HomeMy WebLinkAboutCC - Storm Drainage Calcs ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is Intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
Stapc for Peak Discharge Rate using tir.•n�tir!;-nil Mezhoa cakuIat..d for pow4meloips2bst
Calculate post-Development Flaws pre '••veI,Dment flaw,. . :•asc number of oome ficifiliex to create rrew tat,.i
User input in yellow cells.
1 Project Name Julia Subdivision
2 Is area drainage basin map provided? YES
(map must be included with stormwater calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max) 2
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasln Subbasin
1 Subbasin 2 3 4 5 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) SF 41,969 41,166
Acres 1.91
6 Determine the Weighted Runoff Coefficient(C) 0.95 0.35
C=[(C1xA1)+(C2xA2)+(CnxAn)j/A Weighted Avg 0.65
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate
min [io Min. Estimated Runoff Coefficients for Various Surfac-
- Type of Surface Runoff Coefficients"t
8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 1 2.58 in r Business
areas o.70-0.9s
y Calculate the Post-Development peak discharge(QPeak) C6.k 3.21 cis Urban nalffhborhoods 0.50-0.70
Residential
_ Single Family 0.35-0.50
10 Calculate total runoff vol(V)(for sizing primary storage) V 4,306 n Multi-family 0.60-0.75
V=Ci(Tc=60)Ax3600 Residential rural 0.25-0.40
11 Calculate Volume of Runoff Reduction Vrr Apartment Dwellin Areas 0.70
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Industrial and commercial
Ughtareas 0.80
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) r. 2,691 ft Heavy areas 0.90
12 Detention'Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 0.20-0.25
PlaViii 0.20-0.35
Railroad yard areas 0.20-0.40
13 VOlu me Su mm ary Unlmsxoved areas 0.10-0.30
Surface Storage:Basin Streets
Basin Forebay V 431 Asphalt 0.95Concrete 0.95
Primary Treatment/StorageBasin V 3,876 ft- Brkk 0.95
Subsurface Storage Roofs _ 0.95
Volume Without Sediment Factor(See BMP 20 Tabl V 4,306 It-- Gravel 0.75
Fields:Sandy soil Soil Type
Slope A�.I
Flat:0-2% 0.
Average:2-6% 0.
Stee :>6% 1370.
Adapted from ASCE
G:\R24050_JuIiaSubdivision\EngArch\Reports\Stormwater\R24050-JUlia_ACHD_SD_CALCS 4/23/2024,10:51 AM
Version 10.5,November 2018
OCHD Calculation Sheet for Sizing Basins
NOTE:This worksheet Is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation
methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these
calculations In order to be accepted.
User Input In yellow cells.
1 Project Name Julia Subdivision
2 Enter number of Basins 125 max) 2
3 Number of Cells(Forebay+Prima ry=2,Primary Only=1) 1
4 Design Storm 100 Unk to:[Qv�
5 Weighted Runoff Coefficient C 0.65 QV2
QV TR55
6 Area A(Acres) 1.91 acres
7 Approved Discharge Rate(if applicable', 0.00 cfs
8 2-Primary Treatment/Storage V 4,306 ft'
Toggle between Forebay and Primary Basin,enter d4ta and print for each
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t <__________________ a 'S* Sfreal�ez
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Primary Basin
9 Select Primary Basin Shape 3-Rectangle
10 Width of Primary Basin Bottom W 40.0 ft
11 Length of Primary Basin Bottom 1. 90.0 It
12 Side Slopes(1-1:1) H:1 3.00
13 Enter Bottom Elevation 100.00 ft
14 Enter Top Bank Elevation 101.75 h
15 Enter Water Surface Elevation(WSE) 101.25 ft
16 Distance Between Forebay and Primary Basin(blank if na) 0.00 ft
17 Enter Elevation Berm 0.00 ft
18 Enter High Groundwater Elevation 0.00 ft
19 Min.Freeboard Requiremen: 0.50
20 Freeboard Provided
21 Infiltration Area for Primary/Storage Basin Infiltration? 8.00 In/hr Note:infiltration required i!
Design Infiltration Rate Enter 0 for no infiltratior bottom slope<2%orO outflow
22 Infiltration Area for Primary A,„e 0 ft`
Enter 0 for no infiltration
23 Adjusted Storage Required
Storm Duration i total Q Runoff Vol Perc Vol Pre-Dev Total Max Vol
Discharge Discharge Reqd
Min Hr in/hr cfs ft3 ft3 ft3 ft, ft3
50 1.00 0.96 1.20 4,306 0 0 0 4,306
p tfa6e •r onr- p:
Saved Surface
Basin Basin Surface Surfaeo Area A at Volume
Saved Stags Side Slope Width at Length at Area A at Area A at Stage.(ft2) �BelowStage
(ft) New Stage(ft) (H:V) Stage(ft) Stage(ft) Stage(ftrj Stage(ft) OVERhDDE
100.00 100.00 3.000 1 40.0 90.0 1 3,601 0",
100.25 3.000 41.5 91.5 3,797
100.50i 3.000 43.0 93.0 3.999
_ 100.75 3.C� 4" 94.5 4,205
101.0C 3.000 46.�0 96.0 4,416
101.25 3.000 47.5 97.5 4,631
)
1.25 ft depth for storage STORAGE OK
25 Do"prmary/srarage basin"vecapauty'
26 Time to drain primary/storage basin 0.0 hours
90%volume in 48-hours minimum
G:\R24050_JuliaSubdivision\EngArch\Reports\Stormwater\R24050-Julia_ACHD_SD_CALCS 4/23/2024,10:51 AM
Version 10.0,May 2018
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
51e 0,fnr Pe!l It Div-harge Roe u%i rig the Ratio oat Mel huJ cticu lgMd For pest dove l nprne nt
i alcuJate pOst•Development Flows(for pre-oevelopmem ilo,v-..i cr.;}<+num!• r M=tore(,'rn[iii[,± r[ cra-3;r na'.v tlh'
User input in yellow cells.
1 Project Name Julia Subdivision,Facility 2
2 Is area drainage basin map provided? vE S
(map must be included with stormwoter calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) SF 12,493 11,206
Acres 0.54
6 Determine the Weighted Runoff Coefficient(C) 0.95 0.35
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.67
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate
min 10 Min, Estimated Runoff Coefficients for Various Surfac,
- Type of Surface Runoff Coefficients"(
S Determine the average rainfall intensity(1)from IDF Curve based on Tc i 2.58 In r Business
Downtown areas 0.70-0.95
9 Calculate the Post-Development peak discharge(QPeak) QP.., 0.99 cfs urban neighborhoods 0.50-0.70
Residential
Single Family 0.35-0.50
10 Calculate total runoff vol(V)(for sizing primary storage) V 1,253 it Multi-family 0.60-0.75
V=-G(Tc=60)Ax3600 Residential(mrall 0.25-0.40
11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70
Enter Percentile Storm I(95th percentile=0.60 in) 95th Industrial and Commercial
0.60 in tight areas 0.80
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V,r 783 ft, Heavyareas 0.90
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) Cfs Parks,cemeteries 0.10-0.25
Playgrounds 0.20-0.35
_ Railroad yard areas 0.20-0.40
13 Volume Summary Unimproved areas 0.10-0.30
Surface Storage:Basin StreetsAsphalt 0.95
Basin Forebay V 125 ft Concrete 0.95
Primary Treatment/Storage Basin V 1,128 ft _Brick 0.95
Subsurface Storage Roofs 0.95
_
Volume Without Sediment Factor(See BMP 20 Tab) V 1,253 Gravel 0.75Fields:sandy soil soil Type
Slope A B C D
Flat:0-2% 0.04 0.07 0.11 0.
Average:2-6% 0.09 0.12 0.15 O.
Steep:>6% 0.13 0.18 0.23 0.
Adapted from ASCE
G:\R24050 JuliaSubdivision\EngArch\Reports\Stormwater\R24050-Julia ACHD_SD_CALCS 4/23/2024,10:51 AM
Version 10.5,November 2018
AND Calculation Sheet for Sizing Basins
NOTE:This worksheet Is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation
methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these
calculations In order to be accepted.
User input in yellow cells.
1 Project Name Julia Subdivision,Facility 2,Pond 2
2 Enter number of Basins(25 max) 2
3 Number of Cells(Forebay+Prima ry=2,Primary Only=1) 1
4 Design Storm 100 Link to: Qv
5 Weighted Runoff Coefficient C 0.62 lav2�=]
QV TR55
6 Area A(Acres) 0.54 0cres
7 Approved Discharge Rate(if applicable) 0.00 cfs
8 2-Primary Treatment/Storage V 1.164 h'
Toggle between Forebayand Primcaygasin,.enter data and-printfar earh
aYeSlgeL 3Ye S1Re% Sae Sl"r
1
4 IYr A fiver }1rr
--..........C........a SW L ->• alt Sloes
Primary Bash,
9 Select Primary Basin Shape S-Irregular
10 Width of Primary Basin Bottom W 010 ft
11 Length of Primary Basin Bottom L 0.0 N
12 Side Slopes(HA) HA 3.00
13 Enter Bottom Elevation 2S47.00 IN
14 Enter Top Bank Elevation 2548.40 ft
15 Enter Water Surface Elevation(WSEI 2547.90 ft
16 Distance Between Forebay and Primary Basin(blank IF nai 0.00 ft
17 Enter Elevation Berm 0.0o ft
18 Enter High Groundwater Elevation 0.00 ft
19 Min.Freeboard Requirement 0.50
20 Freeboard Provided
21 Infiltration Area for Primary/Storage Basin Infiltration? 8.00 in/hr Nare�infiltration required if
Design Infiltration Rate,Enter 0 for nn infiltration bottom slone4%or 0 ourflory
22 Infiltration Area for Primary As_ p ftr
Enter 0 for no infiltration
23 Ad usted Storage Required
Storm Duration I total Q Runoff Vol Perc Vol Pre-Dev Total I Max Vol
Discharge Dischante Read
Min Hr in/hr cfs fta ft' ft3 ft3 fts
60 1.00 0.96 0.32 1,164 0 0 0 1,164
I
` Saved Surface
Basin I Basin Surface ) Surface Area A at volume
Saved Stage Side Slope Width at I Length at Area A at I Area A at Stage(fr) Below Stage
(it) New Stage(ft) (H:V) Stage(it) Stage(ft) Stage(ft') Stage(ft') C!VEfitDE (ft')
254700 2547,00 -3.000 0.0 0.0 Override C.
2.54730, 3.000 O.0 0.0 Override 298.63
2547.40 3.000 0.0 0.0 Override 355.69
2547.&; 3,000 0.0 0.0 Override 416.,01
2547.80 3.000 0.0 0.0 Override 479.53
2548.00- 3,o00 0.0 0.0 Override 546.42
2548,20 3.000 0.0 0.0 Override 61().5i
2'.48.40` 3.000 0.0 0.0 Override 639.85 -
2548.W 3.000 O.0 0.0 Override 832.53
I
1.0 it depth for storage TOO SMALL
25 Does primary/storage basin have capacity?
26 Time to drain primary/storage basin 0.0 hours
90%volume in 48-hours minimum
G:\R24050_luliaSubdivision\EngArch\Reports\Stormwater\R24050-Julia ACHD_SD_CALCS 4/23/2024,11:13 AM
Version 10.0,May 2018