SW6220905_Design Calculations_20220929

HAYES POI NTE
Storm Water and Erosion & Sedimentation Control Calculations
Owner:
Land 2020, Inc
350 Wagoner Drive
Sanford, NC 27330

Hayes Pointe 2
The certification shown below applies only to the items listed on this 'Table of Contents'
Table of Contents
Drainage Area Map
1 Page
Runoff Coefficient
1 Page
Kirpich Equation
1 Page
NOAA Rainfall Intensity
1 Page
Mannings n
3 Pages
Permanent Diversion Ditch
1 Page
Temporary Sediment Basin
1 Page
Rip Rap Outlet Aprons
4 Pages
Curb Inlet Capacity (Sump and Non -Sump)
2 Pages
Storm Pipe Capacity
1 Page
Inlet Spread; Max Drainage Area
1 Page
Riser Anti -floatation Calculations
1 Page
HILLIARD . __-
ENGINEERING
Author: Jarrod E. Hilliard, PE, CFM
PO Box 249 Sanford, NC 27331
[phone]
NC License No. P-0836
Date: 6/21/22

DRAINAGE AREA MAP

SEDIMENT BASIN 01
m.; �„DA: 14.61 ac.
da: 14.61 ac.
E Y c: 0.4 (single family residential);
SILT F CE DE . 548 LF ~ rTi 110: 5.15 in/hr
INRO D: F 3 Ac.
CONVERT
ON r,•Py� CONVERTERT TOO WET POND
AFTER ALL UPSTREAM
0.16 A . AREA IS STABILIZED 8
�m 13 Ac. VERSION SW zJ
OPEN SP C d v.20 Ac. c"
113,6265q.
n 2.61 Ac �0
w
0,20 A � '°& 3
r
6 0
1.94 Ac.
0.37
a LL ( LL
v '�rtff co, nFri�es
c 3 zm y
oed W m o
=a -
O '
1 _ 76.75' 70.00'
m70.00' �0.00' 70.00'
70.
U. 1 " 0.07 Ac,,,
171.43'
65.36' •,'81.05' - .. a erff
_ C S
0.72 Ac. ps sl0s' sl.as'
r
0.67 Ac. �Y0.72 Ac.
4� 0.6i Ac.
171.4' c
i rN
v�V
1��x p pC
�p
0.8 Ac. ~
171.43' O
1 t
i 1 1.43' r
�b LAx�., ...xx...xx,...xx
~
~ ~ ~
17143
f g r�
0.9 Ac �� "'o
0
Q
171.43'
e S1.Os'
81.05' S7.45'
fY V o 0.1 0 09 Acn
yes 145.45' -
—.43' 0.34 Ac. Y 160.99' _ 0.72
160.62'
p % N r4
A=ij.25 ACRES n 170
EDr : L'
;SILT F L
OPEN SPACE
i s,n6sq. Feet OPEN SPACE
' 0.20Ac 24,1685q.F'pt _
0.55 A
• ., sy , e
i
.�
�.
'•••••�•�•Y...Y.�VYYYVVYYYVVV:i.•.•.••• m

RUNOFF COEFFICIENT

0
Table 8.03b
Value of Runoff Coefficient
(C) for Rational Formula
Land Use
C
Land Use
C
Business:
Lawns:
Downtown areas
0.70-0.95
Sandy soil, flat, 2%
0.05-0.10
Neighborhood areas
0.50-0.70
Sandy soil, ave.,
0.10-0.15
2-7%
Residential:
Sandy soil, steep,
0.15-0.20
Single-family areas
0.30-0.50
7%
Multi units, detached
0.40-0.60
Heavy soil, flat, 2%
0.13-0.17
Multi units, Attached
0.60-0.75
Heavy soil, ave.,
0.18-0.22
Suburban
0.25-0.40
2-7%
Industrial:
Heavy soil, steep,
0.25-0.35
Light areas
0.50-0.80
7%
Heavy areas
0.60-0.90
Agricultural land:
Parks, cemeteries
0.10-0.25
Bare packed soil
Smooth
0.30-0.60
Playgrounds
0.20-0.35
Rough
0.20-0.50
Cultivated rows
Railroad yard areas
0.20-0.40
Heavy soil no crop
0.30-0.60
Heavy soil with
Unimproved areas
0.10-0.30
crop
0.20-0.50
Streets:
Sandy soil no crop
0.20-0.40
Asphalt
0.70-0.95
Sandy soil with
Concrete
0.80-0.95
crop
0.10-0.25
Brick
0.70-0.85
Pasture
Heavy soil
0.15-0.45
Drives and walks
0.75-0.85
Sandy soil
0.05-0.25
Woodlands
0.05-0.25
Roofs
0.75-0.85
NOTE: The designer
must use judgement
to select the appropriate
C
value within the range
for the appropriate land use. Generally,
larger
areas with permeable
soils, flat slopes, and dense vegetation
should
have lowest C values.
Smaller areas
with slowly permeable
soils, steep
slopes, and sparse vegetation should
be assigned highest C
values.
Source: American Society of Civil Engineers
8.03.6 Rev. 6/06

KIRPICH EQUATION

HAYES POINTE
KIRPICH EQUATION
FOR TIME OF CONCENTRATION COMPUTATIONS
T. = L K/1281 LL3/HI0.385
IN
L: 962
H: 2
T,: 16.69 Minutes
Use: 16.69 minutes

N OAA DATA

Precipitation Frequency Data Server
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=3 5.25 73&...
NOAA Atlas 14, Volume 2, Version 3
Location name: Spring Lake, North Carolina, USA*t''��'
Latitude: 35.2573°, Longitude:-78.9144° i
Elevation: 169.35 ft** a
*source ESRI Maps k °d
**source 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 PFgraphical I Maps_&_aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)l
Average
recurrence interval (years)
Duration
1
2
5
10
25
50
1 100
00
200
500
1000
0.433
0.511
0.594
0.657
0.730
0.783
0.832
0.878
0.933
0.976
5-min
(0.392-0.482)
(0.463-0.569)
(0.538-0.661)
(0.593-0.729)
(0.657-0.809)
(0.703-0.866)
(0.743-0.920)
(0.780-0.970)
(0.821-1.03)
(0.853-1.08)
0.692
0.817
0.951
1.05
7.16
1.25
1.32
7.39
1.48
1.54
10-min
(0.627-0.770)i(0.740-0.909)
(0.861-1.06)
(0.949-1.17)
1 (1.05-1.29)
1 (1.18-1.46)
(1.24-1.54)
(1.30-1.63)
(1.34-1.70)
0.865
7.03
7.20
7.33
7.48
7.58
7.67
7.76
7.86
7.93
15-min
(0.783-0.
(0.931-1.14)
1 (1.09-1.34)
20-1.4
(1.33-1.64)
1 (1.42-1.75)
1 (1.49-1.85)
1 (1.56-1.94)
(1.63-2.05)
(1.69-2.13)
1.19
1.42
1.77
1.93
2.19
2.38
2.56
2.73
2.96
3.12
30-min
(1.07-1.32)
(1.29-1.58)
(1.55-1.90)
(1.74-2.14)
(1.97-2.42)
1 (2.13-2.63)
1 (2.29-2.83)
1 (2.433.02)
(2.60-3.26)
(2.73-3.45)
7.48
7.78
2.79
2.57
2.91
3.22
3.53
3.83
4.24
4.56
60-min
(1.34-1.65)
(1.61-1.98)
(1.99-2.44)
(2.27-2.78)
(2.623.22)
1 (3.15-3.90)
(3.41-4.24)
(3.73-4.68)
(3.99-5.04)
1.73
2.10
2.62
3.03
3.57
4.00
4.44
4.88
5.47
5.94
2-hr
(1.55-1.96)
1 (1.88-2.37)
1 (2.35-2.95)
1 (2.71-3.41)
1 (3.17-4.02)
1 (3.55-4.50)
1 (3.90-4.98)
1 (4.265.48)
(4.73-6.13)
(5.10-6.66)
1.84
2.23
2.80
3.26
3.89
4.40
4.93
5.48
6.25
6.88
3-hr
(1.65-2.08)
1 (2.00-2.52)
1 (2.513.16)
(2.92-3.67)
(3.45-4 37) j
(3.88-4.95)
1 (4.32-5.53)
1 (4.775.15)
(5.38-7.01)
(5.85-7.71)
6-hr
(1.99-2.45)
9-2.
2.66
(2.41-2.95)
3.34
(3.023.71)
3.90
52�.32)
4.66
(4.185.16
��
6.65
(5.81-7.33)
7.62
(6.58-8.40)
8.42
(7.18-9.28)
2.59
3.14
3.96
4.65
5.60
6.40
7.24
8.14
9.42
10.5
12-hr
(2.35-2.88)
1 (2.84-3.48)
1 (3.58-4.40)
1 (4.18-5.16)
1 (5.005.19)
1 (5.67-7.05)
1 (6.35-7.96)
1 (7.073.94)
1 (8.06-10.4)
1 (8.85-11.5)
3.06
3.70
4.69
5.47
6.55
7.42
8.32
9.25
10.5
11.6
24-hr
1(2.843.
(3.43-4.01)
1 (4.345.07)
05-5.9
(6.03-7.08)
1 (7.61-8.98)
(8.44-9.98)
(9.56-11.4)
(10.5-12.5)
3.56
4.29
5.40
6.27
7.47
8.44
9.43
10.5
11.9
13.0
2-day
(3.313.83)
(3.99-4.62)
(5.005.81)
(5.80-6.74)
(6.893.04)
(7.75-9.08)
(8.64-10.2)
1 (9.55-11.3)
(10.8-12.8)
(11.8-14.1)
3.77
4.55
5.68
6.58
7.82
8.81
9.84
10.9
12.4
13.5
3-day
(3.52-4.05)
(4.24-4.88)
(5.285.10)
(6.10-7.05)
(7.233.38)
(8.11-9.45)
(9.03-10.5)
1 (9.97-11.7)
(11.2-13.3)
(12.3-14.6)
3.99
4.80
5.97
6.89
8.77
9.79
70.2
77.3
72.8
74.0
4-day
(3.73-4.27)
(4.49-5.14)
(5.565.38)
(6.41-7.36)
(7.563.72)
(8.48-9.81)
(9.42-10.9)
1 (10.4-12.1)
(11.7-13.7)
(12.7-15.0)
4.62
5.52
6.78
7.78
9.15
10.2
11.4
12.5
14.7
15.4
7-day
(4.30-4.95)
1 (5.14-5.93)
1 (6.31-7.28)
1 (7.23-8.34)
1 (8.47-9.81)
1 (9.45-11.0)
1 (10.5-12.2)
1 (11.5-13.5)
(12.9-15.2)
(14.0-16.6)
5.27
6.29
7.60
8.63
70.0
11.1
12.2
13.4
74.9
76.7
10-day
(4.955.62)
1 (5.90-6.70)
1 (7.12-8.10)
1 (8.07-9.19)
1 (9.34-10.7)
1 (11.3-13.0) 11
(12.3-14.2)
(13.7-15.9)
(14.7-17.2)
7.10
8.40
10.00
11.2
12.9
74.2
15.6
16.9
18.7
20.2
20-day
(6.66-7.58)
(7.88-8.97)
(9.36-10.7)
1 (10.5-12.0)
1 (12.0-13.8)
1 (14.4-16.6)
(15.6-18.1)
(17.3-20.0)
(18.5-21.6)
30-day
8.84
70.4
72.2
73.6
75.3
76.7
78.7
79.5
27.3
22.7
(8.31-9.41)
(9.80-11.1)
(11.4-13.0)
1 (12.7-14.4)
1 (14.3-16.3)
1 (16.8-19.3)
(18.1-20.8)
(19.7-22.8)
(20.9-24.3)
45-day
11.2
13.2
15.1
16.7
18.6
20.1
21.6
23.0
24.9
26.3
(10.6-11.9)
1 (12.4-14.0)
1 (14.3-16.1)
1 (15.7-17.7)
1 (17.5-19.7)
1 (18.9-21.3)
1 (20.2-22.9)
1 (21.5-24.4)
(23.2-26.5)
(24.4-28.0)
13.4
15.7
17.9
19.6
21.7
23.3
24.9
26.4
28.4
29.9
60-day
(12.7-14.2)
(14.9-16.6)
(16.9-18.9)
(18.5-20.7)
(20.5-22.9)
(22.0-24.6)
(23.4-26.3)
(24.8-27.9)
(26.6-30.1)
(28.0-31.7)
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 greaterthan 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
1 of 4 3/24/2022, 11:15 AM

Precipitation Frequency Data Server
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=3 5.25 73&...
NOAA Atlas 14, Volume 2, Version 3
Location name: Spring Lake, North Carolina, USA*t''��'
Latitude: 35.2573°, Longitude:-78.9144° i
Elevation: 169.35 ft** a
*source ESRI Maps k °d
**source 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 PFgraphical I Maps_&_aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)l
Average
recurrence interval (years)
Duration
1
����������
2
5
10
25
50
100
200
500
1000
5.20
6.73
7.73
7.88
8.76
9.40
9.98
70.5
77.2
11.7
5-min
(4.705.78)
(5.56-6.83)
(6.46-7.93)
(7.12-8.75)
(7.88-9.71)
(8.44-10.4)
(8.92-11.0)
(9.36-11.6)
(9.85-12.4)
4.15
4.90
5.77
6.30
6.98
7.48
7.94
8.35
8.85
9.22
10-min
(3.76-4.62)
(4.44-5.45)
(5.175.35)
(5.69-7.00)
(6.28-7.74)
(6.715.27)
(7.09-8.77)
(7.42-9.22)
(7.79-9.77)
1 (8.06-10.2)
3.46
4.10
4.87
5.37
5.90
6.37
6.69
7.02
7.43
7.71
15-min
(3.133.85)
(3.72-4.57)
(4.365.35)
(4.80-5.90)
(5.30-6.54)
1 (5.97-7.39)
(6.24-7.76)
1 (6.54-8.20)
1 (6.74-8.52)
2.37
2.84
3.42
3.85
4.37
4.75
5.12
5.47
5.97
6.25
30-min
(2.15-2.64)
(2.57-3.16)
(3.103.80)
(3.48-4.27)
(3.93-4.84)
1 (4.57-5.66)
(4.865.04)
1 (5.20-6.53)
1 (5.46-6.90)
7.48
1.78
2.79
2.57
2.91
3.22
3.53
3.83
4.24
4.56
60-min
(1.34-1.65)
(1.61-1.98)
(1.99-2.44)
(2.27-2.78)
(2.62-3.22)
1 (3.15-3.90)
(3.41-4.24)
(3.73-4.68)
(3.99-5.04)
0.866
1.05
1.37
1.52
1.79
2.00
2.22
2.44
2.73
2.97
2-hr
(0.776-0.97 fl
(0.942-1.18)
1 (1.17-1.48)
1 (1.35-1.71)
1 (1.59-2.01)
1 (1.77-2.25)
1 (1.95-2.49)
1 (2.13-2.74)
(2.37-3.07)
(2.55-3.33)
0.614
0.742
0.932
1.09
1.29
1.47
7.64
1.83
2.08
2.29
3-hr
(0.551-0.693)
(0.667-0.838)
(0.836-1.05)
(0.971-1.22)
(1.15-1.45)
(1.29-1.65)
1 (1.44-1.84)
1 (1.59-2.05)
1 (1.79-2.33)
1 (1.95-2.57)
0.367
0.444
0.558
0.651
0.779
0.885
0.99
1.11
1.27
1.41
6-hr
(0.332-0.408)
(0.403-0.493)
(0.505-0.619)
(0.587-0.722)
(0.698-0.862)
(0.787-0.978)
(0.877-1
(0.970-1.22)1
(1.10-1.40)
(1.20-1.55)
0.215
0.260
0.329
0.386
0.465
0.531
0.607
0.675
0.782
0.870
12-hr
(0.195-0.239)
(0.236-0.289)
(0.297-0.365)
(0.347-0.428)
(0.415-0.514)
(0.471-0.585)
(0.527-0.661)
(0.586-0.742)
(0.669-0.859)
(0.734-0.955)
0.127
0.154
0.195
0.273
0.309
0.346
0.385
0.439
0.482
24-hr
.228
118-0.138)
(0.143-0.167)
(0.181-0.211)
10-0.24
(0.251-0.295)
(0.284-0.334)
(0.317-0.374)
(0.352-0.416)
(0.399-0.475)
(0.436-0.522)
0.074
0.089
0.112
0.131
0.156
0.176
0.196
0.218
0.248
0.271
2-day
(0.069-0.080)
(0.083-0.096)
(0.104-0.121)
(0.121-0.140)
(0.143-0.167)
(0.161-0.189)
(0.180-0.212)
(0.199-0.235)
(0.225-0.267)
(0.245-0.293)
0.052
0.063
0.079
0.091
0.109
0.122
0.137
0.151
0.172
0.188
3-day
(0.049-0.056)
(0.059-0.068)
(0.073-0.085)
(0.085-0.098)
(0.100-0.116)
(0.113-0.131)
(0.125-0.147)
(0.138-0.162)
(0.156-0.185)
(0.170-0.202)
0.042
0.050
0.062
0.072
0.085
0.096
0.107
0.118
0.134
0.146
4-day
(0.039-0.044)
(0.047-0.054)
(0.058-0.066)
(0.067-0.077)
(0.079-0.091)
(0.088-0.102)
(0.098-0.114)
(0.108-0.126)
(0.122-0.143)
(0.133-0.157)
0. 227
1 0.033
F 0.040
0.046
0.054
0.067
0.068
0.075 IF
0.084
F 0.092
7-day
(0.026-0.029)
(0.031-0.035)
(0.038-0.043)
(0.043-0.050)
(0.050-0.058)
(0.056-0.065)
(0.062-0.073)
(0.068-0.080)
(0.077-0.090)
(0.083-0.099)
0.022
F 0.026
I 0.032
0.036
0.042
0.046
0.057
0.056
0.062
0.067
10-day
(0.021-0.023)
(0.025-0.028)
(0.030-0.034)
(0.034-0.038)
(0.039-0.044)
(0.043-0.049)
(0.047-0.054)
(0.051-0.059)
(0.057-0.066)
(0.061-0.072)
0.015
0.018
0.027
0.023
0.027
0.030
0.032
0.035
0.039
0.042
20-day
(0.014-0.016)
(0.016-0.019)
(0.019-0.022)
(0.022-0.025)
(0.025-0.029)
(0.028-0.032)
(0.030-0.035)
(0.033-0.038)
(0.036-0.042)
(0.039-0.045)
0.012
0.014
0.017
0.019
0.027
0.023
0.025
0.027
0.030
0.032
F30-day
30-day
(0.012-0.013)
(0.014-0.015)
(0.016-0.018)
(0.018-0.020)
(0.020-0.023)
(0.022-0.025)
(0.023-0.027)
(0.025-0.029)
(0.027-0.032)
(0.029-0.034)
0.010
0.012
0.014
0.015
0.017
0.019
0.020
0.021
0.023
0.024
F45-day
�(0.010-0.011)
(0.012-0.013)
(0.013-0.015)
(0.015-0.016)
(0.016-0.018)
(0.017-0.020)
(0.019-0.021)
(0.020-0.023)
(0.021-0.025)
(0.023-0.026)
0.009
0.017
0.012
0.014
0.015
0.016
0.017
0.018
0.020
0.027
60-day
(0.009-0.010)
(0.010-0.012)
(0.012-0.013)
(0.013-0.014)
(0.014-0.016)
(0.015-0.017)
(0.016-0.018)
(0.017-0.019)
(0.018-0.021)
(0.019-0.022)
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 higherthan currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
Back to Top
PF graphical
1 of 4 3/24/2022, 11:16 AM

MANNINGS n

This section describes a method for estimating the roughness coefficient n for
use in hydraulic computations associated with natural streams, t3oodways, and
excavated channels. The procedure applies to the estimation of n in Manning's
formula (appendix 8.05).
Designed By: JEH Date: 03/31/22
Checked By: JEH Date: 03/31/22
Company: Hilliard Engineering, PLLC
Project Name: Hayes Pointe
Project No.:
Site Location (City/Town) Harnett Co.
Site Id. n/a
Step 1. Selection of basic value of n. Select a basic n value for a straight,
uniform. smooth channel in the natural materials involved. The conditions of
straight alignment, uniform cross section, and smooth side and bottom surfaces
without vegetation should be kept in mind. Thus. basic n varies only with the
material than forms the sides and bottom of the channel. Select the basic n for
natural or excavated channels from Table 8.04a. If the bottom and sides of a
channel consist of different materials. select an intermediate value_
Channels in earth
Basic n value i(n=0.020) 1 0.02 Table 8.04a
Step 2. Selection of modifying value for surface irregularity. This factor
is based on the degree of roughness or irregularity of the surfaces of channel
sides and bottom. Consider the actual surface irregularity, first in relation
to the degree of surface smoothness obtainable with the natural materials
involved_ and second in relation to the depths of flow expected. If the surface
irregularity is comparable to the best surface possible for the channel materials,
assign a modifying value of zero. Irregularity induces turbulence that calls for
increased modifying values_ Table 8.04b may be used as a guide to selection
of these modifying values.
Modifying value: channel
surface irregularity Smooth (0.000) 0 Table 8.04b
Step 3. Selection of modifying value for variations in the shape and size of
cross sections. In considering this factor, judge the approximate magnitude of
increase and decrease in successive cross sections as compared to the average.
Gradual and uniform changes do not cause significant turbulence. Turbulence
1ncrPa`cec with the freonenry and ahnmtnecc of alternation from larve tn small

channel sections.
Shape changes causing the greatest turbulence are those for which flow shifts
from side to side in the channel. Select modifying values based on Table
8.O4c_
Modifying value: channel
cross section Gradual (0.000) 0 Table 8.04c
Step 4. Selection of modifying value for obstructions. This factor is based
on the presence and characteristics of obstructions such as debris deposits.
stumps, exposed roots, boulders, and fallen and lodged logs. Take care that
conditions considered in other steps not be double -counted in this step.
In judging the relative effect of obstructions, consider the degree to which
the obstructions reduce the average cross -sectional area at various depths and
the characteristics of the obstructions. Sharp -edged or angular objects induce
more turbulence than curved, smooth -surfaced objects. Also consider the
transverse and longitudinal position and spacing of obstructions in the reach.
Select modifying values based on Table 8.O4d.
Modifying value: effect of
Obstructions Negligible (0.000) 0 Table 8.04d
Step 5. Selection of modifying value for vegetation. The retarding effect
of vegetation is due primarily to turbulence induced as the water flows around
and between limbs, stems, and foliage and secondarily to reduction in cross
section- As depth and velocity increase, the force of flowing water tends to
bend the vegetation_ Therefore, the ability of vegetation to cause turbulence is
related to its resistance to bending. Note that the amount and characteristics of
foliage vary seasonally. In judging the retarding effect of vegetation. consider
the follovang: height of vegetation in relation to depth of flow, its resistance to
bending, the degree to which the cross section is occupied or blocked, and the
transverse and longitudinal distribution of densities and heights of vegetation
in the reach. Use Table 8.O4e as a guide.
Modifying value: vegetation JHigh (0.025-0.050) 1 0.0375 Table 8.04e
Step 6. Computation of U, for the reach. The first estimate of roughness
for the reach, ns, is obtained by neglecting meandering and adding the basic n
value obtained in step 1 and modifying values from steps 2 through 5.
ns = n + i modifying values
Straight channel subtotal, ns 0.0575
Step 7. Aleander. The modifying value for meandering is not independent of
the other modifying values. It is estimated from the nr obtained in step 6, and
A^ r"r% of the mPonAPrinrr 1Pnrrth to Ao c"irrht to . gvth Ths- mnAifcnnrr ■ship

ual 1AlLV Va ual. LCur'4LL aV lul au QLrut 14ur'llL. am, auVuaaYuar' Ysa4l
for meandering may be selected from Table 8.04f
Length of meandering
channel (ft) 0
Length of straight line (ft) 416
Meander ratio (ft/ft) 0
Modifying value:
meandering of channel Minor (0.00) 0 Table 8.04f
Meandering modification 0.000
Step 8. Computation of it for a channel reach with meandering. Add the
lnodlfvinQ value obtalned Ill step to �a.. obtauied In step 6.
Final roughness coefficient,
0.058

PERMANENT DIVERSION DITCH

OBJECTIVE:
SOLUTIONS:
RUNOFF CONDITIONS
MAXIMUM
Slope Condition
SHEAR STRESS:
RECOMMENDED LINING:
TERMINOLOGY:
Permanent Diversion Swale With Berm
Hayes Pointe
Verify Capacity of Diversion Ditch Based Upon Q10 storm event.
Check that swale will non-erosively pass the Q10 storm event
Mannings Flow Equation
c: A (ac): 110 (cfs):
0.4 0.37 5.15
m
010 = 0.76 rfs
d =
n =
B =
Z Left =
Z Right =
Avg. S =
0.780
ft (min. flow depth for Q10 storm)
(computed)
ft (min. width)
:1 (Side Slope)
:1 (Side Slope)
ft/ft (avg. slope)
A =
P =
R =
Q10 Storm =
V10 Storm =
W =
1.83
4.93
0.37
0.76
0.42
4.68
FTA2
FT
CFS
FPS
FT
0.058
0
3
3
0.001000
Berm Height.
0.720
ft
Total Depth From Top of Berm to Bottom of Ditch:
1.50
ft
Bottom Berm Width:
6.00
ft
Top of Berm Width 1
2.00
ft
T= Shear Stress Y=
62.4
PCF
T= 0.049 PSF d=
0.78
FT
S=
0.00
FT/FT
Seed and Mulch With Contractor's Blend
SAY: 12" DEPTH, 5' NATURAL FLOW SPREAD AT TERMINUS
Q =
Peak Discharge,(CFS)
V =
Permissible Velocity, (FPS)
d =
Maximum Depth of Water, (FT)
Vt=
Trial Velocity, (FPS)
n =
Manning's "n" Coefficient
V*R =
Product of Velocity and Hydraulic Radius
B =
Bottom Width of Channel, (FT)
Z =
Side Slope of Channel (Z:1)
CHANNEL LINING:
With velocities less than 2 f/s use Seed and Mulching
With velocites greater than 2 f/s use Temporary Ditch Liner
: if T < 1 then use Coir Wattle against silt fence
: if T > 1 then use other lining
A = Cross -Sectional Area of Flow, (FT^2)
P = Wetted Perimeter of the Flow, (FT)
R = Hydraulic Radius, (FT)
S = Slope of the Channel, (FT/FT)
Q = Discharge,(CFS)
V = Velocity, (FPS)
W = Top Width of Water in Channel, (FT)
Y = Specific Weight of Water (62.4 PCF)

TEMPORARY SEDIMENT BASIN

Sediment Basin
Okay
14.61 Disturbed Area (Acres)
30.1 Peak Flow from 10-year Storm (cfs)
26298 Required Volume ft'
13112 Required Surface Area ft2
81.0 Suggested Width ft
161.9 Suggested Length ft
90 Trial Top Width at Spillway Invert ft
163 Trial Top Length at Spillway Invert ft
3 Trial Side Slope Ratio Z:1
3 Trial Depth ft (2 to 13 feet above grade)
72 Bottom Width ft
145 Bottom Length ft
10440 Bottom Area ft2
37503 Actual Volume ft3 Okay
14670 Actual Surface Area ft2 Okay
Use Spillway Capacity Sheet to Size Primary and Emergency Spillways
4 Skimmer Size (inches)
0.333 Head on Skimmer (feet)
3 Orifice Size (1/4 inch increments)
3.13 Dewatering Time (days)
Dewatering Time should be 2-5 days
Orifice A: 0.04906 sf
2gh: 21.4452
cD: 0.6
Qo: 0.13632 cfs
Skimmer Size
(Inches)
1.5
2

RIP RAP OUTLET APRONS

User Input Data
Calculated Value
Reference Data
Designed By: JEH 5/23/2022
Checked By: JEH 5/23/2022
Company: Hilliard Engineering, PLLC
Project Name: Hayes Pointe
Project No.: HC2201
Site Location (City/Town) Spring Lake, NC
Culvert Id. Outlet to Forebay
Total Drainage Area (acres) 14.61
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe. If the tailwater depth is less
than half the outlet pipe diameter, it is classified minimum tailwater condition.
If it is greater than half the pipe diameter, it is classified maximum condition.
Pipes that outlet onto wide fiat areas with no defined channel are assumed
to have a minimum tailwater condition unless reliable flood stage elevations
shoe- otheru7se.
Outlet pipe diameter, Do (in.)
Tailwater depth (in.)
Minimum/Maximum tailwater?
Discharge (cfs)
Velocity (ft./s)
30
6
Min TW (Fig. 8.06a)
24.07
!�%ZI
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b, and determine d50 riprap size and minimum apron length
(L). The d$o size is the median stone size in a well -graded riprap apron_
Step 3. Determine apron width at the pipe outlet. the apron shape. and the
apron width at the outlet end from the same figure used in Step 2-
Minimum TW
Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 0.5

Minimum apron length, La (ft.) 18
Apron width at pipe outlet (ft.) 7.5
Apron shape Trapezoidal
Apron width at outlet end (ft.) 20.5
Step 4. Deternune the maximum stone diameter-
dmax = 1.5 x d50
Minimum TW
Max Stone Diameter, dmax (ft.) 0.75
Step'--,. Deterimne the apron duck-ness_
Apron Thickness(ft.)
Apron thickness = -1.5 x dr,�
Minimum TW
1.125
7.5
Trapezoidal
2.5
Maximum TW
0
Maximum TW
0
Step 6. Fit the riprap apron to the site by making it level for the minimum
length, La, from Figure 8.06a or Figure 8.06b. Extend the apron farther
downstream and along channel banks until stability is assured. Keep the
apron as straight as possible and align it with the flow of the receiving stream.
Make any necessary alignment bends near the pipe outlet so that the entrance
into the receiving stream is straight.
Some locations may require lining of the entire channel cross section to assure
stability.
It may be necessary to increase the size of riprap where protection of the
channel side slopes is necessary (Appendix 8.05). Where overfalls exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8_

User Input Data
Calculated Value
Reference Data
Designed By: JEH 5/23/2022
Checked By: JEH 5/23/2022
Company: Hilliard Engineering, PLLC
Project Name: Hayes Pointe
Project No.: HC2201
Site Location (City/Town) Spring Lake, NC
Culvert Id. STORM OUTFALL MAX
Total Drainage Area (acres) 14.61
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe. If the tailwater depth is less
than half the outlet pipe diameter, it is classified minimum tailwater condition.
If it is greater than half the pipe diameter, it is classified maximum condition.
Pipes that outlet onto wide fiat areas with no defined channel are assumed
to have a minimum tailwater condition unless reliable flood stage elevations
shoe- otheru7se.
Outlet pipe diameter, Do (in.)
Tailwater depth (in.)
Minimum/Maximum tailwater?
Discharge (cfs)
Velocity (ft./s)
15
6
Min TW (Fig. 8.06a)
14.43
`§WiT
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b, and determine d50 riprap size and minimum apron length
(L). The d$o size is the median stone size in a well -graded riprap apron_
Step 3. Determine apron width at the pipe outlet. the apron shape. and the
apron width at the outlet end from the same figure used in Step 2-
Minimum TW
Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 0.6

Minimum apron length, La (ft.) 16
Apron width at pipe outlet (ft.) 3.75
Apron shape Trapezoidal
Apron width at outlet end (ft.) 17.25
Step 4. Deternune the maximum stone diameter-
drt%dx = 1.5 x d50
Minimum TW
Max Stone Diameter, dmax (ft.) 0.9
Step'--,. Deterimne the apron duck-ness_
Apron Thickness(ft.)
Apron thickness = I.5 x {_I
Minimum TW
1.35
3.75
Trapezoidal
1.25
Maximum TW
0
Maximum TW
0
Step 6. Fit the riprap apron to the site by making it level for the minimum
length, La, from Figure 8.06a or Figure 8.06b. Extend the apron farther
downstream and along channel banks until stability is assured. Keep the
apron as straight as possible and align it with the flow of the receiving stream.
Make any necessary alignment bends near the pipe outlet so that the entrance
into the receiving stream is straight.
Some locations may require lining of the entire channel cross section to assure
stability.
It may be necessary to increase the size of riprap where protection of the
channel side slopes is necessary (Appendix 8.05). Where overfalls exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8_

CURB INLET CAPACITY

Curb Inlet Capacity for Sump Condition
Hayes Pointe
10-Year Design Storm
OBJECTIVE: Size Curb Inlet to intercept stormwater runoff by determining max drainage area
Assume 50% Clogged for Sumps
BASE DESIGN ON USE OF: Type of Grate Proposed: Curb Inlet
RUNOFF: c:
0.9
(max impervious area)
I:
5.15
inches per hour
*A:
1.26
acres (max drainage area to any 1 inlet)
Q10:
5.84
cfs
Orifice Equation:
Total Post-Dev(Q10)=
5.84
cfs
Post-Dev. Q(10)=
5.84
cfs (per inlet)
CD-
0.67
g=
32.2
ft/sZ
d=
0.240
ft (3" max. head, 6' lane spread)
Clear Opening Area Required=
318.6
sq. in
Clear Opening Area Required Assuming 50% Blockage=
477.96
sq. in
SOLUTION: Select Curb Inlet open area With approx.:
478.0 sq. in
USE:
Number of Curb Inlets:
Length:
Brand:
Model:
Open Area Obtained (sq. in.)
1
35.75"
East Jordan Iron Works
V4066-5
481
* Target as max drainage area to any 1 inlet

Curb Inlet Capacity for Non -Sump Condition
Hayes Pointe
10-Year Design Storm
OBJECTIVE: Size Curb Inlet to intercept stormwater runoff by determining max drainage are:
BASE DESIGN ON USE OF: Type of Grate Proposed: Curb Inlet
RUNOFF: c: 0.9 (max impervious area)
I: 5.15 inches per hour
*A: 1.900 acres (max drainage area to any 1 inlet)
010: 8.81 cfs
Orifice Equation:
Total Post-Dev(Q10)= 8.81 cfs
Post-Dev. Q(10)= 8.81 cfs (per inlet)
CD- 0.67
g= 32.2 ft/sZ
d= 0.240 ft (3" max. head, 6' lane spread)
Clear Opening Area Required= 480.49 sq. in
SOLUTION: Select Curb Inlet open area with approx.: 481.0 sq. in
USE:
Number of Curb Inlets:
Length:
Brand:
Model:
Open Area Obtained (sq. in.)
1
35.75"
East Jordan Iron Works
V4066-5
481
* Target as max drainage area to any I inlet

STORM PIPE CAPACITY

1]I]4U1
PIPE 01
PIPE 02
PIPE 03
PIPE 04
PIPE 05
PIPE 06
PIPE 07
PIPE 08
PIPE 09
PIPE 10
PIPE 11
PIPE 12
PIPE 13
PIPE 14
PIPE 15
PIPE 16
PIPE 17
PIPE 18
PIPE 19
PIPE 20
PIPE 21
PIPE 22
PIPE 23
PIPE 24
PIPE 25
PIPE 26
PIPE 27
PIPE 28
HAYES POINTE
D
Pipe Dia. (Inches)
S
Pipe Slope
Velocity (fps)
Discharge (gpm)
Discharge (cfs)
NUMBER OF PIPES
TOTAL CAPACITY (cfs)
15
0.100%
1.66 fps
917
2.04
1
2.04
15
0.100%
1.66 fps
917
2.04
1
2.04
15
0.100%
1.66 fps
917
2.04
1
2.04
24
0.100%
2.28 fps
3,211
7.15
1
7.15
15
0.100%
1.66 fps
917
2.04
1
2.04
24
0.100%
2.28 fps
3,211
7.15
1
7.15
15
0.100%
1.66 fps
917
2.04
1
2.04
30
0.100%
2.64 fps
5,821
12.97
1
12.97
15
0.100%
1.66 fps
917
2.04
1
2.04
30
0.100%
2.64 fps
5,821
12.97
1
12.97
30
0.100%
2.64 fps
5,821
12.97
1
12.97
30
0.150%
3.24 fps
7,130
15.89
1
15.89
15
0.100%
1.66 fps
917
2.04
1
2.04
15
0.100%
1.66 fps
917
2.04
1
2.04
18
0.100%
1.88 fps
1,491
3.32
1
3.32
15
0.100%
1.66 fps
917
2.04
1
2.04
24
0.100%
2.28 fps
3,211
7.15
1
7.15
36
0.100%
2.98 fps
9,466
21.09
1
21.09
36
0.100%
2.98 fps
9,466
21.09
1
21.09
15
0.100%
1.66 fps
917
2.04
1
2.04
36
0.100%
2.98 fps
9,466
21.09
1
21.09
36
0.100%
2.98 fps
9,466
21.09
1
21.09
15
0.100%
1.66 fps
917
2.04
1
2.04
36
0.100%
2.98 fps
9,466
21.09
1
21.09
36
0.100%
2.98 fps
9,466
21.09
1
21.09
36
0.100%
2.98 fps
9,466
21.09
1
21.09
36
0.150%
3.65 fps
11,594
25.83
1
25.83
36
0.150%
3.65 fps
11,594
25.83
1
25.83
C I (in/hr) A (ac) Q (cfs) Capacity o.k?
0.4
5.15
0.9
5.15
0.4
5.15
0.9
5.15
0.4
5.15
5.15
0.4
5.15
5
0.4
5.15
0.9
5.15
0.9
5.15
0.4
5.15
0.09
5.15
0.4
5.15
0.4
5.15
0.9
5.15
0.4
5.15
0.9
5.15
0.9
5.15
0.4
5.15
0.9
5.15
0.9
5.15
0.4
5.15
0.9
5.15
0.9
5.15
0.4
5.15
0.4
5.15
0.4
5.15
0.72
1.4832
0.09
1.90035
0.88
1.8128
4.223
0.34
0.7004
0.06
5.2015
0.94
1.9364
0.05
7.36965
0.8
1.648
0.08
9.38845
0.01
9.4348
0.74
15.6627
0.07
0.03245
0.72
1.51565
0.67
2.89585
0.07
0.32445
0.72
4.7035
0.03
15.8017
0.01
15.8481
0.57
1.1742
0.04
17.2077
f 0
17.2077
0.36
0.7416
0.03
18.0883
0
18.0883
0.46
0.9476
0
19.0359
2.31
23.7945
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
rI

INLET SPREAD

OBJECTIVE:
SOLUTIONS:
RUNOFF CONDITIONS
MAXIMUM
Slope Condition
SHEAR STRESS:
MAXIMUM 6' ROADWAY GUTTER SPREAD
HAYES POINTE
BASED UPON MAXIMUM ALLOWABLE DRAINAGE AREA TO ANY SINGLE CURB CUT OUTLET
3% CROWN ROADWAY WITH CURB AND GUTTER
Verify Capacity of Roadway Gutter to Prevent More Than 6' Spread During 4 in/hr Storm Event.
Check that gutter will pass the storm event without the flow depth along the gutter rising
more than 0.25' (Approx. 3")
Mannings Flow Equation
MAX
c: A (ac): I (in/hr):
0.4 1.050 4.00
(Allowable)
Q10 = 1.68 cfs
d =
n =
8 =
Z Left =
ZRight=
Min. S =
0.250
ft (allowable flow depth)
(Table 8, Design Manual)
ft (min. width)
:1 (Vertical Curb)
:1 (3%crown)
t/ t
A =
P =
R =
Q25 Storm =
V25 Storm =
W =
1.04
8.59
0.12
1.68
1.61
8.33
FT^2
FT
CFS
FPS
FT
0.016
0
0
33.33
1 0.005000
T=
T=
Shear Stress
0.078
PSF
Y=
d=
S=
62.4
0.25
0.01
PCF
FT
FT/FT
BY ADJUSTING MAXIMUM ALLOWABLE DRAINAGE AREA, THE
DRAINAGE AREA TO ANY SINGLE CURB CUT SHOULD BE NO MORE THAN:
FOR FULLY IMPERVIOUS AREA SCENARIOS, THE
TERMINOLOGY:
DRAINAGE AREA TO ANY SINGLE CURB CUT SHOULD BE NO MORE THAN:
Q=
Peak Discharge, (CFS)
V =
Permissible Velocity, (FPS)
d =
Maximum Depth of Water, (FT)
Vt =
Trial Velocity, (FPS)
n =
Manning's "n" Coefficient
V*R =
Product of Velocity and Hydraulic Radius
B =
Bottom Width of Channel, (FT)
Z =
Side Slope of Channel (Z:1)
CHANNEL LINING:
With velocities less than 2 f/s use Seed and Mulching
With velocites greater than 2 f/s use Temporary Ditch Liner
: if T < 1 then use Coir Wattle against silt fence
: if T > 1 then use other lining
1.050 ACRES
0.47 ACRES
A= Cross -Sectional Area of Flow, (FT^2)
P = Wetted Perimeter of the Flow, (FT)
R = Hydraulic Radius, (FT)
S = Slope of the Channel, (FT/FT)
Q= Discharge, (CFS)
V = Velocity, (FPS)
W = Top Width of Water in Channel, (FT)
Y = Specific Weight of Water (62.4 PCF)

RISER ANTI -FLOATATION CALCULATIONS

HAYES POINTE
HARNETT COUNTY, NC
ANTI -FLOATATION COMPUTATIONS
Enter Data
LEGEND
FOR RECTANGULAR SECTION STRUCTURE
Verfiy Data
CONTROL:
Unit Weight of Water:
62.4
Ibs/cf
Unit Weight of Conc.
150
Ibs/cf
STRUCTURE WEIGHT:
o ft
162.00 ft- msI (Rim Elevation)
STRUCTURE SIDES:
162.00 ft-msl (Top of Sides)
Riser Inside Length Dimension:
3 ft
Riser Inside Width Dimension:
2.16
ft
Thickness of Concrete:
0.5
ft
0.5 ft
Riser Outside Length Dimensions:
4
Riser Outside Width Dimensions:
3.16
160 ft-msl (Barrel Invert)
Volume of Sides:
12.32
cf
159.5 ft-msl (Initial Bottom of Structure)
Weight of Concrete Sides:
1,848
Ibs
160.00 ft-msl (Invert with Anti -Float)
159.50 ft-msl (Bottom with Anti -Float)
0.5
ft
STRUCTURE BOTTOM:
STRUCTURE TOP:
Riser Inside Length Dimension:
3
ft
Riser Inside Length Dimension: 3 ft
Riser Inside Width Dimension:
2.16
ft
Riser Inside Width Dimension: 2.16 ft
Thickness of Concrete:
0.5
ft
Thickness of Concrete: 0 ft
Riser Outside Length Dimensions:
4
ft
Riser Outside Length Dimensions: 4 ft
Riser Outside Width Dimensions:
3.16
ft
Riser Outside Width Dimensions: 3.16 ft
Volume of Bottom:
6.32
cf
Volume of Top Slab: 0 cf
Weight of Concrete Bottom:
0,948
Ibs
Weight of Concrete Bottom: 0,000 Ibs
INITIAL WEIGHT OF STRUCTURE:
2,796
LBS
INITIAL DESIGN O.K.
BOUYANCY FORCE:
ANTIFLOTATION:
Weir Elevation:
162
ft-msl
Use Bottom Inv. Elev: 160.00 ft-msl (Fill with Concrete)
Trial Bottom of Box:
159.5
ft-msl
Additional Stir. Wt: 0,000 Ibs
Inside Area of Riser:
6.48
sq. ft
Add. Bouy. Force: 0,000 Ibs
Outside Area of Riser:
12.64
sq. ft
TOTAL STR. WT: 2,796
Volume of Water Displaced:
31.6
cf
TOTAL BOUYANCY: 1,972
Initial Bouyancy Force:
1,972
Ibs
Safety Factor: 1.42 (Minimum S.F. must be >=1.1)
Message: Design o.k.