SW3221001_Design Calculations_20230216 (2)

STORM CALCULATIONS
FOR
BRIGHTON PARK
MOUNT PLEASANT, CABARRUS COUNTY, NC
PREPARED BY:
LATHAM-WALTERS ENGINEERING, INC.
16507-A NORTHCROSS DRIVE
HUNTERSVILLE, N.C. 28078
Phone: [phone] Fax: [phone]
N.C. Corporate License C-1815
FOR
NIBLOCK HOMES, LLC
759 CONCORD PARKWAY NORTH SUITE 20
CONCORD, NC 28027
DATE: August 4, 2022
REVISED: 2/9/2023

Carlos L. Ruano P.E.
Latham -Walters Engineer, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
Brighton Park Stormwater System Design Summary
Stormwater system was designed in accordance with the latest version of the NCDOT's
Guidelines for Drainage Studies & Hydraulic Design, NCDOT Subdivision Manual, & Concord's Technical
Standards Manual.
Roadway inlet locations, capacities, gutter spread, and storm drain pipe system was analyzed
and designed using a ten-year discharge (Q10) with a minimum time of concentration of 5 minutes. An
intensity of 4 inches/hour was used for calculating spread and determination of appropriate locations
for inlet placement. Allowable gutter spread is limited to gutter width plus %travel lane (total of 7 feet
with valley gutter) per the latest version of the NCDOT Subdivision Manual. Per Concord UDC, may flow
may spread to crown of street for Local & Alley.
Concord's Rainfall Intensity Table 2-2 was utilized for hydraulic analysis. Coefficient of 0.50 was
determined by the average BUA per lot. Intensity storm of 7.26 in/hr was used for 10-year return period.
Storm pipes were design by Rational method.
Sediment basins & erosion control measures were based off NCDEQ's Erosion & Sediment
Control Planning & Design Manual.

10
8
0
6
t
4
N
L
U
2
W
4 1
0.8
0.6
0.4
0.2
SECTION 2
STORMWATER RUNOFF
R�ru�
!'�\ pU ar�od
yed rS
?
�s
0.2 0.4 0.6 0.8 1 2 4 6 8 10 20
Duration -Hours
Figure 2-2 Intensity -Duration -Frequency Curves for Concord, NC
TABLE 2-3
ORDINATES OF THE IDF CURVES FOR CONCORD, NC
Duration
Return Period (years)
Hours
Minute
s
1
2
5
10
25
50
100
0
5
4.80
5.66
6.60
7.26
8.00
8.52
8.98
10
3.83
4.54
5.29
5.81
6.38
6.78
7.13
15
3.19
1 3.80
4.46
4.90
5.39
5.72
6.01
30
2.19
2.62
3.17
3.55
3.99
4.31
4.60
1
1.36
1.65
2.03
2.31
2.66
2.92
3.17
2
0.79
0.96
1.19
1.36
1.58
1.75
1.92
3
0.56
0.68
0.85
0.98
1.15
1.29
1.42
6
0.34
0.41
0.51
0.59
0.70
0.79
0.87
12
0.20
0.24
0.31
0.35
0.42
0.48
0.53
24
0.12
0.14
0.18
0.21
0.25
0.28
0.31
Adopted January 10, 2008 2-5 Technical Standards Manual

EXISTING STORM NETWORK ON HWY-73

Hydraflow Storm Sewers Extension for Autodesk® AutoCAD® Civil 3D® Plan
EX.DI-1
EX. DI-2
Project File: 2020.17 - EX.STORM Hwy73.stm
Outfall
Number of lines: 2 1 Date: 8/4/2022
Storm Sewers v2018.30

TR55 Tc Worksheet
Hydraflow Storm Sewers Extension for AUtodeskS AutoCADO Civil 3DO by Autodesk, Inc. v2018.30
Line No. 4
4
Description
A
B
C
Totals
Sheet Flow
Manning's n-value
= 0.240
0.011
0.011
Flow length (ft)
= 100.0
0.0
0.0
Two-year 24-hr precip. (in)
= 3.12
0.00
0.00
Land slope (%)
= 5.86
0.00
0.00
Travel Time (min)
= 9.40 +
0.00 +
0.00 =
9.40
Shallow Concentrated Flow
Flow length (ft)
= 629.00
0.00
0.00
Watercourse slope (%)
= 4.82
0.00
0.00
Surface description
= UnPaved
Paved
Paved
Average velocity (ft/s)
=3.54
0.00
0.00
Travel Time (min)
= 2.96 +
0.00 +
0.00 =
2.96
Channel Flow
X sectional flow area (sqft)
= 0.00
0.00
0.00
Wetted perimeter (ft)
= 0.00
0.00
0.00
Channel slope (%)
= 0.00
0.00
0.00
Manning's n-value
= 0.015
0.015
0.015
Velocity (ft/s)
=0.00
0.00
0.00
Flow length (ft)
= 0.0
0.0
0.0
Travel Time (min)
= 0.00 +
0.00 +
0.00 =
0.00
Total Travel Time, Tc..............................................................................
12.36 min

Dschedule
Page 1
Line
Inlet
Gnd/Rim
Drng
Total
Runoff
i
i
Flow
Invert
Invert
Capac
Line
Line
Line
Vol
Line
Cover
No.
ID
El Up
Area
Area
Coeff
Inlet
Sys
Rate
Up
Dn
Full
Size
Length
Slope
Dn
ID
Up
(ft)
(ac)
(ac)
(C)
(in/hr)
(in/hr)
(cfs)
(ft)
(ft)
(cfs)
(in)
(ft)
M)
(ft/s)
(ft)
1
EX. DI-2
622.95
0.33
8.05
0.50
7.24
5.61
22.56
614.15
605.72
46.25
24
236.654
3.56
14.62
3
6.80
2
EX.DI-1
625.15
7.72
7.72
0.50
5.61
5.61
21.67
621.97
616.05
86.05
24
48.000
12.33
22.79
4
1.18
Project File: 2020.17 - EX.STORM Hwy73.stm
Number of lines: 2
Date: 8/4/2022
NOTES: Intensity = 88.24 / (Inlet time + 15.50) ^ 0.83 -- Return period = 10 Yrs. ; ** Critical depth
Storm Sewers

PROPOPSED STORM NETWORK ON HWY-73
}
CDk
I
i
pB�
t I{ T V p
ar-
I l
}
I AWHALTWDENW9
hew a-
,..1>. -a+---
06EPLAY UP TO
a
� l
j. � F �o'
!.; i i
:I
Poe.
ME
� p4F
r
Pae '�•-
RELOCATE LNY€SJPPLES (►1
39d
S
y 4 y k -
f
1 I
___ I
C-
�,
b
In 4
y 9 • i
h y�
6
i OLEANDER STRLL'T-
I '
WP4)PtK'R1w

Hydraflow Storm Sewers Extension for Autodesk® AutoCAD® Civil 3D® Plan
SDMH-2
CB-3
DGI-4
DGI-8
Project File: 2020.17 - Prop.STORM Hwy73.stm
Riser-2
Number of lines: 8 1 Date: 2/9/2023
Storm Sewers v2018.30

Dschedule
Page 1
Line
Inlet
Gnd/Rim
Drng
Total
Runoff
i
i
Flow
Invert
Invert
Capac
Line
Line
Line
Vel
Line
Depth
Depth
Cover
No.
ID
El Up
Area
Area
Coeff
Inlet
Sys
Rate
Up
Dn
Full
Size
Length
Slope
Dn
ID
Dn
Up
Up
(ft)
(ac)
(ac)
(C)
(in/hr)
(in/hr)
(cfs)
(ft)
(ft)
(cfs)
(in)
(ft)
M)
(ft/s)
(ft)
(ft)
(ft)
1
EX.DI-2
622.95
0.38
1.57
0.50
7.26
6.48
8.20
614.15
605.72
46.25
24
236.654
3.56
11.10
3
0.57
1.02**
6.80
2
DI-5
627.92
0.57
1.18
0.50
7.26
6.72
4.37
620.99
616.41
21.16
18
132.430
3.46
9.43
4
0.46
0.80**
5.43
3
DGI-8
635.53
0.61
0.61
0.60
7.26
7.26
2.66
632.00
621.24
15.13
15
229.890
4.68
5.10
0.55
0.65**
2.28
4
Riser-2
638.00
0.01
0.01
0.01
7.26
7.26
2.75
630.39
617.77
35.98
18
126.170
10.00
12.01
0.28
0.63**
6.11
5
SDMH-2
631.55
0.01
1.39
0.01
7.26
7.01
4.84
627.10
627.00
8.48
18
18.000
0.56
4.95
0.81
0.85**
2.95
6
CB-2
632.87
0.21
1.38
0.50
7.26
7.06
4.87
627.44
627.30
8.51
18
25.000
0.56
4.98
0.81
0.85**
3.93
7
CB-3
632.87
0.11
1.17
0.50
7.26
7.14
4.18
627.84
627.64
8.48
18
36.000
0.56
4.78
0.74
0.78**
3.53
8
DGI-4
0.00
1.06
1.06
0.50
7.26
7.26
3.85
628.53
628.09
5.67
15
67.000
0.66
4.96
0.76
0.79**
n/a
--[Project File: 2020.17 - Prop.STORM Hwy73.stm
Number of lines: 8
Date: 2/10/2023
NOTES: Intensity = 71.97 / (Inlet time + 12.40) ^ 0.80 -- Return period = 10 Yrs. ; ** Critical depth
Storm Sewers

SAND FILTER-2

Mt. Pleasant, NC
Sand Filter Calculation
1. Calculate Runoff Coeff, (Rv)
Drainage area to filter, Ad =
Impervious area to filter forebay=
Impervious percentage =
Rv = 0.05 + 0.9(la) _
2. Calculate req'd water quality volume (WQV)
Brighton Park
2
10.33 ac
4.43 ac.
42.86%
0.43569888
Storage:
Cum
Elev.
Area
Vol.
Vol
632.5
15777
0
0
634
18796
25929.75
25929.75
636
22040
40836
66765.75
638
25511
47551
114316.75
Calculate Depth for WQ Volume:
632.5
0
633.45
16338
634
25929.75
Elevation of WQ Volume =
3. Discount WQv:
0.75 x WQv
4. Site Hydrologic Input Parameters:
633.45
12253.34 cuft
WQV = (Rv/1 x Ad/1 x 43560 sf/1 ac x Rd/1 x ft/12 in)
WQV = 16338 cf (used to size Af)
WQV= 0.3751 ac-ft.
Cn Pre = 68.0
Cn Post = 81.0 to pond
Tnhla 4 R Raciiltc of Hvrlrnlnnir. ('alriilatinnc frnm Hvrlm('Prl
Condition
Q 1- ear
Q 10- r.
Q 25- r
Q 50 yr
Runoff
Pre Dev.
6.28
25.11
34.11
42.44
Post. Dev.
23.81
57.82
72.24
85.12
Routed
0.46
2.75
10.34
25.88
Peak Stage
634.32
636.11
636.41
636.81
Disch. Time
1140 hours
1
1
11.2'
IFreeboardl

5. Minimum Surface Area for Sand Media
2042 SA (ft2)
2 FS
12253 DV (FT3)
2 K (in/hr)
72 T (hours)
6. Sediment Sand Sizing
12253 Design Volume (ft3)
6127 Sediment Chamber (ft3)
6127 Sand Chamber (ft3)
7. Sand Filter Drawdown Calculation
Equation 2u Minimum Surface area f r a,r Mrntrafm. Syatem
*12
SA = FS * DV K'T
where: SA = required minimum surface area of infiltration system (W)
FS = factor of safety (minlm
um of 2 is r—mmended)
DV = design volume (ft3)
K = hydraulic conductivdy of soil (in/hr)
T = maximum dewatering Ume (72 hours)
Coeff. Of Permeability of filter media =2 in/hr 0.166667 ft/hr
Volume of water drained in one hour = 0.167 ft/hr x SA ft2 = 340.3707 cf/hour 0.095 cfs
Drawdown Time = WQV/Drawdown Rate = 48.00 hrs 2 days
8. Underdrain Calculations:
78 I.f of underdrain shown; provide 6" perforated pvc pipe with 3/8" perforations spaces 3" o.c. - 4 longitudinal rows
spaced 90 degrees apart.
150 I.f. of pipe I.f. x 4 rows/ft x 4 holes/ft = 2400 holes
50% of perforations = 1200 holes
Capacity of one hole = 0.0083 cfs based upon CA(2gh)A0.5
Total Capacity = 9.96 cfs which is 105.3 times the capacity of the sand filter.
Total Capacityof 6" PVC @ 0.50% is 0.40 cfs (0.20 cfs assuming 50% clogged) from Mannings and BMP Manual.
9. Antiflotation Calculation
7.5 Height of Riser, ft.
6 Area of Riser, s.f.
45 Volume of Riser, c.f.
2808 Weight of Water @ 62.4 pcf
3088.8 Weight of water with safety factor of 1.1
82.6 Buoyant Wt. of Concrete = (145-62.4) pcf
1.38 Volume of Concrete Req'd in c.y.
37.39 Volume of Concrete Req'd in c.f.
45 Volume of Concrete in Structure (cf)
-7.61 Volume of Concrete Required (cf)
0.5 ft thick
2.8 Length/Width
(If negative, additional concrete weight not required)

Brighton Park
Mt. Pleasant, NC
10. Infiltration Rate
Q = Af(k)(h+df)/(df)
Latham -Walters Engineering, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
where Af = surface area of filter bed = 2042 sf
df = filter bed depth, ft. = 1.5 ft.
k = coefficient of permeability of filter media (ft/day) = ft/day
h = average height of water above filter bed (ft) 12, etc.
h
Q
cf/day
Q
cfs
1
13614.83
0.158
2
19060.76
0.221
3
24506.69
0.284
4
29952.62
0.347
5
35398.55
0.410
6
40844.48
0.473
7
46290.41
0.536
8
51736.34
0.599
9
57182.28
0.662
10
62628.21
0.725

Inlet Report
Hydraflow Express Extension for AUtodeskS AutoCADS Civil 3DO by Autodesk, Inc. Thursday, Jan 12 2023
PROP. DI-5 DA:.61 ac 1:7.26 C:.6
Drop Curb Inlet
Calculations
Location
= Sag
Compute by:
Known Q
Curb Length (ft)
= 12.00
Q (cfs)
= 2.66
Throat Height (in)
= 5.00
Grate Area (sqft)
_ -0-
Highlighted
Grate Width (ft)
_ -0-
Q Total (cfs)
= 2.66
Grate Length (ft)
_ -0-
Q Capt (cfs)
= 2.66
Q Bypass (cfs)
_ -0-
Gutter
Depth at Inlet (in)
= 2.11
Slope, Sw (ft/ft)
= 0.300
Efficiency (%)
= 100
Slope, Sx (ft/ft)
= 0.300
Gutter Spread (ft)
= 0.59
Local Depr (in)
_ -0-
Gutter Vel (ft/s)
_ -0-
Gutter Width (ft)
_ -0-
Bypass Spread (ft)
_ -0-
Gutter Slope (%)
_ -0-
Bypass Depth (in)
_ -0-
Gutter n-value
= -0-

Inlet Report
Hydraflow Express Extension for AUtodeskS AutoCADO Civil 31DO by Autodesk, Inc. Thursday, Jan 12 2023
EX. DI-2 DA:.38 ac 1:7.26 C:.6
Drop Curb Inlet
Calculations
Location
= Sag
Compute by:
Known Q
Curb Length (ft)
= 12.00
Q (cfs)
= 1.68
Throat Height (in)
= 5.00
Grate Area (sqft)
= -0-
Highlighted
Grate Width (ft)
= -0-
Q Total (cfs)
= 1.68
Grate Length (ft)
= -0-
Q Capt (cfs)
= 1.68
Q Bypass (cfs)
= -0-
Gutter
Depth at Inlet (in)
= 1.55
Slope, Sw (ft/ft)
= 0.300
Efficiency (%)
= 100
Slope, Sx (ft/ft)
= 0.300
Gutter Spread (ft)
= 0.43
Local Depr (in)
= -0-
Gutter Vel (ft/s)
= -0-
Gutter Width (ft)
= -0-
Bypass Spread (ft)
= -0-
Gutter Slope (%)
= -0-
Bypass Depth (in)
= -0-
Gutter n-value
= -0-

Channel Report
Hydraflow Express Extension for AUtodeskS AutoCADO Civil 31DO by Autodesk, Inc.
VCD-1 DA: 2.68 ac
C:0.6 I: 7.261N/HR
Trapezoidal
Bottom Width (ft)
= 2.00
Side Slopes (z:1)
= 3.00, 2.00
Total Depth (ft)
= 2.00
Invert Elev (ft)
= 600.00
Slope (%)
= 2.00
N-Value
= 0.150
Calculations
Compute by:
Known Q
Known Q (cfs)
= 11.67
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
Thursday, Jan 12 2023
= 1.55
= 11.67
= 9.11
= 1.28
= 10.37
= 0.75
= 9.75
= 1.58
Elev (ft) Section Depth (ft)
603.00
3.00
602.50
2.50
602.00
2.00
601.50
1.50
601.00
1.00
600.50
600.00
tiaa tin
0.50
0.00
-0 50
Ot
2 4 6
8
Reach (ft)
10 12 14
16

Channel Report
Hydraflow Express Extension for AUtodeskS AutoCADO Civil 31DO by Autodesk, Inc.
VCD-2 DA: 1.06 ac
C:0.6 I: 7.261N/HR
Trapezoidal
Bottom Width (ft)
= 2.00
Side Slopes (z:1)
= 3.00, 2.00
Total Depth (ft)
= 2.00
Invert Elev (ft)
= 600.00
Slope (%)
= 2.00
N-Value
= 0.150
Calculations
Compute by:
Known Q
Known Q (cfs)
= 4.62
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
Thursday, Jan 12 2023
= 1.01
= 4.620
= 4.57
= 1.01
= 7.45
= 0.46
= 7.05
= 1.03
Elev (ft) Section Depth (ft)
603.00
3.00
602.50
2.50
602.00
2.00
601.50
601.00
1.50
1.00
Ot
600.50
600.00
tiaa tin
0.50
0.00
-0 50
Ot
2 4 6
8
Reach (ft)
10 12 14
16

Channel Report
Hydraflow Express Extension for AUtodeskS AutoCADO Civil 31DO by Autodesk, Inc.
VCD-3 DA: 0.61
ac C:0.6 I: 7.261N/HR
Trapezoidal
Bottom Width (ft)
= 2.00
Side Slopes (z:1)
= 3.00, 2.00
Total Depth (ft)
= 2.00
Invert Elev (ft)
= 600.00
Slope (%)
= 2.00
N-Value
= 0.150
Calculations
Compute by:
Known Q
Known Q (cfs)
= 2.66
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
Thursday, Jan 12 2023
= 0.78
= 2.660
= 3.08
= 0.86
= 6.21
= 0.33
= 5.90
= 0.79
Elev (ft) Section Depth (ft)
603.00
3.00
602.50
2.50
602.00
2.00
601.50
1.50
601.00
1.00
600.50
600.00
tiaa tin
0.50
0.00
-0 50
Ot
2 4 6
8
Reach (ft)
10 12 14
16

Channel Report
Hydraflow Express Extension for AUtodeskS AutoCADO Civil 31DO by Autodesk, Inc.
VCD-4 DA: 0.57 ac
C:0.6 I: 7.261N/HR
Trapezoidal
Bottom Width (ft)
= 2.00
Side Slopes (z:1)
= 3.00, 2.00
Total Depth (ft)
= 2.00
Invert Elev (ft)
= 600.00
Slope (%)
= 2.00
N-Value
= 0.150
Calculations
Compute by:
Known Q
Known Q (cfs)
= 2.48
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
Thursday, Jan 12 2023
= 0.75
= 2.480
= 2.91
= 0.85
= 6.05
= 0.32
= 5.75
= 0.76
Elev (ft) Section Depth (ft)
603.00
3.00
602.50
2.50
602.00
2.00
601.50
1.50
601.00
1.00
MUF
600.50
600.00
tiaa tin
0.50
0.00
-0 50
Ot
2 4 6
8
Reach (ft)
10 12 14
16

Channel Report
Hydraflow Express Extension for AUtodeskS AutoCADO Civil 31DO by Autodesk, Inc.
VCD-5 DA: 0.38 ac
C:0.6 I: 7.261N/HR
Trapezoidal
Bottom Width (ft)
= 2.00
Side Slopes (z:1)
= 3.00, 2.00
Total Depth (ft)
= 2.00
Invert Elev (ft)
= 600.00
Slope (%)
= 2.00
N-Value
= 0.150
Calculations
Compute by:
Known Q
Known Q (cfs)
= 1.66
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
Thursday, Jan 12 2023
= 0.62
= 1.660
= 2.20
= 0.75
= 5.35
= 0.25
= 5.10
= 0.63
Elev (ft) Section Depth (ft)
603.00
3.00
602.50
2.50
602.00
2.00
601.50
1.50
601.00
1.00
—
600.50
600.00
tiaa tin
0.50
0.00
-0 50
Ot
2 4 6
8
Reach (ft)
10 12 14
16