HomeMy WebLinkAboutSW6220905_Design Calculations_20220929 (2)HAYES POI NTE
WET POND
VOLUME, ROUTING AND DRAWDOWN 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
Simple Method; Pre -Development
1 Page
Simple Method; Post -Development
1 Page
Stage Storage Function
2 Pages
NOAA Rainfall Intensity & Depth
2 Pages
1 Year, 24 Hour Routing
3 Pages
10 Year, 6 Hour Routing
3 Page
25 Year, 6 Hour Routing
3 Page
50 Year, 6 Hour Routing
3 Pages
100 Year, 6 Hour Routing
3 Pages
Temporary Volume Drawdown
1 Page
Riser Anti -Floatation Calculations
1 Page
HILLIARD
ENGINEERING
Author: Jarrod E. Hilliard, PE, CFM
PO Box 249 Sanford, NC 27331
(919) 352-2834
NC License No. P-0836
Date: 6/21/22
SIMPLE METHOD
PRE -DEVELOPMENT
1 YEAR, 24 HOUR
Hayes Pointe VOLUME COMPUTATIONS
MINIMUM VOLUME REQUIRED. USE SIMPLE METHOD
Regulatory Requirement:
Phase II
Additional Requirements:
Non -erosive discharge
PRE -DEVELOPMENT
Design Storm Event Return Interval/Duration:
1
year 24 hour
Post Watershed Size:
14.61
acres
Pre Watershed Size:
14.61
acres
Peak Discharge Rainfall Intensity:
0.127
in/hr
Pre -Development c:
0.16
Post -Development c:
0.4
Estimated Percent Impervious Area:
0
% Total Composite CN
Impervious Area:
0.000
acres
Pervious Area:
14.610
acres
Design Storm Event Precipitation:
1.00
inch Minimum requirement
Major Hydrologic Soil Group:
B
GoA
Pervious Land Use CN:
55
Woods, good condition
Impervious Land Use CN:
98
RUNOFF DETERMINATION:
Simple Method
la: 0 (Impervious fraction)
RD: 1.00 in (Water Quality Storm)
A: 14.61 acres (Watershed Area)
RUNOFF COEFFICIENT (Rv): Formula: R v=0.05+0.9"l a
Rv: 0.05
VOL. REQUIRED (V): Formula: V=RD*Rv A
(V): 2,652 ft3 = 19,835 gallons
(V): 0.731 acre -inches
55
SIMPLE METHOD
POST -DEVELOPMENT
1 YEAR, 24 HOUR
Hayes Pointe VOLUME COMPUTATIONS
MINIMUM VOLUME REQUIRED. USE SIMPLE METHOD
Regulatory Requirement:
Phase II
Additional Requirements:
Non -erosive discharge
POST -DEVELOPMENT
Design Storm Event Return Interval/Duration:
1
year 24 hour
Post Watershed Size:
14.61
acres
Pre Watershed Size:
14.61
acres
Peak Discharge Rainfall Intensity:
0.127
in/hr
Pre -Development c:
0.16
Post -Development c:
0.4
Estimated Percent Impervious Area:
25.4
% Total Composite CN
Impervious Area:
3.711
acres
Pervious Area:
10.899
acres
Design Storm Event Precipitation:
1.00
inch Minimum requirement
Major Hydrologic Soil Group:
B
GoA
Pervious Land Use CN:
72
113 acre residential district
Impervious Land Use CN: 98
RUNOFF DETERMINATION:
Simple Method
la: 0.254 (Impervious fraction)
RD: 1.00 in (Water Quality Storm)
A: 14.61 acres (Watershed Area)
RUNOFF COEFFICIENT (Rv): Formula: R v=0.05+0.9"l a
Rv: 0.2786
VOL. REQUIRED (V): Formula: V=RD*Rv A
(V): 14,775 ft3 = 110,520 gallons
(V): 4.070 acre -inches
79
STAGE -STORAGE FUNCTION
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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/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
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
1 YEAR, 24 HOUR ROUTING
FORMULATING PRE -POST DEVELOPMENT HYDROGRAPHS
Utilize small watershed method & center -weighted storm (Malcom)
Return Period 1 year
1= 0.127 in/hr 1 year, 24 hr Intensity
Cpre 0.16 (Composite Rational C, See Drainage Area/Computations Map)
Cpost 0.40 (Single -Family Residential, See Drainage Area/Computations Map)
A= 14.61 acre
A= 636,412 sf Rainfall 3.06 in (1 year, 24 hour storm)
Qpre=
0.30 cfs
PRE CN
Qpost=
0.74 cfs
POST CN
Vol - Pre
2,652 cf
simple method per NCDEQ
Vol - Post
14,775 cf
simple method per NCDEQ
Tpre
107 min
Tpost
239 min
Time Step
5 min
55II S= 8.1811 Q*= 0.21 in
79 S= 2.66 Q*= 1.23 in
0.2*S: 1.6363636
(If rainfall is less than 20% S, Q*=0)
10-YEAR INFLOW
1 of 1
HYDROGRAPH ROUTING THROUGH WET POND
1-YEAR, 24 HOUR STORM
FORMULAS FROM EC MANUAL 8.07.5
Type Structure: Riser with Circular Drawdown Outlet and Barrel
Orifice Equation: Q= CDA(2gh)0.5
Pipe Flow Formula: Q= a[ 2gh / 1+Km+KpL ]0.5
Weir Flow Formula: Q=CLH15
Cr(Orifice):
Height Change, Weir to
Orifice Flow
C.
Primary Riser Diam.
Circum. of Riser
Area of Riser
Riser Drawdown Outlet
Orifice Diam.
Number of Orifices
Riser Drawdown Outlet
Vol. Lost to InfiI
0.58
2.00
3.00
30.0
7.85
4.91
in. (24"X29.5" yard inlet equivalent)
ft
0.02 ftz
cf/h r
Km
1.0
Standard
Kp
0.0309
(Table 8.07a)
Length of Barrel
292
ft
Barrel Diam.
15
in
Barrel Area: a
1.23
ft2
NOTE: Heights measured from normal pool elevation
Normal Pool Height =
0.00
ft
(161. 00 normal pool MSL Ele v.)
Height of Riser Weir =
1.00
ft
Stage Storage Function: S = 23,970 * Z 1.10
(162.00 riser weir MSL Elev.)
10-YEAR HYDROGRAPH ROUTING
1 of 1
a
Q
C�
O
w
0
2
z
O
z
w
w
0
O
2
i1
V
N
Q
W
T-
1
1
1
/
1
1
1
1
1
1
1
1
I
I
1
00,
♦
O
O
(11) o6els `(Slo) Mold
O
O
O
O
LO
O
O
O
O
IT
O
O
O
O
M
O
O
O
O
N
O
O
O
O
0
0
0
0
0
I•
o y
o
o
o
CO
o
o
o E
o
0
0
0
0
0
0
0
0
0
LO
0
0
0
0
0
0
0
0
co
O
O
O
O
N
O
O
O
O
0
15
0
0
rn
0 U)
I
I
c�
0 �-y
o V
a >
aD
o
� a
I I
10 YEAR, 6 HOUR ROUTING
FORMULATING PRE -POST DEVELOPMENT HYDROGRAPHS
Utilize small watershed method & center -weighted storm (Malcom)
Return Period 10 year
1= 5.150 in/hr 10 year, Tc Intensity
Cpre 0.16 (Composite Rational C, See Drainage Area/Computations Map)
Cpost 0.40 (Single -Family Residential, See Drainage Area/Computations Map)
A= 14.61 acre
A= 636,412 sf Rainfall 3.9 in (10 year, 6 hour storm)
Qpre= 12.04 cfs PRE CN 72II S= 3.89II Q*= 1.39 in
Qpost= 30.10 cfs POST CN 79 S= 2.66 Q*= 1.88 in
Vol - Pre 73,739 cf 0.2`S: 0.7777778
Vol - Post 99,844 cf (If rainfall is less than 20% S, Q`=0)
Tpre 73 min
Tpost 40 min
Time Step 1 min
10-YEAR INFLOW
1 of 1
HYDROGRAPH ROUTING THROUGH WET POND
10-YEAR STORM
FORMULAS FROM EC MANUAL 8.07.5
Type Structure: Riser with Circular Drawdown Outlet and Barrel
Orifice Equation: Q= CDA(2gh)0.5
Pipe Flow Formula: Q= a[ 2gh / 1+Km+KpL ]0.5
Weir Flow Formula: Q=CLH15
Cr(Orifice):
Height Change, Weir to
Orifice Flow
C.
Primary Riser Diam.
Circum. of Riser
Area of Riser
Riser Drawdown Outlet
Orifice Diam.
Number of Orifices
Riser Drawdown Outlet
Vol. Lost to InfiI
0.58
2.00
3.00
30.0
7.85
4.91
in. (24"X29.5" yard inlet equivalent)
ft
0.02 ftz
cf/h r
Km
1.0
Standard
Kp
0.0309
(Table 8.07a)
Length of Barrel
292
ft
Barrel Diam.
15
in
Barrel Area: a
1.23
ft2
NOTE: Heights measured from normal pool elevation
Normal Pool Height =
0.00
ft
(161. 00 normal pool MSL Ele v.)
Height of Riser Weir =
1.00
ft
Stage Storage Function: S = 23,970 * Z 1.10
(162.00 riser weir MSL Elev.)
10-YEAR HYDROGRAPH ROUTING
1 of 1
a
a
0
Z
O
Z
LW
r
W
a
W
0
T
O O O O O
O O O O O
M N
(11) 86els (SID) M01 j
O
O
0
O
N
O
O
O
O
O
O
LO
I•
E
H
25-YEAR, 6 HOUR ROUTING
FORMULATING PRE -POST DEVELOPMENT HYDROGRAPHS
Utilize small watershed method & center -weighted storm (Malcom)
Return Period 25 year
1= 5.730 in/hr 25 year, Tc Intensity
Cpre 0.16 (Composite Rational C, See Drainage Area/Computations Map)
Cpost 0.40 (Single -Family Residential, See Drainage Area/Computations Map)
A= 14.61 acre
A= 636,412 sf Rainfall -in (25 year, 6 hour storm)
Qpre= 13.39 cfs PRE CN 72II S= 3.89II Q*= 1.94 in
Qpost= 33.49 cfs POST CN 79 S= 2.66 Q*= 2.51 in
Vol - Pre 102,857 cf 0.2`S: 0.7777778
Vol - Post 133,186 cf (If rainfall is less than 20% S, Q`=0)
Tpre 92 min
Tpost 48 min
Time Step 1 min
1 of 1
HYDROGRAPH ROUTING THROUGH WET POND
25-YEAR STORM
FORMULAS FROM EC MANUAL 8.07.5
Type Structure: Riser with Circular Drawdown Outlet and Barrel
Orifice Equation: Q= CoA(2gh)0.5
Pipe Flow Formula: Q= a[ 2gh / 1+Km+KpL ]0.5
Weir Flow Formula: Q=CLH15
Cr(Orifice):
Height Change, Weir to
Orifice Flow
C.
Primary Riser Diam.
Circum. of Riser
Area of Riser
Riser Drawdown Outlet
Orifice Diam.
Number of Orifices
Riser Drawdown Outlet
Vol. Lost to InfiI
0.58
2.00
3.00
30.0
7.85
4.91
in. (24"X29.5" yard inlet equivalent)
ft
0.02 ftz
cf/h r
Km
1.0
Standard
Kp
0.0309
(Table 8.07a)
Length of Barrel
292
ft
Barrel Diam.
15
in
Barrel Area: a
1.23
ft2
NOTE: Heights measured from normal pool elevation
Normal Pool Height =
0.00
ft
(161. 00 normal pool MSL Ele v.)
Height of Riser Weir =
1.00
ft
Stage Storage Function: S = 23,970 * Z 1.10
(162.00 riser weir MSL Elev.)
1 of 1
2
a
a
0
Z
O
Z
LW
r
W
a
W
N
O O o O o
O O o O O
(11) 86els (SID) M01 j
O
O
0
O
N
O
O
O
O
O
0
LO
I•
E
H
50-YEAR, 6 HOUR ROUTING
FORMULATING PRE -POST DEVELOPMENT HYDROGRAPHS
Utilize small watershed method & center -weighted storm (Malcom)
Return Period 50 year
1= 6.130 in/hr 50 year, Tc Intensity
Cpre 0.16 (Composite Rational C, See Drainage Area/Computations Map)
Cpost 0.40 (Single -Family Residential, See Drainage Area/Computations Map)
A= 14.61 acre
A= 636,412 sf Rainfall 5.3 in (50 year, 6 hour storm)
Qpre= 14.33 cfs PRE CN 72II S= 3.89II Q*= 2.43 in
Qpost= 35.82 cfs POST CN 79 S= 2.66 Q*= 3.06 in
Vol - Pre 128,946 cf 0.2`S: 0.7777778
Vol - Post 162,370 cf (If rainfall is less than 20% S, Q`=0)
Tpre 108 min
Tpost 54 min
Time Step 1 min
1 of 1
HYDROGRAPH ROUTING THROUGH WET POND
50-YEAR STORM
FORMULAS FROM EC MANUAL 8.07.5
Type Structure: Riser with Circular Drawdown Outlet and Barrel
Orifice Equation: Q= CoA(2gh)0.5
Pipe Flow Formula: Q= a[ 2gh / 1+Km+KpL ]0.5
Weir Flow Formula: Q=CLH15
Cr(Orifice):
Height Change, Weir to
Orifice Flow
C.
Primary Riser Diam.
Circum. of Riser
Area of Riser
Riser Drawdown Outlet
Orifice Diam.
Number of Orifices
Riser Drawdown Outlet
Vol. Lost to InfiI
0.58
2.00
3.00
30.0
7.85
4.91
in. (24"X29.5" yard inlet equivalent)
ft
0.02 ftz
cf/h r
Km
1.0
Standard
Kp
0.0309
(Table 8.07a)
Length of Barrel
292
ft
Barrel Diam.
15
in
Barrel Area: a
1.23
ft2
NOTE: Heights measured from normal pool elevation
Normal Pool Height =
0.00
ft
(161. 00 normal pool MSL Ele v.)
Height of Riser Weir =
1.00
ft
Stage Storage Function: S = 23,970 * Z 1.10
(162.00 riser weir MSL Elev.)
1 of 1
2
a
a
0
Z
O
Z
LW
r
W
a
W
0
0
0 0 0 0 0
(11) 86els (SID) M01 j
O
O
0
O
N
O
O
O
O
O
0
LO
I
E
H
100 YEAR, 6 HOUR ROUTING
FORMULATING PRE -POST DEVELOPMENT HYDROGRAPHS
Utilize small watershed method & center -weighted storm (Malcom)
Return Period 100 year
1= 6.510 in/hr 100 year, Tc Intensity
Cpre 0.16 (Composite Rational C, See Drainage Area/Computations Map)
Cpost 0.40 (Single -Family Residential, See Drainage Area/Computations Map)
A= 14.61 acre
A= 636,412 sf Rainfall -in (100 year, 6 hour storm)
Qpre= 15.22 cfs PRE CN 72II S= 3.89II W= 2.96 in
Qpost= 38.04 cfs POST CN 79 S= 2.66 W= 3.64 in
Vol - Pre 157,010 cf 0.2`S: 0.7777778
Vol - Post 193,254 cf (If rainfall is less than 20% S, Q`=0)
Tpre 124 min
Tpost 61 min
Time Step 1 min
1 of 1
HYDROGRAPH ROUTING THROUGH WET POND
100-YEAR STORM
FORMULAS FROM EC MANUAL 8.07.5
Type Structure: Riser with Circular Drawdown Outlet and Barrel
Orifice Equation: Q= CoA(2gh)0.5
Pipe Flow Formula: Q= a[ 2gh / 1+Km+KpL ]0.5
Weir Flow Formula: Q=CLH15
Cr(Orifice):
Height Change, Weir to
Orifice Flow
C.
Primary Riser Diam.
Circum. of Riser
Area of Riser
Riser Drawdown Outlet
Orifice Diam.
Number of Orifices
Riser Drawdown Outlet
Vol. Lost to InfiI
0.58
2.00
3.00
30.0
7.85
4.91
in. (24"X29.5" yard inlet equivalent)
ft
0.02 ftz
cf/h r
Km
1.0
Standard
Kp
0.0309
(Table 8.07a)
Length of Barrel
292
ft
Barrel Diam.
15
in
Barrel Area: a
1.23
ft2
NOTE: Heights measured from normal pool elevation
Normal Pool Height =
0.00
ft
(161. 00 normal pool MSL Ele v.)
Height of Riser Weir =
1.00
ft
Stage Storage Function: S = 23,970 * Z 1.10
(162.00 riser weir MSL Elev.)
1 of 1
a
a
0
O
0
z
O
H
z
W
H
W
a
W
0
0
T
O O O O O
O O O O O
(11) 86els (SID) M01 j
O
O
0
O
N
O
O
O
o �
o �
o E
a�
O
O
O
LO
I•
E
H
DRAWDOWN CALCULATIONS
z_
C)
a
W
'i N
LO LO 'i
'i 'i
v
3
C
m
E
a
0
c
0
01
LZ
v
Q)
E
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v
m
2
(0
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CL
a)
r
E
E
c
2
c-I
L
to
QN
x
u
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m
ti
N m a
O N Ln O
O 00m
v �n O N Oat ci O
n
O
^'^
.. 01 01 01
h E E E ..
NO
O C t C t c m
0 <
N = O. N (0 v
0
Ln
00
00 io
pp )n O
v oo m rn
O
m
to 0 c-I N m 0
N
0
0) 0) 0)
r^ H E E E . .
m V
v O O C L c t c m
0 <
N = coo co `-' co
a
'n
o� Cl)
m
v r^, rn v Co rn
'n rn N
m
o w'
v v ^
0 0 w 0
ti
O
^
N N E E E ..
N
m V
v O O C L c t c m
<
N = coo m `-' co v
0 0
Lo
v
00 W
n
00
v � Ln-1 No0
^. O
N
0 r,
v m ry
W 0 0 rn o
0
0
^�
E E E ..
m
m
0 <
v
N -
0 0
Ln
00
m
00 n
Pry 'n o
m
V Ln V 0 m N
v m •� 0 �^ N
O V
l0 0 O ^ N �--�
0
c ^ry
0\
.. 01 01 01
v F in F in F j,
mmV= O O O t c t c
0 <
N
c
to
00
)n
O
V to Ln W 0
m 0 ul N 00
N W
O N
V
to C O 00 W N
O
V
0
c ^ry
0) 0) 0)
y E .. E E ..
m V v
O m
0 Q
Kp VALUE
0
2gh os
3. Pipe Flow: Q = a [ 1 + K. + KV L
where:
Q = discharge in cubic feet per second (cfs)
a = cross -sectional area of the barrel in square feet
g = acceleration due to gravity, 32.2 ft/sec2
h = head above the centerline of the outlet end of the barrel
Km = coefficient of minor losses, can be assumed to be 1.0 for
most principal spillway systems
L = barrel length in feet
KP = pipe friction coefficient:
_ 5087n2 (See Table 8.07c for KP values for
di4'3 common size of pipe.)
n = Manning's coefficient of roughness, use n = 0.025 for
corrugated metal pipe
n = 0.015 for reinforced concrete pipe
di = inside diameter of the barrel in inches
Select riser and barrel dimensions so that the riser has a cross -sectional area
at least 1.5 times that of the barrel. Spillway hydraulics are improved by
maximizing weir flow and minimizing orifice flow. See Table 8.07b for
recommended riser/barrel proportions.
Table 8.07a KP Values for Common Sizes of Pipe
Pipe Diameter
(inches)
Flow Area
(square feet)
Manning's Coefficient
0.015
0.025
6
0.196
0.1050
0.2916
8
0.349
0.0715
0.1987
10
0.545
0.0531
0.1476
12
.0785
0.0417
0.1157
14
1.069
0.0339
0.0942
15
1.23
0.0309
0.0859
16
1.40
0.0284
0.0789
18
1.77
0.0243
0.0674
21
2.41
0.0198
0.0549
24
3.14
0.0165
0.0459
27
3.98
0.0141
0.0393
30
4.91
0.0123
0.0341
36
7.07
0.0096
0.0267
42
9.62
0.0078
0.0218
48
12.57
0.0066
0.0182
54
15.90
0.0056
0.0156
60
19.64
0.0049
0.0135
8.07.6 Rev. 5/13
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.