SW3220305_Design Calculations (Pipes)_20220615

Brown AND Caldwell
SUBJECT: Stormwater Network Sizing
SYSTEM:
CLIENT: Water and Sewer Authority of Cabarrus County
PROJECT NAME: Rocky River Regional Wastewater Treatment Plant Expansion
PROJECT NUMBER: 156673
ons to size the stormwater
DISCIPLINE: Civil
CREATED BY: Daniel Wright
CHECKED BY: Kim Devendorf
DATE: 5/5/22
CURRENT
REVISION: 0
TANDARD APPLICATION SOFTWARE USED
QC Checker Section Sign -Off: -
Software Nam
L PREFERENCES
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Item No. D.Version/Date
CALCULATION BASIS AND ASSUMPTIONS
QC Checker Section Sign -Off: -
C Factors
Impervious Area 0.95
Pervious Area -Grass 0.3
Pervious Area -Soil 0.6
Basin Areas and C Factors
Impervious
Composite
Basin #
Area x
C Impery
+ Pervious area
x C' Pery
_ Total Area =
'C'
ENDWALL 1
0.08
0.95
3.81
0.3
3.89
0.31
STD 1 - DI
0.036
0.95
0.37
0.3
0.41
0.36
STD 4 - DI
0.13
0.95
0.46
0.3
0.59
0.44
TRENCH DRAIN
0.21
0.95
0.78
0.3
0.99
0.44
EXIST DI
0.11
0.95
0.35
0.3
0.46
0.46
TOC (min) 5.00 Assumed
Intensity (10-yr) (in/hr) 7.32
Basin Flow (Q=CIA)
asin c s
ENDWALL 1
8.92
STD 1 - DI
1.07
STD 4 - DI
1.92
TRENCH DRAIN
3.18
EXIST DI
1.55
0.46 D 8/3S1/2 lannings equation for pipe flow flowing full
Q=�
n
p = Qn1 3/8 Mannings Equation solved for diameter
0.46s1/2
See attached ficiure for drains a basin and i e labels. Pipes with a second basin indicate it
ipe asm asm
PIPE - 1
ENDWALL - 1
N/A
PIPE - 2
STD 1 - DI
N/A
PIPE - 3
ENDWALL - 1
STD 1 -DI
PIPE - 4*
STD 4 - DI
TRENCH D
PIPE - 5
STD 4 -DI
N/A
PIPE - 6
TRENCH D
N/A
PIPE - 7*
EXIST DI
N/A
n 0.011
Concrete Mai
*Existing pipe
flow from two drainage basins
1.07
0.50
0.68
8.20
15
9.99
0.50
1.58
18.95
24
5.10
0.50
1.23
14.72
24
Exist 24" Pipe
1.92
6" width
See conclusion note
3.18
1.74
0.81
9.76
12
1.55
1.74
0.62
7.45
12
Exist 12" Pipe
n
:02 PM
Provided diameters are all larger than the required diameter that was calculated. The trench drain dimension is sized at a 6" width due to suppliers
recommending 6" wide drains for flows up to 4 cfs and the actual flow is 3.18 cfs.
5/10/2022 Page 1 of 1
9:01 AM 8x11 Portrait Calculation STRM-Pipe-Sizing

Brown mb Caldwell
SUBJECT: Stormwater Network Sizing
SYSTEM: 0
CLIENT: Water and Sewer Authority of Cabarrus County
PROJECT
NAME: Rocky River Regional Wastewater Treatment Plant Expansion
PROJECT
NUMBER: 156673
Drainage Area Map
DISCIPLINE: Civil
CREATED BY: Daniel Wright
CHECKED BY: Dave Varjabedian
DATE: 01 /10/22
REVISION: 0
5/5/2022 Page 7 of 7
3:53 PM 8x11 Portrait Data -Ref STRM-Pipe-Sizing