HomeMy WebLinkAboutCC - Storm Drainage Calcs -CKENGINEERING P. C .
Civil Engineering * Project Management
DRAINAGE CALCULATIONS FOR:
Greycri f Estates Subdivision #5
Meridian,Ada County, Idaho
November 8th, 2023
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9412
11/08/23
CiS.T�TE OF \OP��Q'
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Prepared for:
KB HOME IDAHO, LLC
1299 N. Orchard St, Suite 210
Boise, ID 83702
Sabrina Durtschi
(208)-250-6161
Prepared by:
CK Engineering, P.C.
Chad Kinkela, P.E.
130o E. State St. Ste 102
Eagle, ID 83616
(208)-639-1992
CK Engineering 13oo E.Stake St Suite tot Eagle,ID 836t6
208.869.osgo mobile
chad@ck-engineers.com
1C. ENGINEERING P . C .
' Civii Engineering * Project Management
Drainage Narrative for
GREYCLIFF ESTATES SUBDIVISION #5
Greycliff Estates Subdivision #5 consists of 4 drainage areas that drain
to 2 different permanent Seepage Beds. These seepage beds will be owned and
maintained by the Ada County Highway District (ACHD) and built using ACHD's
requested Best Management Practices (BMP's)
The geotechnical engineering report that was referenced as part of this
design was created by Natural Resource Solutions LLC, dated February 17, 2021.
The design infiltration rate used for this project was set at 8"/hr.All storm drain
facilities will require onsite percolation testing at the location and depth of
infiltration in order to verify this percolation rate. Over excavation may be
required to reach material that will allow 8"/hr percolation. If over excavation is
required, clean pit run may be used as a backfill to get back to grade. If 8"/hr
cannot be achieved, the facility will need to be redesigned. Groundwater is not
expected to be present on site and is anticipated to be below 25 feet deep in this
area.
Seepage Trench #1
Seepage Trench #1 will be a public, permanent storm drain facility
designed per ACHD BMP20. It will accept runoff from drainage areas #1—#2.
These areas combine for a total area of 3.82 acres. The total time of concentration
for this area is calculated at 38.69 minutes.This results in a too year storm
intensity of 1.25 in/hr and a 25 year intensity of o.90 in/hr. The total weighted C
value of a single family subdivision is 0.50.These combined numbers result in a
total too year flow of 2.39 CFS to Seepage Bed #1 and a total 25 year flow of
1.72CFS to Seepage Bed #1. Considering the calculated storm run-off numbers,
the required too year storm volume for the Seepage Bed #1 is 8,250 CF. Seepage
Bed #x is to be 15'Wxll'Dxli6'L. With a void ratio of 0.4 and design infiltration
rate of 8"/hr. This bed will be sufficiently sized. Please see the attached
calculations for Seepage Bed #1.
CK Engineering 13oo E.State St Suite 102 Eagle,ID 83616
208.869.o590 mobile
chad@ck-engincers.com
C- ENGINEERING P. C.
Civil Engineering * Project Management
Seepage Trench #2
Seepage Trench #2 will be a public, permanent storm drain facility
designed per ACHD BMP20. It will accept runoff from drainage areas #3-#4.
These areas combine for a total area of 2.03 acres. The total time of concentration
for this area is calculated at 38.72 minutes.This results in a too year storm
intensity of 1.25 in/hr and a 25 year intensity of o.90 in/hr. The total weighted C.
value of a single family subdivision is 0.50.These combined numbers result in a
total too year flow of 1.27 CFS to Seepage Bed #2 and a total 25 year flow of 0.92
CFS to Seepage Bed #2. Considering the calculated storm run-off numbers, the
required too year storm volume for the Seepage Bed #2 is 4,396 CF. Seepage Bed
#2 is to be 15'Wx11'Dx62'L. With a void ratio of 0.4 and design infiltration rate of
8"/hr. This bed will be sufficiently sized. Please see the attached calculations for
Seepage Bed #2.
Attached:
1. Storm drain calculations for 2 seepage beds and 2 sand and grease traps
within this project.
2. 11"x17" colored drainage area exhibit for new phase #5 drainage areas
3. Geotechnical Engineering Report
End of Narrative
CK Engineering i3oo E.State St Suite 102 Eagle,ID 836t6
208.869.0590 mobile
chad@ck-engineers.com
TIME OF CONCENTRATION
PROJECT Greydiff Subdivision#5
BASIN: Seepage Bed#1 (D.A.s#1-2)
OVERLAND SHEET FLOW IT1):
T _ 0.007(nd" ,WHERE: n= 0.24
` �P �0.5 --- L1= 106
2 P2= 1.2
where:
s= 0.01
Tt - travel time(hr),
n Manning's roughness coefficient Ti (hrs)= 0.537
L = flow length(ft)
P2 2.year,24-hour rainfall(in) T 1 (min)= 32.22
s - slope of hydraulic grade line
(land slope,ft/ft)
GUTTER CONCENTRATED FLOW:
s2= 0.0044
V =20. 60" ,WHERE: V2= 1.35
L2= 524
T2= L2N2 T2 (s)= 388.6067
T2(min)= 6.48
CHANNEL/PIPE FLOW: IT3)
Pipe D(in)=
2 1
V_ 1.49r3s2 , WHERE: Ac(ft)= 0.00
n Pw(ft)= 0.00
where: r= 0.00
V = average velocity(ft/s)
s= 0.0000
r= hydraulic radius(ft)and is equal to a/p,, n= 0.000
a= cross sectional flow area(W) V3= 0.00
pW= wetted perimeter(ft)
s= slope of the hydraulic grade line(channel L3= 0
slope,ft/ft)
n= Manning's roughness coefficient for open
channel flow. T3(s)= 0.00
T3(min)= 0.00
T3 = L3/1/3
TOTAL TIME OF CONCENTRATION (Tl+T2+T3)
Tc= 38.69 min
TIME I in hr TIME I in hr TIME I in hr
10 min 2.58 50 min 1 12 hr 0.16
15 min 2.18 1 hr 0.96 24 hr 0.1
20 min 1.81 2 hr 0.54
30 min 1.51 3 hr 0.4
40 min 1.15 6 hr 0.25
100 YR STORM INTENSITY GIVEN WITH TIME OF CONCENTRATION
.38.69"rain 1:2 :(IN/HR)
WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF
C= 0.5 Q=c(I)(A)
DRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN
DA#1 63352 1.454 1.25 0.5 0.91 cfs CB#1
DA#2 103018 2.365 1.25 0.5 1.48 cfs CB#2
TOTAL: 166370 3.819 1.25 0.5 2.39 cfs
25 YR STORM INTENSITY GIVEN WITH TIME OF CONCENTRATION
38.69,MI .91(IN/HR)
WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF
A Q=c(I)(A)
DRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN
DA#1 63352 1.454 0.9 0.5 0.65 cfs CB#1
DA#2 103018 2.365 0.9 0.5 1.06 cfs CB#2
TOTAL: 166370 3.819 1.25 0.5 1.72 cfs
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 most result In facilities that meet or exceed these calculations in order to be accepted.
(hw.iBprt In yellow cells.
1 Project Name GraydHf Estates Subdivision#5-Seepage Bed 41
2 Is area drainage basin map provided? YES
(map must he included with stormwater calculations)
3 Enter Design Storm(1DD-Year or 2S•Year With 300-Year Flood Route) 100,
4 Enter number of storage fac lities(25 max) 1
Click to Show More Subbasins f
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin2 3 4 5 Subbasin( 7 8 9 10
S Area of Drainage Subbasin(SF or Acres) SF 63r352 203r018
Acres 3.82
6 Determine the Weighted Runoff Coefficient(C) 0.s0 O.so
C=(tC1xA1)+(C2xA2)+(CnxAn))/A Weighted Avg] 0.50
7 alit,[akulate�
Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 min i�M,. E Estimated Runoff Coefficients for Various Surface
- Type of Surface }Runoff Coefficients"r
Business
Oawntown area r 0.70-0.95
Hydraulic urban nelgp borhoods 0.50-0.70
Radius Flow Residential
Intercept A/Wet VelocityY Flow Time Skyle Family o.3s-0.50
iD P Size in Slo a ft/lt Coeff. Len h Manningn Perm s mini Multi-,tlfaralK O.2".40
Resklentlal trurall 0.25-0.40
WE t u P Fhrw Apartment owellin;Areas 0.70
a 0 0 0 0.000 0.00 industrial and Cx mmerclal
Llghtareas 0.90
race,?areas 0.90
ent 2:Gutter Shallow Concentrated now m
Pa+ks,Cemeteries 0.10-0.25
t 0.004 0.619 524 1.3 6.5 MeyiErounds I0.20-0.35
Railroad xe�d arws-- 1 0.20-0.40
fSelrant 3:Overland Sheet Flow B Tit-SS[300-ft
c 0.010 106 0.240 3.3 32.2
Computed77 38.7
t-ser-Entered Tc= 38.7
8 Determine the average rainfall intensity(1)from IDF Curve based on Tc I LZS i r
9 Calculate the Post-Development peak discharge(QPeak) Clow 2.39 cta
10 Calcuate total runoff M(V)(for sizing primarystorage) V 61600 ft
V e Cl(rcaGD A 6OG
11 Calculate Volume of Runoff Reducvon Vrr
Enter Peraentge Storm I(95th percentile+0.60 in} 95th 0.60 1
Enter Runoff FedLrctlon Vol(9Stb Percentile=0.60•-a x Area x Q V 4,12S R'
12 Detention:Apprmed Discharge Rate toSurface Waters(Ifapplicable) O.00;cfs
13 Volume Summary unlmproved areas 0.10-0.30
Surface Storage-0asin streets
m .95
13anforebay V 660 ft' Concrete .0s5
PrTary Treatment/Storage Ba. V 5,940 Asphalt 0fe orki 10.95
Subsurface Storage Reefs 10.95
10.73
Volume Without Sediment Factcr(SeeBMP20Tab� V 6,600 fts Fields:Sandy sail ScuType
Slope A B C .0
Flat:0-2% 0.04 0.07 0.11 IN
Average:2.6% 0.09 0.12 0.11 Q.
5t :n6% 0.13 mis i o.23 P
Adapted from ASCE
DUB Homes\Greycliff Sub\DOCUMENTS\PHASE S\DRAINAGE CALCS\GRYCLFRS SEEPAGEBED 41_10.24.23.xlsm 11/9/2023,4 31 PM
Version 10.0,May 2018
ACHD Calculation Sheet for Sand/Grease Traps
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 Engineers methodology must
result in facilities that meet or exceed these calculations in order to be accepted.
User input in yellow cells.
1 Project Name Graycliff Estates Subdivision#S-Seepage Bed fit
2 Enter number of Sand/Grease Traps(25 maxi 1
Number of Peak Flow Baffle Throat Velocity Is the
Vault Size Spacing width Area(ftz) 0.5 fps Velocity
S1G Traps Q-cfs inch inch max. ok?
1000 G 1 2.39 20 60 8.33 0.29
Reference for Throat widths(inch)
Boise ADS
Vault Lar-ken WQU,
BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
QU1000 n/a n/a 60
QU1500 n/a n/a 60
DAKB Homes\Greydiff Sub\DOCUMENTS\PHASE S\DRAINAGE CALCS\GRVCLF#5 SEEPAGEBED tt1_10-24-23.xlsm 11/9/2023,4:31 PM
Version 10.0,May 2018
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
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 Engineers methodology must result in facilities that
meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak Q,V"tab
Calculate Post-Development Flows(for pre-development Rows,Increase number of storage facilities to create new tab)
User input In yellow cells.
1 Project Name Greycn f Estates Subdivision i15-Seepage Bed 61
2 Enter number of Seepa a Beds i.25 max) 1
3 Design Storm 100
4 Weighted Runoff Coefficient C 0.50 Link to: �av rass
5 Area A(Acres) 3.82 acres
6 Approved discharge rate(if applicable) D.00 cis
7 Is Seepage Bed in Common Lot? No V 8,250 fts 25%Sediment
8 Set Total Design Width of All Drain Rock W 15.0 ft
9 Set Total Design Depth of All Drain Rock 0 11.0 ft
Rock Only,Do Not Include Filter Sand Depth or Cover
10 Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
11 Design Infiltration Rate(8 In/hr max) Perc 8.00 infhr
12 Size of WQ Perf Pipe(Pert 18n Dia pipe 18 in
13 Size of Overflow Perf Pipe(Perfs 360°),REQD If QSOD>3.3 cfs in
14 Calculate Total Storage per Foot Spf 71.2 Oft
15 Calculate Design Length L 116 ft
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 116 ft
17 Variable Infiltration Window W SWW 15.0 ft
18 Time to Drain SA hours
90%volume in 48-hours minimum -
19 Length of WQ&Overflow Perf pipes 116 ft
20 Perf Pipe Checks.Qperf>=Qpeak;
where Qip erf=CdxA)M 2xg%H)
Note:This assumes chambers are organized in a rectangular layout.
1-StormTech,
1 Type of Chambers SC74D
2 Volume to Store V 0 ft,
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 2.50 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft;/Linn
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 fl?/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ftz
9 Volume Infiltration Vperc 0 ftr/hr
10 Time to Drain hours
90%volume in 48-hours minimum
M\KB Homes\Greyciiff Sub\DOCUMENTS\PHASE 5\DRAINAGE CALCS\GRYCLFg5 SEEPAGEBED#1_10-24-23.xism 11/9/2023,4.31 PM
Version 10.0,May 2018
TIME OF CONCENTRATION
PROJECT. Greycliff Subdivision#5
BASIN: Seepage Bed#2 (D.A.s#3-4)
OVERLAND SHEET FLOW(TI :
0.007(nL)" , WHERE: n = 0.24E
Tt = lP }0.69o.4 L1= 122
2 P2= 1.2
where:
s= 0.131
Tt = travel time(hr),
n = Manning's roughness coefficient T1 (hrs)= 0.601
L = flow length(ft)
P2 = 2-year,29-hour rainfall(in) T1 (min)= 36.05
s = slope of hydraulic grade line
(land slope,ft/ft)
GUTTER CONCENTRATED FLOW:
s2= 0.004
V -20,cWR)" ,WHERE: V2= 1.29
L2= 20fi
Tz= L2/V2 T2 (s)= 160.2295
T2(min)= 2.67
CHANNEUPIPE FLOW:M)
Pipe D(in)= 0
2 1
V_ 1.49082 ,WHERE: Ac(ft)= 0.00
n Pw(ft)= 0.00
where: r= 0.00
s= 0.0000
V = average velocity(f/s)
r= hydraulic radius(ft)and is equal to alp„, n= 0.000
a= cross sectional flow area(W) V3= 0.00
p,,= wetted perimeter(ft)
s= slope of the hydraulic grade line(channel L3= 0
slope,ft/ft)
n= Manning's roughness coefficient for open
channel flow. T3(s)= 0.00
T3(min)= 0.00
T3 = L3N3
TOTAL TIME OF CONCENTRATION T1+T2+T3
Tc= 38.72 min
TIME I in hr TIME I in hr TIME I in hr
10 min 2.58 50 min 1 12 hr 0.16
15 min 2.18 1 hr 0.96 24 hr 0.1
20 min 1.81 2 hr 0.54
30 min 1.51 3 hr 0.4
40 min 1.15 6 hr 0.25
100 YR STORM INTENSITY GIVEN WITH TIME OF CONCENTRATION
38.72 min 5;(IN/HR)
WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF
C= S J --'} Q=c(I)(A)
DRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN
DA#3 45876 1.053 1.25 0.5 0.66 cfs CB#3
DA#4 42773 0.982 1.25 0.5 0.61 cfs CB#4
TOTAL: 88649 2.035 1.25 0.5 1.27 cfs
25 YR STORM INTENSITY GIVEN WITH TIME OF CONCENTRATION
38:7 M '�� - t _0_9 (IN/HR)
WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF
C= D:5 Q=c(I)(A)
DRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN
DA#3 45876 1.053 0.9 0.5 0.47 cfs CB#3
DA#4 42773 0.982 0.9 0.5 0.44 cfs CB#4
TOTAL: 88649 2.035 1.25 0.5 0.92 cfs
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 Engineers methodology must result in facilities that meet or exceed these calculations in order to be accepted.
4
User Input In yellow cells.
1 Project Name Graycliff Estates Subdivision NS•Seepage Bed 02
2 Is area drainage basin map provided? YES
(map must be included with stormwoter calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(2S max) 1
Click to Show More Subbasins
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 S Subbasin 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres► SF 45,06 42,773
Acre 2.04
6 Determine the Weighted Runoff Coefficient(C) 0�4 !
C=((C1xA1)+JC2xA2)+(CnxAn)j/A Weighted AvgJ 0,50
7 [.:-.er cakuiate�
Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 min Min Estimated Runoff Coefficients for Various Surfaa
— Type of Surface Runoff Coefficients"t
Business
Downtown•rags 0.70A.95
Hydraulic urban ni ilthbcrhoods 0.50-0.70
Radius Flow Residential
Intercept A/Wet Velocity V Flaw Time I shral.F.mily 0.35-0.50
ID PI a Size in Sloe ft Coeff. Length Manningn Perm s min Mutt-Z74y 0.6".75
Residential(rurall 0.25-0.40
Segment 1:Pipe now I Apartment DwellinLAreas 0,70
a 0 0 1 1 0 1 0.000 0.00 i Indrrstdaland Commercial
UgM•rasp 0.30
ment 2•Gutter Shahiaw Concentrated Flow He■5k areas 0.90
Yams,Cemeteries 0.10-0.25
b D.004 1 0.519 1 206 1 1 1.9 2.7 F v�agrounds 0.20.0.35
Railroad Vard preps 0.20-0.40_
ment 3:Overland Sheet Fk1wB TR-55 �300 it
c 0.010 122 1 0.240 3A 36.1
Computed Tc= 38.7
U rteredTc- 38.7
8 Determine the average rainfall Intensity;i)from IDF Curve based on Tc i L2S InIFr
9 Calculate the Post-Development peak discharge(gPeak) Qva.t L27 cfs
10 Calculate total runoffvol(V)(for sizing primary sto(age) V 3,517 ft
V-C1(Tc-6D)Ax36W
11 Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm 1(95th percentile-0.60 in) 95Nt 1160 In
Enter Runoff Reduction Vol(95th Percentilea0.60-In x.Area x C) VR 2,198 It.
' 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) MW icfs
13 Volume Summary unimpmved areas 0.10-0.30
Surface Storage:Bas:n streets
Asphs Basin Fambay V 3S2 fta C*mFq 0.95
Concrete 0.95
Primary Treatment/StorageBasin V 3,16S ' Brick 0.9S _-
Subsurface Storage Roots _ 0.95
I Gravel 0.75
Volume Without Sediment Factor(See BMP20Tab) V 3,517 Fields:Sandy soll Soil Type
slope A B C D
Flst.0-2% 0.04 0.07 0.11 0.
Average:26% 0.09 0.12 0.15 0.
Steep:>6% 0.13 f 0.18 0.23 10.
Adapted from ASCE
D:\KB Homes\Greycliff Sub�DOCUMENTS\PHASE 5\DRAINAGE CAtCS\GRYCLFNS SEEPAGESED a2_10-24-23 xlsm 11/9/2023,4;31 PM
Version 10.0,May 2018
ACHD Calculation Sheet for Sand/Grease Traps
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 Graycliff Estates Subdivision#5-Seepage Bed fit
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
Vault Size Spacing width Area(ftx) 0.5 fps Velocity
S/G Traps Q-cfs inch inch max. ok7
1000 G 1 1.27 20 60 8.33 0.15
Reference for Throat widths(inch)
Boise ADS
Vault Lar-ken WQU,
BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
QU1000 n/a n/a 60
QU1500 n/a n/a 60
DAKB Homes\Greycliff Sub\DOCUMENTS\PHASE 5\13RAINAGE CALCS\GRYCLF#5 SEEPAGEBED#2_10-24-23.xlsm 11/9/2023,4:32 PM
Version 10.0,May 2018
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
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 Engineers methodology must result In facilities that
meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls Information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development Rows,Increase number of storage facilities to create new tab)
User Input In yellow tells.
1 Project Name GraycBif Estates Subftislon#5-Seepage Bed 02
2 Enter number of Seepage Beds(25 max) 1
3 Design Storm 100
4 Weighted Runoff Coefficient C 0.50 link to: V -
QV TR55
S Area A(Acres) 2.04 acres
6 Approved discharge rate(if applicable) 0.00 cfs
7 Is Seepage Bed in Common Lot? No V 4,396 ftr 25%Sediment
8 Set Total Design Width of All Drain Rock W 15.0 ft
9 Set Total Design Depth of All Drain Rock D 11.0 ft
Rock Only,Do Not Include Filter Sand Depth or Cover
10 Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"[hips
31 Design Infiltration Rate(8 in/hr max) Perc 8.OD In/hr
12 Site of WO Perf Pipe(Perf 180°) Dia pipe 18 In
13 Size of overflow Perf Pipe(Perfs 36CP),READ If Q300>3.3 tfs In
14 Calculate Total Storage per Foot Spf 71.2 Oft
15 Calculate Design Length L 62 ft
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 62 ft
17 Variable Infiltration Window W SWW 15.0 ft
18 Time to Drain 6.4 hours
90%volume in 4"ours minimum -
19 Length of WQ&Overflow Pert Pipes 62 ft
20 Perf Pipe Checks.01perf>=dpeak;
where Ciperf-CdxAxJ(2xgxH)
Note:This assumes chambers are organized In a rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ftz
3 Installed Chamber Width Cw 4.2S ft
Installed Chamber Depth Cd 2-50 ft
Installed Chamber Height Ch 7-12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 f?/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ftz/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ft'
9 Volume Infiltration Vperc 0 ft;/hr
10 Time to Drain hours
90%volume in 48-hours minimum
DAKB Homes\GreycliR Sub\DOCUMENTS\PHASE 5\DRAINAGE CALCS\GRYCLNI5 SEE PAGESED 02 10 24 23.xism 11/9/2023,4-32 PM
Version 10.0,May 2018
DRAINAGE AREAS
SEEPAGE BED 11 N
D-1 = 63,352 SQFT. — CB#1 — SO TRAP #1 0 80' 160'
D-2 = 103,018 SQFT. — CB#2 — SO TRAP #1 W E
TOATAL AREA = 166,370 SQFT. SCALE 1" = 80'
S
SEEPAGE BED 12
D-3 = 45,876 SQFT. — CB#3 — SO TRAP #2
D-4 = 42,773 SQFT. — CB#4 — SO TRAP #2
TOTAL AREA = 88.649 SOFT
EXISTING
GRAYCLIFF #4 _ - - -�s� - - - - 22
38 23 I
EXISTING
1 2 BLocK�3 4 5 6 7 8
eLocK� 0 T (D (D 0 G 9 10 11 12 13 GRAYCLIFF #4
39 I 14 15
/ 40 / I
BLOC- I - -
+N + +
S&G TRAP #1 108-.50_L F
SEEPAGE BED #1 D-1 CB
- r
—D--3
T III—III — IiII —IIiIIIII
—
/ K3
Z LL. (26)
122 LF
24 23 22 (19 1830 �7 � CB#32 22 �In ��CB#2'
CB#1 524LF CB#3 20 6FXLt CB#1 C6#3
CB#4
108.50LF9LF S&G TRAP 2 214LF 109LF
CB#2 CB 2 SEEPAGE BED #2 CB#4
4 48 49 50 51 52 53 1 O2 OO I5 CJ D-4 U�8 m J45
I
P'l 7////
KB HOMES D RA �l AG E REVISIONS: DRAWN BY: DRS
CHECKED BY: CSK CK ENGINEERING
G R EY C U F F ESTATES SUBDVISION #5 DATE: 10/24/23 1300 E. STATE ST., SUITE 102
616
M ER D AN ADA COUNTY DAHO AR EAS FILE: X_MESE_GRYIFFSU .DWG EAGLE, D 83-1
PHONE 208-639-1992
9 9 D R: D:\KB HOMES\GREYCLIFF SUB\CKDWGS\PHASE 5