HomeMy WebLinkAboutWPO202200041 Calculations 2022-09-29GRANGER PROPERTY STORMWATER
MANAGEMENT CALCULATIONS PACKET
Date of Calculations
SEPTEMBER 23, 2022
PREPARED BY:
COLLINS eN(2iNEERING
200 GARRETT STREET, SUITE K
CHARLOTTESVILLE, VA 22902
434.293.3719 PH
434.293.2813 FX
www.collins-engineering.com
4
Soils Table
(Source: NRCS Web Soil Survey Online Database)
Albemarle County, Virginia (VA003)
Map
Unit
Map Unit Name
Percent
percent of
Symbol
2C
Albemarle fine
12.3%
sandy loam, 7
to 15 percent
slopes
2D
Albemarle fine
27.S%
sandy loam, 15
to 25 percent
slopes
13E
Catoctin silt
0.1%
loam, 25 to 45
percent slopes,
very stony
21B
Culpeper fine
30.9%
sandy loam, 2
to 7 percent
slopes
21C
Culpeper fine
16.5%
sandy loam, 7
to 15 percent
slopes
39E
Hazel loam, 25
2.0%
to 45 percent
slopes
47E
Philomont
8.7%
sandy loam, 25
to 45 percent
slopes
56B
Meadowvllle
1.9%
loam, 2 to 7
percent slopes
Totals for Area of
100.00/0
Interest
Note: The majority of the soils' properties within this development are composed of hydrologic type
B soils.
Precipitation Data
(Source: NOAA's National Weather Service, Hydrometerorological Design Studies Center, Atlas 14
Point Precipitation Frequency Estimates)
� Morgan`
1
o i p
( S
1 i
\
\
\
\
6
4 J° yp
c° \
eo 0
? c L\ p4p 03� 4 rlTpei
Soap 4\9
4 ®` SpOp
200m Pa
�gtt __ Pad o
POINT PRECIPITATION FREQUENCY (PF) ESTIMATES
WITH 90%CONFIDENCE INTERVALS AND SUPPLEMENTARY INFORMATION
NOAA Atlas 14, Volume 2, Version 3
PDS-based precipitation frequency estimates with 90% confidence Intervals (in inches)1
Average recurrence interval (years)
DuraOon
1 2
��D��D�000
5 10
25 50 100
200 500 1000
240r
.743.I2) (3. 2-413)
(4.23528) (/.99-822)
(8.08-8681) p.01-8..81) (8.00. 0.1)
011
(9.07-11.8) (10A-13.8) (11.1�])
SCS TR-55 Calculations
U.S. Department of Agriculture
Natural Resources Conservation Service
TR 55 Worksheat 2: Runoff Curve Number and Runoff
FL-ENG-21A
O6/oa
Project: Granger Properly Designed By: FGM, PE Date: 9/23/2022
Location: Sunset Avenue Extended Checked By: SRC, PE Date: 9/23/2022
Check One: Present X Developed X
1. Runoff curve Number (CN)
Drain Area
Drainage
Soil name and hydrologic
Cover description
Area
ProductofCalcualued'S'
CN(weighted)=
Description
group (Appendix A)
(Cover type, treatment, and hydrologic condition; percent
CN
(Acres)
Area
total product/
Value
impervious;unconnected/ connected impervious area ratio)
total area
Dal
Impervious Areas
98
am
0.0
(Pre-Dev)
B
lawn in Good Condition
61
0.59
36.0
57
7.46
Woods in Good Condition
55
0.96
52.8
DA2
Impervious Areas
98
am
0.0
(Pre-Dev)
B
lawn in Good Condition
61
1.10
67.1
58
7.36
Woods in Good Condition
55
1.45
n.8
DA3
Impervious Areas
98
am
0.0
Pre De .)
B
lawns in Good Condition
61
0.61
37.2
57
7.40
Woods in Good Condition
55
O.BS
48.0
DA4
Impervious Areas
98
am
0.0
(P'Dev)
B
lawns in Good Cond"Rion
61
0.98
59.8
57
].fi0
Woods in Good Condition
55
2.26
124.3
OAS
Impervious Areas
98
am
0.0
Pre De .)
B
lawns in Good Condition
61
0.99
60.4
57
].45
Woods in Good Condition
55
1.59
87.5
Impervious Areas
98
am
0.0
OA6
DA6
B
lawns in Good Condition
61
am
17.1
55
8.D9
(P
Woods in Good Condition
55
5.85
3218
Impervious Areas
98
am
0.0
DAJ
B
lawns in Good Condition
61
1.47
89J
59
6.84
(Pre-Dev)
Woods in Good Condition
55
0.54
29.7
DAS
Impervious Areas
98
5.64
552.4
(Post Dav)
B
lawns in Good Condition
61
13.21
806.0
72
3.88
Woods in Good Condition
55
am
0.0
Impervious Areas
98
am
53.1
DA2
(Post Dav)
B
lawns in Good Condition
61
0.16
9.7
90
1.16
Woods in Good Condition
55
am
0.0
2. Runoff
1-Year Storm
2-Year Storm
30-Year Storm
Drainage Area Description
Fre9uenc,Wars
1
2
10
Na
Rainfall, P(24 hour -inches
3.05
3.0
5.S8
n/a
Runoff, Q-inches
M27
0.50
1.45
DA1(Pre-Dee.)
Runoff, Q-inches
an
0.51
1.47
DA2(Pre-Dee.)
Runoff, Q-inches
0.27
0.51
1.46
DA3 (Pre-Dev.)
Runoff, Q-inches
an
0.48
1.41
DA4(Pre-Dev.)
Runoff, Q-inches
M27
0.50
1.45
DA5(Pre-Dev.)
Runoff, Q-inches
0.n
0A2
1.30
DA 6 (Pre-Dev.)
Runoff, Q-inches
an
0.59
1.61
DA](Pra-Dev.)
Runoff, Q-inches
am
1.25
2.65
DA3(Post-Dev)
Runoff, Q-inches
100
2.59
4.40
DA2(Post -Day)
o
N �
0 0
H_
E
E
w
x
m
F
a
w
`0
0
w
F.
o
v
x x
c
y
u
a
c
w
u
w
v
w n
0
ri y
G
O O
uw u
a c
w q
C
w
O
VI y .q
K
r u`
N O
C N tp N
i°
O
O
o o ri o
o
molj lauue4Dio.ObT
o
m
a
O
O
-/+ 5/34 OT le
vi
C N p t0 O
-1
m p
iO o "'
O
o
mol j lauue4D d°
O
d
.OSb'T
„ a o m v
m N tp O
a
m
O
ill N O
C M p
V' O "q MI O
O
n .q
C m 0 1p
O
.--I m
N O O O N `""�
O
ry e o
a
m
c m o
o n
„ v o m m
m
a
i o n n
ry
C m
O - tvM l OO
O U.
a
i o m o
0
0 o a w m o
N
C m N p t0 O
"� tvl O
O
m 0 .y
C "'� N
O
O
O ti N ti 0 O
N N
O
O
OWO
.-I a O O O
a
N
C N N O t0 ei
ei
p ti �
0
a
w
O eq m
O
C m l°
O
O U• O
O
N p t0
a
N
N ^
C N
emi
O ell
O
rn a
w �
m n w
x c r
o n
m o a a w m x 16
N °V Ov w
m w
> N
y>
F o c o o o o, o `w z a
LLnJ o+ c Ev ti �'" * n F
w L L ti a u L v o g 0 �° m'^ r o v e u
m v m Ko n w w v �° >>$ n u '^ ao rn w Ems,
w c= w° w O m m w a .= m
b "° c 1O 3 c c ,w, a
4 't m LL c E V t LL m w u o w "° m m" LL ii m a
F3 u° cv�i 3¢ 3o u` 3 m u > F3? N
U° n m rn o .i ry m a m �o n m rn o w
O
O
w m m YO
N N U Z
; #
\\ /
<0
w
§.§|
\!
!.§|
.\\
.
f:{
,|
\
!&]\!f)]$
WATERSHED SUMMARY #1 FOR CHANNEL & FLOOD PROTECTION COMPLIANCE
CN
Area,
ac.
Time of
Conc., hrs.
1-year
Flow, cfs
2-year
Flow, cfs
10-year
Flow, cfs
DA 1 (Pre-Dev.)
57
1.55
0.21
0.45
0.85
2.44
DA 2 (Pre-Dev.)
58
2.55
0.31
0.33
1.17
0.02
DA 3 (Pre-Dev.)
57
1.49
0.13
0.34
1.11
3.18
DA4 (Pre-Dev.)
57
3.24
0.17
0.70
1.31
6.70
DA 5 (Pre-Dev.)
57
2.58
0.17
0.59
1.89
5.47
DA 6 (Pre-Dev.)
55
6.13
0.17
0.76
1.50
8.69
57
17.54
3.18
7.83
26.51
CN Area, Time of 1-year 2-year 10-year
ac. Conc., hrs. Flow, cfs Flow, cfs Flow, cfs
DA 1 (Post-Dev.) 1 72 18.85 0.20 0.73 17.16 49.84
WATERSHED SUMMARY #2 FOR CHANNEL & FLOOD PROTECTION COMPLIANCE
Pre -Development
FCN Area, Time of 1-year 2-year 10-year
ac. Conc., hrs. Flow, cfs Flow, cfs Flow, cfs
DA 7 (Pre-Dev.) 59 2.01 0.19 0.39 1.29 3.51
CN Area, Time of 1-year 2-year 10-year
ac. Conc., hrs. Flow, cfs Flow, cfs Flow, cfs
DA 2 (Post-Dev.) 1 90 0.70 0.10 0.05 1.65 3.50
9 VAC 25-870-66 Channel & Flood Protection Analysis
9 VAC 25-870-66
Section B: Channel Protection
(Channel Protection Analysis #1)
"Concentrated stormwater flow shall be released into a stormwater conveyance system and shall meet
the criteria in subdivision 1, 2 or 3 of this subsection..."
Section B.1: Manmade stormwater conveyance systems
"When stormwater from a development is discharged to a manmade stormwater conveyance system,
following the land -disturbing activity, either..." a. or b. shall be met:
Section B.l.b.
"The peak discharge requirements for concentrated stormwater flow to natural stormwater conveyance
systems in subdivision 3 of this subsection shall be met."
Section B.3
"... the maximum peak flow rate from the one-year 24-hour storm following the land -disturbing activity
shall be calculated either.." a. or b."
Section B.3.a.
In accordance with the following methodology:
Q Developed <_ I.F. * (Q Pre -Developed * RV Pre -Developed ) / RV Developed
Q Allowed <
0.75 cfs
Where: Q Pre -Developed =
3.18 cfs
(From Worksheet 4 Watershed Summary)
CN Pre -Developed =
57
(From Worksheet 4 Watershed Summary)
S Pre -Developed =
7.68
(From SCS TR-55 eq. 2-4)
RV Pre -Developed =
0.25 in.
(From SCS TR-55 eq. 2-3)
CN Post -Developed -
72
(From Worksheet 4 Watershed Summary)
S Post -Developed =
3.88
(From SCS TR-55 eq. 2-4)
RV Post -Developed =
0.84 in.
(From SCS TR-55 eq. 2-3)
I.F. =
0.80
(Factor of Safety)
Q Developed =
0.73 cfs
Section B.4 Limits of Analysis
The analysis terminates at the SWIM facility since subsection B.3.a is met.
9 VAC 25-870-66 (Flood Protection Analysis #1)
Section C: Flood Protection
"Concentrated stormwater flow shall be released into a stormwater conveyance system and
shall meet one of the following criteria as demonstrated by use of acceptable hydrologic and
hydraulic methodologies:"
Section C.2.a.:
"Concentrated stormwater flow to stormwater conveyance systems that currently
experience localized flooding" [i.e. the floodplain] shall confine "the postdevelopment peak
flow rate from the 10-year 24-hour storm event within the stormwater conveyance system to
avoid the localized flooding."
NOTE:
The peak 10-yr. backwater elevation is contained within the underground detention system.
SCS TR-55 peak 10-yr, 24-hour Backwater Elevation = 435.20 ft
Top Elevation of Underground Detention System = 435.50 ft
Section C.3.c Limits of Analysis
"The stormwater conveyance system enters a mapped floodplain," hereby terminating the
analysis.
9 VAC 25-870-66
Section B: Channel Protection
(Channel Protection Analysis #2)
"Concentrated stormwater flow shall be released into a stormwater conveyance system and shall meet
the criteria in subdivision 1, 2 or 3 of this subsection..."
Section B.1: Manmade stormwater conveyance systems
"When stormwater from a development is discharged to a manmade stormwater conveyance system,
following the land -disturbing activity, either..." a. or b. shall be met:
Section B.l.b.
"The peak discharge requirements for concentrated stormwater flow to natural stormwater conveyance
systems in subdivision 3 of this subsection shall be met."
Section B.3
"... the maximum peak flow rate from the one-year 24-hour storm following the land -disturbing activity
shall be calculated either.." a. or b."
Section B.3.a.
In accordance with the following methodology:
Q Developed <_ I.F. * (Q Pre -Developed * RV Pre -Developed ) / RV Developed
Q Allowed <
0.05 cfs
Where: Q Pre -Developed =
0.39 cfs
(From Worksheet 4 Watershed Summary)
CN Pre -Developed =
59
(From Worksheet 4 Watershed Summary)
S Pre -Developed =
6.84
(From SCS TR-55 eq. 2-4)
RV Pre -Developed =
0.33 In.
(From SCS TR-55 eq. 2-3)
CN Post -Developed =
90
(From Worksheet 4 Watershed Summary)
S Post -Developed -
1.16
(From SCS TR-55 eq. 2-4)
RV Post -Developed =
2.00 in.
(From SCS TR-55 eq. 2-3)
I.F. =
0.80
(Factor of Safety)
Q Developed =
0.05 cfs
Section B.4 Limits of Analysis
The analysis terminates at the onsite subareas since subsection B.3.a is met.
9 VAC 25-870-66 (Flood Protection Analysis #2)
Section C: Flood Protection
"Concentrated stormwater flow shall be released into a stormwater conveyance system and
shall meet one of the following criteria as demonstrated by use of acceptable hydrologic and
hydraulic methodologies:"
Section C.2.b.:
The point of discharge "releases a postdevelopment peak flow rate for the 10-year 24-hour
storm event that is less than the predevelopment peak flow rate from the 10-year 24-hour
storm event. Downstream stormwater conveyance systems do not require any additional
analysis to show compliance with flood protection criteria if this option is utilized."
NOTE:
Pre -Development 10-yr 24-hr SCS TR-55 Peak Flow = 3.51 cfs
Post -Development 10-yr 24-hr 5CS TR-55 Peak Flow = 3.50 cfs
Section C.3 Limits of Analysis
The flood protection analysis terminates at the subareas since subsection C.2.b is met.
SCS TR-55 Pre -Development Hydrographs
Worksheet Sb (Modified for Clarity): Basic watershed Data
1-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 1 (Pre-Dev.) 0.21 0.21 0.49 0.0007
Hydrograph Time 1-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.03
12.0
0.12
12.1
0.36
12.2
0.45
12.3
0.32
12.4
0.18
12.5
0.13
12.6
0.10
12.7
0.08
12.8
0.07
13.0
0.06
13.2
0.05
13.4
0.05
13.6
0.04
13.8
0.04
14.0
0.04
14.3
0.03
14.6
0.03
15.0
0.03
15.5
0.03
16.0
0.02
16.5
0.02
17.0
0.02
17.5
0.02
18.0
0.02
19.0
0.02
20.0
0.01
22.0
0.01
26.0
0.00
0.50
0.40
0.30
0.20
0.10
0.00
-0.10
SCS TR-55 Pre -Development Unit
Hydrograph (DA 1)
30.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
2-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 1 (Pre-Dev.) 0.21 0.21 0.40 0.0012
Hydrograph Time 2-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.05
12.0
0.22
12.1
0.66
12.2
0.85
12.3
0.60
12.4
0.33
12.5
0.24
12.6
0.19
12.7
0.16
12.8
0.13
13.0
0.11
13.2
0.10
13.4
0.09
13.6
0.08
13.8
0.07
14.0
0.07
14.3
0.06
14.6
0.06
15.0
0.05
15.5
0.05
16.0
0.04
16.5
0.04
17.0
0.04
17.5
0.04
18.0
0.03
19.0
0.03
20.0
0.03
22.0
0.02
26.0
0.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
o.o
SCS TR-55 Pre -Development Unit
Hydrograph (DA 1)
5.0 10.0 15.0 20.0 25.0
30.0
Worksheet 5b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 1 (Pre-Dev.) 0.21 0.21 0.27 0.0035
Hydrograph Time 10-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.14
12.0
0.63
12.1
1.91
12.2
2.44
12.3
1.74
12.4
0.97
12.5
0.69
12.6
0.55
12.7
0.46
12.8
0.39
13.0
0.33
13.2
0.28
13.4
0.26
13.6
0.23
13.8
0.21
14.0
0.20
14.3
0.17
14.6
0.16
15.0
0.15
15.5
0.14
16.0
0.12
16.5
0.11
17.0
0.11
17.5
0.10
18.0
0.09
19.0
0.08
20.0
0.07
22.0
0.07
26.0
0.00
3.00
2.50
2.00
1.50
1.00
0.50
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 1)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
1-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 2 (Pre-Dev.) 0.31 0.31 0.48 0.0011
Hydrograph Time 1-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.00
12.1
0.03
12.2
0.17
12.3
0.33
12.4
0.31
12.5
0.24
12.6
0.21
12.7
0.18
12.8
0.16
13.0
0.13
13.2
0.11
13.4
0.10
13.6
0.09
13.8
0.09
14.0
0.08
14.3
0.07
14.6
0.07
15.0
0.06
15.5
0.06
16.0
0.05
16.5
0.05
17.0
0.05
17.5
0.05
18.0
0.04
19.0
0.04
20.0
0.03
22.0
0.03
26.0
0.00
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 2)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
2-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 2 (Pre-Dev.) 0.31 0.31 0.40 0.0020
Hydrograph Time 2-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.02
12.0
0.13
12.1
0.51
12.2
1.07
12.3
1.17
12.4
0.93
12.5
0.62
12.6
0.45
12.7
0.35
12.8
0.29
13.0
0.21
13.2
0.18
13.4
0.16
13.6
0.14
13.8
0.13
14.0
0.12
14.3
0.10
14.6
0.10
15.0
0.09
15.5
0.08
16.0
0.07
16.5
0.07
17.0
0.06
17.5
0.06
18.0
0.06
19.0
0.05
20.0
0.04
22.0
0.04
26.0
0.00
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 2)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet 5b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 2 (Pre-Dev.) 0.31 0.31 0.26 0.0059
Hydrograph Time 10-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.00
12.1
0.01
12.2
0.02
12.3
0.02
12.4
0.02
12.5
0.01
12.6
0.01
12.7
0.01
12.8
0.00
13.0
0.00
13.2
0.00
13.4
0.00
13.6
0.00
13.8
0.00
14.0
0.00
14.3
0.00
14.6
0.00
15.0
0.00
15.5
0.00
16.0
0.00
16.5
0.00
17.0
0.00
17.5
0.00
18.0
0.00
19.0
0.00
20.0
0.00
22.0
0.00
26.0
0.00
0.03
0.02
0.02
0.01
0.01
0.00
0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 2)
Worksheet Sb (Modified for Clarity): Basic watershed Data
1-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 3 (Pre-Dev.) 0.13 0.13 0.49 0.0006
Hydrograph Time 1-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.04
12.1
0.34
12.2
0.24
12.3
0.13
12.4
0.11
12.5
0.10
12.6
0.09
12.7
0.07
12.8
0.07
13.0
0.06
13.2
0.06
13.4
0.05
13.6
0.05
13.8
0.05
14.0
0.04
14.3
0.04
14.6
0.04
15.0
0.04
15.5
0.03
16.0
0.03
16.5
0.03
17.0
0.03
17.5
0.03
18.0
0.02
19.0
0.02
20.0
0.02
22.0
0.02
26.0
0.00
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 3)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
2-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 3 (Pre-Dev.) 0.13 0.13 0.40 0.0012
Hydrograph Time 2-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.18
12.0
0.67
12.1
1.11
12.2
0.62
12.3
0.26
12.4
0.20
12.5
0.18
12.6
0.15
12.7
0.13
12.8
0.11
13.0
0.11
13.2
0.09
13.4
0.08
13.6
0.07
13.8
0.07
14.0
0.06
14.3
0.06
14.6
0.05
15.0
0.05
15.5
0.04
16.0
0.04
16.5
0.04
17.0
0.04
17.5
0.03
18.0
0.03
19.0
0.03
20.0
0.02
22.0
0.02
26.0
0.00
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 3)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet 5b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Ct (mi2-in)
DA 3 (Pre-Dev.) 0.13 0.13 0.27 0.0034
Hydrograph Time 10-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.52
12.0
1.93
12.1
3.18
12.2
1.78
12.3
0.74
12.4
0.58
12.5
0.51
12.6
0.43
12.7
0.36
12.8
0.33
13.0
0.30
13.2
0.26
13.4
0.23
13.6
0.21
13.8
0.20
14.0
0.18
14.3
0.16
14.6
0.15
15.0
0.14
15.5
0.13
16.0
0.12
16.5
0.11
17.0
0.10
17.5
0.10
18.0
0.09
19.0
0.08
20.0
0.07
22.0
0.06
26.0
0.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
SCS TR-55 Pre -Development Unit
Hydrograph (DA 3)
0.0 5.0 10.0 15.0 20.0 25.0
30.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
1-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 4 (Pre-Dev.) 0.17 0.17 0.50 0.0013
Hydrograph Time 1-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.09
12.1
0.70
12.2
0.49
12.3
0.25
12.4
0.22
12.5
0.20
12.6
0.17
12.7
0.15
12.8
0.14
13.0
0.13
13.2
0.12
13.4
0.11
13.6
0.10
13.8
0.09
14.0
0.09
14.3
0.08
14.6
0.08
15.0
0.07
15.5
0.07
16.0
0.06
16.5
0.06
17.0
0.05
17.5
0.05
18.0
0.05
19.0
0.04
20.0
0.04
22.0
0.04
26.0
0.00
0.80
030
0.60
0.50
0.40
0.30
0.20
0.10
0.00
SCS TR-55 Pre -Development Unit
Hydrograph (DA 4)
0.0 5.0 10.0 15.0 20.0 25.0
30.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
2-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 4 (Pre-Dev.) 0.17 0.17 0.41 0.0024
Hydrograph Time 2-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.17
12.1
1.31
12.2
0.92
12.3
0.48
12.4
0.42
12.5
0.38
12.6
0.33
12.7
0.29
12.8
0.26
13.0
0.24
13.2
0.22
13.4
0.20
13.6
0.19
13.8
0.18
14.0
0.16
14.3
0.15
14.6
0.14
15.0
0.14
15.5
0.12
16.0
0.11
16.5
0.10
17.0
0.10
17.5
0.10
18.0
0.09
19.0
0.08
20.0
0.07
22.0
0.07
26.0
0.00
SCS TR-55 Pre -Development Unit
Hydrograph (DA 4)
Worksheet 5b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 4 (Pre-Dev.) 0.17 0.17 0.27 0.0072
Hydrograph Time 10-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
1.10
12.0
4.06
12.1
6.70
12.2
3.75
12.3
1.55
12.4
1.23
12.5
1.07
12.6
0.90
12.7
0.77
12.8
0.69
13.0
0.64
13.2
0.54
13.4
0.49
13.6
0.45
13.8
0.42
14.0
0.38
14.3
0.34
14.6
0.31
15.0
0.30
15.5
0.27
16.0
0.24
16.5
0.22
17.0
0.21
17.5
0.20
18.0
0.19
19.0
0.17
20.0
0.14
22.0
0.14
26.0
0.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 4)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
1-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 5 (Pre-Dev.) 0.17 0.17 0.49 0.0011
Hydrograph Time 1-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.08
12.1
0.59
12.2
0.41
12.3
0.21
12.4
0.19
12.5
0.17
12.6
0.15
12.7
0.13
12.8
0.12
13.0
0.11
13.2
0.10
13.4
0.09
13.6
0.08
13.8
0.08
14.0
0.07
14.3
0.07
14.6
0.06
15.0
0.06
15.5
0.06
16.0
0.05
16.5
0.05
17.0
0.05
17.5
0.04
18.0
0.04
19.0
0.04
20.0
0.03
22.0
0.03
26.0
0.00
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 5)
Worksheet Sb (Modified for Clarity): Basic watershed Data
2-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 5 (Pre-Dev.) 0.17 0.17 0.40 0.0020
Hydrograph Time 2-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.31
12.0
1.15
12.1
1.89
12.2
1.06
12.3
0.44
12.4
0.35
12.5
0.30
12.6
0.25
12.7
0.22
12.8
0.20
13.0
0.18
13.2
0.15
13.4
0.14
13.6
0.13
13.8
0.12
14.0
0.11
14.3
0.10
14.6
0.09
15.0
0.08
15.5
0.08
16.0
0.07
16.5
0.06
17.0
0.06
17.5
0.06
18.0
0.05
19.0
0.05
20.0
0.04
22.0
0.04
26.0
0.00
2.00
1.80
L60
L40
L20
1.00
0.80
0.60
0.40
0.20
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 5)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet 5b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Ct (mi2-in)
DA 5 (Pre-Dev.) 0.17 0.17 0.27 0.0058
Hydrograph Time 10-yr Discharges
(hrs.)
(crs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.90
12.0
3.32
12.1
5.47
12.2
3.06
12.3
1.27
12.4
1.00
12.5
0.87
12.6
0.74
12.7
0.63
12.8
0.57
13.0
0.52
13.2
0.44
13.4
0.40
13.6
0.37
13.8
0.34
14.0
0.31
14.3
0.28
14.6
0.25
15.0
0.25
15.5
0.22
16.0
0.20
16.5
0.18
17.0
0.18
17.5
0.16
18.0
0.16
19.0
0.14
20.0
0.12
22.0
0.11
26.0
0.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 5)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet 5b (Modified for Clarity): Basic watershed Data
1-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 6 (Pre-Dev.) 0.17 0.17 0.53 0.0021
Hydrograph Time 1-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.01
12.1
0.20
12.2
0.76
12.3
0.66
12.4
0.46
12.5
0.38
12.6
0.33
12.7
0.28
12.8
0.25
13.0
0.21
13.2
0.19
13.4
0.18
13.6
0.16
13.8
0.15
14.0
0.14
14.3
0.13
14.6
0.12
15.0
0.12
15.5
0.11
16.0
0.10
16.5
0.09
17.0
0.09
17.5
0.08
18.0
0.08
19.0
0.07
20.0
0.06
22.0
0.06
26.0
0.00
OM
030
0.60
0.50
o.a0
0.30
0.20
0.10
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 6)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet 5b (Modified for Clarity): Basic watershed Data
2-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 6 (Pre-Dev.) 0.17 0.17 0.44 0.0040
Hydrograph Time 2-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.03
12.1
0.40
12.2
1.50
12.3
1.30
12.4
0.89
12.5
0.74
12.6
0.64
12.7
0.55
12.8
0.49
13.0
0.42
13.2
0.38
13.4
0.35
13.6
0.32
13.8
0.30
14.0
0.28
14.3
0.25
14.6
0.24
15.0
0.23
15.5
0.21
16.0
0.19
16.5
0.18
17.0
0.17
17.5
0.16
18.0
0.16
19.0
0.14
20.0
0.12
22.0
0.11
26.0
0.00
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 6)
5.0 10.0 15.0 20.0 25.0 30.0
Worksheet 5b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 6 (Pre-Dev.) 0.17 0.17 0.29 0.0125
Hydrograph Time 10-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.49
12.0
2.24
12.1
6.80
12.2
8.69
12.3
6.20
12.4
3.44
12.5
2.47
12.6
1.97
12.7
1.62
12.8
1.37
13.0
1.16
13.2
1.01
13.4
0.91
13.6
0.84
13.8
0.76
14.0
0.70
14.3
0.61
14.6
0.57
15.0
0.54
15.5
0.49
16.0
0.44
16.5
0.40
17.0
0.37
17.5
0.36
18.0
0.34
19.0
0.30
20.0
0.26
22.0
0.24
26.0
0.00
10.00
9.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 6)
5.0 10.0 15.0 20.0 25.0
30.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
1-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 7 (Pre-Dev.) 0.19 0.19 0.45 0.0010
Hydrograph Time 1-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.00
12.0
0.01
12.1
0.10
12.2
0.39
12.3
0.34
12.4
0.23
12.5
0.19
12.6
0.16
12.7
0.14
12.8
0.13
13.0
0.11
13.2
0.10
13.4
0.09
13.6
0.08
13.8
0.08
14.0
0.07
14.3
0.06
14.6
0.06
15.0
0.06
15.5
0.05
16.0
0.05
16.5
0.05
17.0
0.04
17.5
0.04
18.0
0.04
19.0
0.04
20.0
0.03
22.0
0.03
26.0
0.00
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
-0.05
SCS TR-55 Pre -Development Unit
Hydrograph (DA 7)
.0
Worksheet Sb (Modified for Clarity): Basic watershed Data
2-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 7 (Pre-Dev.) 0.19 0.19 0.37 0.0018
Hydrograph Time 2-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.07
12.0
0.33
12.1
1.01
12.2
1.29
12.3
0.92
12.4
0.51
12.5
0.37
12.6
0.29
12.7
0.24
12.8
0.20
13.0
0.17
13.2
0.15
13.4
0.13
13.6
0.12
13.8
0.11
14.0
0.10
14.3
0.09
14.6
0.09
15.0
0.08
15.5
0.07
16.0
0.06
16.5
0.06
17.0
0.06
17.5
0.05
18.0
0.05
19.0
0.04
20.0
0.04
22.0
0.04
26.0
0.00
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-0.20
SCS TR-55 Pre -Development Unit
Hydrograph (DA 7)
30.0
Worksheet 5b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Below
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
DA 7 (Pre-Dev.) 0.19 0.19 0.25 0.0050
Hydrograph Time 10-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.00
11.3
0.00
11.6
0.00
11.9
0.20
12.0
0.91
12.1
2.75
12.2
3.51
12.3
2.51
12.4
1.39
12.5
1.00
12.6
0.80
12.7
0.66
12.8
0.55
13.0
0.47
13.2
0.41
13.4
0.37
13.6
0.34
13.8
0.31
14.0
0.28
14.3
0.25
14.6
0.23
15.0
0.22
15.5
0.20
16.0
0.18
16.5
0.16
17.0
0.15
17.5
0.15
18.0
0.14
19.0
0.12
20.0
0.11
22.0
0.10
26.0
0.00
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
-0.50 0.0
SCS TR-55 Pre -Development Unit
Hydrograph (DA 7)
5.0 10.0 15.0 20.0 25.0 30.0
Underground Detention System #1 Routing Calculations
Graham Murray
From:
Pat Valentine <Pat.Valentine@ContechES.com>
Sent:
Friday, September 23, 2022 11:27 AM
To:
Graham Murray
Cc:
Matthew Kennedy
Subject:
Granger Property - Charlottesville
Graham,
Contech has reviewed the two CMP layouts you sent this morning. Both systems appear to comply with industry
standards, and we see no issues with either system.
Thanks,
Pat Valentine P.E.*
StormwaterConsultant I Virginia
Contech Engineered Solutions LLC
Richmond, VA
804-971-0400
P at. V a l e nt i n e to co me c h E S. co m
www.ContechES.com
*Licensed in MD
Granger UGD System No. 1 Routings
BasinFlow printout
INPUT:
Basin: Granger UGD System No. 1 Routings- Post -Development DA 1
13 Contour Areas
Elevation(ft)
Area(sf)
Computed Vol.(cy)
424.00
2253.00
0.0
424.50
2253.00
41.7
425.50
3740.00
151.5
426.50
4236.00
299.2
427.50
4524.00
461.3
428.50
4681.00
631.8
429.50
4731.00
806.1
430.50
4681.00
980.4
431.50
4524.00
1150.8
432.50
4236.00
1313.0
433.50
3740.00
1460.7
434.50
2253.00
1570.5
435.50
2253.00
1653.9
Start-Elevation(ft)
6 Outlet Structures
Outlet structure 0
Orifice
name:
area (sf)
diameter or depth (in)
width for rect. (in)
coefficient
invert (ft)
multiple
discharge
Outlet structure 1
Orifice
424.00 Vol.(cy)
Low -Flow Orifice
0.067
3.500
0.000
0.500
424.500
1
into riser
name: Mid -Flow Orifices
area (sf)
1.969
diameter or depth (in)
19.000
width for rect. (in)
0.000
coefficient
0.500
invert (ft)
432.250
multiple
2
discharge into
riser
Page 1
[Eiti
Outlet structure 2
Orifice
Granger UGD System No. 1 Routings
name: High -Flow Orifice
area (sf)
3.976
diameter or depth (in)
27.000
width for rect. (in)
0.000
coefficient
0.500
invert (ft)
432.250
multiple
1
discharge into
riser
Outlet structure 3
Weir
name: Access Manhole for Inspection
diameter (in)
30.000
side angle
0.000
coefficient
3.000
invert (ft)
436.000
multiple
1
discharge
into riser
Outlet structure 4
Orifice
name: Primary Outlet
area (sf) 3.142
diameter or depth (in) 24.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 424.470
multiple 1
discharge out of riser
Outlet structure 5
Orifice
name: Bypass Outlet
area (sf) 1.767
diameter or depth (in) 18.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 432.250
multiple 1
discharge through dam
Page 2
Granger UGD System No. 1 Routings
3 Inflow Hydrographs
Hydrograph 0
SCS
name: 1-yr
24-hr SCS Design Storm
Area (acres)
18.850
CN
72.000
Type 2
rainfall, P (in)
3.050
time of conc. (hrs)
0.2000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
17.192
peak time (hrs)
11.970
volume (cy)
2121.796
Hydrograph 1
SCS
name: 2-yr
24-hr SCS Design Storm
Area (acres)
18.850
CN
72.000
Type 2
rainfall, P (in)
3.690
time of conc. (hrs)
0.2000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
25.584
peak time (hrs)
11.970
volume (cy)
3157.391
Hydrograph 2
SCS
name: 10-yr 24-hr SCS Design Storm
Area (acres) 18.850
CN 72.000
Type 2
rainfall,
P (in)
5.580
time of conc.
(hrs)
0.2000
time increment
(hrs)
0.0200
time limit
(hrs)
30.000
fudge
factor
1.00
routed
true
peak flow
(cfs)
54.438
peak time
(hrs)
11.970
volume (cy)
6718.438
Page 3
Granger UGD System No. 1 Routings
OUTPUT:
Routing Method: storage -indication
Hydrograph 0
Routing Summary of Peaks: 1-yr 24-hr SCS Design Storm
inflow (cfs) 17.085 at 11.98 (hrs)
discharge (cfs) 0.732 at 13.14 (hrs)
water level (ft) 432.104 at 13.28 (hrs)
storage (cy) 1250.107
Hydrograph 1
Routing Summary of Peaks: 2-yr 24-hr SCS Design Storm
inflow (cfs) 25.423 at 11.98 (hrs)
discharge (cfs) 17.159 at 12.08 (hrs)
water level (ft) 433.112 at 12.08 (hrs)
storage (cy) 1405.518
Hydrograph 2
Routing Summary of Peaks: 10-yr 24-hr
inflow (cfs) 54.096 at
discharge (cfs) 49.837 at
water level (ft) 435.204 at
storage (cy) 1629.256
Fri Sep 23 10:00:39 EDT 2022
SCS Design Storm
11.98 (hrs)
12.02 (hrs)
12.02 (hrs)
Page 4
Underground Detention System #2 Routing Calculations
Granger UGD System No. 2 Routings
BasinFlow printout
INPUT:
Basin: Granger UGD System No. 2 Routings- Post -Development DA 2
13 Contour Areas
Elevation(ft)
Area(sf)
438.50
230.00
439.00
230.00
440.00
320.00
441.00
350.00
442.00
368.00
443.00
377.00
444.00
380.00
445.00
377.00
446.00
368.00
447.00
350.00
448.00
320.00
449.00
230.00
450.00
230.00
Start-Elevation(ft)
6 Outlet Structures
Outlet structure 0
Orifice
name:
area (sf)
diameter or depth (in)
width for rect. (in)
coefficient
invert (ft)
multiple
discharge
Outlet structure 1
Orifice
Computed Vol
438.50 Vol.(cy)
Low -Flow Orifice
0.005
0.938
0.000
0.500
439.000
1
into riser
name: Mid -Flow Orifices
area (sf)
0.235
diameter or depth (in)
6.563
width for rect. (in)
0.000
coefficient
0.500
invert (ft)
446.850
multiple
3
discharge into
riser
Page 1
•(CY)
0.0
4.3
14.4
26.8
40.1
53.9
67.9
81.9
95.7
109.0
121.4
131.6
140.1
P-JIGES
Outlet structure 2
Orifice
Granger UGD System No. 2 Routings
name: High -Flow Orifice
area (sf)
0.087
diameter or depth (in)
4.000
width for rect. (in)
0.000
coefficient
0.500
invert (ft)
448.670
multiple
1
discharge into
riser
Outlet structure 3
Weir
name: Access
diameter (in)
side angle
coefficient
invert (ft)
multiple
discharge i
Outlet structure 4
Orifice
Manhole for Inspection
24.000
0.000
3.000
452.450
1
to riser
name: Primary Outlet
area (sf) 1.227
diameter or depth (in) 15.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 438.970
multiple 1
discharge out of riser
Outlet structure 5
Orifice
name: Bypass Outlet
area (sf) 1.227
diameter or depth (in) 15.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 446.750
multiple 1
discharge out of riser
Page 2
Granger UGD System No. 2 Routings
3 Inflow Hydrographs
Hydrograph 0
SCS
name: 1-yr
24-hr SCS Design Storm
Area (acres)
0.700
CN
90.000
Type 2
rainfall, P (in)
3.050
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
1.803
peak time (hrs)
11.917
volume (cy)
190.902
Hydrograph 1
SCS
name: 2-yr
24-hr SCS Design Storm
Area (acres)
0.700
CN
90.000
Type 2
rainfall, P (in)
3.690
time of conc. (hrs)
0.1000
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
2.333
peak time (hrs)
11.917
volume (cy)
246.972
Hydrograph 2
SCS
name: 10-yr 24-hr SCS Design Storm
Area (acres) 0.700
CN 90.000
Type 2
rainfall,
P (in)
5.580
time of conc.
(hrs)
0.1000
time increment
(hrs)
0.0200
time limit
(hrs)
30.000
fudge
factor
1.00
routed
true
peak flow
(cfs)
3.942
peak time
(hrs)
11.917
volume (cy)
417.291
Page 3
Granger UGD System No. 2 Routings
OUTPUT:
Routing Method: storage -indication
Hydrograph 0
Routing Summary of Peaks
inflow (cfs)
discharge (cfs)
water level (ft)
storage (cy)
Hydrograph 1
Routing Summary of Peaks:
inflow (cfs)
discharge (cfs)
water level (ft)
storage (cy)
Hydrograph 2
Routing Summary of Peaks
inflow (cfs)
discharge (cfs)
water level (ft)
storage (cy)
1-yr 24-hr SCS Design Storm
1.795 at 11.92 (hrs)
0.054 at 12.16 (hrs)
446.849 at 12.32 (hrs)
107.053
2-yr 24-hr SCS Design Storm
2.322 at 11.92 (hrs)
1.652 at 12.02 (hrs)
447.442 at 12.02 (hrs)
114.643
10-yr 24-hr SCS Design Storm
3.923 at 11.92 (hrs)
3.502 at 11.96 (hrs)
448.607 at 11.96 (hrs)
127.971
Mon Sep 19 11:39:48 EDT 2022
Page 4
Riprap Outlet Protection Calculations
Q v.TLET ?PONCn" J CALCLA I 11.0A S
tdGtl 5 te-
Ito ' Lt9.8 �F5
Qoaj&) 50 cr5
'PCP, t"1AWI G'S �'pvl��leM) 7N�E
FLoW q)C-Pvr'1 SS ' t �ZAMevrea,
7t-le2EfckE UC-C cCK pI.Al(
-ZS tAsEo 'to OestGN i}c� o rat t
4,�ec�crsar.�
w = Z S'
wa =
1 �
✓a5o : 6" (R�arwM4w��j
uG4 SKSwA 4-a
t�EStcn� ` 10 c�S
x eca. MANNZn ', E&VIvt o4l vwc
Ttovv UePrt1 as < ,Ja OXA^.-T44,
uSEo "ta l�E�dhl °rtk� cT.n°rtGT
Wa° 3,a
Ne\Lr QEa �EyCM PutrG 3 \8-\, OEF[I� a� aaE sW+u Pad
N0� LESS ThAN 6� WLTNI. A MY,N, (�ELOMM�t.✓JG,}y C,Cap' t'P�E S'CL�E fiC t(
t /6"xl �\ fMo�rx okTl�r �P��CcT:a�,
SnA�c i'K�Cdk:fGoe C'yE A Mir+, a� O,"IS ` J
K T%W L 'OGSSGxW- L-A' 39 `
vow cL, A\ STV'4
wsEo Q,4') wzm A
vCJq� CL, AI. SceNE ro 3E
1992
3.18
—a.-'--__=
tee. ��go'Yad.
SS�����O-�iGR�il • 1lY'a�'
I '61
III - 165
MIRE-
M� .
ems..
OJWMERO
Wz
RUN
- a
_ '_.
WI
;
_
pia
•�
�
-
,oar.
�wm
Lap
"
-
- _=_�
_
•,
=_- a== =='-=_ '- =��
Source: USDA-SCS Plate 3.18-3
n
III - 164
1992
3.18
PIPE OUTLET CONDITIONS
A A
'IPE OUTLET TO FIAT
.REA WITH NO DEFINED
'HANNEL
I a
d
7-
SECTION A -A FILTER CLOTH KEY IN 6'-9"; RECOMMENDED FOR ENTIRE PERIMETER
f
3do (MIN.)
'IPE OUTLET TO WELL
IEFINED CHANNEL
I
d
SECTION A —A
FILTER CLOTH KEY IN 6"-9% RECOMMENDED FOR ENTIRE PERIMETER
NOTES: 1. APRON LINING MAY BE RIPRAP, GROUTED RIPRAP, GABION
BASKET, OR CONCRETE.
2. La IS THE LENGTH OF THE RIPRAP APRON AS CALCULATED
USING PLATES 3.16-3 AND 3.16-4.
3. d = 1.5 TIMES THE MAXIMUM STONE DIAMETER, BUT NOT
LESS THAN 6 INCHES.
Source: Va. DSWC
Plate 3.18-1
III - 157
Virginia Runoff Reduction Method
Water Quality Calculations
CEq VkgWaRumffRetlunbn Melbol DeveAWwnt Camp&�Speotlsbeee-Vemion3.0
2013 belt BMPSeanaaW and 3aeMWwu
nolem N— i Gmryer PmpeM CLEAR ALL amPungn Speui/iamiwDrsnGem: Hn3 Drafl 3ttls 85e
Information 9/ll/2032 m
Post-Development Project (Treatment Volume and Loads)
Lantltow laoesl
ASam
asgm
CS
bseRe
reeb
reeejueuSP.ebael-undmidee,
&]6
4d
&]6
nlaep-e �eee, paeeeb
w,wm.�e
zo.99
xim
m�Cm 1+neY
6B]
691
leo/daen SpeanrearmmtrpmernaMa®rMee
WN Me VIgWVRemgRduvtlm MetlW
36.56
fnnstants
Runuflic wne,1114
Mnmi man nnrnenl
i
Aam
asM.
C..
bSp9a
rng¢ R,nu 11 Evem llnenerl
100
revoee
0.03
0.03
OW
O115
nul'"hIrus lirJ EMC(100
0.16
..,
i R20
i 0.-
0.]5
genlRp EMClmyll
186
0.95
I ue5
1 0.9.
095
nrRcrPw 1W..MJ
0.92
reme, r..n
oso
Post -Development Requirement for Site Area
rP Lead ReduRion Required Lb/yr) I 9..
foreY/Opm Spe¢(Aerlavaal
B.]6
—dried Mlbred]
0.03
xra,eM
vx
Lemsearermaerlaae4
m99
weymea as larfl
0.1.
%eueurearef
SNd
I nPamurn (uer Iao61
6.81
0.a(irryrAue)
0.95
xlmLenioux
19x
in ;�-'tdume 0.91G9
vs3
u
p
g
0
0
0
0
0
0
p�
g
p
op
w
s
f
Q
Q
Q
c00
p
p
O
p
G
L
U
Q
O
p
O
O
O
O
p
O
G
p
8
G
Q
O
O
O
O
O
X
Q
0
0
0
0
8
D
O
O
G
O
O
O
G7
Q
0
0
0
0
0
]L
Q
O
O
O
O
8
Q
O
G
O
G
G
U
O
G
G
G
.CQ
G
0
U
pp
pp
pp
pp
pp
p
p
p
G
�.3
V
d
Y
3
a
io
i
P
O
0
0
0
0
O
H
O
H
a;.6
p1
1�
O
N
Y
U
U
W
W
ia
W
W
�
Q
p___
W
d_
_C
_C
Y
�
L___
C_
d_
S
\
d
\
d
O
L
Q
W
V'
Z
p
O
L
p
p
G
(7
p
O.
G
p
C
N
O
Q
ON
O
W_
Z_
W_
N
W_
Q
6
O
C.
W
f¢
Yl
Q
W
l
W
C Q
i
L
f
O
1
C Q
O
C
2
W
f
_O
!
8Q�
W
6
Y
V
0
.
Z
G
C
Z
o
f
Z
C.
Z
Z
K
Z
Y
�.
Z
O
Kd
Z
f0
OLL
O
p
Q
O_
gyp/
O
�OOpO
6
Q
Cp
G
OO_F
J
Z
W
Z.
yi'
W
d
W
f
W
W
f
p
C
Z
y
N
»
C
p
p
p
G
C
i
N
p
n
-
i
a.
w
�p
s
3
029
3
=`2.
N
O
LL
s
F
W
O
f
f
F
N
W
Q
K
Z
w
V
m
O
N
C
z
C.
f_
Z_
Y
f_
6
O
Y
Z
a
Z
Z
Z
U
7
LO+
Q
d
H
i
K
C
w
C
7
K