SW3210602_Design Calculations_20210809

BURNS &MMONNELL.
Site Drainage Report
N EXTe ra
ENERGY!4
RESOURCES
Nextera Energy Resources
Blackburn Solar - Point of Interconnect
Project No. 127835
Revision 1
7/27/2021

Site Drainage Report
prepared for
Nextera Energy Resources
Blackburn Solar - Point of Interconnect
Catawba County, North Carolina
Project No. 127835
Revision 1
7/27/2021
prepared by
Burns & McDonnell Consultants, Inc.
C-1435
Kansas City, Missouri
COPYRIGHT © 2020 BURNS & McDONNELL CONSULTANTS, INC.

Nextera Energy Resources
11
INDEX AND CERTIFICATION
Site Drainage Report
Project No. 127835
Report Index
Chapter Number
Number Chapter Title of Pages
1.0 Design Narrative 1
2.0 Stormwater Features Drainage Area Map 1
3.0 Rational Method Peak Discharge Calculations 11
4.0 Stormwater Features Calculations 4
Appendix A Reference Information 8
Certification
I hereby certify, as a Professional Engineer in the state of North Carolina, that the information in this document was
assembled under my direct personal charge. This report is not intended or represented to be suitable for reuse by the
Nextera Energy Resources or others without specific verification or adaptation by the Engineer.
.�' ZN CARP *#r
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Mark S. Smedvig, Jr, P.E.,`,N - 041110
Date: 7/27/2021

BURNS`MEDONNELL..
Chapter 1:
Design Narrative

Blackburn Solar Point of Interconnect
Design Narrative
A 4.80 acre site -development project is proposed to be developed on rolling terrain in southern
Catawba County, North Carolina. This a low -density utility development which will require stormwater
to be transported through vegetated conveyances. The total property is 57.663 acres and features a
ridge that splits the site drainage of the property into two directions. The 4.80 acre project area is on the
western side of the property adjacent to an existing utility right-of-way. The proposed project will
include an approximately 0.25 mile long access road to a 0.48 acre switchyard pad. Stormwater will flow
from the crest of the ridge westward to the project site where it will be collected in roadside ditches
that run parallel to the access road. The roadside ditches are designed in accordance with the
requirements for vegetated conveyances and have side slopes no steeper than 3 feet horizontal to 1
foot vertical. The roadside ditches will convey stormwater to culverts that will carry water under the
access road and ultimately off -site. The site does not drain to any tributaries or streams on the property
but ultimately drains into the South Fork of the Catawba River. Several jurisdictional wetlands and
intermittent and perennial streams are located on the property north and east of the development area
and will not be impacted by the project.

BURNS MEDONNELL.,
Chapter 2:
Stormwater Features Drainage
Area Map

DITCH 4 1.2 AC
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DITCH 5 AC
PAD + GRADED AREA - 0.69 AC
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SILT FENCE PROVIDED 2801,�
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L� h' DITCH 2 1SILT FENCE
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PROVIDEDSILT FENCE 630 • A00
40,
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10
row
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aw '
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BURNS`MEDONNELL_
Chapter 3:
Rational Method Peak
Discharge Calculations

PEAK DISCHARGE CALCULATION
Description: Ditch 1, Southeast Edge of Access Road
Calculated By: C. Jergensen Date: 7/27/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 7/27/2021
Drainage Area = 3.36 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW
(Eq 1) Tc = 30.0 min.
(5 minute minimum)
Rainfall Intensity i = 3.74 in/hr
Description of Area C A
Grassed, Steep Slopes 0.4 2.39
Woods 0.3 0.82
Gravel Surfaces 0.6 0.15
Total = 3.36
Weighted Coefficient "C" = 0.385
C=F(CA)/FA
Q = 4.83208 cfs
Q = C*i *A
I Design Flow Volume:
4e9
CA
0.956
0.246
0.09
1.292
ds
-;1S
Eq 1 L
(8.03.2) _(1.49 S"' * 1; * C )213
n ( T1. 43,200
_
60
(roughness coefficient) nsheet = 0.24
(flow length in feet) Lsheet = 400 (ft)
(slope) Ssheet = 0.04 (ft/ft)
Trial T,
(minutes)
Trial I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
24.8
6
7.33
25.2
7
7.03
25.6
8
6.72
26.1
9
6.42
26.5
10
6.11
27.1
11
5.92
27.4
12
5.73
27.8
13
5.54
28.2
14
5.35
28.5
15
5.16
29.0
20
4.69
30.1
25
4.21
31.4
30
3.74
32.9
40
3.30
34.6
50
2.87
36.6
60
2.43
39.1
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated Tc
(minutes)
30
3.74
32.9

PEAK DISCHARGE CALCULATION
Description: Ditch 2, Northeast Edge of Access Road
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area = 5.03 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW Eq 1
(Eq 1) Tc = 25.0 min. (8.03.2)
(5 minute minimum)
Rainfall Intensity i = 4.21333 in/hr
Description of Area C A
Grassed, Steep Slopes 0.4 1.45
Woods 0.3 3.41
Gravel Surfaces 0.6 0.17
Total = 5.03
Weighted Coefficient "C" _
C=E(CA)/FA
Q = 7.18373 cfs
Q = C*i *A
0.339
Design Flow Volume: 7e2
CA
0.58
1.023
0.102
1.705
cfs
s; s
L
1.49*SJL!
n ( 43,200
60
(roughness coefficient) nsneet = 0.24
(flow length in feet) Lsneet = 400 (ft)
(slope) Ssheet = 0.085 (ft/ft)
Trial Tc
(minutes)
Trial I;
(inches/hour)
Calculated T,
(minutes)
5
7.64
20.8
6
7.33
21.1
7
7.03
21.5
8
6.72
21.9
9
6.42
22.3
10
6.11
22.7
11
5.92
23.0
12
5.73
23.3
13
5.54
23.6
14
5.35
23.9
15
5.16
24.3
20
4.69
25.2
25
4.21
26.3
30
3.74
27.6
40
3.30
29.0
50
2.87
30.7
60
2.43
32.8
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated Te
(minutes)
25
4.21
26.3

PEAK DISCHARGE CALCULATION
Description: Culvert 1, Appx Sta 3+75 (Ditch 1 + Ditch 2)
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area = 8.39 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW Eq 1
(Eq 1) Tc = 30.0 min. (8.03.2)
(5 minute minimum)
Rainfall Intensity i = 3.74 in/hr
Description of Area C A
Grassed, Steep Slopes 0.4 3.84
Woods 0.3 4.23
Gravel Surfaces 0.6 0.32
Total = 8.39
Weighted Coefficient "C" _
C=F(CA)/FA
Q = 11.2088 cfs
Q = C*i *A
0.357
Design Flow Volume: 113
CA
1.536
1.269
0.192
2.997
cfs
- - 3/5
L
1.49 _S112 C
(-43,200)113
60
(roughness coefficient) nsheet = 0.24
(flow length in feet) Lsheet = 400 (ft)
(slope) Ssheet = 0.04 (ft/ft)
Trial T,
(minutes)
Trial I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
25.5
6
7.33
25.9
7
7.03
26.4
8
6.72
26.8
9
6.42
27.3
10
6.11
27.9
11
5.92
28.2
12
5.73
28.6
13
5.54
29.0
14
5.35
29.4
15
5.16
29.8
20
4.69
31.0
25
4.21
32.3
30
3.74
33.9
40
3.30
35.7
50
2.87
37.7
60
2.43
40.3
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated T,
(minutes)
30
3.74
33.9

PEAK DISCHARGE CALCULATION
Description: Ditch 3, Southwest Edge of Access Road
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area = 2.75 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW Eq 1
(Eq 1) Tc = 25.0 min. (8.03.2)
(5 minute minimum)
Rainfall Intensity i = 4.21333 in/hr
Description of Area C A
Grassed, Steep Slopes 0.4 2.68
Woods 0.3 0
Gravel Surfaces 0.6 0.07
Total = 2.75
Weighted Coefficient "C" _
C=I(CA)/FA
Q = 4.69365 cfs
Q = C*i *A
Design Flow Volume: 4.
0.405
CA
1.072
0
0.042
1.114
cfs
3/5
L
1 49xSU2_ I *C
n 43,200
)2/3
T =
60
(roughness coefficient) nsheet = 0.24
(flow length in feet) Lsheet = 300 (ft)
(slope) Ssheet = 0.032 (ft/ft)
Trial Tc
(minutes)
Trial I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
21.8
6
7.33
22.2
7
7.03
22.6
8
6.72
23.0
9
6.42
23.4
10
6.11
23.9
11
5.92
24.2
12
5.73
24.5
13
5.54
24.8
14
5.35
25.2
15
5.16
25.5
20
4.69
26.5
25
4.21
27.7
30
3.74
29.0
40
3.30
30.5
50
2.87
32.3
60
2.43
34.5
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated Tc
(minutes)
25
4.21
27.7

PEAK DISCHARGE CALCULATION
Description: Ditch 4, Northeast Pad Ditch
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area - 1.2 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW Eq 1
(Eq 1) Tc = 20.0 min. (8.03.2)
(5 minute minimum)
Rainfall Intensity i = 4.68667 in/hr
Description of Area C A
Grassed, Steep Slopes 0.4 0.89
Woods 0.3 0.3
Gravel Surfaces 0.6 0.01
Total = 1.2
Weighted Coefficient "C" _
C=I(CA)/FA
Q = 2.11837 cfs
Q = C*i *A
0.377
I Design Flow Volume: 21
CA
0.356
0.09
0.006
0.452
cfs
L
(.49*SV2 YI. *C 2/3
�t 43,200
T,. _
60
(roughness coefficient) nsheet = 0.24
(flow length in feet) Lsneet = 300 (ft)
(slope) Ssneet = 0.067 (ft/ft)
Trial T,
(minutes)
Trial I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
18.0
6
7.33
18.3
7
7.03
18.6
8
6.72
18.9
9
6.42
19.3
10
6.11
19.7
11
5.92
19.9
12
5.73
20.2
13
5.54
20.5
14
5.35
20.7
15
5.16
21.1
20
4.69
21.9
25
4.21
22.8
30
3.74
23.9
40
3.30
25.2
50
2.87
26.6
60
2.43
28.4
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated Tc
(minutes)
20
4.69
21.9

PEAK DISCHARGE CALCULATION
Description: Ditch 5, Switchyard Road Ditch After Split
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area = 0.33 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW Eq 1
(Eq 1) Tc = 8.0 min. (8.03.2)
(5 minute minimum)
Rainfall Intensity i = 6.722 in/hr
Description of Area C A
Grassed, Steep Slopes 0.4 0.28
Woods 0.3 0
Gravel Surfaces 0.6 0.05
Total = 0.33
Weighted Coefficient "C" _
C=F(CA)/FA
Q = 0.95452 cfs
Q = C*i *A
0.430
Design Flow Volume: 160
CA
0.112
0
0.03
0.142
cfs
L
1.49*S112I *C
43,200 2/3
T� 60
(roughness coefficient) nsheet = 0.24
(flow length in feet) Lsheet = 100 (ft)
(slope) Ssneet = 0.1 (ft/ft)
Trial Tc
(minutes)
Trial I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
7.8
6
7.33
8.0
7
7.03
8.1
8
6.72
8.2
9
6.42
8.4
10
6.11
8.6
11
5.92
8.7
12
5.73
8.8
13
5.54
8.9
14
5.35
9.0
15
5.16
9.2
20
4.69
9.5
25
4.21
9.9
30
3.74
10.4
40
3.30
10.9
50
2.87
11.6
60
2.43
12.4
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated Tc
(minutes)
8
6.72
8.2

PEAK DISCHARGE CALCULATION
Description: Culvert 2, Appx Sta 10+75 (Ditch 4 + Ditch 5)
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area = 1.53 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW Eq 1
(Eq 1) Tc = 20.0 min. (8.03.2)
(5 minute minimum)
Rainfall Intensity i = 4.68667 in/hr
Description of Area C A
Grassed, Steep Slopes 0.4 1.17
Woods 0.3 0.3
Gravel Surfaces 0.6 0.06
Total = 1.53
Weighted Coefficient "C" =
C=F(CA)/EA
Q = 2.78388 cfs
Q = C*i *A
Design Flow Volume: 2e8
CA
0.468
0.09
0.036
0.594
cfs
L
7/3
n ( 43,200
T�. 60
(roughness coefficient) nsheet = 0.24
(flow length in feet) Lsheet = 300 (ft)
(slope) Ssheet = 0.067 (ft/ft)
Trial Tc
(minutes)
Trial I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
17.8
6
7.33
18.1
7
7.03
18.4
8
6.72
18.7
9
6.42
19.1
10
6.11
19.4
11
5.92
19.7
12
5.73
19.9
13
5.54
20.2
14
5.35
20.5
15
5.16
20.8
20
4.69
21.6
25
4.21
22.6
30
3.74
23.7
40
3.30
24.9
50
2.87
26.3
60
2.43
28.1
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated Tc
(minutes)
20
4.69
21.6

PEAK DISCHARGE CALCULATION
Description: Ditch 6, Northwest Pad Ditch
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area = 0.15 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW
(Eq 1) TG = 5.0 min.
(5 minute minimum)
Rainfall Intensity i = 7.64 in/hr
Description of Area C A
Grassed, Steep Slopes 0.4 0.15
Woods 0.3 0
Gravel Surfaces 0.6 0
Tota I = 0.15
Weighted Coefficient "C" = 0.400
C=I(CA)/FA
Q = 0.4584 cfs
Q = C*i *A
IDesign Flow Volume: 0e5
CA
0.06
0
0
0.06
cfs
- - 3l5
Eq 1 L
(8.03.2) �49 * S"� I * C
_ n (431200)
T�. 60
(roughness coefficient) nsheet = 0.24
(flow length in feet) LSneet = 50 (ft)
(slope) Ssheet = 0.1 (ft/ft)
Trial Tc
(minutes)
Trial I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
5.3
6
7.33
5.4
7
7.03
5.5
8
6.72
5.6
9
6.42
5.7
10
6.11
5.8
11
5.92
5.9
12
5.73
6.0
13
5.54
6.0
14
5.35
6.1
15
5.16
6.2
20
4.69
6.5
25
4.21
6.7
30
3.74
7.1
40
3.30
7.4
50
2.87
7.9
60
2.43
8.4
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
5.3

PEAK DISCHARGE CALCULATION
Description: Property - Pre -Development
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area = 57.66 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
OVERLAND FLOW
SHEET FLOW Eq 1
(Eq 1) Tc = 30.0 min. (8.03.2)
(5 minute minimum)
Rainfall Intensity i = 3.74 in/hr
Description of Area C A CA
Grassed, Steep Slopes 0.4 3.66 1.464
Woods 0.3 54 16.2
Gravel Surfaces 0.6 0 0
Total = 57.66 17.664
Weighted Coefficient "C" = 0.306
C=I(CA)/FA
Q = 66.0634 cfs
Q = C*i *A
IDesign Flow Volume: 66.1 cfs
1.4- - 9 � S 1/2 I.* C 213
(43,200)
T -
- 60
(roughness coefficient) nsneet = 0.24
(flow length in feet) Lsheet = 400 (ft)
(slope) Ssheet = 0.05 (ft/ft)
Trial Tc
(minutes)
Trial I;
(inches/hour)
Calculated Tc
(minutes)
5
7.64
25.4
6
7.33
25.8
7
7.03
26.2
8
6.72
26.7
9
6.42
27.2
10
6.11
27.7
11
5.92
28.1
12
5.73
28.4
13
5.54
28.8
14
5.35
29.2
15
5.16
29.7
20
4.69
30.8
25
4.21
32.2
30
3.74
33.7
40
3.30
35.5
50
2.87
37.5
60
2.43
40.1
Final T,
(minutes)
Final I;
(inches/hour)
Calculated Tc
(minutes)
30
3.74
33.7

PEAK DISCHARGE CALCULATION
Description: Property - Post -Development
Calculated By: C. Jergensen Date: 6/1/2021 Project Name: Blackburn Duke POI
Checked By: M. Bird Date: 6/9/2021
Drainage Area = 57.66 Acres Design Return Period: 10 Years
RATIONAL METHOD
1-50 acres
TIME OF CONCENTRATION
SHEET FLOW
(Eq 1) Tc = 30.0 min.
(5 minute minimum)
Rainfall Intensity i = 3.74 in/hr
Description of Area C A CA
Grassed, Steep Slopes 0.4 6.52 2.608
Woods 0.3 50.14 15.042
Gravel Surfaces 0.6 1 0.6
Total = 57.66 18.25
Weighted Coefficient "C" = 0.317
C=E(CA)/FA
Q = 68.255 cfs
Q = C*i *A
I Design Flow Volume: 68.3 c fs
Eq 1 L
8.03.2 1.49*S'12 I xC
T _ n ( 43,200 )2/3
60
(roughness coefficient) nsheet = 0.24
(flow length in feet) Lsheet = 400 (ft)
(slope) Ssheet = 0.05 (ft/ft)
Trial T,
(minutes)
Trial I;
(inches/hour)
Calculated T,
(minutes)
5
7.64
25.0
6
7.33
25.4
7
7.03
25.9
8
6.72
26.3
9
6.42
26.8
10
6.11
27.4
11
5.92
27.7
12
5.73
28.1
13
5.54
28.5
14
5.35
28.9
15
5.16
29.3
20
4.69
30.4
25
4.21
31.8
30
3.74
33.3
40
3.30
35.0
50
2.87
37.0
60
2.43
39.6
Final Tc
(minutes)
Final I;
(inches/hour)
Calculated Tc
(minutes)
30
3.74
33.3

References
Surface Manning's
"n"
Smooth Surface:
0.011
Bare Earth:
0.020
Fallow:
0.050
Cultivated, < 20% residue:
0.060
Cultivated, > 20% residue:
0.170
Grass, short:
0.150
Grass, dense:
0.240
Grass, Bermuda:
0.410
Woods, light:
0.400
Woods, dense:
0.800
Table 2-3. Typical C Values
Type of Surface Rational C Value
Pavement 0.7-0.9
Gravel surfaces
0.4-0.6
Grassed, steep slopes
0.3-0.4
Grassed, flat slopes
0.2-0.3
Woods
0.1 -0.2

BURNS MSDONNELL
Chapter 4:
Stormwater Features
Calculations

Trapezoidal Channel (13131 - Drainage Feature Sizing.fm8)
Label
Solve For
Friction Method
Roughness
Channel Slope
Normal Depth
Coefficient
(ft/ft)
(in)
Ditch 1
Normal Depth
Manning Formula
0,030
0.019
5.3
Ditch 2
Normal Depth
Manning Formula
0.030
0.029
5.7
Ditch 3
Normal Depth
Manning Formula
0.030
0.037
4.5
Ditch 4
Normal Depth
Manning Formula
0.030
0.010
4.3
Ditch 5
Normal Depth
Manning Formula
0.030
0.030
2.1
Ditch 6
Normal Depth
Manning Formula
0.030
0.015
1.7
Left Side Slope
Right Side Slope
Bottom Width
Discharge
Flow Area
Wetted
(H:V)
(H:V)
(ft)
(cfs)
(ftz)
Perimeter
(ft)
4.000
4.000
2.00
4.90
1.6
5.6
4.000
4.000
2.00
7.20
1.9
5.9
3.000
3.000
2.00
4.70
1.2
4.4
3.000
3.000
2.00
2.20
1.1
4.3
3.000
3.000
2.00
1.00
0.4
3.1
3.000
3.000
2.00
0.50
0.3
2.9
Hydraulic Radius
Top Width
Critical Depth
Critical Slope
Velocity
Velocity Head
(in)
(ft)
(in)
(ft/ft)
(ft/s)
(ft)
3.5
5.51
5.1
0.020
2.97
0.14
3.8
5.80
6.3
0.019
3.89
0.23
3.2
4.26
5.3
0.020
3.98
0.25
3.1
4.14
3.5
0.022
2.00
0.06
1.7
3.03
2.2
0.025
2.31
0.08
1.4
2.85
1.4
0.029
1.46
0.03
Specific Energy
Froude Number
Flow Type
Notes
Messages
(ft)
0.58
0.959
Subcritical
0.71
1.213
Supercritical
0.62
1.331
Supercritical
0.42
0.687
Subcritical
0.26
1.080
Supercritical
0.17
0.744
Subcritical
Bentley Systems, Inc. Haestad Methods Solution FlowMaster
BB1 - Drainage Feature Sizing.fm8 Center [10.00.00.02]
6/7/2021 27 Siemon Company Drive Suite 200 W Page 1 of 1
Watertown, CT 06795 USA + 1 -203-755-1666

Culvert Calculator Report
Culvert 1
Solve For: Headwater Elevation
Culvert Summary
Allowable HW Elevation
Computed Headwater Elevi
Inlet Control HW Elev.
Outlet Control HW Elev.
918.66 ft
918.54 ft
918.51 ft
918.54 ft
Headwater Depth/Height
Discharge
Tailwater Elevation
Control Type
0.92
11.30 cfs
917.16 ft
Outlet Control
Grades
Upstream Invert
Length
917.16 ft
36.00 ft
Downstream Invert
Constructed Slope
916.98 ft
0.005000 ft/ft
Hydraulic Profile
Profile
Slope Type
Flow Regime
Velocity Downstream
M2
Mild
Subcritical
4.99 fUs
Depth, Downstream
Normal Depth
Critical Depth
Critical Slope
0.92 ft
0.98 ft
0.92 ft
0.006051 ft/ft
Section
Section Shape
Section Material
Section Size
Number Sections
Circular
Concrete
18 inch
2
Mannings Coefficient
Span
Rise
0.013
1.50 ft
1.50 ft
Outlet Control Properties
Outlet Control HW Elev.
Ke
918.54 ft
0.20
Upstream Velocity Head
Entrance Loss
0.33 ft
0.07 ft
Inlet Control Properties
Inlet Control HW Elev. 918.51 ft
Inlet Type Groove end projecting
K 0.00450
M 2.00000
C 0.03170
Y 0.69000
Flow Control
Area Full
HDS 5 Chart
HDS 5 Scale
Equation Form
Unsubmerged
3.5 ft2
1
3
1
Title: Blackburn POI Project Engineer: cjjergensen
c:\...\documents\bb1 - poi culvert.cvm Burns & McDonnell CulvertMaster v3.3 [03.03.00.04]
06/09/21 08:12:25 AM© Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA [phone] Page 1 of 1

Culvert Calculator Report
Culvert 2
Solve For: Headwater Elevation
Culvert Summary
Allowable HW Elevation 921.00 ft
Computed Headwater Elevi 919.00 ft
Inlet Control HW Elev. 918.95 ft
Outlet Control HW Elev. 919.00 ft
Headwater Depth/Height 0.62
Discharge 2.80 cfs
Tailwater Elevation 917.68 ft
Control Type Entrance Control
Grades
Upstream Invert
Length
918.08 ft
40.00 ft
Downstream Invert
Constructed Slope
917.68 ft
0.010000 ft/ft
Hydraulic Profile
Profile
Slope Type
Flow Regime
Velocity Downstream
S2
Steep
Supercritical
5.03 ft/s
Depth, Downstream
Normal Depth
Critical Depth
Critical Slope
0.53 ft
0.53 ft
0.64 ft
0,005089 ft/ft
Section
Section Shape
Section Material
Section Size
Number Sections
Circular
Concrete
18 inch
1
Mannings Coefficient
Span
Rise
0.013
1.50 ft
1.50 ft
Outlet Control Properties
Outlet Control HW Elev.
Ke
919.00 ft
0.20
Upstream Velocity Head
Entrance Loss
0.24 ft
0.05 ft
Inlet Control Properties
Inlet Control HW Elev. 918.95 ft
Inlet Type Beveled ring, 33.7° bevels
K 0.00180
M 2.50000
C 0.02430
Y 0.83000
Flow Control
Area Full
HDS 5 Chart
HDS 5 Scale
Equation Form
Unsubmerged
1.8 ft`
3
B
1
Title: Blackburn POI Project Engineer: cjjergensen
c:\...\documents\bb1 - poi culvert.cvm Burns & McDonnell CulvertMaster v3.3 [03.03.00.04]
06/09/21 11:24:44 AMC) Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA [phone] Page 1 of 1

TABLE I042-1
ACCEPTANCE
CRITERIA FOR RIP RAP AND STONE FOR EROSION CONTROL
Class
Required Stone Sizes, Inches_
Minimum
Midrange
- -a
Maximum
A
z
e
d
S
_ ! _ _ A - —
12
S
10
17
2
-9-----
14
23
La = 16'
La=6'
CULVERT 1
V=4.99 FT/S
d=0.92 FT - USE 12"
Q = 11.3 CFS
20,
3Ia 1---'
nutlet
pipx, ~ }
diameter (D,l
La --K
l or 17.5fJx
l' ai
C
�'�iIL
ac
CULVERT 2
V=5.03 FT/S
d=0.62 FT - USE 12"
Q = 2.8 CFS
.`ppelidices
10 20 3v ,IUU ZU0 �UU
Discharge (ft-3isec)
1
d50 = .65' or
? 7.8", use
Class B
0 d50 = .25'
3010 or 3", use
Class A
t;urvos may not be extrapolated,
Fis.uc 0.06u Duggr Dfol.116i plotocibn prowniun Iram a nand pipe lim,ng lull, rr'lriittum AONalerco-)ditial (Tw <0.5 diameter).
Ihn - 1193
8.06.3

BURNS `MEDONNELL_
Appendix A:
Reference Information

3/8/2021
Precipitation Frequency Data Server
NOAA Atlas 14, Volume 2, Version 3
(D Location name: Robbins, North Carolina, USA*
Latitude: 35.5*, Longitude: -79.6'
Elevation: 468.2 ft**
source: ESRI Maps M-4source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1
Average recurrence interval(years)
Duration ����
1 2 5 10 25 50 100 200 500 1000
5.09 6.01 6.97 7.64 8.40 8.89 9.34 9.72 10.1 10.4
5-min
(4.63-5.59) (5.48-6.62) (6.35-7.68) 1 (6.95-8.40) 1 (7.58-9.22) 1 (8.02-9.76) 1 (8.38-10.2) 1 (8.68-10.7) 1 (8.96-11.1) 1 (9.14-11.5)
4.06 4.81 5.58 6.11 6.69 7.08 7.42 7.70 8.02 8.21
10-min
(3.70-4.47) (4.38-5.30) (5.08-6.15) (5.56-6.72) (6.05-7.34) (6.38-7.77) (6.65-8.14) (6.88-8.46) (7.09-8.80) (7.20-9.02)
3.38 4.03 4.71 5.16 5.65 5.98 6.25 6.48 6.72 6.87
15-min
(3.09-3.72) 11 (3.67-4.44) 11 (4.28-5.18) 11 (4.68-5.66) 1 (5.11-6.20) 1 (5.39-6.56) 1 (5.61-6.86) 1 (5.78-7.12) 1 (5.95-7.38) 1 (6.03-7.55)
2.32 2.78 3.34 4.19 4.50 4.79 5.04 5.35 5.56
30-min IF-3.74
1
(2.12-2.55) (2.54-3.07) (3.04-3.68) 1 (3.39-4.10) 1 (3.78-4.59) 1 (4.06-4.94) 1 (4.29-5.25) 1 (4.50-5.54) 1 (4.73-5.88) (4.88-6.11)
1.45 1.75 2.14 2.43 2.79 3.05 3.30 3.54 3.84 4.06
60-min
(1.32-1.59) (1.59-1.92) (1.95-2.36) (2.21-2.67) (2.52-3.06) (2.75-3.35) (2.96-3.62) (3.16-3.88) (3.39-4.22) 1 (3.56-4.46)
0.856 1.04 1.29 1.47 1.71 1.88 2.05 -----IF--4 2.60
2-hr
(0.778-0.M-) (0.942-1.15) (1.17-1.42) 1 (1.33-1.63) 1 (1.53-1.88) 1 (1.68-2.08) (1.83-2.27) 1 (1.96-2.45) (2.13-2.69) (2.25-2.87)
0.606 0.735 0.915 1.05 1.23 1.37 1.51 1.65 1.84 1.98
3-hr
(0.552-0.670) (0.669-0.813) (0.832-1.01) (0.954-1.16) 1 (1.11-1.36) 1 (1.23-1.51) 1 (1.34-1.66) 1 (1.45-1.81) 1 (1.60-2.02) (1.71-2.18)
0.365 0.441 0.550 0.634 0.747 0.835 0.924 1.01 1.14 1.23
6-hr
(0.333-0.402) (0,403-0.485) (0.502-0.605) (0.576-0.696) (0.674-0.817) (0.748-0.912) (0.821-1.01) (0.893-1.11) (0.988-1.24) 1 (1.06-1.35)
0.216 0.261 0.327 0.380 0.451 0.508 0.567 0.628 0.712 0.780
12-hr
(0.197-0.237) (0.239-0.288) (0.298-0.360) (0.345-0.417) (0.406-0.493) (0.454-0.554) (0.502-0.617) (0.550-0.683) (0.614-0.775) (0.662-0.849)
0.124 0.150 0.188 0.218 0.258 0.290 0.323 0.357 0.403 0.439
24-hr
(0.115-0.134) (0.139-0.162) (0.174-0.203) (0.201-0.235) (0.238-0.279) (0.267-0.314) (0.296-0.349) (0.326-0.386) (0.367-0.436) (0.399-0.475)
0.073 0.088 0.109 0.126 0.148 0.166 0.184 0.203 0.229 0.249
2-day
(0.068-0.078) (0.082-0.094) (0.101-0.118) (0.117-0.136) (0.137-0.160) (0.153-0.179) (0.170-0,199) (0.187-0.220) (0.209-0.248) (0.226-0,270)
0.051 0.062 0.077 0.088 0.104 0.116 0.129 0.142 0.160 0.174
3-day
(0.048-0.055) (0.058-0.067) (0.071-0.082) (0.082-0.095) (0.096-0.112) (0.108-0.125) (0.119-0.139) (0.131-0.153) (0.147-0.173) (0.159-0.188)
0.- 0.049 0.060 0.070 0.082 0.092 0.102 0.112 0.126 0.137
4-day
(0.038-0.044) (0.046-0.053) (0.057-0.065) (0.065-0.074) (0.076-0.088) (0.085-0.098) (0.094-0.109) (0.103-0.120) (0.115-0.135) (0.125-0.147)
0.027 0.032 0.039 0.045 0.052 0.058 0.064 0.071 0.079 0.086
7-day
(0.025-0.029) (0.030-0.034) (0.036-0.042) (0.042-0.048) (0.049-0.056) (0.054-0.062) (0.059-0.069) (0.065-0.076) (0.073-0.085) (0.079-0.092)
0.021 0.025 0,031 0.035 0.040 0.044 0.049 0.053 0.059 0.064
10-day
(0.020-0.023) (0.024-0.027) (0.029-0.033) (0.033-0.037) (0.038-0.043) (0.042-0.047) (0.045-0.052) (0.049-0.056) (0.055-0.063) (0.059-0.068)
0.014 0.017 0.020 0.023 0.026 0.028 0.031 0.034 0.037 0.040
20-day
(0.014-0.015) (0.016-0.018) (0.019-0.021) (0.021-0.024) (0.024-0.027) (0.027-0.030) (0.029-0.033) (0.031-0.036) (0.035-0.040) (0.037-0.043)
0.012 IF 0.014 0.016 0.018 O.O2-O7F 0.022 0.024 7F 0.026 0.028 0.030
30-day
(0.011-0.013) (0.013-0.015) (0.015-0.017) (0.017-0.019) (0.019-0.021) (0.021-0.023) (0.023-0.025) (0.024-0.027) (0.026-0.030) (0.028-0.032)
0.010 0.012 0.014 0.015 0.017 0.018 0.019 0.020 0.022 0.023
45-day
(0.010-0.011) (0.011-0.012) (0.013-0.014) (0.014-0.016) (0.016-0.017) (0.017-0.019) (0.018-0.020) (0.019-0.021 0.021-0.023) (0.022-0.024
) ( )
-- 0.019 0.020
0.009 0.011 OAl2 0.013 0.014 0.015 0.016
60-day
(0.009-0.009) (0.010-0.011) (0.011-0.013) (0.012-0.014) (0.014-0.015 0.015-0.016) (0.016-0.017 0.016-0.018) (0.018-0.020) (0.018-0.021
) ( ) ( )
Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a
given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
Back to Top
PF graphical
https:llhdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?tat=35.5000&Ion=-79.6000&data=intensity&units=english&series=pds 1 /4

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https:llhdsc.nws.noaa.govlhdsc/pfdslpfds_printpage.html?lat=35.5000&Ion=-79.6000&data=intensity&units=english&series=pds 3/4

3/8/2021
Precipitation Frequency Data Server
Back to Top
US Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring, MD 20910
Questions?: HDSC.Questions lnoaa.gov
Disclaimer
https:llhdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.htmI?Iat=35.5000&Ion=-79.6000&data=intensity&units=engIish&series=pds 4/4

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MAP LEGEND
Area of Interest (AOI)
U
Area of Interest (AOI)
Soils
Q
Soil Map Unit Polygons
.n.I
Soil Map Unit Lines
Soil Map Unit Points
Special
Point Features
Uo
Blowout
0
Borrow Pit
X
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
l
Landfill
Lava Flow
cb
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
a�a
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
,e
Sodic Spot
Soil Map —Catawba County, North Carolina
(Blackburn - Duke POI Soil Survey)
MAP INFORMATION
—
Spoil Area
The soil surveys that comprise your AOI were mapped at
1:15,800.
Stony Spot
Please rely on the bar scale on each map sheet for map
Very Stony Spot
measurements.
r
wet Spot
Source of Map: Natural Resources Conservation Service
Other
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
.�
Special Line Features
Maps from the Web Soil Survey are based on the Web Mercator
Water Features
projection, which preserves direction and shape but distorts
Streams and Canals
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
Transportation
accurate calculations of distance or area are required.
Rails
This product is generated from the USDA-NRCS certified data as
ew!
Interstate Highways
of the version date(s) listed below.
u.�.
US Routes
Soil Survey Area: Catawba County, North Carolina
-__
Major Roads
Survey Area Data: Version 20, Jun 2, 2020
Local Roads
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Background
Date(s) aerial images were photographed: Apr 8, 2015—Nov 28,
�i
Aerial Photography
2017
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
USDA Natural Resources Web Soil Survey 5/13/2021
Conservation Service National Cooperative Soil Survey Page 2 of 3

Soil Map —Catawba County, North Carolina
Blackburn - Duke POI Soil Survey
Map Unit Legend
Map Unit Symbol
Map Unit Name
Acres in AOI
Percent of AOI
CaB
Cecil sandy loam, 2 to 6
0.6
0.1 %
percent slopes
1.6%
CaD
Cecil sandy loam, 10 to 15
14.0
percent slopes
CeC2
Cecil clay loam, 6 to 10
59.8
6.9%
percent slopes, moderately
eroded
ChA
Chewacla loam, 0 to 2 percent
1.8
0.2%
slopes, frequently flooded
CoA
Congaree loam, 0 to 2 percent
26.0
3.0%
slopes, frequently flooded
LcB
Lloyd loam, 2 to 6 percent
327.1
37.9%
slopes
LcC
Lloyd loam, 6 to 10 percent
16.8
1.9%
slopes
LcD
Lloyd loam, 10 to 15 percent
9.1
1.1%
slopes
LcE
Lloyd loam, 15 to 25 percent
9.6
1.1 %
slopes
LdB2
Lloyd clay loam, 2 to 6 percent
99.4
11.5%
slopes, moderately eroded
LdC2
Lloyd clay loam, 6 to 10
181.8
21.1%
percent slopes, moderately
eroded
MkF4
Madison-Udorthents complex,
44.3
5.1%
25 to 45 percent slopes,
gullied
PaE3
Pacolet clay loam, 10 to 25
66.5
7.7%
percent slopes, severely
eroded
W
Water
6.2
0.7%
Totals for Area of Interest
862.9
100.0%
USDA Natural Resources Web Soil Survey 5/13/2021
Conservation Service National Cooperative Soil Survey Page 3 of 3

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