101
...............:...............:.....
r
.....
f1116:75
9 —
...........
Ru
nft
_, _, ; � Ares-2296 air
-
_ _ f _ _RUnQ#f-\lolume4iiM of
N 7 �
w
Runoff De th 3 �
3 6
p
LL F1t w Len th=275'
. ..._;.....
514.
........... .....:..... .....:..... ........... .....:..... .....:..... .....:......
4
...... ................................................
3
2
------------------------------------------------------------
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 38
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 of
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= 0.00-120.00 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 7' Top Width= 19.00'
Length= 1,130.0' Slope= 0.0159 7'
Inlet Invert= 372.00', Outlet Invert= 354.00'
Reach DO: NCDOT Road Ditch
Hydrograph
..............................................._................................................_................................................_................................................_................................_.............._..............................._.............._..............................._.............._.............................................. F Inflow24 ......................................................................
.....:..... .....:.....
21.47 cfs
Outflow
23 .....:..... .....:..... .
22 ........._ ........�nflov� Area= 27 a
21 .............:........... .....................:.............................................:........................................................................ _ ..... ..... - .... _ ..........................._ .... _ ...... ..... _ .... _ ..... ................_ ....
........................................................................... ..... ..... ..... ..... ....
20 18.97 cfs h" 1.13
"�" ""
k Flo : .................
; ax a ps
16 .......... .
15 ............_ 1'1"-0 036........
14
w
u 13
�13 .
12 ............_ .......................................................................................................... ...... ..... ...... ....
0 11 .... ..... ..... _ ..... _ ..... ..... _ ..... _ ..... ..... _ ..... _ ..... ..... _ .... _ ...... ............. ... ..... . . ........ .......i...�...........
LL
9 .....
....................................... _ ..... ..... ..... _ ..... ..... ..... _ ..... .....
8 p :CI :::::::::: :'�:: ::".. 4:::::C:fS::::.:::::
7 ............... .......................................................................................................... ..... _............................... ..... _............................... ..... _............................... ..... _.............................. ...... _..............
6 ..............
5 ..............
4 ............. .............................................................................................._............... ..... _..............._............... ..... _.............._................ ..... _.............._................ ..... _.............._............... ...... _..............
3 ............. .................................................................. ..... ..... ..... ..... ..... ..... .... ...... ..... .... ...... ..... .... ..... ...... ....
2
1
0-'
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 39
Summary for Reach D1: Draw
Inflow Area = 17.971 ac, 0.00% Impervious, Inflow Depth = 2.57" for 25y 24h event
Inflow = 39.22 cfs @ 12.20 hrs, Volume= 3.845 of
Outflow = 29.66 cfs @ 12.33 hrs, Volume= 3.845 af, Atten= 24%, Lag= 8.1 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.79 fps, Min. Travel Time= 10.6 min
Avg. Velocity = 0.13 fps, Avg. Travel Time= 61.8 min
Peak Storage= 18,832 cf @ 12.33 hrs
Average Depth at Peak Storage= 0.99'
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 7' Top Width= 88.00'
Length= 500.0' Slope= 0.0620 7'
Inlet Invert= 316.00', Outlet Invert= 285.00'
Reach D1: Draw
Hydrograph
............................._............................_j.......... ..... ..... ....
[ Inflow
Outflow
3942
.22 cfs
....:..... .....:..... .......... ........... ........... .
38
36 .....
u4vg Flo : [1ph 09
34 .. .. .. ...... .....:..... ........... .......... ........... ........... .
V.
11:
32 29.66 cfs a.Yl..._ i..'.. .. .`9....fps
. ..........
30 ...............:..............................................:............................... ..... .... ...... ..... ....
28
................ ......................:............................................................................
0400
_ 26 ...............I.............................._................ ..... .... ................. ..... .... ................. ..... .... ................ ...... ....
w
t 2400.0
22 ...............:.............................................:............................................. ..... ..... .... ...... ..... .... ...... ..... ....
0 20 �70:0V.. ..._�. �...........
LL
18 ............
.................................................................................................................................................... ..... .... _ ...... ..... .... _ ...... ..... .... _ ..... ...... ....16 .....
1
C6 actr 52.
... ... ..... .....2 ..... ..... ....
......................... ....................................... ............ ..........2 ...... ..... .... _ ...... ..... .... _ ..... ...... ....
10 ................................................................
........
8 _.........................................._.........................................._........... ..... _ ..... _ ..... ..... _ .... _ ...... ..... _ .... _ ......
6 ........................................................................................._...........
4
2-
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 40
Summary for Reach D2: Draw
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 7' Top Width= 72.00'
Length= 430.0' Slope= 0.0977 7'
Inlet Invert= 327.00', Outlet Invert= 285.00'
Reach D2: Draw
Hydrograph
1 ❑Outflow
Avg. FlOW Depth=0.00'
Max Vet=0.00 fps
n=0.400
N
L=430.0'
V S 0.0977 T
LL
Capacity=211 .86 cfs
0.00 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 41
Summary for Reach D3: Draw
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 7' Top Width= 110.00'
Length= 228.0' Slope= 0.1667 7'
Inlet Invert= 353.00', Outlet Invert= 315.00'
Reach D3: Draw
Hydrograph
1 ❑Outflow
Avg. FlOW Depth=O. Q'
Max Vet=0.00 fps
n=0.400
N
L=228.0
V
S=0.1667 T
LL
Capacity=432.67 cfs
0.00 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 42
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= 0.00-120.00 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 7' Top Width= 21.00'
Length= 500.0' Slope= 0.0720 7'
Inlet Invert= 351.00', Outlet Invert= 315.00'
Reach D4: Ditch Next to Road
Hydrograph
Inflow
:..... .....:..... .....:..... ..._:..... Outflow
28.18 cfs - - - - - - - - - - - - -
30
0A ea=85ad1n r............_;...........
28
.. .............................._..............._..............................._ .... _ .............._..............._
26 AVaI.....Flo�nr....De'pth-215
..24 23.15 cfs .......«............._i...............«...............«............._i.......... ..... ..... ..... ..... ..... ..... .... ...... ..... .... ...... ..... .... ..... ...... ....
.......... .
22
.....:.....
M
20
..............................«.......... .... ..... ...... ....
w 18
w
3 16
O ............_i ...................._i...............«......................... ............ ..... ..... ..... ..... ..... ..... .... ...... ..... .... _y.
............. ......;............................................;............._...............................;............................................................. ..... .............._ ...... ..... .............._ ...... ..... .............._ ..... ...... ....
12
10
...........
Ca :
pa .
............. .... _..............._ .... .... _ ... _.................................... _.............._.................. ..._:..... ........... ..
8
6
.............. .;...............;..............;............................................... ..... _ ..... _ ..... ..... _ .... _ ...... ..... _ .... _ ...... ..... _ .... _ ..... ...... _ ....
4
2=
0=
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 43
Summary for Reach D& Draw
Inflow Area = 17.971 ac, 0.00% Impervious, Inflow Depth = 2.57" for 25y 24h event
Inflow = 29.66 cfs @ 12.33 hrs, Volume= 3.845 of
Outflow = 19.45 cfs @ 12.59 hrs, Volume= 3.845 af, Atten= 34%, Lag= 15.5 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.80 fps, Min. Travel Time= 20.4 min
Avg. Velocity = 0.16 fps, Avg. Travel Time= 101.8 min
Peak Storage= 23,763 cf @ 12.59 hrs
Average Depth at Peak Storage= 1.28'
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 7' Top Width= 52.00'
Length= 982.0' Slope= 0.0570 7'
Inlet Invert= 285.00', Outlet Invert= 229.00'
Reach D& Draw
Hydrograph
Inflow
.............
32 29.66 cfs
;..... .....,..... ..... Outflow
I.n
30 —
awe rep— , �
...................;......... .... ... _ ..... .... ... _ ..... .... .............._ ....................................
28 ......................................................................................... ..... _ .... � ........F..l.onr.....D. h=..�....2.$..............
26
9 p
(
24 a ._V.e .�..... ..........
....
22
-
... 19.45 cfs ..... ..... ..... _ ..... ..... ..... _ ..... ..... ..... _ ..... ..... .... _ ...... ..... .... _ ...... ..........M.— . ..,
20
1g —
i ............................................. ................ ..... _..............
3 16
o �nn
FL 14 V0 ..._1.{�...........
.....:..... .....:..... .....:..... .....:...
.w.
12
//++ //++
................._..........................................._..........................................._..........................................._...............:. .._ ... .].t.l.. .... .... .. .. ...... _.. .......lt. .. ...........
10
.............:. .;...............;...............;...............;...............;..............................._............... _..............._............... _.............._................................_.............._..............
8
.......... ....................................................................
6
4
2=
0=
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 44
Summary for Reach D6: Draw
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= 0.00-120.00 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 7' Top Width= 86.00'
Length= 1,720.0' Slope= 0.0500 7'
Inlet Invert= 315.00', Outlet Invert= 229.00'
Reach D6: Draw
Hydrograph
................................................................................................................................................ ..... ..... ..... ..... .... ...... ..... .... ...... ..... .... ..... ...... ....
23.15 cfs
❑Outflow
24 ............ .....................................f.............................................f......................................... r6"-8. ....a..c..........
1: 0 A.
Avg: ROWv D h=0 5$
20 .... ...... ..... . .... . ..... ...... ....
Max Vel= .50 f
18 ........................ ............................................................. .... .... .... .... .... ..... ..... .... ... .....
16 ............_........... .... {}.= ..�4VV
..........
N
u 14
L— 720.0
3 �+
0 12 �70:000 LL
10
7.76 cfs C act.... =' 98.54.....cf$.
.......... .......... .....
6 ..... _ ..... ..... .... ................. ..... .... ................. ..... .... ................ ...... ....
4 ............. ............... . ............... .. ................................................................................ _ ..... ..... ..... _ ..... ..... .... _ ...... ..... .... _ ...... ..... .... _ ..... ...... ....
2-
0=
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 45
Summary for Reach D7: Outfall to Avent Creek
Inflow Area = 26.524 ac, 0.57% Impervious, Inflow Depth = 2.60" for 25y 24h event
Inflow = 27.20 cfs @ 12.59 hrs, Volume= 5.755 of
Outflow = 27.06 cfs @ 12.63 hrs, Volume= 5.755 af, Atten= 1%, Lag= 2.4 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs
Max. Velocity= 0.73 fps, Min. Travel Time= 3.0 min
Avg. Velocity = 0.13 fps, Avg. Travel Time= 16.6 min
Peak Storage= 4,827 cf @ 12.63 hrs
Average Depth at Peak Storage= 1.35'
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 7' Top Width= 60.00'
Length= 130.0' Slope= 0.0385 7'
Inlet Invert= 229.00', Outlet Invert= 224.00'
Reach D7: Outfall to Avent Creek
Hydrograph
Inflow
30 Outflow
27.20 cfs
28 ... 27.06 cfs ......«............._i...............«...............«............._i...............«...............«.......... ..... ..... ..... idW A1re 26 524 aC
—
............... ...... _............_..........................................._...........................................
26
............... _ A9 Flow Dph � 5'. .... = 3 ..........
24
22 Max Vel= ....7.3....E .. ...........
0 ps
...
20 _
18
H 1
16 —
3
LL S-00385 T
............................................................................................................................................. .... .............._ ..... .... .... _ .... ..... ....
12
..........._. —
10
Pkft
...............:............
_ .....:.....
8
...
...............:..............:._.... .....:..... .
.._:..... .....:..... ..
6
..........................................:...............................................;..............._ ..... _ ..... ..... _ .... _ ...... ..............._ .... _ ...... ..... _ .... _ ..... ...... _ ....
4
2=
0=
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 46
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= 0.00-120.00 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 7' Top Width= 30.00'
Length= 240.0' Slope= 0.0375 7'
Inlet Invert= 325.00', Outlet Invert= 316.00'
Reach DD: Diversion Ditch
Hydrograph
C Inflow
23 ...... ..... .... _ ..... ...... .... Outflow
20.88 cfs
22
20.83 cfs
......_:..............:.............:...............:........
19 ................ Avg..'......lo�v..... 1.ep. h-.o...2: ::::::::::
17
Max el-5.17 fp
16 ............. ......................................................................................................... ..... ..... _ ..... ..... .... _ ...... ..... .... _................................
15
n=0.022
14
N
w 13 4 ;. o
..... �...........
12
.
3 ..... ....
LL ............. .....................I............._«...............«....................... ..... ..... ..... ..... ..... ..... .... ...... ..... .... y..0 :...1.....� ....
9 .............................;...............,..............;.............................................
8 ..............
pkIty=73443.... .fs..........
...
6 ...... _..............
5 ............. ................................................. ..... ..... ..... ..... .... ...... ..... .... ...... ..... .... ..... ...... ....
4 .......... .................................................................................. _ ..... ..... ..... _ ..... ..... .... _ ...... ..... .... _................................
3 ...........................
2
1 ---------------
0-'
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 47
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 of
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= 0.00-120.00 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 7' Top Width= 16.50'
Length= 540.0' Slope= 0.0037 7'
Inlet Invert= 358.00', Outlet Invert= 356.00'
Reach SO: Access Drive Swale
Hydrograph
Inflow
12 ............ Outflow
10.89 cfs
11 ..........................................._..............................;.......... ..... _ ..... _ ........_..........hiflow.....A.r...ea- ,.29.6....ac..........
10 .. 9.71 cfs ....................._i...............«............................_i.......... ..... ..... ..... ..... ..... ...._; �4�rg HOW �p�h=pE7
9
_
Max: Ve 9 9 f
......................... .. p
n= s
:
= 40..0_ L 5
6
o
..........
LL s-00037
5 ............. ....................................
a
4
.....................................................................................................:..............................:......
...............
api y _I � _s
3 .....
2 ............. ....................................................................................................... ..... _ ..... _ .....
1=
0=
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 48
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= 0.00-120.00 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 7' Top Width= 24.00'
Length= 390.0' Slope= 0.0269 7'
Inlet Invert= 330.50', Outlet Invert= 320.00'
Reach S1: Swale
Hydrograph
.....:..... .....:..... .....:..... .....:..... Inflow
28
25.18 cfs
❑Outflow
26 25.00 cfs
rya=.5.3. .2....a.. ..........
tinfi W A.
24 .............. ......................,...............;..............................,...............;..............................,...............;............................._.............................................;..................................... ..
Av Flown De t..............
:0:50 _.
........._ ....... .... .... .... ... ..... ....
22
20
.......... .....:..... .....:.....
18 _
in16 ............_I ...................._I........................................ ..... ..... ..... ..... ..... ..... ..... .... ...... ..... .... ......
w L=390.0'
3
14 .............I ....................I............................................I.......................... _ ..... ..... ..... _ ..... ..... .... _ ...... ..... .... _ ...... .....
:r
... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... . .......:.....
............_ .........
Cpcty34018c
8
6 ............. ..............................................................................................._................ ..... _............................... ..... _............................... ..... _............................... ..... _.............................. ...... _..............
4 .... ....:............................................:............................................. ..... ..... ..... ..... ..... .... ...... ..... .... ...... ..... .... ..... ...... ....
2-
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 49
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 of
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= 0.00-120.00 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 7' Top Width= 12.00'
Length= 455.0' Slope= 0.0233 7'
Inlet Invert= 345.00', Outlet Invert= 334.40'
Reach S2: CC Swale
Hydrograph
Inflow
28
cfs ❑Outflow
25.47
►�}
26 25.18cfs I1lfl"ov.....Area=f.. . .. ....�.. ..........
24 Av Flow: De'.........JDI th"*
.... .... .... .... .... .... ....
22
:
Max: e p20
18 n"=o" VL..........
16
L=45v.0
314
o o
LL 12 �/. ...�
.....:..... .....:.
n....
..............
10 N Q
.....:..... .....:.....
..._;..... .
8
.... ..............._ .... _ ..... ..............._.............._ ..... ..............._.............._ .... ................_....................... .....:..... ..._: ..... .....:..... ..._:
6
4 ..... .... ...... ..... .... ..... ...... ....
2
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC-Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 50
Summary for Pond 1 P: Pond
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 of
Outflow = 18.39 cfs @ 12.20 hrs, Volume= 2.006 af, Atten= 40%, Lag= 8.1 min
Primary = 18.39 cfs @ 12.20 hrs, Volume= 2.006 of
Secondary= 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.01 hrs
Starting Elev= 322.14' Surf.Area= 8,230 sf Storage= 14,450 cf
Peak Elev= 324.79' @ 12.20 hrs Surf.Area= 12,330 sf Storage= 41,247 cf (26,797 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= 660.4 min calculated for 1.674 of (84% of inflow)
Center-of-Mass det. time= 468.0 min ( 1,316.9 - 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 (Turned on 3 times)
#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 Primary 322.14' Tube/Siphon/Float Valve 2.500" Diameter, C= 0.600
20.0' Long Tube, Hazen-Williams C= 130
Inlet/ Outlet Elev. = 0.00' /322.00' Starts@322.14' Breaks@322.13'
#3 Device 1 324.25' 44.0"W x 6.0" H Vert. Orifice/Grate X 4.00 C= 0.600
#4 Device 1 325.50' 48.0" x 48.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5 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

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 51
Primary OutFlow Max=18.38 cfs @ 12.20 hrs HW=324.79' TW=316.81' (Dynamic Tailwater)
1=Culvert (Passes 18.18 cfs of 36.39 cfs potential flow)
L3=Orifice/Grate (Orifice Controls 18.18 cfs @ 2.48 fps)
4=Orifi ce/G rate
( Controls 0.00 cfs)
2=Tube/Siphon/Float Valve (Tube Controls 0.20 cfs @ 5.96 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=322.14' TW=325.00' (Dynamic Tailwater)
L5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Pond 1 P: Pond
Hydrograph
........... .....:..... .....:..... .....:..... ........... .....:..... .....:................ ........... ....
Inflow
30.53cfs......... ................................i..............i............_.................................................... ... .... .... .... ... .... oU fflOW
Secondary Primary
❑.... Oove = ar..................................i......... .... .... .... .... ....34 )32 �...........
30 ....................... .... .... .... .... .... ....
28 �+
J fora......................... � �7 c .
26
24 ..................... ..................................................................................... .... .... .... _ .... .... .... .... _ .... .... ... _ .... _ .... .... ... _ ....
18.39 cfs
22
18.39 cfs
20 .. .................................................................................................... .... .... _ .... .... .... .... _ .... .... ... _ .... _ .... .... ... _ ....
N
U .......i..............................i............................................. .... .... .... .... .... .... .... .... .... .... ... .... .... .... ... ....
18
3 ................................................................... .... .... .... .... .... .... .... .... .... .... ... ....
0
16
14
12 ................................................................... .... .... .... .... .... .... .... .... .... .... ... .... .... .... ... ....
10 ....
8 .................................................. .... .... .... .... .... .... .... .... .... .... ... .... .... .... ... ....
6
4
0.00 cfs
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC-Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 52
Summary for Pond C 1: Replaced Culvert
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 = 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 of
Secondary= 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 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)
L1=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)
L2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Pond C 1: Replaced Culvert
Hydrograph
Inflow
......... 28.18 cfs ._............................. .... .... _ .... .... .... .... _ .... .... ... _ .... _ .... .... ... _ ....
_..... ..._............... ..... L_Outflow
28.18 cfs r N Primary
..................................................................................... ea-8- 53 ac
28.18 cfs "f Gw A ❑Secondary
30 �...........
28 P.eak _ _Iev= S_ .fiT..............
26 ...._........................................................................................................... .... _ .... .... .... .... _ .... .... ... _..............._ .... .... ... _ ....
24
22
20
18
U '
16
0
LL ....,.....
12 ....
10 .... ... .... ... ....
8 ............. .... .... ....
6
4
o.00 as
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

20220116_Harnett County_NW CC—Construction Cond Type 1124-hr 25y24h Rainfall=6.75"
Prepared by HDR, Inc Printed 1/17/2023
HydroCAD® 10.00-25 s/n 11397 ©2019 HydroCAD Software Solutions LLC Page 53
Summary for Pond C2: Proposed Culvert
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 = 25.18 cfs @ 12.06 hrs, Volume= 1.648 af, Atten= 0%, Lag= 0.0 min
Primary = 25.18 cfs @ 12.06 hrs, Volume= 1.648 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 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)
L1=Culvert (Inlet Controls 25.15 cfs @ 5.23 fps)
Pond C2: Proposed Culvert
Hydrograph
zs.fa as
❑Inflow
28 Prima ry
26 25.18 cfs ;...........................................................
;..............................;............._..............................
;............................. '
�nfloW Area=6.362 ac
24
El: 36.7
2
_ea
2 ev .
........._ ... ....
20
.....:..... .....:.....
H 16
..............: ............
,.......
er 18
:Round Culv
14 n.".Q..�012
3 :
0
_ L 45
10 .............: ......................................:...............:...............................:.............. ..... ...... .... ..... ...... .... ..... ..... ..... ...... .....
.1
8
6 ............ ........................................................................................................ ................_.............._ ..... ................_.............._ ..... ..............._ ..... ...... ..... _ ..... ...... ..... _ ....
4 ............ .................................................. ..... ...... .... ..... ...... .... ..... ..... ..... ...... ..... ..... ...... ..... ....
2
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
Time (hours)

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024
Attachment E—Wet Pond Calculations
Attachment E — Wet Pond
Calculations

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

Harnett County Solid Waste Department I Stormwater Permit Application—May 2024 �1�
Attachment E.1 —Wet Pond Design Calculations J
This page intentionally left blank.

Harnett County Wet Pond Calculations �\ � .CARp�!%�
O
Using Simple Run-off Calcuation to determine Design Volume °' A
40654
Simple Method for Runoff Volume ,� .,GINS;.
Rv = 0.05 + 0.9 * la
Where: Rv = Runoff coefficient(unitless)
IA = Impervious fraction(unitless)
DV = 3630 * Ro * Rv*A
Where: DV - Design volume(cu ft)
RD = Design storm depth(in)
A = Drainage area(ac)
Where IA is 1.379/8.123
Rv=0.05 +0.9* la or 0.05 +0.9*(1.379/8.123)
Rv= 0.2027884
Then determine the design volume (Dv)
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?: Main Pool Volume,Veep
VMP = 0.87* HRT * DV
5
Where: 0.87 = Factor to adjust for the volume in the forebay
V., 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
VPP— shelf
Davg=
};hnftnm of shrl f
Where: Da A - Average depth(feet)
VP - Main pool volume at permanent pool elevation(feeP)
%heu = Volume over the shelf only(feet')-see below
Ab.noa ofvwf = Area of main pool at the bottom of the shelf(feet)
Vshaif= 0.5*DepthMa,o,,,shalf*Perlmeterpe,M poa*Wldtha brna gad pan of ahaif
Where: Depth.axnv—h.9 = Depth of water at the deep side of the shelf as
measured from the permanent pool(feet)
Perimeter,,,,,,pod = Perimeter of main pool at the bottom of the
shelf(feet)
Widths,,,ah d P rW.nag = Width from the deep side to the dry side of the
shelf as measured at permanent pool(feet)
Where Vpp is= 14,581 CF
Vshelfis0.5x1.0X235If* 6ft= 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-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)a.s
VVhere: Q = Discharge(cfs)
Co = Coefficient of discharge per Table 6(unitless)
A = Cross-sectional area of orifice entrance(sq ft)
g = Acceleration of gravity(32.2 ftlsec2)
Ho = Driving head from water surface to centroid
orifice(ft) "usually use Ha/3 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,Ca
{Malcom 1989)
Entrance Condition
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)
I I:.
Q
R,
Where Cd = 0.60 and Ho is 2.11'
Q= 3 x(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