HomeMy WebLinkAboutSDP200900084 CalculationsProject:Meadowcreek Parkway Basin: Det. Pond Sta. 69 +00 Left Engineer SGI
Checker.
VDOT PROJ # 0631- 002 -128, C502 Date:
Pre Developed Conditions Post Developed Conditions
C =0.35 C =0.44
Area (ac) =24.46 Area (ac) =24.46
Tc (min) =20.0 Tc (min) =17.2
1 Rainfall Intensity- Duration - Frequency Data
County:Albemarle
Source:
Frequency of Occurrence Frequency of Occurrence Frequency of Occurrence
2 - year 10 - year 100 - year
time Intensity time Intensity time Intensity
min)in /hr)min)in /hr) min)in /hr)
5 5.18 5 6.67 5 8.76
10 4.12 10 5.37 10 7.01
15 3.44 15 4.55 15 5.98
20 2.97 20 3.97 20 5.29
25 2.63 25 3.54 25 4.79
30 2.36 30 3.21 30 4.40
35 2.14 35 2.94 35 4.09
40 1.97 40 2.72 40 3.83
45 1.82 45 2.54 45 3.62
50 1.70 50 2.38 50 3.43
55 1.59 55 2.24 55 3.27
60 1.50 60 2.12 60 3.13
Pond Results Summary
2 -Year 10 -Year 100 -Year
Qmax (pre) =25 cfs Qmax (pre) = 34 cfs Qmax (pre) = 57 cfs
Qmax (post) =35 cfs Qmax (post) = 46 cfs Qmax (post) = 76 cfs
Qcritical=35 cfs Qcritical= 45 cfs Qcritical= 62 cfs
MODRAT Max.
0.28 acre-feet
MODRAT Max.
0.36 acre-feet
MODRAT Max.
0.63 acre-feet
Pond Volume =Pond Volume =Pond Volume =
Reservoir Routing Results
Outflow Qmax =24 f cfs Outflow Qmax =1 34 Ids Outflow Qmax =1 61 cfs
Max. Pond Max. Pond Max. Pond
Storage =
0.54 acre -feet
Storage
0.61 acre -feet
Storage =
0.74 acre -feet
Max. Pond Max. Pond Max. Pond
Water Surface 408.87 feet Water Surface 409.21 feet Water Surface 409.86 feet
Elevation =Elevation. =Elevation. =
ga la ' :wL 0
Project:Meadowcreek Parkway Basin: Det. Pond Sta. 69 +00 Left Engineer:SGI
0 Checker.0
VDOT PROJ *0631-002-12R, C502 Date:06/25/2007
Hydrologic Parameters Modified Rational Method
Recurrence Interval:2 Year
County: Albemarle VDOT County Number: 2
Inflow Hydrograph Determination
Modified Rational Method according to Virginia Stormwater Manual Handbook, 1999
Inflow and Release Rate Hydrographs
2 -Year Storm - Modified Rational Method
Compute Release Rate Hydrograph
Pre Developed Conditions 40
C = 0.35
C(f) = 1.00 35 f
Area (ac) = 24.46
Tc (min) = 20.0 Time (min) Q (cfs) 30
1 (in /hr) = 2.97 0 0
Q (cfs) =25 24.24 25 25
U
Eq.1 20 I-
Compute Inflow Hydrograph o
Post Developed Conditions Time Discharge B 15
I —C = 0 44 min) Q crit (cfs)
C(f) = 1.00 0.00 0
Area (ac) = 24.46 17.20 35
Tc (min) = 17.2 17.40 35
T crit
l (in /hr) =
17.40 43.20 03.24 0 l
I crit (in /hr) = 3.22
0 10 20 30 40 50
Q (cfs) =35 Time (min)
Q crit (cfs) =35
Maximum Storage Volume by MODRAT:12101 cubic feet
0.28 acre -feet
Calculation Check
areas under the hydrograph by geometry
Inflow=45090.94
outflow=32989.59
Storage Volume= 12101.35
Check Message= OK
Project.Meadowcreek Parkway Basin: Det. Pond Sta. 69 +00 Left Engineer:SGI
0 Checker:0
VDOT PROJ # 0631 - 002 -128, C502 hate:06/25/2007
Hydrologic Parameters Modified Rational Method
Recurrence Interval:10 Year
County Albemarle VDOT County Number: 2
Inflow Hydrogra ph Determination
Modified Rational Method according to Virginia Stormwater Manual Handbook, 1999
Inflow and Release Rate Hydrographs
10 -Year Storm - Modified Rational Method
Compute Release Rate Hydrograph
Pre Developed Conditions 50 i
C = 0.35 45
C(f) = 1.00
Area (ac) = 24.46 40
Tc (min) = 20.0 Time (min) Q (cfs)35
I (in /hr) = 3.97 0 0
Q (cfs) =34 24.50 34 5 30 I.j
3ComputeInflowHydrographo
25
Post Developed Conditions Time Discharge t 20 -i
C = 0.44 min) Q crit (cfs) 15C(f) = 1.00 0.00 0
Area (ac) = 24.46 17.20 45 10
Tit (min) = 17.2 18.20 45
0
T crit min 18.20 4044.00 0
I (in /hr) = 4.29
I crit (in /hr) = 4.18 0 10 30 40 502Q
Time (cfs) =46 Time (min)
Q crit (cfs) =45
Maximum Storage Volume by MODRAT:15828 cubic feet
0.36 acre -feet
Calculation Check
areas under the hydrograph by geometry
Inflow=60678.59
outflow=44850.16
Storage Volume= 15828.43
Check Message= OK
Project:Meadowcreek Parkway Basin: Det. Pond Sta. 69 +00 Left Engineer:SGI
0 Checker.0
VDOT PROJ St 0631=002-12 0502 06/25/2007Datc:
Hydrologic Parameters Modified Rational Method
Recurrence Interval:100 Year
County: Albemarle VDOT County Number: 2
Inflow Hydrograph Determination
Modified Rational Method according to Virginia Stormwater Manual Handbook, 1999
Inflow and Release Rate Hydroyraphs
100 -Year Storm - Modified Rational Method
Compute Release Rate Hydrograph
Pre Developed Conditions 70 i
1.25C(f) -1.25 i 60
Area (ac) = 24 46
Tc (min) = 20.0 Time (min) Q (cfs)50 F
I (in /hr) = 5.29 0 0
Q (cfs) =57 29.71 57 40
Compute Inflow Hydrograph oX30 -
Post Developed Conditions Time Discharge c i
C = 0 44 min) Q crit (cfs)
C(f) = 1.25 0.00 0 20
T crit (min) = 27.60 53.40 0
Area (ac)24.46 17.20 62
Tit min
27.60
27.60 62 10
I (in /hr) = 5.68 0 6 --
I crit (in /hr) = 4.59 0 10 20 30 40 50 60
Q (cfs) =76 L Time (min)
Q crit (cfs) =62
Maximum Storage Volumeby MODRAT:27338 cubic feet
0.63 acre -feet
Calculation Check
areas under the hydrograph by geometry
Inflow=118088.7
outflow=90750.86
Storage Volume. 27337.82
Check Message: OK
Project: Meadowcreek Parkway Basin:Det. Pond Sta. 69 +00 Left Engineer.SGI
0 Checker'0
VDOT PROJ # 0631- 002 -128, C502 Date:06/25/2007
STAGE STORAGE CALCULATIONS
V =10 * IA1 + A2 + SQRT(A1 *A2)I
Elevation Area nor Depth Inc. Volume TOTAL VOLUME
ft)acres ft acre -ft acre -ft cu.ft
405.00 0.10 0.00 0.00 0.00 0.00
406.00 0.12 1.00 0.11 0.11 4784.99
407.00 0 14 1.00 0.13 0 24 10442.19
408 00 0 16 1.00 0.15 0.39 16971.35
409.00 0.19 1.00 0.17 0.56 24585.00
410 00 0.21 1.00 0.20 0.76 33293.36
0.00 0.00 0.00 0.00
0 00 0.00 0.00 0.00
0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00
Project.Meadowcreek Parkway Basin:Det. Pond Sta. 69 Engineer:SGI 1
0 Checker:0 I
VDOT PROJ # 0631 - 002 -128, C502 Date:06/25/2007
Virginia State Stormwater Management BMP Calculations (VDOT Methodology)
Objective Provide a 30 hour drawdown time for BMP pool based on the selected water quality depth and BMP volume options Use minimum 3 -inch orifice.
Total Drainage Area to SWM Basin 24.46 Acres
Total Project Area (mcl slopes) to SWM Bann Acres
Total Impervious Area to SWM Basin 5.10 Acres
Water Quality Depth Option (0 5 -Inch is multiplied by the number entered)2.0 multiple of 0.5 -inch
This design Is based on 1 0 Inch of runoff I
Option Volume (Ac -ft) Elevation (ft)
1 BMP Volume Required for Entire Drainage Area 2.038 NUM!
2 BMP Volume Required for Project Area Only 0 000 405.00
3 BMP Volume Required for Impervious Area Only 0 425 408.20
Stage - Storage Relationship for SWM Basin
Elevation (ft)Storage (Cu Ft)Storage (Ac -Ft)
405.00 0 0 000
406.00 4785 0.110
407.00 10442 0.240
408.00 16971 0 390
409.00 24585 0.564
410.00 33293 0.764
0.00 0 0.000
0.00 0 0.000
0.00 0 0 000
BMP Volume and Elevation Calculations
For this SWM Basin, Water Quality is based on BMP Volume Required for Impervious Area Only
Water Quality Volume Required 0.425 Ac -Ft occurs @ 408.20 feet
Water Quality Volume Provided 0.407 Ac -Ft occurs @ 408.10 feet
Water Quality Pool Drawdown Time
Invert of BMP Opening 405.00 Feet (Elevation)
Dia of BMP Opening 2.5 Inches
Area of BMP Opening 0.03 Square Feet
Centroid of BMP Opening 405.10 Feet (Elevation)
BMP Drawdown Time 31.00 Hours
Based on Incremental Calculations)
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Prolecl Meadowcreek Parkway Basin:Det. Pond Sta. 69 +00 Left Engineer SGI
0 Checker 0
VDOT PROJ # 0631 -002 -128, C502 Date.
Min Elev.405.0
Top of Dam Elev= 410.9
Reservoir Routing Variables and Relationships
See Instructions below table to set the interpolation 1,Tiges ronec!!y Perc Elevation Discharge Storage (2S /dt) +0 (2S /dt) +O (2S /dt) +O
Stage flow Edit source data for both graphs to include the ft) cfs) cf) 2YR 10YR 100YR
ft) cfs) desired range of discharge of storage array
405.0 0.00 0 00 405.00 0.00 0 0.00 0.00 0 00
405.5 0.10 416 _.- -0 02 405 12 0.02 565 10.97 10.97 10.97
0 04 405 24 0 05 1129 21.93 21.93 21.93
406.5 0.19 414 I 0 06 405 35 0.07 1694 32.90 32.90 32.90
407.0 0.23 m 412 j 0.08 405 47 0.10 2259 43 87 43 87 43.87
407.5 0.25 I 0 10 405.59 0 11 2823 54 82 54 82 54 82
408.0 0.28 I o 410 -0.12 405 71 0 12 3388 65.78 65 78 65 78
408.5 9.41 408 0 14 405 83 0.14 3952 76.73 76 73 76.73
409.0 29.56 w 0.16 405 94 0 15 4517 87 69 87 69 87.69
409.5 40.83 406 0.18 406.06 0.16 5136 99.69 99 69 99.69
410.0 69.19 404 - -- - 0 20 406.18 0.17 5803 112.64 112.64 112 64
410.5 107.28 0 50 100 150 200 250 0.22 406.30 0.18 6471 125.58 125 58 125 58
411.0 152.62 0.24 406 42 0 19 7138 138.53 138 53 138.53
411.5 203.58 Discharge (cfs)0.26 406.53 0.20 7806 151.47 151 47 151.47
412.0 #NUM!j 0.28 406.65 0.20 8473 164.42 164.42 164 42
412.5 #NUMI 0.30 406.77 0.21 9141 177,36 177 36 177.36
413.0 #NUM!0.32 406 89 0.22 9809 190.31 190.31 190 31
413.5 #NUMI
411
I I 0.34 407.01 0.23 10481 203.35 203.35 203.351
414.0 #NUMI 410 - -0.36 40712 0.23 11252 218.29 218.29 218.29
414.5 #NUM! a> 409 I -0.38 407.24 0.24 12022 233.23 233.23 233 23
415.0 #NUMI 408
0 40 407.36 0 25 12793 248.17 248.17 248.17
415.5 #NUM! 0 0.42 407.48 0.25 13563 263.10 26310 26310
416.0 #NUM!407 -i 0.44 407.60 0.26 14334 278.04 278.04 278.04
416.5 #NUMI a'1 406 0 46 407.71 0.26 15104 292.98 292 98 292.98
417.0 #NUMI w
405 0.48 407.83 0.27 15874 307.92 307.92 307.92
417.5 #NUMI 0 50 407.95 0.28 16645 322.85 322.85 322 85
418.0 #NUM!404 -- --+ 1 0.52 408 07 1.52 17489 340.46 340 46 340 46
418.5 #NUMI 0.00 0.20 0 40 0.60 0.80 1.00 0.54 408.19 3.68 18387 360.02 360.02 360.02
419.0 #NUMI Storage (acre -feet)0.56 408.30 5.83 19286 379.59 379.59 379.59
419.5 #NUMI 0.58 408.42 7.99 20184 399.15 399.15 39915
420.0 #NUM!0 60 408.54 11.02 21083 419.60 419 60 419.60
420.5 #NUM!0.62 408.66 15.78 21981 441.77 441.77 441.77
Project: Meadowcreek Parkway Basin Det. Pond Sta. 69 +00 Left Engineer:SGI
0 Checker:0
VDOT PROD # 0631 - 002 -128, 0502 Date.06125/20
Reservoir Routing
Reservoir Routing Computations Modified Rational 2 Year Event
Modified Rational Inflow Hydrograph 40 i—
Direct Solution Method - Reservoir Routing 35 I Inflow 1
30 i1 — Outflow
2 Year Storm Event
w 25
u
Pre - Developed Q 25 cfs
Post - Developed Q - Peak 35 cfs
20
Post - Developed Q (crit)35 cfs u- 15
Pond out 0 - Peak 24 cfs 10
Pond outflow is less than Q(pre)5
Routing 0 -
Max Q out Max El T (hrs) Max St. (cu-ft)20 30 40 50 60 70
24.50 408.87 0.43 23628 Time (min)
Quality Control Check for Program Accuracy
Time Step (min)= 1.7 Total Inflow Total Outflow Storage I- (O +S)] / I
cubic -feet cubic -feet cubic -feet Error
45091 30200 14891 0.00%
Project. Meadowcreek Parkway Basin:Det. Pond Sta. 69 +00 Left Engineer:SGI
0 Checker:0
DOT PROJ # 0631- 002 -128, C502 Date:06/25/2007
Reservoir Routing
Reservoir Routing Computations Modified Rational 10 Year Event
Modified Rational Inflow Hydrograph 50
Direct Solution Method - Reservoir Routing 45 Inflow
40 Outflow - --
10 Year Storm Event 35
30
Pre - Developed Q 34 cfs 25
Post - Developed Peak 46 cfs o 20 J
HPondoutQ - Peak (
crit) )
34 cfs
LL
15 I
Exceeding Q(pre)10
Post - Developed Q crit 45 cfs
5 1
Routing 0 I I
Max Q out Max El T (hrs) Max St (cu -ft)0 10 20 30 40 50 60 70
34.28 409.21 0.40 26410 Time (min)
Quality Control Check for Program Accuracy
Time Step (min).- 1.7 Total Inflow Total Outflow Storage fl-(0-S)] / I
cubic -feet cubic -feet cubic -feet Error
60679 45759 14919 0.00%
Project: Meadowcreek Parkway Basin:Det. Pond Sta. 69 +00 Left Engineer:SGI
0 Checker:0
VDOT PROD 4 0631 - 002-128, C502 Date:06/25/2007
Reservoir Routing
Reservoir Routing Computations 70
Modified Rational 100 Year Event
i
Modified Rational Inflow Hydrograph
Direct Solution Method - Reservoir Routing 60
Inflow
Outflow
100 Year Storm Event 50
15 40
Pre - Developed 0 57 cts
Post - Developed Q - Peak 76 cts 0 30
Post - Developed Q (crit)62 cfs r `
Pond out Q Peak 61 cfs 20
Exceeding Q(pre)10
Routing 0
Max Q out Max El T (hrs) Max St. (cu -ftt)0 10 20 30 40 50 60 70
61.08 409.86 0.46 32048 Time (min)
Quality Control Check for Program Accuracy
Time Step (min)= 1.7 Total Inflow Total Outflow Storage I- (O -S)] / I
cubic -feet cubic -feet cubic -feet Error
118089 103003 15086 0.00%