HomeMy WebLinkAboutWPO202000037 Calculations 2021-08-06GALAXIE FARM
STORMWATER MANAGEMENT CALCULATIONS PACKET
(Amendment #1 to WPO 202000037)
SCOTT/R. Ct?LLINS2
Lic. No. 035791 �
7/19/21
Date of Calculations
JULY 19, 2021
I:1C1W-AW4III -i'il
® COLLINS ENGINEERING
200 GARRETT STREET, SUITE K
CHARLOTTESVILLE, VA 22902
434.293.3719 PH
434.293.2813 FX
www.collins-engineering.com
SCS TR-55 Calculations
Soils Table (Source: NRCS Web Soil Survey Online Database)
Albemarle County, Virginia (VA003)
Map percent of
Unit Map Unit flame A0I
Symbol
71B Rabun clay loam, 15.3%
2 to 7 percent
slopes
72C3 Rabun clay, 7 to
20.9%
15 percent
slopes, severely
eroded
72D3 Rabun clay, 15
38.2%
to 25 percent
slopes, severely
eroded
79B Meadowville silt
25.6%
loam, 2 to 7
percent slopes
Totals for Area of
100.00/0
Interest
The NRCS web soil survey defines this development's soils as predominantly having a hydrologic group type B.
Precipitation Data
(Source: NCAA's National Weather Service, Hydrometerorological Design Studies Center, Atlas 14
Point Precipitation Frequency Estimates)
Map �
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POINT PRECIPITATION FREQUENCY (PF) ESTIMATES
WITH 90Ye CONFIDENCE INTERVALS AND SUPPLEMENTARY INFORMATION
NOAA Atlas 14, Volume 2, Version 3
PDS•based precipitation frequency estimates with 90% confidence intervals (in inches)'
A"mge rerm iM mal(years)
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3.01
(2.733A7)
3.67
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/.70
(4.215.27) 11
555
(4.96521) 11
6.63
(6.06-7.60) 11
7.92
(6.98A80) 11
9.11
(7.97-10.1) 11
105
(9.04-11.6)
123
(10.6-13.8) 11
14.2
(11.9A5.7)
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U.S. Department of Agriculture
Natural Resources Conservation Service
TR 55 Worksheet 3: Time of Concentration (Tt) or Travel Time (Tt)
Project: Galaxie Farm
Location: Galaxie Farm Ln.
Designed By:
Checked By:
Check
One:
Present
X
Developed X
Check
One:
Tt
X
Tt
Segment ID:
Sheet Flow: (Applicable to Tt only)
1 Surface description (Table 3-1)
2 Manning's roughness coeff., n (Table 3-1
3 Flow length, L (total L < 100) (ft)
4 Two-year 24-hour rainfall, PZ (in.)
5 Land slope, s (ft/ft)
6 Compute Tt = [0.007(n*L)0.8) / P20.5 S A
Shallow Concentrated Flow:
7 Surface description (paved or unpaved)
8 Flow Length, L (ft)
9 Watercourse slope, s (ft/ft)
10 Average velocity, V (Figure 3-1) (ft/s)
11 Tt=L/3600*V
Channel Flow:
12 Cross sectional flow area, a (ft)
13 Wetted perimeter, Pw (ft)
14 Hydraulic radius, r = a/Pw (ft)
15 Channel Slope, s (ft/ft)
16 Manning's Roughness Coeff, n
17 V= [ 1.49r2/3s05 ] / n
18 Flow length, L (ft)
19 Tt= L / 3600*V
20 Watershed or subarea Tt or Tt
(Add Tt in steps 6, 11 and 19)
Note: The shoretest SCS Tc is 0.10 hrs.
FGM,PE Date: 7/30/2021
SRC, PE Date: 7/30/2021
Through subarea n/a
Onsite DA A
Onsite DA A
Onsite DA B
(Pre-Dev.)
(Post-Dev.)
(Post-Dev.)
Short
Short
Short
Grass
Grass
Grass
0.15
0.15
0.15
100
100
75
3.67
3.67
3.67
0.06 0.06 0.12
0.10 0.10 0.06
Unpaved
Unpaved
425
100
0.09
0.10
4.8
5.2
0.02
0.01
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of 3
Channel and Flood Protection Computations
(For Onsite Subareas A & B)
9 VAC 25-870-66
Section B: Channel Protection
(Onsite Subarea A, Site Outfall #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.1.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 Allowed (Calcuated( 15 1.F• * (Q Pre -Developed * [RV Pre -Developed)) (RV Developed )
Q Allowed (Calcuated( <
Where: Q Pre -Developed =
CN Pre -Developed=
S Pre -Developed —
RV Pre -Developed =
CN Post -Developed —
S Post -Developed —
RV Post-Developed—
I.F. _
Q Developed
1.75 cfs
5.44 cfs
(From Worksheet 4 Watershed Summary)
64
(From Worksheet 4 Watershed Summary)
5.66
(From SCS TR-55 eq. 2-4)
0.48 in.
(From SCS TR-55 eq. 2-3)
79
(From Worksheet 4 Watershed Summary)
2.72
(From SCS TR-55 eq. 2-4)
1.20 in.
(From SCS TR-55 eq. 2-3)
0.80
(Factor of Safety)
1.46 cfs
Section B.4 Limits of Analysis
The analysis terminates at the detention faclity since "...subsection 3 of this subsection is utilized to
show compliance with the channel protection criteria..."
9 VAC 25-870-66 (Onsite Subarea A, Site Outfall #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.b.:
The point of discharge (the SWM facility), "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."
10-Year, 24-Hour Pre -Development Subarea A Peak Flow Rate = 21.93 cfs
10-Year, 24-Hour Post -Development Subarea A Peak Flow Rate = 20.93 cfs
Section C.3 Limits of Analysis
The flood protection analysis terminates at the SWM facility since subsection C.2.b is met.
9 VAC 25-870-66 (Onsite Subarea B, Site Outfall #2)
Section B: Channel Protection
"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.1.a.
"The manmade stormwater conveyance system shall convey the postdevelopment peak flow
rate from the two-year 24-hour storm event without causing erosion of the system."
Note, the 2-year 24-hour storm event is not erosive on the concrete pipes and in the riprap
lined outlet protection located within Cow Branch.
Section B.4 Limits of Analysis
"stormwater conveyance systems shall be analyzed for compliance with channel protection
criteria to a point where either.." a. or b. are met
Section B.4.a.
"Based on land area, the site's contributing drainage area is less than or equal to 1.0% of the
total watershed area;"
Note, the analysis terminates at the point of analysis (i.e. the location in Cow Branch where
manmade riprap improvements are proposed).
9 VAC 25-870-66 (Onsite Subarea B, Site Outfall #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.a:
The point of discharge (site outfall #2), "Confines the postdevelopment peak flow rate from the
10-year 24-hour storm event within the stormwater conveyance system [i.e. the storm sewer and
riprap] to avoid the localized flooding."
10-Year, 24-Hour Design Storm Peak Back Water Surface Elevation = 464.54 ft
Lowest Rim Elevation Envisioned in Storm Sewer System = 470.75 ft
(No overtopping Occurs in Structures 12 & 14)
Section C.3 Limits of Analysis
....stormwater conveyance systems shall be analyzed for compliance with flood protection
criteria to a point where:" a, b or c are met.
Section C.3.a.:
"The site's contributing drainage area [i.e. Onsite Subarea B] is less than or equal to 1.0% of the
total watershed area draining to a point of analysis in the downstream stormwater conveyance
system [i.e. the culverts and riprap];"
Pre -Development SCS TR-55 Hydrographs
(For Onsite Subarea A)
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)
Onsite DA A (Pre-Dev.) 0.12 0.12 0.37 0.0058
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
0.90
12.0
3.30
12.1
5.44
12.2
3.05
12.3
1.26
12.4
1.00
12.5
0.87
12.6
0.73
12.7
0.62
12.8
0.56
13.0
0.50
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
0.27
15.0
0.24
15.5
0.22
16.0
0.20
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
6.00
5.00
4.00
3.00
2.00
1.00
0.00
-1.00
SCS TR-55 Pre -Development Unit
Hydrograph (Onsite DA A)
0.0
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)
Onsite DA A (Pre-Dev.) 0.12 0.12 0.31 0.0095
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
1.46
12.0
5.40
12.1
8.90
12.2
4.98
12.3
2.06
12.4
1.63
12.5
1.42
12.6
1.20
12.7
1.02
12.8
0.92
13.0
0.82
13.2
0.72
13.4
0.66
13.6
0.60
13.8
0.55
14.0
0.50
14.3
0.46
14.6
0.44
15.0
0.40
15.5
0.36
16.0
0.32
16.5
0.29
17.0
0.29
17.5
0.27
18.0
0.26
19.0
0.23
20.0
0.19
22.0
0.18
26.0
0.00
SCS TR-55 Pre -Development Unit
Hydrograph (Onsite DA A)
Worksheet 51b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Belov
Subarea Tc (hrs.) Tt (hr.) la / P Am`Q (mil -in)
Onsite DA A (Pre-Dev.) 0.12 0.12 0.20 0.0234
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
3.61
12.0
13.31
12.1
21.93
12.2
12.28
12.3
5.09
12.4
4.03
12.5
3.49
12.6
2.95
12.7
2.51
12.8
2.27
13.0
2.02
13.2
1.78
13.4
1.62
13.6
1.48
13.8
1.36
14.0
1.24
14.3
1.12
14.6
1.08
15.0
0.98
15.5
0.89
16.0
0.80
16.5
0.73
17.0
0.70
17.5
0.66
18.0
0.63
19.0
0.56
20.0
0.47
22.0
0.45
26.0
0.00
25.00
20.00
15.00
10.00
5.00
0.00
0
SCS TR-55 Pre -Development Unit
Hydrograph (Onsite DA A)
Proposed Dry Detention Basin 'A' Routing Calculations
(For Onsite Subarea A)
Galaxie Farm- Basin Routings
BasinFlow printout
INPUT:
Basin: Galaxie Farm- Basin Routings
7 Contour Areas
Elevation(ft)
Area(sf)
Computed Vol.(cy)
470.00
110.00
0.0
472.00
653.00
25.5
474.00
1658.00
108.2
476.00
3090.00
281.3
478.00
4971.00
577.1
480.00
6216.00
990.6
482.00
8129.00
1520.3
Start—Elevation(ft)
5 Outlet Structures
Outlet structure 0
Orifice
470.00 Vol.(cy) 0.00
name: Barrel
area (sf) 1.767
diameter or depth (in) 18.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 469.900
multiple 1
discharge out of riser
Outlet structure 1
Orifice
name: Low -Flow Orifice
area (sf) 0.136
diameter or depth (in) 5.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 470.000
multiple 1
discharge into riser
Page 1
Galaxie Farm- Basin Routings
Outlet structure 2
Orifice
name: Mid -Flow Orifices
area (sf) 0.785
diameter or depth (in) 12.000
width for rect. (in) 0.000
coefficient 0.500
invert (ft) 477.330
multiple 5
discharge into riser
Outlet structure 3
Weir
name: Riser
diameter (in) 48.000
side angle 0.000
coefficient 3.300
invert (ft) 479.500
multiple 1
discharge into riser
transition at (ft) 1.215
orifice coef. 0.500
orifice area (sf) 12.566
Outlet structure 4
Weir
name: Emergency Spillway
length (ft) 40.000
side angle 75.960
coefficient 3.300
invert (ft) 480.500
multiple 1
discharge through dam
4 Inflow Hydrographs
Hydrograph 0
SCS
name: 1-yr 24-hr SCS TR-55 Design Storm
Area (acres) 7.750
CN 79.000
Type 2
rainfall, P (in) 3.040
time of conc. (hrs) 0.1100
time increment (hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 11.747
peak time (hrs) 11.923
volume (cy) 1267.864
Page 2
Galaxie Farm- Basin Routings
Hydrograph 1
SCS
name: 2-yr
24-hr SCS TR-55 Design Storm
Area (acres)
7.750
CN
79.000
Type 2
rainfall, P (in)
3.670
time of conc. (hrs)
0.1100
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
16.390
peak time (hrs)
11.923
volume (cy)
1769.000
Hydrograph 2
SCS
name: 10-yr
24-hr SCS TR-55 Design Storm
Area (acres)
7.750
CN
79.000
Type 2
rainfall, P (in)
5.550
time of conc. (hrs)
0.1100
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
31.644
peak time (hrs)
11.923
volume (cy)
3415.500
Hydrograph 3
SCS
name: 100-yr
24-hr SCS TR-55 Design Storm
Area (acres)
7.750
CN
79.000
Type 2
rainfall, P (in)
9.130
time of conc. (hrs)
0.1100
time increment (hrs)
0.0200
time limit (hrs)
30.000
fudge factor
1.00
routed
true
peak flow (cfs)
63.352
peak time (hrs)
11.923
volume (cy)
6837.930
Page 3
Galaxie Farm- Basin Routings
OUTPUT:
Routing Method: storage -indication
Hydrograph 0
Routing Summary
of
Peaks: 1-yr 24-hr
SCS TR-55 Design Storm
inflow
(cfs)
11.746
at
11.92
(hrs)
discharge
(cfs)
1.455
at
12.22
(hrs)
water level
(ft)
477.288
at
12.28
(hrs)
storage
(cy)
455.690
Hydrograph 1
Routing Summary
of
Peaks: 2-yr 24-hr
SCS TR-55 Design Storm
inflow
(cfs)
16.388
at
11.92
(hrs)
discharge
(cfs)
8.385
at
12.06
(hrs)
water level
(ft)
477.933
at
12.06
(hrs)
storage
(cy)
564.794
Hydrograph 2
Routing Summary
of
Peaks: 10-yr 24-hr
SCS TR-55 Design Storm
inflow
(cfs)
31.641
at
11.92
(hrs)
discharge
(cfs)
20.929
at
12.04
(hrs)
water level
(ft)
479.369
at
12.04
(hrs)
storage
(cy)
850.193
Hydrograph 3
Routing Summary
of
Peaks: 100-yr
24-hr
SCS TR-55 Design Storm
inflow
(cfs)
63.347
at
11.92
(hrs)
discharge
(cfs)
61.002
at
11.94
(hrs)
water level
(ft)
480.928
at
11.94
(hrs)
storage
(cy)
1218.911
Wed Jul 28 11:18:25 EDT 2021
Page 4
Post -Development SCS TR-55 Hydrographs
(For Onsite Subarea B)
Worksheet 51b (Modified for Clarity): Basic watershed Data
1-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Belov
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (m1
2-in)
Onsite DA B (Post-Dev.) 0.10 0.10 0.16 0.0019
Hydrograph Time 1-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.05
11.3
0.06
11.6
0.10
11.9
0.63
12.0
1.22
12.1
1.90
12.2
1.17
12.3
0.41
12.4
0.28
12.5
0.23
12.6
0.20
12.7
0.16
12.8
0.14
13.0
0.12
13.2
0.11
13.4
0.10
13.6
0.09
13.8
0.08
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
0.02
22.0
0.02
26.0
0.00
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
SCS TR-55 Post -Development Unit
Hydrograph (Onsite DA B)
0.0 5.0 10.0 15.0 20.0 25.0
30.0
Worksheet 51b (Modified for Clarity): Basic watershed Data
2-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Belov
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
Onsite DA B (Post-Dev.) 0.10 0.10 0.13 0.0026
Hydrograph Time 2-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.06
11.3
0.09
11.6
0.14
11.9
0.86
12.0
1.67
12.1
2.61
12.2
1.61
12.3
0.56
12.4
0.38
12.5
0.32
12.6
0.27
12.7
0.22
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
0.08
15.0
0.08
15.5
0.07
16.0
0.06
16.5
0.05
17.0
0.05
17.5
0.05
18.0
0.05
19.0
0.04
20.0
0.03
22.0
0.03
26.0
0.00
3.00
2.so
2.00
Lso
1.00
0.50
0.00
SCS TR-55 Post -Development Unit
Hydrograph (Onsite DA B)
0.0 5.0 10.0 15.0 20.0 25.0
30.0
Worksheet 51b (Modified for Clarity): Basic watershed Data
10-yr. 24-hr. SCS TR-55 Method Unit Hydrograph for the la/P & Tc Listed Belov
Subarea Tc (hrs.) Tt (hr.) la / P Am*Q (mi2-in)
Onsite DA B (Post-Dev.) 0.10 0.10 0.09 0.0049
Hydrograph Time 10-yr Discharges
(hrs.)
(cfs)
0.0
0.00
11.0
0.12
11.3
0.17
11.6
0.26
11.9
1.63
12.0
3.15
12.1
4.92
12.2
3.04
12.3
1.06
12.4
0.72
12.5
0.60
12.6
0.51
12.7
0.42
12.8
0.37
13.0
0.32
13.2
0.28
13.4
0.25
13.6
0.22
13.8
0.20
14.0
0.19
14.3
0.17
14.6
0.16
15.0
0.14
15.5
0.13
16.0
0.11
16.5
0.10
17.0
0.10
17.5
0.09
18.0
0.09
19.0
0.07
20.0
0.06
22.0
0.06
26.0
0.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
SCS TR-55 Post -Development Unit
Hydrograph (Onsite DA B)
0.0 5.0 10.0 15.0 20.o
Storm Sewer Analysis
1. For verification of Onsite DA B's channel and flood protection compliance, and
2. For the proposed bypass storm sewer system associated with the ESC plan.
Note: For the bypass storm sewer system's contributing drainage area, please
see the sheet entitled 'Drainage Plan for the Bypass Storm Sewer' and the
section at the back of this report entitled 'Synchronized Hydrographs to the
Bypass Storm Sewer'.
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Water Quality Calculations Using the DEQ
Virginia Runoff Reduction Method for New Developments
(Compliance is met through a nutrient credit purchase.)
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Pro)ect Nam: Go avie Farm- VSMIs Amendment Nl m�sme y®Ils
Datee: 7/30/2021 ® hies
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(Site Information
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Synchronized Hydrographs that Contribute to the Bypass Storm Sewer
(These hydrographs were generated so that the proposed bypass storm sewer
associated with the ESC plan could be sized appropriately. These peak flows are
reflected in the storm sewer computations for the bypass storm sewer.)
Avinity I
Outflow Hydrograph
(From Basin's Routings)
Time (hrs)
Outflow (cfs)
0.0
0.00
0.5
0.00
1.0
0.06
1.5
0.19
2.0
0.35
2.5
0.48
3.0
0.59
3.5
0.68
4.0
0.75
4.5
0.81
5.0
0.87
5.5
0.92
6.0
0.95
6.5
1.18
7.0
1.23
7.5
1.29
8.0
1.36
8.5
1.44
9.0
1.59
9.5
1.77
10.0
1.92
10.5
2.15
11.0
2.49
11.5
3.02
11.9
4.63
12.0
5.51
12.1
17.61
12.2
37.20
12.3
34.03
12.4
26.36
12.5
19.84
13.0
7.02
13.5
5.86
14.0
5.59
14.5
5.28
15.0
4.93
15.5
4.57
16.0
4.20
16.5
3.80
17.0
3.40
17.5
3.02
18.0
2.64
18.5
2.29
19.0
1.97
19.5
1.70
20.0
1.45
20.5
1.24
21.0
0.96
21.5
0.93
22.0
0.89
22.5
0.86
23.0
0.82
23.5
0.79
24.0
0.77
24.5
0.55
25.0
0.27
25.5
0.11
26.0
0.03
26.5
0.00
27.0
0.00
27.5
0.00
28.0
0.00
28.5
0.00
29.0
0.00
29.5
0.00
30.0
0.00
30.5
0.00
31.0
0.00
a0.00
35.00
30.00
25.00
20.00
15.00
10.00
s.00
0.00
-s.00
Outflow Hydrograph (10-yr Design Storm)
35.0
Avinity II
Outflow Hydrograph
(From Basin's Routings)
Time (hrs)
Outflow (cfs)
0.0
0.00
0.5
0.17
1.0
0.27
1.5
0.33
2.0
0.36
2.5
0.38
3.0
0.40
3.5
0.41
4.0
0.43
4.5
0.44
5.0
0.46
5.5
0.48
6.0
0.50
6.5
0.52
7.0
0.53
7.5
0.55
8.0
0.57
8.5
0.60
9.0
0.63
9.5
0.68
10.0
0.72
10.5
0.78
11.0
0.87
11.5
1.00
11.9
2.10
12.0
2.98
12.1
7.35
12.2
8.50
12.3
8.40
12.4
8.35
12.5
5.10
13.0
3.00
13.5
2.83
14.0
2.61
14.5
2.33
15.0
2.02
15.5
1.63
16.0
1.29
16.5
1.26
17.0
1.23
17.5
1.20
18.0
1.16
18.5
1.13
19.0
1.09
19.5
1.05
20.0
1.00
20.5
0.95
21.0
0.89
21.5
0.84
22.0
0.78
22.5
0.72
23.0
0.65
23.5
0.59
24.0
0.54
24.5
0.43
25.0
0.29
25.5
0.16
26.0
0.06
26.5
0.02
27.0
0.01
27.5
0.00
28.0
0.00
28.5
0.00
29.0
0.00
29.5
0.00
30.0
0.00
30.5
0.00
31.0
0.00
10.00
9.60
8.60
2.60
6.00
5.00
4.60
3.00
2.60
1.00
am
Outflow Hydrograph (10-yr Design Storm)
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0
Structure ESl
Inflow Hydregraph for Oeecland Runoff
(Does not Include Routed A Inity I & II)
Time (min.)
Inflow(cfs)
1.0
2.17
2.0
4.33
3.0
6.50
4.0
8.67
5.0
10.83
6.0
13.00
7.0
15.16
8.0
17.33
9.0
19.50
10.0
21.66
11.0
23.83
12.0
26.00
13.0
28.16
14.0
30.33
1S.0
32.49
16.0
34.66
17.0
36.83
18.0
35.53
19.0
34.23
20.0
32.93
21.0
31.64
22.0
30.34
23.0
29.04
24.0
27.75
25.0
26A5
26.0
25.15
27.0
23.85
28.0
22.56
29.0
21.26
30.0
19.96
31.0
18.67
32.0
17.37
33.0
16.07
34.0
14.77
35.0
13AS
36.0
12.18
37.0
10.88
38.0
9.59
39.0
8.29
40.0
6.99
41.0
5.69
42.0
4.40
43.0
3.10
44.0
1.80
45.0
0.51
46.0
0.00
47.0
0.00
48.0
0.00
49.0
0.00
so.0
0.00
51.0
0.00
52.0
0.00
53.0
0.00
54.0
0.00
55.0
0.00
56.0
0.00
5].0
0.00
58.0
0.00
59.0
0.00
60.0
0.00
n0 00
35 W
30 00
zs o0
20 00
is o0
MOO
son
OM
5 00
Inflow Hydrograph (10-yr Design Storm)
5ynchronized (Inflow) unit Hydrograph To Proposed Strui EiI
This inflow hydrograph sychronizes the Avinity I outflow hydrograph, the Avinity II outflow, hydrograph and the Str. ES3 inflow
hydrograph to determine the peak flow to structure ES-1(i.e. the upstream point of the bypass storm sewer).
Hydrograph Time 10yr Discharges
(hrs.) (cfs)
0.0
2.17
0.1
13.00
0.2
26.00
0.3
36.83
0A
27.75
0.5
20.13
0.6
12.18
0.7
4.40
0.8
O.W
0.9
O.W
1.0
0.33
1.5
0.52
2.0
0.70
2.5
0.86
3.0
0.99
3.5
LIM)
4.0
1.18
4.5
1.26
5.0
1.33
5.5
1.40
6.0
1.45
6.5
1.69
7.0
1.77
7.5
1.85
8.0
1.93
8.5
2.03
9.0
2.22
9.5
2.44
10.0
1.64
10.5
2.93
11.0
3.36
11.5
4.02
11.9
6.73
12.0
8.50
12.1
24.96
12.2
4530
12.3
42.43
12A
34.71
12.5
24.94
13.0
10.03
13.5
8.69
14.0
8.20
14.5
7.61
15.0
6.95
15.5
6.20
16.0
5.48
16.5
5.06
17.0
4.63
17.5
4.21
18.0
3.81
18.5
3.41
19.0
3.06
19.5
2.74
20.0
2.45
20.5
2.19
21.0
1.85
21.5
1.)T
22.0
1.67
22.5
1.57
23.0
1.48
23.5
1.39
24.0
1.31
24.5
0.98
25.0
0.57
25.5
0.28
26.0
0.09
26.5
0.02
27.0
0.01
27.5
0.01
28.0
0.00
28.5
0.00
29.0
0.00
29.5
0.00
30.0
0.00
30.5
0.00
31.0
0.00
Structure 4
Inflow Hytlrograph
(Amounts for Overland Runoff &
SWM Facility ID 0446.01)
Tme(min.)
Inflow(cfs)
1.0
1.64
2.0
3.27
3.0
4.91
4.0
6.55
5.0
8.18
6.0
9.82
7.0
11.45
8.0
13.09
9.0
14.73
10.0
16.36
11.0
18.00
12.0
22.17
13.0
21.27
14.0
22.91
15.0
24.54
16.0
23.56
17.0
22.58
18.0
21.60
19.0
20.62
20.0
19.65
21.0
18.67
22.0
17.69
23.0
16.71
24.0
15.73
25.0
14.75
26.0
13.77
22.0
12.79
28.0
11.81
29.0
10.83
30.0
9.85
31.0
8.87
32.0
7.89
33.0
6.91
34.0
5.93
35.0
4.95
36.0
3.97
32.0
2.99
38.0
2.01
39.0
1.03
40.0
0.05
41.0
0.00
42.0
0.00
43.0
0.00
44.0
0.00
45.0
0.00
46.0
0.00
47.0
0.00
48.0
0.00
49.0
0.00
50.0
0.00
51.0
0.00
52.0
0.00
53.0
0.00
54.0
0.00
55.0
0.00
56.0
0.00
52.0
0.00
58.0
0.00
59.0
0.00
60.0
0.00
Inflow Hydrograph (10-yr Design Storm)
30 W
SM
Mn 40.0 50.0 sa.o 70.0
NOTE:
This inflow hytlrograph was completed to ensure the proposed bypass pipes
1& 3 are appropriately sized. The bypass' proposed structure 4 will accept
this upland offsite runoff with the developmet of Galaxie Farm.
Note, this hytlrograph takes into consideration the overland flow captured
by the existing culvert beneath Galaxie Farm lane and the approved WPO
201200022, SWM Facility ID 0446.01. This SWM facility contains 3 outlet
control structures. The primary control (underdrains and a connected
riser/barrel system) and the tertiary control (emergency spillway) release
runoff to a subarea outside of Galaxie Farm's watershed. The secondary
control (a second riser/barrel system) is partially activated during the 10yr
design storm and releases runoff to Galaxie Farm's watershed (peak flow of
2.53 cfs at a time of 12.11 hrs. per the asbuilt routings).
Synchronized (Inflow) Unit Nydmgraph to Proposed Structure 4
This inflow hydragraph sychronizes the Str. ESl hydragraph (whi A accounts for the Avinity I outflow, hydragraph, the Avinity II outflow,
hydragraph and the structure ESVs overland flaw) and the St, 4 inflow hydragraph (which accounts for the SWM Facility ID 0446.01 and
structure 4's overland flaw). This inflow hydmgraph daes not take into account the minor offsite areas flawing directly to structures 4 & 6.
new areas/Flaws are amounted for separately in the swim sewer compuations.
Hydragraph Time 10, Discharges
(hm.) (cfs)
0.0
3.80
0.1
22.81
0.2
48.16
0.3
59.41
0.4
43.4T
0.5
29.98
0.6
48.18
0.7
4.40
0.8
0.00
0.9
0.00
1.0
0.33
1.5
0.52
2.0
OJO
2.5
0.86
3.0
0.99
3.5
1.09
0.0
1.18
0.5
1.26
5.0
1.33
5.5
1.40
6.0
1.45
6.5
1.69
7.0
1.77
7.5
1.85
8.0
1.93
8.5
2.03
9.0
2.22
9.5
2.44
10.0
2.64
10.5
2.93
11.0
3.36
11.5
4.02
11.9
6.73
12.0
8.50
12.1
24.%
12.2
45.70
12.3
42.43
12.4
M.71
12.5
24.94
13.0
10.03
13.5
8.69
14.0
8.20
14.5
7.61
15.0
6.95
15.5
6.20
16.0
5.48
16.5
5.06
17.0
4.63
17.5
4.21
18.0
3.81
18.5
3.41
19.0
3.06
19.5
2.74
20.0
2.45
20.5
2.19
21.0
1.85
21.5
1.77
22.0
1.67
22.5
1.57
23.0
1.48
23.5
1.39
24.0
1.31
24.5
0.98
25.0
0.59
25.5
0.28
26.0
0.09
26.5
0.02
27.0
0.01
27.5
0.01
28.0
0.00
28.5
0.00
29.0
0.00
29.5
0.00
30.0
0.00
30.5
0.00
31.0
0.00
NOTE:
Approved WPO 201200022, SWM Facility ID 0446.01, releases a peak flaw of 2.53
cfs at a time of 12.11 ha. (per the asbuilt routings). While this outflow does not
synchronize with the adjacent downstream subarea/ inflow hydrogaph shown on
the previous page, it daes synchronic, with the Avinity I and Avinity II peak
autflaws resulting from the attenuation in these facilities. As a result, the 2.53 chs
peak outflow from SWM Facility ID 0446.01 was added to this synchronized
hydmgraph to ensure its runoff was properly accounted far.