HomeMy WebLinkAboutWPO201300016 Calculations 2013-03-01 The Westlake Hills Phase I Channel Adequacy Report &
Calculations
Overview
The following channel adequacy calculations were analyzed by dividing the watershed
into five major sections. Drainage areas#1A(SWM#1), #1B, and#3 flow to the channel
along the northern boundary of the site. Drainage areas#2A (SWM #2) & 2B encompass
the Lickinghole Creek watershed. Summaries of these sections are described below and
further clarification can be found in the attached sheet entitled Channel Adequacy
Exhibit.
Drainage Area, D.A. #1A:
This section consists of drainage flowing to the proposed retention basin(SWM#1). This
watershed has the following characteristics:
D.A.= 31.76 ac.
CN= 77.9 (69.0 in the Pre-Development Scenario)
Type II distribution
P= 3.7 inches (2-year event)
Tc= 0.30 hours
Drainage Area, D.A. #1B:
This watershed is predominantly undisturbed with the proposed development. This
drainage area contains the following characteristics:
D.A.= 148.39 ac.
CN= 62.4
Type II distribution
P= 3.7 inches (2-year event)
Tc= 1.02 hours
Drainage Area, D.A. #2A:
This section consists of drainage flowing to the proposed bioretention basin(SWM#2).
This watershed has the following characteristics:
D.A.= 6.76 ac.
CN= 79.5 (57.1 in the Pre-Development Scenario)
Type II distribution
P= 3.7 inches (2-year event)
Tc= 0.18 hours
Drainage Area, D.A. #2B
This watershed is undisturbed with the proposed development. This drainage area
contains the following characteristics:
D.A.= 8,000 ac. (DA#2A is less than 1% of this area)
Drainage Area, D.A. #3:
This watershed is undisturbed with the proposed development, but drains to the channel
being analyzed. This watershed has the following characteristics:
D.A.= 34.93 ac.
CN= 55
Type II distribution
P= 3.7 inches (2-year event)
Tc=0.37 hours
The pre-development onsite ground cover is predominately forest. The detailed soils
information is provided on the E&S Sheets 30 & 31 and the majority is soil group B. The
ground cover for the soil was analyzed as being in good condition.
Summary of Calculations
Drainage area#1A was routed through SWM#1 and generated a peak 2-year flow of
7.25 cfs. The calculations showing this can be viewed in the attached documents.
The calculations resulting from drainage areas #1B and#3 created 2-year peak flows of
48.97 cfs and 7.71 cfs, respectfully. The combined flows from drainage areas#1A, 1 B
and 3 generate a maximum 2-year flow of 63.93 cfs draining to channel along the
northern boundary. This is a worst case scenario because it assumes all three peak flows
occur simultaneously, despite the fact the time of peak flow being released from SWM#1
is much later than that of drainage area#1B. The combined flow of 63.93 cfs was used
during the analysis of cross sections#1-4. Further downstream channel adequacy has
previously been approved by the County within the Foothills WPO 201200047 plans,
which demonstrate capacity with a higher flow rate.
Drainage area#2A was routed through SWM#2 and generated a peak 2-year flow of
3.98 cfs and a peak 10-year flow of 12.51. It flows into a proposed riprap channel and
then directly into Lickinghole Creek. The 10 year flow of 12.51 was used during the
analysis of the proposed riprap channel cross section#5. Since 1% of the upstream
drainage area#2B is larger than the drainage area of 2A, no further downstream analysis
was required. Calculations supporting this are also shown in the attached documents.
The five cross sections analyzed are representative of their respective channels.
MS-19 Cross Section#1:
Note: Loam & cobbles mixture within channel banks)
f _ �9 �` `�
* `r
• -
_
\Lid;,..
The channel at cross section 1, which has a 1.3 percent slope, contains the following
characteristics:
Within the Channel Banks:
Description: (loam& cobbles mixture)
value for channel bottom: 0.055*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
**Permissible Velocities are in accordance with Table 5-22 of the VESCH
Maximum Computed Depth=1.71'
Maximum Computed Velocity=4.04 ft/s (within channel banks)
Complex Channel-Cross Section#1
Input:
Slope 0.013
Flow(given) 63.930
line x y n
0 0.000 584.000 0.055 (first n value not used)
1 2.000 582.000 0.055
2 8.000 581.600 0.055
3 12.000 582.000 0.055
4 14.000 584.000 0.055
Output:
Depth 1.706
(y) ( 583.306)
Channel bed segment output:
line Q V A P
1 1.57 1.84 0.85 1.85
2 36.50 4.04 9.03 6.01
3 24.29 4.03 6.02 4.02
4 1.57 1.84 0.85 1.85
Fri Nov 15 12:37:19 EST 2013
MS-19 Cross Section#2:
Note: Loam & cobbles mixture within channel banks)
,,,,-.......-4---
•{YRt.4 r ° - R 4♦ ,-
�w ��' '_. '" a v.��� mss► � t...
S .k r h . inc /.'sr Ali t.1
6 4 1t ! p Y
"A''' r V�� ,i.
F�r-
y + t i
..*Fife
.a...„, s ,y J .,w ' .:
ff yam+. y' :..�
The channel at cross section 2, which has a 1.3 percent slope, contains the following
characteristics:
Within the Channel Banks:
Description: (loam& cobbles mixture)
`n' value for channel bottom: 0.060*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
***Permissible Velocities are in accordance with Table 5-14 of the VESCH
Maximum Computed Depth=1.70'
Maximum Computed Velocity=3.77 ft/s (within channel banks)
Complex Channel-Cross Section#2
Input:
Slope 0.013
Flow(given) 63.930
line x y n
0 0.000 582.000 0.060(first n value not used)
1 4.000 580.000 0.060
2 8.500 579.700 0.060
3 14.000 580.000 0.060
4 16.000 582.000 0.060
Output:.
Depth 1.695
(y) ( 581.395)
Channel bed segment output:
line Q V A P
1 4.01 2.06 1.94 3.12
2 26.19 3.77 6.95 4.51
3 32.02 3.77 8.50 5.51
4 1.71 1.76 0.97 1.97
Fri Nov 15 12:37:35 EST 2013
MS-19 Cross Section#3:
Note: Loam & cobbles mixture within channel banks)
.
K - - -.A 1
@
a aE
le
.,. .
- ♦ +� "`'`' < 9
t-*, „a y ,,,, . t
' .fib ,
:O¢
. ,. .
- � ..
4'1' !CV".0. ' t„„ .
* �...
1 —;
The channel at cross section 3, which has a 1.2 percent slope, contains the following
characteristics:
Within the Channel Banks:
Description: (loam& cobbles mixture)
`n' value for channel bottom: 0.055*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
***Permissible Velocities are in accordance with Table 5-14 of the VESCH
Maximum Computed Depth=1.60'
Maximum Computed Velocity=3.70 ft/s (within channel banks)
Complex Channel-Cross Section #3
Input:
Slope 0.012
Flow(given) 63.930
line x y n
0 0.000 578.000 0.055 (first n value not used)
1 1.000 576.000 0.055
2 7.000 575.600 0.055
3 13.000 576.000 0.055
4 15.000 578.000 0.055
Output:
Depth 1.602
(y) ( 577.202)
Channel bed segment output:
line Q V A P
1 0.45 1.23 0.36 1.34
2 31.14 3.70 8.41 6.01
3 31.14 3.70 8.41 6.01
4 1.21 1.67 0.72 1.70
Fri Nov 15 12:38:39 EST 2013
MS-19 Cross Section#4
Note: Loam & cobbles mixture within channel banks)
J 4
V . 4
y-
'
`
Yi 4.- 3 4.4.,..-, r air t +
v .•
jr !:� y
0 4 , p'h
.� a
? s!_, +'.p• a!i.. ✓
�s` ,
1 y i 'F '
Ala
The channel at cross section 4, which has a 1.3 percent slope, contains the following
characteristics:
Within the Channel Banks:
Description: (loam& cobbles mixture)
`n' value for channel bottom: 0.07*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
***Permissible Velocities are in accordance with Table 5-14 of the VESCH
Maximum Computed Depth=2.18'
Maximum Computed Velocity=3.73 ft/s (within channel banks)
Complex Channel-Cross Section #4
Input:
Slope 0.013
Flow(given) 63.930
line x y n
0 0.000 576.000 0.070 (first n value not used)
1 2.000 574.000 0.070
2 5.500 573.500 0.070
3 10.000 574.000 0.070
4 13.000 576.000 0.070
Output:
Depth 2.178
(y) ( 575.678)
Channel bed segment output:
line Q V A P
1 2.40 1.71 1.41 2.37
2 25.12 3.72 6.75 3.54
3 32.38 3.73 8.67 4.53
4 4.02 1.90 2.11 3.02
Fri Nov 15 12:39:27 EST 2013
MS-19 Cross Section#5
(Note: Proposed Riprap Channel from SWM#2 outfall pipe)
The proposed channel at cross section 5, which has a 8.0 percent slope, contains the
following characteristics:
Within the Channel Banks:
Description: (proposed riprap)
`n' value for channel bottom: 0.033*
Permissible Velocity: 6.0 ft/s**
*Manning's 'n'values are in accordance with Tables 5-16 through 5-21 of the VESCH
***Permissible Velocities are in accordance with Table 5-14 of the VESCH
Maximum Computed Depth=0.218'
Maximum Computed Velocity-4.62 ft/s (within channel banks)
Complex Channnel-Cross Section#5
Input:
Slope 0.080
Flow (given) 12.511
line x y n
0 0.000 550.000 0.033 (first n value not used)
1 3.000 549.000 0.033
2 15.000 549.000 0.033
3 18.000 550.000 0.033
Output:
Depth 0.218
(y) ( 549.218)
Channel bed segment output:
line Q V A P
1 0.20 2.81 0.07 0.69
2 12.11 4.62 2.62 12.00
3 0.20 2.81 0.07 0.69
Wed Nov 13 16:38:34 EST 2013
24-Hour SCS Method Calculations
U.S.Department of Agriculture FL-ENG-21A
Natural Resources Conservation Service 06/04
TR 55 Worksheet 2:Runoff Curve Number and Runoff
Project: Westlake Hills Designed By: KKW,PE Date: 5/14/2013
Location: Crozet along Future Connector Road Checked By: KKW,PE Date: 5/14/2013
Check One: Present X Developed X
1.Runoff curve Number(CN)
Cover description
Drainage Soil name and CN(weighted)=
(Cover type,treatment,and hydrologic condition; Area Product of CN Calculated'5'
Area hydrologic group CN total product/
Description (Appendix A) percent impervious;unconnected/connected (Acres) x Area Value
impervious area ratio)
total area
D.A#1
Impervious Areas 98 7.10 695.8
(Present) B Woods in Good Condition 55 6.10 335.5 69.0 4.50
Lawns in Good Condition(75%+Groundcover) 61 15.15 924.2
D.A.#1
Impervious Areas 98 14.77 1447.5
(Developed) B Woods in Good Condition 55 1.36 74.8 77.9 2.83
Lawns in Good Condition(75%+Groundcover) 61 15.63 953.4
D.A#2 Impervious Areas 98 0.00 0.0
(Present) B Woods in Good Condition 55 4.06 223.3 57.1 7.52
Lawns in Good Condition(75%+Groundcover) 61 2.14 130.5
D.A.#2
Impervious Areas 98 3.34 327.3
(Developed) B Woods in Good Condition 55 0.00 0.0 79.5 2.57
Lawns in Good Condition(75%-i-Groundcover) 61 3.33 203.1
2.Runoff
2-Year Storm 10-Year Storm Drainage Area Description
Frequency-years 2 10 n/a
Rainfall,P(24 hour)-inches 3.7 5.6 n/a
Runoff,0-inches 1.07 2.40 D.A#1(Present)
Runoff,Q-inches 1.65 3.22 D.A.#1(Developed)
Runoff,Q-inches 0.50 1.44 D.A#2(Present)
Runoff,4-inches 1.76 3.38 D.A.#2(Developed)
Runoff,0-inches
Runoff,0-inches
Runoff,0-inches
Runoff,0-inches
U.S.Department of Agriculture FL-ENG-21A
Natural Resources Conservation Service 06/04
TR 55 Worksheet 3:Time of Concentration(T,)or Travel Time(T,)
Project: Westlake Hills Designed By: KKW,PE Date: 5/14/2013
Location: Crozet along Future Connector Road Checked By: KKW,PE Date: 5/14/2013
Check One: Present X Developed X
Check One: T, X T, Through subarea n/a
D.A#1 D.A.#1 D.A#2 D.A.#2
Segment ID: (Present) (Developed) (Present) (Developed)
Sheet Flow:(Applicable to T,only)
Dense Grass Dense Grass Dense Grass Dense Grass
1 Surface description(Table 3-1)
2 Manning's roughness coeff.,n(Table 3-1 0.24 0.24 0.24 0.24
3 Flow length,L(total L<100)(ft) 100 100 100 100
4 Two-year 24-hour rainfall,P2(in.) 3.7 3.7 3.7 3.7
5 Land slope,s(ft/ft) 0.02 0.02 0.06 0.06
6 Compute Tr=[0.007(n*L)08]/P20.5 504 I 0.22 I 0.22 I 0.14 I 0.14
Shallow Concentrated Flow:
7 Surface description(paved or unpaved) Unpaved Unpaved Unpaved Unpaved
8 Flow Length,L(ft) 486 486 680 709
9 Watercourse slope,s(ft/ft) 0.038 0.038 0.138 0.082
10 Average velocity,V(Figure 3-1)(ft/s) 5.3 5.3 5.75 5
11 Tr=L/3600*V I 0.03 I 0.03 I 0.04 I 0.04
Channel Flow: a. o LL o N/A
J J N a)
12 Cross sectional flow area,a(ft2) o
n o n o
Tg > c > E
13 Wetted perimeter,P„,(ft) o m ■ ego' 0
14 Hydraulic radius,r=a/P„,(ft) v ° 0 iu E 0
c r o v =_ Q
•15 Channel Slope,s(ft/ft) E c E °
16 Manning's Roughness Coeff,n Y
2/3 O S y CO ..
17V=[1.49r s' ]/n m w ,�', w
18 Flow length,L(ft) ~ a ~ a
19"it=L/3600*V I 0.05 I 0.05 I I
20 Watershed or subarea T,or Tr
(Add T,in steps 6,11 and 19) I 0.30 ' 0.30 ' 0.18 I 0.18 I
U.S.Department of Agriculture FL-ENG-21C
Natural Resources Conservation Service 06/04
TR 55 Worksheet 4:Graphical Peak Discharge Method
Project: Westlake Hills Designed By:KKW,PE Date: 5/14/2013
Location: Crozet along Future Connector Road Checked By:KKW,PE Date: 5/14/2013
Check One: Present X Developed X
Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area
1.Data Description Description Description Description Description Description Description Description
D.A#1. D.A.#1 D.A#2 D.A.#2
(Present) (Developed) (Present) (Developed)
Drainage Area(Am)in miles'= 0.0443 0.0496 0.0097 0.0104
Runoff curve number CN= 69.0 77.9 57.1 79.5
Time of concentration(Tc)= 0.30 0.30 0.18 0.18
Rainfall distribution type= II II II II
Pond and swamp areas spread 0 0 0 0
throughout the watershed=
2.Frequency-years 2 1.0 2 10 2 10 2 10
3.Rainfall,P(24 hour)-inches 3.7 5.6 3.7 5.6 3.7 5.6 3.7 5.6
4.Initial Abstraction,la-inches 0.900 0.900 0.566 0.566 1.504 1.504 0.515 0.515
5.Compute la/P 0.24 0.16 0.15 0.10 0.41 0.27 0.14 0.09
6.Unit peak discharge,Qu-csm/in 600 650 655 680 600 760 800 1000
7.Runoff,Q from Worksheet 2-inches 1.07 2.40 1.65 3.22 0.50 1.44 1.76 3.38
8.Pond and Swamp adjustment factor,Fp 1 1 1 1 1 1 1 1
9.Peak Discharge,Qp-cfs Routed through Routed through Routed through
where Qp=Qu Am Q Fp SWM facility SWM facility 2.88 10.63 SWM facility
Summary of Watersheds
Pre-Development 2-Yr Flow 10-Yr Flow Post-Development 2-Yr Flow 10-Yr Flow
D.A.#1 28.35 ac. 9.77 13.92 D.A.#1 31.76 ac. 7.25 11.98
D.A.#2 15.35 ac. 2.88 10.63 D.A.#2 17.13 ac. 3.98 12.51
= 26.88 ac. 12.65 24.55 r= 26.62 ac. 11.23 24.49
U.S.Department of Agriculture FL-ENG-21A
Natural Resources Conservation Service 06/04
TR 55 Worksheet 2:Runoff Curve Number and Runoff
Project: Westlake Hills Phase I Designed By:JSN,EIT Date: 11/13/2013
Location: Albemarle County Checked By: FGM,PE Date: 11/13/2013
Check One:Present X Developed X
1.Runoff curve Number(CN)
Soil name and Cover description
Drainage Area CN(weighted)=
g (Cover type,treatment,and hydrologic condition; Area Product of CN Calculated'S'
hydrologic group CN total p roduct/
Description percent impervious;unconnected/connected (Acres) x Area Value
(Appendix A) total area
impervious area ratio)
D.A.#3
(Undisturbed) B Woods in Good Condition 55 34.93 1921.2 55.0 8.18
D.A.#18 1/4ac.Lots 75 40.00 3000.0
(Undisturbed) B Woods in Good Condition 55 59.86 3292.3 62.4 6.04
Lawns in Good Condition(75%+Groundcover) 61 48.53 2960.3
2.Runoff
2-Year Storm 10-Year Storm Drainage Area Description
Frequency-years 2 10 n/a
Rainfall,P(24 hour)-inches 3.7 5.6 n/a
Runoff,Q-inches 0.42 1.29 D.A.#3(Undisturbed)
Runoff,0-inches 0.73 1.85 D.A.#1B(Undisturbed)
Runoff,CI-inches
Runoff,Q-inches
Runoff,Q-inches
Runoff,Q-inches
Runoff,0-inches
Runoff,Q-inches
U.S.Department of Agriculture FL-ENG-21A
Natural Resources Conservation Service 06/04
TR 55 Worksheet 3:Time of Concentration(T0)or Travel Time(T5)
Project: Westlake Hills Phase I Designed By:JSN,EIT Date: #########
Location: Albemarle County Checked By: FGM,PE Date: #########
Check One: Present X Developed X
Check One: TO X Tt Through subarea n/a
D.A.#3 D.A.#1B
Segment ID: (Undisturbed) (Undisturbed)
Sheet Flow:(Applicable to TO only)
1 Surface description(Table 3-1) Woods(light brush) Woods(light brush)
2 Manning's roughness coeff.,n(Table 3-1 0.4 0.4
3 Flow length,L(total L<100)(ft) 100 100
4 Two-year 24-hour rainfall,P2(in.) 3.7 3.7
5 Land slope,s(ft/ft) 0.025 0.045
6 Compute Tt=[0.007(n*L)°'8]/P,°5 s0.4 I 0.30 I 0.24 I I I I
Shallow Concentrated Flow:
7 Surface description(paved or unpaved) Unpaved Unpaved
8 Flow Length,L(ft) 875 450
9 Watercourse slope,s(ft/ft) 0.067 0.082
10 Average velocity,V(Figure 3-1)(ft/s) 4.2 4.5
11 T=L/3600°V I 0.06 I 0.03 I I I I I I I
Channel Flow: E + E
12 Cross sectional flow area,a(ft2) v 0 0
—
a c Iv o
3 5) c 3 v
13 Wetted perimeter,Pw(ft) o o
.. L
14 Hydraulic radius,r=a/Pw(ft) c 3 o Y -0 c 3
15 Channel Slope,s(ft/ft) E CU o d c o d
16 Manning's Roughness Coeff,n - c -
2/3° j >
17V=( 1.49r s'5]/n o ro
18 Flow length,L(ft) it
19 Tt=L/3600*V I 0.01 I 0.75 I I I I I I I
20 Watershed or subarea T,or Tt
(Add Tt in steps 6,11 and 19) I 0.37 I 1.02 I I I I I I I
U.S.Department of Agriculture
FL-ENG-21C
Natural Resources Conservation Service 06/04
TR 55 Worksheet 4:Graphical Peak Discharge Method
Project: Westlake Hills Phase I Designed By:15N,EIT Date: 11/13/2013
Location: Albemarle County Checked By:FGM,PE Date: 11/13/2013
Check One: Present X Developed X
Drainage Area Area Drainage Area Drainage Area Drainage Area Drainage Area
1.Data Drainage Area Description Description Description Description Description Description Description
D.A.#3 D.A.#1B
(Undisturbed) (Undisturbed)
Drainage Area(Am)in miles= 0.0546 0.2319
Runoff curve number CN= 55.0 62.4
Time of concentration(Tc)= 0.37 1.02
Rainfall distribution type= II II
Pond and swamp areas spread 0 0
throughout the watershed=
2.Frequency-years 2 10 2 10
3.Rainfall,P(24 hour)-inches 3.7 5.6 3.7 5.6
4.Initial Abstraction,la-inches 1.636 1.636 1.208 1.208
5.Compute la/P 0.44 0.29 0.33 0.22
6.Unit peak discharge,Qu-csm/in 340 500 290 325
7.Runoff,Q from Worksheet 2-inches 0.42 1.29 0.73 1.85
8.Pond and Swamp adjustment factor,Fp 1 1 1 1
9.Peak Discharge,Qp-cfs
where Qp=Qu Am Q Fp 7.71 35.30 48.97 139.39
Routing Calculations
Existing Pond C-Retention Basin - Pond 1
BasinFlow printout
INPUT:
Basin: Westlake Hills - Existing Pond C SWM#1
9 Contour Areas
Elevation(ft) Area(sf) Computed Vol . (cy)
598.00 595.00 0.0
600.00 4349.00 161.8
602.00 10712.00 702.2
604.00 17982.00 1753.4
606.00 25792.00 3366.0
608.00 34715.00 5598.8
610.00 45866.00 8573.7
612.00 61084.00 12521.4
614.00 78078.00 17662.7
Start_Elevation(ft) 606.00 Vol . (cy) 3365.97
4 Outlet Structures
Outlet structure 0
Curve
name: Anti-Vortex Device
multiple 1
Invert (ft) 612.000
discharge into riser
file: sixty.txt
Outlet structure 1
Culvert
name: Barrel
multiple 1
discharge out of riser
D (in) 30.000
h (in) 0.000
Length (ft) 71.800
Slope 0.017
Manning's n 0.013
Inlet coeff. Ke 0.500
Equation constant set 0
Invert (ft) 595.140
Outlet structure 2
Wei r
name: Notched weir
length (ft) 1. 500
side angle 0.000
coefficient 3.000
invert (ft) 610.000
multiple 1
discharge into riser
Outlet structure 3
Orifice
name: Mid-Flow Orifice
area (sf) 0.196
diameter or depth (in) 6.000
width for rect. (in) 0.000
coefficient 0.600
invert (ft) 606.000
multiple 5
discharge into riser
Page 1
Existing Pond C-Retention Basin - Pond 1
3 Inflow Hydrographs
Hydrograph 0
sCs
name: 2-Yr 24-Hour SCS storm event
Area (acres) 31.760
CN 77.900
Type 2
rainfall , P (in) 3.700
time of conc. (hrs) 0.3000
time increment (hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 49.378
peak time (hrs) 12.010
volume (cy) 7010.917
Hydrograph 1
SCS
name: 10-Yr 24-Hour SCS storm event
Area (acres) 31.760
CN 77.900
pe
rainfall , PT(in) 2 5.600
time of conc. (hrs) 0.3000
time increment (hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 96.672
peak time (hrs) 12.010
volume (cy) 13725.915
Hydrograph 2
SCS
name: 100-Yr 24-Hour SCS storm event
Area (acres) 31.760
CN 77.900
pe
rainfall , PT(in) 2 9.100
time of conc. (hrs) 0.3000
time increment (hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 192.346
peak time (hrs) 12.010
volume (cy) 27310.236
OUTPUT:
Routing Method: storage-indication
Hydrograph 0
Routing Summary of Peaks: 2-Yr 24-Hour SCS storm event
inflow (cfs) 49.092 at 12.02 (hrs)
discharge (cfs) 7.246 at 12. 54 (hrs)
water level (ft) 608.602 at 12.56 (hrs)
storage (cy) 6407.780
Hydrograph 1
Routing summary of Peaks: 10-Yr 24-Hour SCS storm event
Page 2
Existing Pond C-Retention Basin - Pond 1
inflow (cfs) 96.112 at 12.02 (hrs)
discharge (cfs) 11.982 at 12.62 (hrs)
water level (ft) 610.606 at 12.62 (hrs)
storage (cy) 9650.982
Hydrograph 2
Routing summary of Peaks: 100-Yr 24-Hour SCS storm event
inflow (cfs) 191.232 at 12.02 (hrs)
discharge (cfs) 63.091 at 12.30 (hrs)
water level (ft) 612.895 at 12.30 (hrs)
storage (cy) 14666.598
Thu Feb 07 15:22:42 EST 2013
Page 3
Westlake Phase 1 Biofilter
BasinFlow printout
INPUT:
Basin: Bioretention Basin 2
7 Contour Areas
Elevation(ft) Area(sf) Computed vol . (cy)
553.00 679.00 0.0
554.00 7291.00 125.9
555.00 8285.00 414.1
556.00 9338.00 740.3
557.00 10578.00 1108.8
558.00 11492.00 1517.4
559.00 12435.00 1960.4
Start_Elevation(ft) 553.00 vol . (cy) 0.00
4 Outlet Structures
outlet structure 0
Orifice
name: Low-Flow orifices
area (sf) 0.196
diameter or depth (in) 6.000
width for rect. (in) 0.000
coefficient 0.600
invert (ft) 555.000
multiple 4
discharge into riser
Outlet structure 1
culvert
name: Barrel
multiple 1
discharge out of riser
D (in) 24.000
h (in) 0.000
Length (ft) 46.700
Slope 0.005
Manning's n 0.013
Inlet coeff. Ke 0.500
Equation constant set 3
Invert (ft) 550.200
Outlet structure 2
Curve
name: Riser
multiple 1
Invert (ft) 556.930
discharge into riser
file: thirty.txt
Outlet structure 3
weir
name: Emergency Spillway
length (ft) 7.000
side angle 63.000
coefficient 3.000
invert (ft) 557.550
multiple 1
discharge through dam
3 Inflow Hydrographs
Page 1
Westlake Phase 1 Biofilter
Hydrograph 0
SCS
name: 2-Yr 24-Hour SCS storm event
Area (acres) 6.670
CN 79.500
pe
rainfall , PT(in) 2 3.700
time of conc. (hrs) 0.1800
time increment (hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 13.092
peak time (hrs) 11.970
volume (cy) 1576.292
Hydrograph 1
SCS
name: 10-Yr 24-Hour SCS storm event
Area (acres) 6.670
CN 79.500
Type 2
rainfall , P (in) 5.600
time of conc. (hrs) 0.1800
time increment (hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 25.101
peak time (hrs) 11.970
volume (cy) 3022.221
Hydrograph 2
SCS
name: 100-Yr 24-Hour SCS storm event
Area (acres) 6.670
CN 79. 500
pe
rainfall , PT(in) 2 9.100
time of conc. (hrs) 0.1800
time increment (hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 49.121
peak time (hrs) 11.970
volume (cy) 5914.122
OUTPUT:
Routing Method: storage-indication
Hydrograph 0
Routing Summary of Peaks: 2-Yr 24-Hour SCS storm event
inflow (cfs) 13.092 at 11.96 (hrs)
discharge (cfs) 3.982 at 12.18 (hrs)
water level (ft) 556.360 at 12.18 (hrs)
storage (cy) 867.488
Hydrograph 1
Routing Summary of Peaks: 10-Yr 24-Hour SCS storm event
inflow (cfs) 25.101 at 11.96 (hrs)
discharge (cfs) 12.512 at 12.12 (hrs)
Page 2
westlake Phase 1 Biofilter
water level (ft) 557.474 at 12.12 (hrs)
storage (cy) 1298.193
Hydrograph 2
Routing Summary of Peaks: 100-Yr 24-Hour SCS storm event
inflow (cfs) 49.120 at 11.96 (hrs)
discharge (cfs) 42.635 at 12.04 (hrs)
water level (ft) 558.231 at 12.04 (hrs)
storage (cy) 1616.519
Mon Jul 29 16:00:03 EDT 2013
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Page 3