HomeMy WebLinkAboutWPO201300015 Calculations 2013-02-20 The Glenmore (lots 24-27&29) Subdivision Channel Adequacy Report& Calculations
Revisions noted in yellow
Overview
The following channel adequacy calculations were analyzed by dividing the watershed
into two major sections, drainage areas#1 and#2. These watersheds drain to the
receiving channel feeding Carroll Creek and are downstream of the proposed stormwater
management facility. Five cross sections were analyzed along this reach,which extend
approximately a tenth of a mile below the proposed facility's outfall. 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. #1:
This section consists of drainage flowing to the proposed extended detention facility.
This watershed has the following characteristics in the post-development state:
D.A.= 16.05 ac.
CN=73.4
Type II distribution
P= 3.7 inches(2-year event)
Tc= 0.21 hours
Drainage Area, D.A. #2:
This watershed is largely undisturbed with the proposed development, but drains to the
channel being analyzed. This watershed predominately consists of natural woods. This
drainage area contains the following characteristics:
D.A.=8.76ac..
CN= 72.1
Type II distribution
P=3.7 inches(2-year event)
Tc=0.20 hours
The following image shows the pre-development onsite ground cover for watershed#1,
which is predominately forest. It also lists the project's main soil types, which
predominantly have a hydrologic soil group of type B. Because these soils are type C,
this was used during the SCS TR-55 analysis of the watersheds for cross sections#1-5.
The ground covers for the soils were analyzed as being in good condition.
Onsite Pre-Develo.ment Ground Cover-DA#1
,,,,qmprrf..",,,ive_ ,op-
,„, D.A. #2
_Tow viii.
'7 r.
s, '',-',/'
4
z
f
Summary of Calculations
Drainage area#1 was routed through the stormwater management facility and generated a
peak 2-year flow of 17.07 cfs. The calculations showing this can be viewed within this
report under the title Stormwater Management Facility Routing Calculations.
The calculations resulting from drainage area#2 created a 2-year peak flow of 12.95 cfs.
The calculations showing this can be viewed within this report under the title SCS
Calculations. The combined flows from drainage areas#1 and 2 generate a maximum 2-
year flow of 30.02 cfs draining to the channel. This is a worst case scenario because it
assumes both peak flows occur simultaneously,despite the fact the time of peak flow
being released from the stormwater management facility is much later than that of
drainage area#2. The combined flow was used during the analysis of cross sections#1-5.
The five cross sections analyzed are representative of the receiving channel.
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MS-19 Cross Section#1:
Note Loam & Cobbles mixture within the channel
Now
..' �
a -
•
'1 , ! -
4,' }AY C
` ‘ i
r
The channel at cross section 1, which has an approximate slope of 3 percent, contains the
following characteristics:
Within the Channel Banks:
Description: (loam& cobbles mixture)
`n' value for channel: 0.065*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
Please see attached derivations.
**Permissible Velocities are in accordance with Table 5-22 of the VESCH
Maximum Computed Depth=1.33'
Maximum Computed Velocity=4.79 ft/s (within channel banks)
Complex Channnel- Cross Section No. 1
Input:
Slope 0.030
Flow (given) 30.021
line x y n
0 0.000 3.000 0.065 (first n value not used)
1 3.000 0.000 0.065
2 7.000 0.000 0.065
3 8.000 1.000 0.065
4 10.000 3.000 0.065
Output:
Depth 1.332
(y) ( 1.332)
Channel bed segment output:
line Q V A P
1 2.13 2.40 0.89 1.88
2 25.53 4.79 5.33 4.00
3 2.31 2.78 0.83 1.41
4 0.05 0.95 0.06 0.47
Wed Apr 17 15:45:04 EDT 2013
file:///C1/Users/Graham/Desktop/Glenmore/Cross%20Section%20No.%201_txt[4/17/2013 4:26:35 PM]
MS-19 Cross Section#2:
(Note: Loam & Cobbles mixture within the channel
lti r4 a y� ,f hor
-i,,.. , i',.... i
�. 3' -
.r.'ir is r ...' �►
' q
* . . ,
- I.
Ali"
,r
The channel at cross section 2, which has an approximate slope of 3.5 percent, contains
the following characteristics:
Within the Channel Banks:
Description: (loam & cobbles mixture)
`n' value for channel: 0.065*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
Please see attached derivations.
**Permissible Velocities are in accordance with Table 5-22 of the VESCH
Maximum Computed Depth=1.23'
Maximum Computed Velocity=4.92 ft/s (within channel banks)
Complex Channnel- Cross Section No. 2
Input:
Slope 0.035
Flow(given) 30.021
line x y n
0 0.000 4.000 0.065 (first n value not used)
1 2.000 1.000 0.065
2 4.000 0.000 0.065
3 8.000 0.000 0.065
4 10.000 3.000 0.065
Output:
Depth 1.232
(y) ( 1.232)
Channel bed segment output:
line Q V A P
1 0.01 0.69 0.02 0.28
2 4.72 3.23 1.46 2.24
3 24.23 4.92 4.93 4.00
4 1.06 2.09 0.51 1.48
Wed Apr 17 15:46:05 EDT 2013
file:///C1/Users/Graham/Desktop/Glenmore/Cross%20Section%20No.%202.txt[4/17/2013 4:26:35 PM]
MS-19 Cross Section#3:
(Note: Loam & Cobbles mixture within the channel
.ih. 5 s., - f'
.
. a s.'i '"" 1r. . s�
9/.4.mot► , "` y r .. - r -1.7h.
IN: ,, ot, , ,,„,, fog/cietii5:, A ,, ,
y.
s
The channel at cross section 3, which has an approximate slope of 3.5 percent, contains
the following characteristics:
Within the Channel Banks:
Description: (loam& cobbles mixture)
`n' value for channel: 0.065*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
Please see attached derivations.
**Permissible Velocities are in accordance with Table 5-22 of the VESCH
Maximum Computed Depth=1.25'
Maximum Computed Velocity=4.95 ft/s (within channel banks)
Complex Channnel- Cross Section No. 3
Input:
Slope 0.035
Flow (given) 30.021
line x y n
0 0.000 5.000 0.065 (first n value not used)
1 3.000 1.000 0.065
2 3.500 0.000 0.065
3 7.000 0.000 0.065
4 10.000 1.000 0.065
5 11.000 2.000 0.065
Output:
Depth 1.246
(y) ( 1.246)
Channel bed segment output:
line Q V A P
1 0.02 0.75 0.02 0.31
2 0.77 2.06 0.37 1.12
3 21.60 4.95 4.36 3.50
4 7.61 3.40 2.24 3.16
5 0.03 0.84 0.03 0.35
Wed Apr 17 15:47:43 EDT 2013
file:///CI/Users/Graham/Desktop/Glenmore/Cross%20Section%20No.%203.txt[4/17/2013 4:26:35 PM]
MS-19 Cross Section#4:
Note: Loam & Cobbles mixture within the channel
+ '''s�w,,
b -=;ir - ''.'tir"" 1-iN ,,,.-P4 47: *`:-*
A-
4f114410
*lit% * N
r
w
The channel at cross section 4, which has an approximate slope of 4 percent, contains the
following characteristics:
Within the Channel Banks:
Description: (loam& cobbles mixture)
`n' value for channel: 0.065*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
Please see attached derivations.
**Permissible Velocities are in accordance with Table 5-22 of the VESCH
Maximum Computed Depth=1.11'
Maximum Computed Velocity=4.90 ft/s (within channel banks)
Complex Channnel- Cross Section No. 4
Input:
Slope 0.040
Flow(given) 30.021
line x y n
0 0.000 6.000 0.065 (first n value not used)
1 2.000 1.000 0.065
2 4.000 0.000 0.065
3 8.000 0.000 0.065
4 13.000 2.000 0.065
Output:
Depth 1.110
(y) ( 1.110)
Channel bed segment output:
line Q V A P
1 0.00 0.34 0.00 0.12
2 3.73 3.05 1.22 2.24
3 21.77 4.90 4.44 4.00
4 4.53 2.94 1.54 2.99
Wed Apr 17 15:50:24 EDT 2013
file:///CV/Users/Graham/Desktop/Glenmore/Cross%20Section%20No.%204.txt[4/17/2013 4:26:36 PM]
MS-19 Cross Section#5:
(Note: Loam & Cobbles mixture within the channel
<" z- "
liv.
' 1 y '•* ,,
f., 1. S. "+�'^_, ;fit ;. .r- ..�`. ,
•
-ft; � ,w �� ice•-: , ,� ��
.. •iA ` <t
itti
a
The channel at cross section 5, which has an approximate slope of 5.5 percent, contains
the following characteristics:
Within the Channel Banks:
Description: (loam& cobbles mixture)
`n' value for channel: 0.065*
Permissible Velocity: 5.0 ft/s**
*Manning's `n'values are in accordance with Tables 5-16 through 5-21 of the VESCH.
Please see attached derivations.
**Permissible Velocities are in accordance with Table 5-22 of the VESCH
Maximum Computed Depth=0.88'
Maximum Computed Velocity=4.94 ft/s (within channel banks)
Complex Channnel- Cross Section No. 5
Input:
Slope 0.055
Flow (given) 30.020
line x y n
0 0.000 4.000 0.065 (first n value not used)
1 2.000 1.000 0.065
2 4.000 0.000 0.065
3 10.000 0.000 0.065
4 13.000 2.000 0.065
Output:
Depth 0.883
(y) ( 0.883)
Channel bed segment output:
line Q V A P
1 0.00 0.00 0.00 0.00
2 2.25 2.89 0.78 1.98
3 26.16 4.94 5.30 6.00
4 1.61 2.75 0.59 1.59
Wed Apr 17 15:50:10 EDT 2013
file:///C1/Users/Graham/Desktop/Glenmore/Cross%20Section%20No.%205.txt[4/17/2013 4:26:36 PM]
Stormwater Management Facility Routing
Calculations
(Revised)
BasinFlow printout
INPUT:
Basin: Glenmore Lots 24-27 Extended Detention Basin
9 Contour Areas
Elevation(ft) Area(sf) Computed Vol.(cy)
336.00 935.00 0.0
338.00 1795.00 99.4
340.00 3131.00 279.6
342.00 4540.00 562.1
344.00 6391.00 965.0
346.00 8345.00 1509.1
348.00 10715.00 2213.2
350.00 13233.00 3098.6
351.00 14680.00 3615.2
Start_Elevation(ft) 336.00 Vol.(cy) 0.00
5 Outlet Structures
Outlet structure 0
Orifice
name: 30hr Drawdown Orifice
area(sf) 0.049
diameter or depth (in) 3.000
width for rect. (in) 0.000
coefficient 0.600
invert (ft) 336.000
multiple 1
discharge into riser
Outlet structure 1
Orifice
name: Mid-Flow Orifices
area(sf) 0.785
diameter or depth (in) 12.000
width for rect. (in) 0.000
coefficient 0.600
invert (ft) 339.000
multiple 3
discharge into riser
Outlet structure 2
Orifice
name: High-Flow Orifices
area(sf) 0.785
diameter or depth (in) 12.000
width for rect. (in) 0.000
coefficient 0.600
invert (ft) 344.000
multiple 3
discharge into riser
file:///Cl/Users/Graham/Desktop/Glenmore/Glemore%20Lots%2024-27%20Extended%20Detention%20Basin.txt[4/17/2013 4:26:36 PM]
Outlet structure 3
Curve
name: 42" Conc. Riser w/Anti-Vortex Device
multiple 1
Invert (ft) 347.820
discharge into riser
file: forty-two.txt
Outlet structure 4
Culvert
name: 36" Barrel
multiple 1
discharge out of riser
D (in) 36.000
h (in) 0.000
Length (ft) 137.000
Slope 0.005
Manning's n 0.013
Inlet coeff. Ke 0.500
Equation constant set 3
Invert (ft) 336.000
3 Inflow Hydrographs
Hydrograph 0
SCS
name: 2-yr 24-hr Peak SCS Storm
Area (acres) 16.050
CN 73.400
Type 2
rainfall, P (in) 3.700
time of conc. (hrs) 0.2100
time increment(hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 23.079
peak time (hrs) 11.982
volume (cy) 2891.709
Hydrograph 1
SCS
name: 10-yr 24-hr Peak SCS Storm
Area (acres) 16.050
CN 73.400
Type 2
rainfall, P (in) 5.600
time of conc. (hrs) 0.2100
time increment(hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 48.114
peak time (hrs) 11.982
file:///C1/Users/Graham/Desktop/Glenmore/Glemore%20Lots%2024-27%20Extended%20Detention%20Basin.txt[4/17/2013 4:26:36 PM]
volume (cy) 6028.639
Hydrograph 2
SCS
name: 100-yr 24-hr Peak SCS Storm
Area (acres) 16.050
CN 73.400
Type 2
rainfall, P (in) 9.100
time of conc. (hrs) 0.2100
time increment(hrs) 0.0200
time limit (hrs) 30.000
fudge factor 1.00
routed true
peak flow (cfs) 100.578
peak time (hrs) 11.982
volume (cy) 12602.309
OUTPUT:
Routing Method: storage-indication
Hydrograph 0
Routing Summary of Peaks: 2-yr 24-hr Peak SCS Storm
inflow(cfs) 23.062 at 11.98 (hrs)
discharge (cfs) 17.072 at 12.08 (hrs)
water level (ft) 341.622 at 12.08 (hrs)
storage (cy) 500.443
Hydrograph 1
Routing Summary of Peaks: 10-yr 24-hr Peak SCS Storm
inflow(cfs) 48.079 at 11.98 (hrs)
discharge (cfs) 29.984 at 12.10 (hrs)
water level (ft) 344.564 at 12.10 (hrs)
storage (cy) 1103.838
Hydrograph 2
Routing Summary of Peaks: 100-yr 24-hr Peak SCS Storm
inflow(cfs) 100.505 at 11.98 (hrs)
discharge (cfs) 64.019 at 12.10 (hrs)
water level (ft) 348.254 at 12.10 (hrs)
storage (cy) 2315.310
Wed Apr 17 09:51:41 EDT 2013
file:///C1/Users/Graham/Desktop/Glenmore/Glemore%20Lots%2024-27%20Extended%20Detention%20Basin.txt[4/17/2013 4:26:36 PM]
S C S 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: Glenmore Leake K2 Lots 24-27 Designed By: FGM,PE Date: 1/13/2013
Location: Located off of Farringdon Road&Running Deer Drive Checked By: FGM,PE Date: 1/13/2013
Check One: Present X Developed X
1.Runoff curve Number(CN)
Drainage Soil name and Cover description
CN(weighted)= Calculated
Area hydrologic group (Cover type,treatment,and hydrologic condition; CN Area Product of CN total product/
Description (Appendix A) percent impervious;unconnected/connected
(Acres) x Area total area '5'Value
impervious area ratio)
D.A#1 Impervious Areas(Two existing residences) 98 0.26 25.5
(Present) C Woods in Good Condition 70 13.79 965.3 71.0 4.09
Lawns in Good Condition(75%+Groundcover) 74 2.00 148.0
D.A.#1 Impervious Areas(Lots 24-27,Roads&2 ex.residences) 98 1.15 112.5
(Developed) C Woods in Good Condition 70 9.49 664.3 73.4 3.63
Lawns in Good Condition(75%+Groundcover) 74 5.41 400.5
Impervious Areas(2 assumed existing residences) 98 0.26 25.5
D.A.#2
(Chl Adq.)
C Woods in Good Condition(approx.remaining 2/3rd) 70 5.67 396.7 72.1 3.86
Lawns in Good Condition(approx.remaining 1/3rd) 74 2.83 209.7
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 1.19 2.58 D.A#1(Present)
Runoff,Q-inches 1.34 2.79 D.A.#1(Developed)
Runoff,Q-inches
Runoff,Q-inches
Runoff,Q-inches 1.26 2.68 D.A.#2(Chl Adq.)
Runoff,Q-inches
Runoff,Q-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(T,)or Travel Time(T,)
Project: Glenmore Leake K2 Lots 24-27 Designed By:FGM,PE Date: 1/13/2013
Location: Located off of Farringdon Road&Running Deer Drive Checked By:FGM,PE Date: 1/13/2013
Check One: Present X Developed X
Check One: T, X T, Through subarea n/a
D.A#1 D.A.#1 D.A.#2
Segment ID: (Present) (Developed) (Chl Adq.)
Sheet Flow:(Applicable to T,only)
Woods Woods Woods
1 Surface description(Table 3-1) (Light Underbrush) (Light Underbrush) (Light Underbrush)
2 Manning's roughness coeff.,n(Table 3-1 0.4 0.4 0.4
3 Flow length,L(total L<100)(ft) 100 100 100
4 Two-year 24-hour rainfall,Pz(in.) 3.7 3.7 3.7
5 Land slope,s(ft/ft) 0.09 0.09 0.1
6 Compute T,=[0.007(n•L)°a]/P2°5 s°' I 0.182 I 0.182 I I I 0.17 I J
Shallow Concentrated Flow:
7 Surface description(paved or unpaved) Unpaved Unpaved Unpaved
8 Flow Length,L(ft) 525 525 600
9 Watercourse slope,s(ft/ft) 0.139 0.139 0167
10 Average velocity,V(Figure 3-1)(ft/s) 6 6 6.5
11 7,=L/3600•V I 0.024 I 0.024 I 1 I 0.03 I I I
Channel Flow:
12 Cross sectional flow area,a(ft2)
13 Wetted perimeter,P,,(ft)
14 Hydraulic radius,r=a/P„,(ft)
15 Channel Slope,s(ft/ft)
16 Manning's Roughness Coeff,n
17 V=[1.49r2/3s s]/n
18 Flow length,L(ft)
19 T,=L/3600.V I I I I I I I I
20 Watershed or subarea T,or T,
(Add T,in steps 6,11 and 19) ( 0.21 ' 0.21 I I ' 0.20 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: Glenmore Leake K2 Lots 24-27 Designed By:FGM,PE Date: 1/13/2013
Location: Located off of Farringdon Road&Running Deer Di Checked By:FGM,PE Date: 1/13/2013
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
(Present) (Developed) (Chl Adq.)
Drainage Area(Am)in miles2= 0.0251 0.0251 0.0137
Runoff curve number CN= 71.0 73.4 72.1
Time of concentration(Tc)= 0.21 0.21 0.20
Rainfall distribution type= II II II
Pond and swamp areas spread 0 0 0
throughout the watershed=
2.Frequency-years 2 10 2 10 2 10
3.Rainfall,P(24 hour)-inches 3.7 5.6 3.7 5.6 3.7 5.6
4.Initial Abstraction,la-inches 0.819 0.819 0.727 0.727 0.773 0.773
5.Compute la/P 0.22 0.15 0.20 0.13 0.21 0.14
6.Unit peak discharge,Qu-csm/in 725 750 725 750 750 775
7.Runoff,Qfrom Worksheet 2-inches 1.19 2.58 1.34 2.79 1.26 2.68
8.Pond and Swamp adjustment factor,Fp 1 1 1 1 1 1
9.Peak Discharge,Qp-cfs Routed through
where Qp=Qu Am Q Fp 21.64 48.45 SWM Facility 12.95 28.44
41.0k44, ^.�SZT' L:�Ci ;1',.f (ALCALATY:C
'} (¢3" &v u, RL COMM�, p'tscw'ID Coo& t rt.) Acct 0f\i, w/ \J M.-(
°e'ri a USM� or��: s= zNS s'"c-J^J LO)
\r`, = Lev @ a xWciN) —
J 339—336
‘()w3 ' 1.5 i4
ck - �_ wNtRG Q ° Qcvr
a 0.\10V L-{0"11'7 �3
CN
a3\1 30 kr 36co s
0$,oce� = 0.0 39, - vis
({'i.ot-{ Tv,kou40{
0.039 ` Lew-row Orksyc�
Q ( CckRLshoaa,_*riC To
a.C443a.1,)(i,$) B.x waa�
®• =
0.O065 �a P,,o O.0066 =
`' 'k o.55 \Ts.
Supplemental Cross Sectional Data
(Revised)
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