27682 #1 SUBMITTAL DRAINAGE TECHNICAL REPORT
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DRAINAGE TECIiNICAL
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REPURI,
for
Shelley Lake - 4"' Aciciitiun
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DRAINAGE REPORT
for
Sheiley Lake - ~Ih Addition
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5►pokane Countyt'tiNashington
~ August, 2002
CLC ##~020134
prepared by+: -
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CL C ,4ssociates, Irrc.
~ 707 W. 7th Avenue, Suife 200
Spokane, WA 99204
(509)458-6840
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This repark has been prep~red by the staff of CLC Associates, In+c. under the directian of
the undersigned professional engineer whose seal and signature appear her€;on,
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EXf'IRES: 01-21-03
~ Doug J. Desmond, P.E.
l]RAfNAGE REPORT FOR SHELLEY LAKE - 4`h AD[]ITIC)N
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PURPOSE
, Shelley Lake 4t'' Addition is part of the Shelley Lake PUD Preliminary Plat and is adjacent to Shelley
Lake 2`"' and 3`d Additions. The purpose of this report is to determine the extent of storm drainage
facilities which will be required to dispose of the increase in stormwater runoff created by the
development of Shelley Lake 4"' Addition. The storm drainage facilities for this project will be
' desi9ned to disPose of runoff from ten-Year desi9n storm. This development is within the Aquifer
Sensitive Area of Spokane County and is subject to `208' requirements. For this project the 10 and
50 year curves from the Spokane, Medical Lake, Reardon, Cheney and Rockford intensity curves
' were used, as well as the SCS iso-pluvial rainfall curves.
ANALYSIS METHODOLOGY
The Rational Method, which is recommended for basins less than ten acres in size, was used to
determine the peak discharges and runoff volumes for all basins included in this report.
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PROJECT DESCRIPTION
' Shelley Lake 4~' Addition includes 39 lots of the 262 lots and 459 units in the approved preliminary
plat and FEIS documents. The Shelley Lake subdivision is located in the NE 1/4 of the SE 1/4 of
Section 24, T. 25 N., R. 44 E., W.M. within Spokane County, Washington.
, TOPOGRAPHY
The general slopes within ihis plat vary from neady flat within several natural saddles to short slopes
, of up to 25-percent. Generally, the area covered by this report would be characterized as rolling.
For development purposes, the natural sloping was used for design and is maintained as possibfe
throughout the project I
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SOILS
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' As can be seen from the accompanying soils map from the Spokane County Soils Survey as
performed by the United States Department of Agnculture (USDA) Soil Conservation Services
(SCS), the site consists of soils type GmB. These soils are described as follows:
' GmB - Garrison verY 9ravellY loam, 0 to 8 Percent slopes: Soils within this soil type formed in
gravelly glacial outwash material from a variety of igneous rock. These soils are described as
somewhat excessively drained. Surface runoff is slow and the hazard of erosion is slight. Spokane
' County Guidelines for Stormwater Manaqement indicate this to be a Soil Group Type B and per-
approved for drywell installation.
, DRAINAGE NARRATIVE
The offsite drainage which flows into Shelley Lake 4"' Addition has been incorporated into the basins
included in this drainage report. As Shelley Lake 4`h Addition is located within the Aquifer Sensitive
Area of Spokane County, all onsite street and future street areas will be collected and treated using
the '208' runoff method as described in the Spokane County Guidelines for Stomnwater
Manaqement. To facilitate this analysis Shelley Lake 49'Addition was divided into four basins (A, B,
C, and D) as shown in the Basin Map. Table 1 lists the basin details. Basins A, B, C, and D were
' CLC Associates, Inc. 2 Shelley Lake 4`h
Addition
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~ analyzed using developed conditiQns.
Table 1 - Faond arrd Basrn 5urnmary
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Pond and Basin Summary ~
~ Pvnd Basin Total Area A Tota! Weighted `C' '"208' Impervious
SF1AC Impervious Area Area SF
S F/AC
~ .11 23,534Jf~.S4 f~.52 12,734
~ 48,~41J1
8 B 1 55,31613,57 25,41910.58 0.27 14,619
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c c 246e398/5,66 +.J54433f2.1tiJ O.T4 55,833
1..J D 335,1JL.1'517+69 67y320d 1.5r.' 0.36 40aa72Ll
Tatal Impervious Area includes paved roac#way area, 1600 s.f. per roof and 750 s.f. per dRVeway. .208r Impervious
Area includes ority the paved taadway area and 750 s.fi. per driveway.
~ 1f
2178" Calculatrans
Wi#hin each basinT the street areas from back of curb to back of curb were calculated tv determine ~
~ the required '208' starage fvr a 10-year storm everrt_ As showrr on the'20$' calculatign worksheets
included, the '208' stc►rage volurnes provided are adequate tv perform the '208' treatment foF #he
first half inch of rainfaff. 1n addition to `208" treatment, the encEosed warkshee#s also shQw #he
~ calcuEat'tvns for the drywell requirements. fihe'208' s#orage and dnywell requirements for each basin
are summarized orr the faliowing Table 2.
~ TabI'e 2- j208' Treatment and Dwvell F~e ~riternerrf Sumrr~a
~ rY
`2(]8' Treatrnent an+d Drywell Summary
Pond Basin `208''Vvlume '208' Area Required A `208' V'oiume Dnywelis
, F~equire~d (+~F) (SF) Pr~avic~ed F~'eq~rire+~
' `(CF)
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A A 531 792 536 _.t~ 1-Type B I
B B 609 663 : 2RTYPe g
c c 2326 3472 2502 2-Type B
~ - D D 1680 2507 2180 3-TYPe B
Based on a'208' starage depth of 8 inches. Side slope volume is nvt includecl.
Ctxrb ,Dropffnle# ArraTysis
~ CL.C Associates, Ijic. ? Stiel1ev 1:4zkc 4
Additiorl
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' The curb drops for Pond A are located in a continuous condition and the inlets for Ponds B, C, and
D are in sump condition. Curb inlet analysis calculations are included in the appendix.
Conclusion
As demonstrated by the calculations and body of this report the storm drainage facilities provided in
this design witl adequately remove from the streets, store and dispose of the stormwater from the
, site for the 10-year design storm as required by Spokane County. Calculation worlcsheets for the 50-
year storm event have been provided to evaluate the perfomnance of the designed drainage
facilities. Additionally, the required '208' treatment area is provided for the runoff from the street
1 impervious areas.
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SHELLEY LAKC 4T'H ADD. S020134
Spokanc Counry, Washington 9/21i2U02 10:24
1 0-Year Stocm Event Engineer: TDft
CURB INLET FLOW CAPACITIES
in Sump Conditions
Curb [nlet Basin Basin + Inlet~ Maximum Macimum ~ By-Pass
Basm Street and Inlet Typc Peak Flow By-Pass* Length Flow Dcpth" Discharge*'`* Flow
Station (cfs) Q (ft) H Q - Qa
LANE A TYPE 2-,_..- 7.6~
B _ STA 12+35.99 LT _ CURB 1.86 1.86 400 /110 o.50 4.37 -2.51
SHELLEY LAKE LANE TYPE 1 -10
D STA 25+40.67 RT CURB 5.04 5.04 5.00 O,iO 5.46 -0.42 ~
NOTE: TYPE 1 CURB INLET TYPE 2 CURB INLET Qa = 3.087 • L' H^ 1.5
Curb Inlet Dcpression = 2 in. Curb Inlet Depression = 2 in, Where L= Length of Gurb Drop, H= Flow Depth
Maximum Inlet Height = 8 in. Curb inlet Length = 4 fl.
Maximum Inlet Height = 6 in,
' By-Pass flows fmm upscream inlets on caniinuous grades.
Maximum Flow Depth is based on Inlet height
't* Calculated per Section 4• 1 of the Spokane County Guidelines
for Stormwater Management
CurbDropS
~ m m m m ~ ~ ~r ~ r r ~ ~ ~ ~■r m m ~ SHELLEY LAKE 4TH ADD, S020134
Spokane County, Washington 91211200214:20
10-Year Design Storm Engineer: TOR
CURB INLET CALCULATIONS
on Continuous Grade
~ Curb Inlet ~ Basin I Basin + I Gutter I I Roughness~ ~ Depth I Oischarge~ Inlet ~ ByPass
Pond ~ Street and I Peak Flawl By-Pass I Slope I Cross slope I Coeff. ~ Z I of Flow lper Lengthi Lenqth ( Flow
Station ~(cfs) ~ 4 I S I 1lZ I n l n ~ d' ~ QalLa" ~ La ( Q• Qa
CARNINE LN I I I I I I I I I N
A STA 13+15,17 LT ~ 1.55 ~ 1.55 ~ 0.0087 ~ 0.0256 ~ 0.016 ~ 2441 ~ 0.191 ~ 0.132 ~ 5 ~ 0.89
~ CARNINE LN ~ I I I I I I I I I
A ~ STA 13+50,45 LT ~ 0 ~ 0.89 0.0087 ~ 0.0256 ~ 0.016 ~ 2441 ~ 0.155 ~ 0.107 ~ 5 ~ 0.35
~ CARNINE LN
A ~ STA 13+89.99 LT ~ 0 ~ 0.35 ~ 0.0087 ~ 0.0256 ~ 0.016 I 2441 ~ 0.110 ~ 0.076 ~ 5 ~ •0.03
~ LANE A I I I I I I I I I I
I I I I I I I I I I I
NOTE: TYPES 1& 2 CURB INLETS
Curb Inlet Oepression = 2 in.
' Calculated per Figure 18 of the Spokane County Guidelines
for Stormwater Management
" Calculated per Figure 16 of the Spokane County Guidelines
for Stormwater Management
~ ~ ~ ~ ~ ~ r ~ r ~ ~ ~ ~ ~ ~ ~ ~ r
5HELLEN' LAKE 4TH ADUITIOiv SO?U I34
SpokancCounry, Washington 9/21/2002 10,09
1 0-Year Storm Event Engineer: DJD
, INLET FLOW CAPACITIES
~ in Sump Conditinns
~ lnlet Basin Basin+ Inlet Maximum Inlet ByPass
Basin Strcet and In{et Type Pcak Flaw ByPass Perimeter Flow Dcpth•• Discharge•*' Flow
Station (cfs) Q_ _ P H Oa Q•Qa
' SHELLEY LAKE LA 'fYPE I _
C• 1 STA 23+25.28 LT~ GRATE 2.58 2.58 3.67 0.50 3.89 • 1.31 SHELLEY LAKE LANF~ TYPE I
G2 STA 23+25.28 RT ~ GRATE 2.69 2.69 3.67 0.50 3.89 -i.?U
Grate Perimeters* Qa = C' P' H^ 1.5
liemngbone = 3.67' Where; C= 3.0, P= Penmeter, N= Flaw Depth
Vaned = 3.GT
WSDOT= 5.91' ' Grate Penmeter = Availabie Perimeter Divided by a Safery f actor af 2.
Maximum Flow Depth is based on curb crest above mlet,
Calculated in accordance with Spokane County Guidelines for
Stomiwater Management, Section 4-1.
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InletSmp
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SHELLEY LAKE 4TH ADDITION
Basin Summary Table
Road Imp. House Area DriveNValk 7otal Peak GIA Vol, GIA Vol. Bowstring
Total Area Area 1800SFILot Area Imp. Area Runoff Flow 1 Req'd Prov'd Vol. Req'd Number & Type
Basln (SF) (Acres) (SF) Houses (SF) (SF) (SF) Coeff. (cfs) (cu.ft) (cu.ft) (cu.ft) of Drywells
A ~ 48,341 ~ 1.11 ~ 8,234 1 6.0 I 10,800 ~ 4,500 ~ 23,534 ~ 0.52 l 2.23 ~ 531 I 534 ~ 1186 1 1- 7ype B
B I 155,316 I 3.57 ~ 10,119 I 6.0 I 10,800 I 4,500 ~ 25,419 I 0.27 ~ 2.41 I 609 ~ 611 I 1702 ~ 1- Type B
C ~ 246,398 1 5.66 1 39,333' l 22.0 1 39,600 1 16,500f I 95,433 1 0.44 1 9.03 I 2326 I 2395 ~ 7085 I 1- Type B
C1 ~ 94,892 ~ 2.16 ~ 15,266 l 11.0 I 19,800 I 8,250 ~ 43,316 0.49 ~ 4.14 ~ ~ ~ ~
C2 ~ 151,506 ~ 3.48 ~ 24,067 ~ 11.0 ~ 19,800 ~ 8,250 ~ 52,117 0.41 ~ 4.93 ~ ~ ~ ~
D ~ 335,065 ~ 7,69 ~ 29,070 ~ 15.0 ~ 27,000 ~ 11,254 ~ 67,320 ~ 0.36 ~ 6.37 ~ 1680 ~ 1690 ~ 6553 ~ 2- Type B
NOTE: C=(0.9'(IMPERVIOUS AREA) + 0.15`(PERVIOUS AREA)JlTOTAL AREA
WHERE C = RUNOFF COEFF,
S020134 CLC ASSOCIATES, INC. 9l1912002
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PEAK FLOW CALCULATION PROJECT: SHELLEY LAKE 4TH ADD.
' BASIN: A
Tot. Area = 1.11 Acres
' Imp. Area = 23,534 SF
C = 0.52
' CASE 1
' 103 ft. 4verland Flow
Ct = 0.15
L = 108 ft.
n = 0.400
S = 0.008
'
Tc = 6.12 min., by Equation 3-2 of Guidelines
' 431 ft. Gutter flow
Z1 = 50.0
Z2 = 3.50
n = 0.016
' S = 0.0092
d= 0.167 ft. Flow W idtr 8.4 ft.
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A R Q Tc Tc total I Qc
' 0.75 0.08 1.27 4.22 10.33 2.20 1.27
' Qpeak for Case 1= 1.27 cfs
' CASE 2
minutes so that the
Case 2 assumes a Time of Concentration less than,,
, peak flow =.90(3.18)(Imp. Area) _ (1.55 cfs', t}i,=P,-3:-1k flnyv f(-,.r th~- F,~jc'n th-r the t%vo flev'js. 1 7 r_.;s
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BOWSTRING METHOD PROJECT: SHELLEY LAKE 4TH ADD.
1 DETENTION BASIN DESIGN BASIN: A
DESIGNER. TDR
DATE: 09/21 /02
1
Time Increment (min) 5
Time of Conc. (min) 10.33
Outflow (cfs) 1
Design Year Flow 10
' Area (acres) 1.11
Treatment Area 12734
'C' Factor 0.52
' '208' Volume Provided 536
Area * C 0.577
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Time Time inc. Intens. Q Devel. Vol.ln Vol.Out Storage
(min) (sec) (inlhr) /1~ (cu ft) (cu ft) (cu ft)
10.33 620 2.20 1.27 1053 620 433
5 300 3.18 . 738 300 438
10 600 2.24 1.29 1040 600 440
15 900 1.77 1.02 1135 900 235
20 1200 1.45 4.84 1181 1200 0
25 1500 1.21 0.70 1195 1500 0
30 1800 1.04 0.60 1207 1800 0
' 35 2100 0.91 0.53 1214 2100 0
40 2400 0.82 0.47 1236 2400 0
45 2700 0.74 0.43 1243 2700 0
' 50 3000 0.68 0.39 1260 3000 0
208' DRAINAGE POND CALCULATIONS
' Required '208' Storage Volume
= Impervious Area x.5 in / 12 in/ft 530.6 cu ft
' 208' Storage Volume Provided 536 cu ft
DRYWELL REQUIREMENTS - 10 YEAR DESIGN STORM
' Maximum Storage Required by Bowstring 440 cu ft
Provided Storage Volume 867 cu ft a 1' Depth
Number and Type of Drywells Required 0 Single
1 Double
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S020134
CLC ASSOCIATES 9/21/2002
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PEAK FLOW CALCULATION PROJECT: SHELLEY LAKE 4TH ADD.
' BASIN: B
Tot. Area = 3.57 Acres
' Imp. Area = 25,419 SF
C = 0.27
CAS E 1
, 422 ft. Overland Flow
Ct = 0.15
L = 422 ft.
n = 0.400
S = 0.030
Tc = 9.32 min., by Equation 3-2 of Guidelines
, 414 ft. Gutter flow
Z1 = 50.0
Z2 = 3.50
n = 0.016
S = 0.0094
d= 0.192 ft. Flow WidtF 9.6 ft.
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A R Q Tc Tc total I Qc
' 0.99 0.10 1.86 3.65 12.97 1.93 1.86
' Qpeak for Case 1= 1.86 cfs
' CASE 2
Case 2 assumes a Time of Concentration less than 5 minutes so that the
' peak flow =.90(3.18)(Imp. Area) = 1.67 cfs So, the Peak flow for the Basin is the greater of the two flows, 1.86 cfs
S020134 CLC ASSOCIATES. INC. 9121I2002
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BOWSTRING METHOD PROJECT: SHELLEY LAKE 4TH ADD.
' DETENTION BASIN DESIGN BASIN: 6
DESIGNER. TDR
DATE: 09121 /02
1
Time Increment (min) 5
Time of Conc. (min) 12.97
Outfiow (cfs) 2
Design Year Flow 10
, Area (acres) 3.57
Impervious Area (sq ft) 14619
'C' Factor 0.27
'208' Volume Provided 663
Area " C 0.964
Time Time Inc. Intens. Q Devel. Vol.ln Vol.Out Storage
(min) (sec) (in/hr) (cfs) (cu ft) (cu ft) (cu ft)
12.97 778 1.93 1.86 1943 1556 386
5 300 3.18 3.07 1232 600 632
10 600 2.24 2.16 1736 1200 536
15 900 1.77 1.71 1987 1800 187
20 1200 1.45 1.40 2047 2400 0
25 1500 1.21 1.17 2058 3000 0
30 1800 1.04 1.00 2070 3600 0
35 2100 0.91 0.88 2074 4200 0
40 2400 0.82 0.79 2106 4800 0
45 2700 0.74 0.71 2115 5400 0
' 50 3000 0.68 0.66 2140 6000 0
208' DRAINAGE POND CALCULATIONS
r Required '208' Storage Volume
= Impervious Area x.5 in / 12 in/ft 609.1 cu ft
208' Storage Volume Provided 663 cu ft
DRYWELL REQUIREMENTS - 10 YEAR DESIGN STORM
' Maximum Storage Required by Bowstring 632 cu ft
Provided Storage Volume 953 cu ft @ 1' Depth
Number and Type of Drywells Required 0 Single
2 Double
S020134
CLC ASSOCIATES 9/21/2002
PEAK FLOW CALCULATION PROJECT: SHELLEY LAKE 4TH ADD.
' BASIN: C
Tot. Area = 5.66 Acres
' Imp. Area = 95,433 SF
C = 0.44
CAS E 1
114 ft. Overland Flow
Ct = 0.15
L = 114 ft.
n = 0.400
S = 0.008
Tc = 6.32 min., by Equation 3-2 of Guidelines
773 ft. Gutter flow
Z1 = 50.0
Z2 = 3.50
n = 0.016
' S = 0.0125
d= 0.2690 ft. Flow W idtr 13.5 ft.
A R Q Tc Tc total I Qc
' 1.94 0.13 5.28 4.72 11.04 2.13 5.29
~ Qpeak for Case 1= 5.29 cfs
' CASE 2
Case 2 assumes a Time of Concentration le 5 minutes so that the
peak flow =.90(3.18)(Imp. Area) = 6.27 cf So, the Peak flow for the Basin is the greater of the two flows, 6.27 cfs
S020134 CLC ASSOCIATES, INC. 9/21/2002
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BOWSTRING METHOD PROJECT: SHELLEY LAKE 4TH ADD.
, DETENTION BASIN DESIGN BASIN: C
DESIGNER: TDR
DATE: 09/21 /02
1
Time Increment (min) 5
Time of Conc. (min) 11.04
Outflow (cfs) 2
Design Year Flow 10
' Area (acres) 5.66
Impervious Area (sq ft) 55833
'C' Factor 0.44
'208' Volume Provided 2502
Area * C 2.490
Time Time Inc. Intens. Q Devel. Vol.ln Vol.Out Storage
(min) (sec) (in/hr) (cu ft) (cu ft) (cu ft)
11.04 662 2.13 5.29 ~ 4699 1325 3374
5 300 3.18 -492 3184 600 2584
10 600 2.24 5.58 4485 1200 3285
15 900 1.77 4.41 4960 1800 3160
20 1200 1.45 3.61 5147 2400 2747
25 1500 1.21 3.01 5199 3000 2199
30 1800 1.04 2.59 5245 3600 1645
' 35 2100 0.91 2.27 5270 4200 1070
40 2400 0.82 2.04 5361 4800 561
45 2700 0.74 1.84 5391 5400 0
50 3000 0.68 1.69 5462 6000 0
208' DRAINAGE POND CALCULATIONS
' Required '208' Storage Volume
= Impervious Area x.5 in / 12 in/ft 2326.4 cu ft
, 208' Storage Volume Provided 2502 cu ft
DRYWELL REQUIREMENTS - 10 YEAR DESIGN STORM
' Maximum Stora9e Required bY 6owstrin9 3374 cu ft
Provided Storage Volume 3828 cu ft @ 1' Depth
Number and Type of Drywells Required 0 Single
2 Double
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S020134
CLC ASSOCIATES 9/21 /2002
PEAK FLOW CALCULATION PROJECT: SHELLEY LAKE 4TH ADD.
BASIN: C1
Tot. Area = 2.18 Acres
Imp. Area = 15,266 SF
C = 0.47
CASE 1
79 ft. Overland Flow
Ct= 0.15
L = 79 ft.
n = 0.400
S = 0.010
Tc = 4.74 min., by Equation 3-2 of Guidelines
542 ft. Gutter flow
Z1 = 50.0
Z2 = 3.50
n = 0.016
S = 0.0214
d = 0.186 ft.
A R Q Tc Tc total I Qc
0.93 0.09 2.58 3.24 7.98 2.51 2.58
~ Qpeak for Case 1= 2.58 cfs
~ CASE 2
Case 2 assumes a Time of Concentration less than 5 minutes so lhat the
peak flow =.90(3.18)(Imp. Area) = 1.00 cfs
So, the Peak flow for the Basin is ihe greater of the two flows, 2.58 cfs
10YrBowstring-JME.xIs CLC ASSOCIATES, INC. 9/2112002
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PEAK FLOW CALCULATiON PROJECT: SHELLEY LAKE 4TH ADD.
' BASIN: C2
Tot. Area = 3.48 Acres
' Imp. Area = 24,067 SF
C = 0.38
' CASE 1
' 114 ft. Overiand Flow
Ct = 0.15
L = 114 ft.
n = 0.400
S = 0.008
1
Tc = 6.32 min., by Equation 3-2 of Guidelines
' 773 ft. Gutter flow
' Z1 = 50.0
Z2 3.50
n = 0.016
S = 0.0125
d = 0.209 ft.
'
A R Q Tc Tc totai I Qc
' 1.17 0.10 2.69 5.59 11.91 2.03 2.69
' Qpeak for Case 1= 2.69 cfs
' CAS E 2
Case 2 assumes a Time of Concentration less than 5 minutes so that the
, peak flow =.90(3.18)(Imp. Area) = 1.58 cfs
So, the Peak flow for the Basin is the greater of the finro flows, 2.69 cfs
10YrBowstring-JME.xIs CLC ASSOCIATES, INC. 9/2112002
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PEAK FLOW CALCULATION PROJECT: SHELLEY LAKE 4TH ADD.
BASIN: D
'
Tot. Area = 7.69 Acres
' Imp. Area = 67,320 SF
C = 0.36
' CASE 1
658 ft. Overland Flow
1
Ct = 0.15
' L = 658 ft.
n = 0.400
S = 0.030
1
Tc = 12.17 min., by Equation 3-2 of Guidelines
423 ft. Gutter flow
Z1 = 50.0
Z2 = 3.50
n = 0.016
t S = 0.0183
d= 0.2460 ft. Flow Widtr 12.3 ft.
1
A R Q Tc Tc total I Qc
1.62 0.12 5.03 2.27 14.43 1.82 5.04
' Qpeak for Case 1= 5.04 cfs
' CASE 2_
Case 2 assumes a Time of Concentration less than 5 minutes so that the
' peak flow =.90(3.18)(Imp. Area) = 4.42 cfs So, the Peak flow for the Basin is the greater of the two flows, 5.04 cfs
'
S020134 CLC ASSOCIATES, INC. 9/21/2002
1
BOWSTRING METHOD PROJECT: SHELLEY LAKE 4TH ADD.
' DETENTION BASIN DESIGN BASIN: D
DESIGNER. TDR
DATE: 09/21 /02
'
Time Increment (min) 5
Time of Conc. (min) 14.43
Outflow (cfs) 3
Design Year Flow 10
' Area (acres) 7.69
Impervious Area (sq ft) 40324
'C' Factor 0.36
'208' Volume Provided 1675
Area * C 2.768
,
Time Time Inc. Intens. Q Devel. Vol.ln Vol.Out Storage
(min) (sec) (in/hr) (cfs) (cu ft) (cu ft) (cu ft)
'
14.43 866 1.82 5.04 5845 2597 3248
5 300 3.18 8.80 3539 900 2639
10 600 2.24 6.20 4986 1800 3186
15 900 1.77 4.90 5853 2700 3153
20 1200 1.45 4.01 5999 3600 2399
'
25 1500 1.21 3.35 6011 4500 1511
34 1800 1.04 2.88 6030 5400 630
' 35 2100 0.91 2.52 6032 6300 0
40 2400 0.82 2.27 6116 7200 0
45 2700 0.74 2.05 6134 8100 0
' 50 3000 0.68 1.88 6202 9000 0
208' DRAINAGE POND CALCULATIONS
' Required '208' Storage Volume
= Impervious Area x.5 in / 12 inlft 1680.0 cu ft
' 208' Storage Volume Provided 2180 cu ft
DRYWELL REQUIREMENTS - 10 YEAR DESIGN STORM
' Maximum Storage Required by Bowstring 3248 cu ft
Provided Storage Volume 3341 cu ft @ 1' Depth
Number and Type of Drywells Required 0 Single
3 Double
S020134
CLC ASSOCIATES 9/21 /2002
PEAK FLOW CALCULATION PROJECT: SHELLY LAKE 4TH BOWSTRING METHOD PROJECT: SHELLY LAKE 4TH
50•Year Design Storm DETENTIpN BASIN DESIGN BASIN:
DESIGNE DNR
BASIN: A DATE: 21-Sep•42
Tot. Area 48,351 SF 1.11 Acres Time Inaemeni (min) 5
Imp. Area 12,734 SF C= 0.9 Time of Conc. (min) 10,01
Perv. Area 35,617 SF C= 0.10 Outflow (cfs) 1
Wt, C= 0.49 Oesign Year Flow 50
Area (acres) 1.11
CASE 1 Impervious Area (sq ft) 12134
'C' Factor 0.49
108 ft. Overland Flow Area' C 0.544
Treatment Area 12,734
Ct = 0.15
L= 108 fl, Time Time Inc, Intens. Q Devel. Vol.ln Vol.Out Storage
n= 0.40 min) sec . pnlhrl ~ (cu ft! (a► h) (cu fl~
S= 0.0080 10.01 601 3.20 1.74 1403 601 802
Tc = 6.12 min., by EquaGan 3-2 ot Guidelines 5 300 4.58 2.49 1001 300 701
10 640 3,21 1.74 1402 600 802
431 ft. Gutter flow 15 904 2.44 1,33 1466 900 566
20 1200 1.98 1,06 1513 1200 313
Z1= 50.0 For Z2 25 1500 1.68 4.91 1554 1500 54
Z2 = 3.5 Type 8=1.4 30 1800 1.46 0.79 1591 1800 •209
n= 0.016 Rolled = 3.5 35 2100 1.30 0.71 1628 2100 472
S= 0.0092 40 2400 1.18 0.64 1668 2400 •732
45 2T00 1,08 0.59 1712 2700 •988
d= 0,1880 ft. FlowWidth 9.4 ft. 50 3000 1,01 0.55 1T55 3000 •1245
. 55 3300 0,94 0,51 1793 3300 -1507
60 3600 0.88 0.48 1824 3600 •1776
A R Q Tc Tc total I Qc 65 3900 0,83 0,45 1857 3900 -2043
0.95 0.09 1,74 3.90 10.01 3.20 1.T4 70 4200 0.79 0,43 1903 4200 -2297
75 4500 0.T7 0.42 1970 4500 •2530
Qpeak for Case 1= 1,74 cfs 80 4800 0.75 0.41 2052 4800 -2748
85 5100 0.73 0.40 2111 5100 -2983
90 5400 0.T0 0.39 2130 5400 •32T0
95 5700 6,66 0.36 2111 5700 •3589
CASE 2 100 6000 0.68 0.37 2295 6400 -3705
Case 2 assumes a Time of ConcentraGon less than 5 minutes so that the "208" TREATMENT REQUIREMENTS
peak flow =.90(Tc=5 intensity)(Imp. Area) = 120 cfs Minimum "208" Volume Required 531 cu A
Provided Treatment Volume 536 cu fl
DRYWELL REQUIREMENTS • 50 YEAR DESlGN STORM
So, the Peak how lor the Basin is the greater oi tfie two flows, Maximum Slorage Required by BowsUing 802 cu ft
1.74 cfs Provided Storage Volume 867 cu ft
Number and Type of Drywells Required 0 Sfngle
1 Oouble
~ ~ r ~ ~ ~ ~ ~ ~ ~ ~ ~r ~ ~ ~ ~ ~ ~
PEAK FLOW CALCULATION PROJECT: SHELLY LAKE 4TH BOWS7RING METHOD PROJECT: SHELLY LAKE 4TH
50•Year Design Storm DETENTION BASIN pESIGN BASIN: B
DESIGNER ONR
BASIN: B DATE: 21•Sep-02
Tot. Area 155,509 SF 3,57 Acres Time Increment (min) ~
Imp. Area 14,619 SF C= 0.9 Time of Conc, (min) 12,66
Perv. Area 140,890 SF C= 0,14 Outflow (cfs) 2
Wt. C= 0.27 Design Year Flow 50
Area (acres) 3.57
CASE 1 Impervious Area (sq t!) 14619
'C Factor 0.27
422 ft. Overland Flow Area ' C 0.964
Treabnent Area 14,619
Ct= 0,15
L= 422 ft. Time Tlme Inc. Intens. Q Devel, Vol.ln Val.Out Storage
n= 0.40 min sec (inlhr) _U0 (cu ft) ~ (cu~ n-
S= 0.0300 12.6~ 760 2.75 2.65 2695 1520 1175
Tc = 9,32 min., by Equatian 3-2 of Guidellnes 5 300 4.58 4.41 1774 600 1174
10 600 3,21 3.09 2485 1200 1285
414 f1. Gucter flow 15 900 2.44 2.35 2726 1800 926
24 1200 1.98 1.91 2184 2440 384
Z1= 50.0 ForZ2 25 1500 1.68 1,62 2841 3000 -159
Z2 = 3,5 Type B=1.0 30 1800 1.46 1,41 2895 3600 -105
n= 0.016 Rolled = 3.5 35 1100 1.30 1.25 2952 4200 -1248
S= 0.0094 40 2400 1.18 1.13 3017 4804 -1783
45 2700 1.08 1.04 3090 5400 •2310
d= 0,2190 ft. Flow Width 11.0 fl, 50 3000 1.01 0.97 3163 6000 •2831
, 55 3300 0.94 0.91 3226 6600 •3374
60 3600 0,88 0.85 3279 7200 -3921
A R Q Tc Tc total I ac 65 3900 0.83 0.80 3334 7800 •4466
1.28 0.11 2.65 3.35 12.66 2.75 2.65 10 4200 0,79 0.77 3414 8400 -4986
75 4500 0.77 0.74 3532 9000 •5468
Qpeak for Case 1= 2.65 cfs 80 4800 0,75 0.73 3676 9600 -5924
85 5100 0,73 0.71 3791 10200 -6409
94 5400 0.70 0.67 3811 10800 •6989
95 5700 0.66 0.63 3776 11400 -7624
CASE 2 100 6000 0.68 0.66 4103 12000 -7897
Case 2 assumes a Time of ConcenUatlan less than 5 minutes so that the "208" TREATMENT REQUIREMENTS
peak flow =.90(Tc=5 inlensity)(Imp. Area) = 1.38 cfs Minimum "208" Volume Required 609 cu fl
Provided Treatrnent Volume 663 cu fl
DRYWELL REQUIREMENTS • 50 YEAR DESIGN STORM
So, che Peak Aow for the Basin is the greater of Ihe lwo flows, Maximum Storage Required by Bowstring 1285 cu it
2.65 cfs Provided Slorage Volume 953 cu ft
Number and Type of Drywells Required 0 Sfngle
2 Double
PEAK FLOW GALCULATION PROJECT: SHELLY LAKE 4TH BOWSTRING METHOD PROJECT: SHELLY LAKE 4TH
50•Year Design Storm DETENTION BASIN DESIGN BASIN: C
DESIGNER DNR
BASIN: C DATE: 21•Sep-02
Tot. Area 246.549 SF 5.66 Acres Time Increment (nun) 5
Imp. Area 95,433 SF C= 0.9 Time ol Conc. (min) 10,62
Perv. Area 151,116 SF C= 0,10 Qutflow (cfs) 2
Wt, C= 0.44 Deslgn Year Flow 50
Area (aues) 5.68
CASE 1 Impervious Area (sq ft) 95433
'C Factor 0,44
114 ft, Overland Flow Area' C 2.490
Treatment Area 55,833
Ct= 0.15
L= 114 A. Time Time Inc. Intens, 0 Devel. Vd.in Vol.Out Storage
n= 0.40 min sec (inmr) ~ (cu ft) (cu ft) (cu ftL..
S= 0.4080 10.6 637 3.09 7,64 652T 1275 5253
Tc = 6,32 min., by EquaGon 3•2 of Guidelines 5 300 4.58 11,40 4584 600 3984
10 600 3,21 7.99 6421 1200 5221
773 fl. Gutter flow 15 900 2.44 6.08 6789 1800 4989
20 1200 1,98 4.93 6988 2400 4588
Z1= 50.0 For 7-2 25 1500 1.68 4,17 7167 3000 4167
Z2 = 3,5 Type B=1.0 30 1800 1.46 3.63 7329 3600 3729
n= 0.016 Rolled = 3.5 35 2100 1.30 3.23 7492 4200 3292
S= 0.0125 40 2400 1.18 2,93 7673 4800 2873 45 2700 1,08 2.T0 78T2 5400 2472
tl= 0.3090 rt. Fiow WidUh 15.5 ft, 50 3000 1.01 2.51 8068 6000 2068
. 55 3300 0,94 2.34 8238 6640 1638
60 3640 0,88 220 8381 7200 1161
A R Q Tc Tc lotal I Qc 65 3900 0,83 2.47 8528 7800 728
2.55 0.15 7.64 4,31 10.62 3.09 7.69 70 4200 0.79 1.98 8738 8400 338
15 4540 0,77 1.92 9046 9000 46
npeak for Case 1= 7.69 cfs BO 4800 0.75 1.68 9419 9600 •181
85 5100 0.73 1.83 9717 10200 -483
90 5400 0,T0 1.74 9773 10800 •1027
95 5700 0,66 1.64 9688 11400 -1712
CASE 2 100 6000 0.68 1.69 10529 12000 -1471
Case 2 assumes a Time o( ConcenUaGon less than 5 minutes so that the "208" TREATMENT REQUIREMENTS
peak flow =.90(Tc=5 intensity)(Imp, Area) = 9.03 cfs Minimum "208" Volume Required 2,326 cu ft
Provided Treatment Volume 2,502 cu ft
DRYWEIL REQUIREMENTS - 50 YEAR DESIGN STORM
So, the Peak flow for the Basin Is the greater of the two 8aws, Maximum Storage Required by Bowstring 5253 cu h
9.03 cfs Provided Storage Volume 3828 cu ft
Number and Type of Drywells Raquired 0 Sinple
2 Doubie
PEAK FLOW CALCULATION PROJECT: SHELLY LAKE 4TH BOWSTRING METH00 PROJECT; SHELLY LAKE 4TH
50•Year Deslgn Storm DETENTION BASIN DESIGN BASIN: D
DESIGNER DNR
BASIN: D DATE: 21-Sep•02
Tot. Area 334,976 SF 7.69 Acres Time Inaement (min) 5
Imp, Area 67,320 SF C= 0.9 Time of Conc, (min) 14.25
Penr, Area 267,656 SF C= 0.10 Outflaw {cfs} 3
Wt C= 0.36 Design Year Flow 50
Area (aues) 7.69
CASE 1 Impervious Area (sq ft) 67320
- 'C' Factor 0.36
658 ft. Overland Flow Area ' C 2.768
Trealment Area 40,320 Ct = 0.15
L= 658 ft. Tfine Time Inc. Intens. Q Devel. Vol.ln VoLOut Storage
n= 0.40 minl Iseci _(inlhr) S1 (cu ft) (cu tl) (cu flL.
S= 0.0300 14.25 855 2.53 6.98 1994 2566 5429
Tc = 12.17 min., by Equation 3-2 of Guidefines 5 300 4,58 12.67 5095 900 4195
10 600 3.21 8,88 7138 1800 5338
423 ft. Guaer flow 15 900 2.44 6.76 8048 2700 5348
20 1200 1.98 5.48 8175 3600 4575
Z1= 50.0 For Z2 25 1500 1,68 4.64 8311 4500 3811
Z2 = 3.5 Type B=1,0 30 1800 1.46 4.04 8447 5400 3447
n= 0.016 Rolled = 3.5 35 2100 1.30 3.60 8595 6300 2295
S= 0.4183 40 2400 1.18 3.26 8771 7240 1571
45 2700 1.08 3.00 8973 8100 873
d= 0,2780 ft. Fiow Width 13.9 ft. 50 3000 1.01 2.79 9175 9000 175
. 55 3300 0.94 2,60 9350 9900 •550
60 3600 0.88 2.44 9497 10800 -1303
A R Q Tc Tc total I Qc 65 3900 Q.83 2.30 9651 11700 -2049
2.07 0.14 6.98 2,09 14,25 2.53 7,01 7Q 4200 0.79 2.20 9876 12600 •2724
. 75 4500 0.77 2.13 10214 135Q0 •3286
Opeak for Case 1= 7,01 cfs 80 4800 0,75 2.09 10625 14400 •3775
85 5100 0,73 2.03 10953 15300 4347
90 5400 0,70 1,93 11007 16200 •5193
95 5100 0.66 1.82 10904 17100 -6196
CASE 2 100 60Q0 0,68 1.89 11844 18000 -6156
Case 2 assumes a 7ime ot Concentratlon less than 5 minutes so that the 0208" TREATMENT REQUIREMENTS
peak flow =.90(Tc=5 intensity)(Imp, Area) = 6.37 cfs Minimum "208" Volume Required 1,680 cu A
Provided Treatment Valume 2,180 cu ft
DRYWELL REQUIREMENTS - 50 YEAR OESIGN STORM
So, the Peak flow fa the Basin is the greater of the two flows, Maximum Storage Required by BowsVing 5429 cu ft
7.01 cis Provlded Starage Valume 3341 cu ft
Number and Type of Drywells Required 0 Single
3 Double
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