HomeMy WebLinkAboutCC - Storm Drainage Calcs -CK
- ENGINEERING P. C .
Civil Engineering * Project Management
DRAINAGE CALCULATIONS FOR:
Greyed f Estates Subdivision *4
Meridian,Ada County, Idaho
June 16, 2023
ASS\O l NA F�
O\STE Ci
9412
6/16/23
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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 I300 E.State St Suite 102 Eagle,ID 83616
208.869.o5go mobile
chad@ck-engincers.com
ENGINEERING P. C .
-C, Civil Engineering * Project Management
J J ] J
Drainage Narrative for
GREYCLIFF ESTATES SUBDIVISION #4
Greycliff Estates Subdivision #4 consists of 7 drainage areas that drain
to 3 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 1.445 acres. The total time of
concentration for this area is calculated at 25.62 minutes. This results in a ioo
year storm intensity of 1.58 in/hr and a 25 year intensity of 1.14 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 1.14 CFS to Seepage Bed #1 and a total 25 year
flow of 0.82CFS to Seepage Bed #1. Considering the calculated storm run-off
numbers, the required loo year storm volume for the Seepage Bed #1 is 3,121 CF.
Seepage Bed #1 is to be 12'Wx11'Dx55'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 1300 E.State St Suite 102 Eagle,ID 83616
208.869.o590 mobile
chad@ck-engineers.com
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-#5.
These areas combine for a total area of 4.05o acres. The total time of
concentration for this area is calculated at 40.15 minutes. This results in a too
year storm intensity of 1.15 in/hr and a 25 year intensity of o.82 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 2.33 CFS to Seepage Bed #2 and a total 25 year
flow of 1.66 CFS to Seepage Bed #2. Considering the calculated storm run-off
numbers, the required too year storm volume for the Seepage Bed #2 is 8,748
CF. Seepage Bed #2 is to be 15'Wxll'Dx123'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.
Existing Area:
Drainage areas #Ei-#E2 flow back to an existing storm drain system
designed in Greycliff Estates Subdivision #3. Please see those calculations. We
have attached the drainage exhibit from those calculations. The areas El and E2
were accounted for with drainage basin 2. Please see the attached calculations for
the existing area.
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 #4 drainage areas
3. Exhibit for existing drainage areas accounted for in phase #3
4. Geotechnical Engineering Report
End of Narrative
CK Engineering 13oo E.State St Suite 102 Eagle,lU 83616
208.869.o590 mobile
chad@ck-engincers.com
N
W E
/ w \
0 100' 200'
EXISTING DRAINAGE .> \
FOR DRAI :_ \
o #E AREA #E1 :i \\ SCALE 1" = 100'
F
DRAINAGE AREA #E1: 24,302 SF - EXISTING PHASE #3 SEEPAGE BED
DRAINAGE DRAINAGE AREA #E1: 31,136 SF - EXISTING PHASE #3 SEEPAGE BED
AREA #E2 I ,. �Ks \ DRAINAGE AREA #1: 35,445 SF - PHASE #4 SEEPAGE BED #1
CATCH IN #3 I \\ DRAINAGE AREA #2: 27,502 SF - PHASE #4 SEEPAGE BED #1
- , ! ( \ DRAINAGE AREA #3: 79,111 SF - PHASE #4 SEEPAGE BED #2
0°0°0°0 0 1 I DRAINAGE AREA #4: 76,010 SF - PHASE #4 SEEPAGE BED #2
o°oD IMIA DRAINAGE AREA #5: 21,292 SF - PHASE #4 SEEPAGE BED #2
BLOOK 5 0 0 0 0 0 .
°0-0000000
MA'000000000 _ DRAINAGE O
000 DRAINAGE AREA #3 O O O O
° AREA #5 3t,
O O 4�1
°00000000000 ; `DRAINAGE O
000000000000 '� AREA #2
CATCH BASIN #5— °°°°0°0°0000 LLLLL
LLLLLLLLLLLLLL LLLLLLLLLLL O O O O
- DRAINAGE
L LLL LLLL LLLL LLL LLLL LLLLLLLL LLLL LLLL O AREA #1 O
TCH BASIN 4 LL-LLLL LLLL LLLL LLLL Lu TEgLF LL LLLL LLLL LLLL LL
# LL LLL LLLL LLLL LLLL LL DRAINAGE . LLLL LLL LLLL LLLL LLLL LL
L LLL LLLL LLLL LLLL LL LLLL LLL LLLL LLL }��1-6qu��7.'1
AREA 4 p O IN
L LLL LLLL LLLL LLLL LL # LLLL LLL LLLL LLLL LLLL L
SEEPAGE BED 112� L LLL LLLL LLLL LLLL LLLLLLLL LLLL LLL LLLL LLLL LLLL LL
A LL L LLL LLLL LLLL LLLL LLLLLLLL LLLL LLL LLLL LLLL LLLL LL O O
L LLL LLLL LLLL LLLL LLL LLLL LLLL LLL LLLL LLLL LLLL LL
LLL LLL LLLL LLLL LLL LLLL LLLL LLLL LL
SEEPAGE BED #1—/z
G RAYC E EE ESTATES S U B D V S 0 N #4 REVISIONS: DRAWN BY: DES
CHECKED BY: Cslt CK ENGINEERING
D R AN A G E EXHIBIT DATE. 06/02/23 1300 E. STATE ST., SUITE 102
M E R D A N , EAGLE, ID 83616
FILE: X-BASE-GRYCLF#4.DWG PHONE 208-639-1992
D I R: D:\KB HOMES\GREYCUFF SUB\CKDWGS\PHASE 4
TIME OF CONCENTRATION
PROJECT: Dry Creek Ranch Village Subdivision#4
BASIN: Seepage Bed #1 (D.A.s#1-2)
OVERLAND SHEET FLOW fT1J:
_0.007(nL)0-A ,WHERE: n = 0.24
_
T` °5 aR L1= 66
(PZ} s P2= 1.2
where:
s= 0.01
Tt = travel time(hr),
n = Manning's roughness coefficient
T1 (hrs)= 0.368
1, = flow length(ft)
P2 = 2-year,24-hour rainfall(in) T1 (min)= 22.05
s = slope of hydraulic grade line
(land slope,ft/ft)
GUTTER CONCENTRATED FLOW:
s 2= 0.0042
V =2Q.Wq)"'� , WHERE: V2= 1.32
L2= 270
T2= L2N2 T2 (s)= 204.9484
T2(min)= 3.42
CHANNEL/PIPE FLOW: [T31
Pipe D(in)= 12
2 1
V _ 1.49r3s2 , WHERE: Ac(ft)= 0.79
n Pw (ft)= 3.14
where: r= 0.25
V = average velocity(f ls) s= 0.0050
r= hydraulic radius(ft)and is equal to a/p,,. n= 0.012
a= cross sectional flow area(W) V3= 3.47
pw= wetted perimeter(ft)
s= slope of the hydraulic grade line(channel L3=1 32
slope,ft/ft)
n= Manning's roughness coefficient for open
channel flow. T3(s)= 9.23
T3(min)= 0.15
T3 = L3N3
TOTAL TIME OF CONCENTRATION (T1+T2+T3)
Tc= 25.62 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
25.62 MIN 1.58(IN/HR)
WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF
C= l0.5 Q=c(I)(A)
DRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN
DA#1 35445 0.814 1.58 0.5 0.64 cfs CB#1
DA#2 27502 0.631 1.58 0.5 0.50 cfs CB#2
TOTAL: 62947 1.445 1.58 0.5 1.14 cfs
25 YR STORM INTENSITY GIVEN WITH TIME OF CONCENTRATION
25.62 MIN (IN/HR)
WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF
C= Q= c(l)(A)
BRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN
DA#1 35445 0.814 1.14 0.5 0.46 cfs CB#1
DA#2 27502 0.631 1.14 0.5 0.36 cfs CB#2
TOTAL: 62947 1.445 1.58 0.5 0.82 cfs
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is Intended to be a guideline to standardize ACHO 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.
r I-nput In yeNg!K cells.
1 Project Name iGraydW Estates Subd"lonlf4-Seepage Bed 81
2 Is area drair age basin map provided? TES
(mop 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(25 max)
Orck to Show More Subbasms L
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10
S Area of Drainage Suttii sin(SF ar Acrril SF 3_R445 27sS02
Acre 1.45
6 Determine the We.ghtee Runoff Coefficient(C) r Ode F,
C=[[C1xA1)+(C2xA2)+;E.rxAn))/A Weight4Avg 0.50
7 [..sec caicutate�
Calculate Oyerlaqd flow Time of Concentration in Minutes(Tc)or use default 10 min 10 µ'" Estimated Runoff Coefficients for Various Surfact
Types of Surface r Runoff Coefficients"t
Business
Downtown areas 10.70-0.95
Hydraulic Urban neithborheodr 10.50-0.70
Radius Flow residential
Intercept A/Wet Velocity V Flow Time II Sings Fam,y o.3s-0.50
ID P eSize J in Sks a ftJft1 Coeff. Length Ilylanifingril Perm s min s Mufti-f—ir 0.60-0.75
moot 1 P Flow Rnkmntw lru -0 rap _ o.2s .ao
A}enment Dwethry Areas 0.70
a 12 0.005 32 M012 1 0,25 1 3.5 0.2 tndustriaiand Commersiat
LYBYrt areas 0.90
forgment 2:Gutter Shadow Concentrated Row Meaq areas 0.90
Parks,Cemeteries 0.10-0.25
b 0.004 0.619 270 1.3 3.4 Plarerounds 0.20-0,35
Railroad yard ore" 0.20-0.40
Segneant 3:Oyedand Sheet F!l B TR-S5<3ODdt
c 0.010 66 1 0.240 3.0 22.1
ComputedTc 2.1.6
User-EnteredTc 25.6
B Determine the average ralnfa' ntensity(1)from IDF Curve based on Tc IL59 In At
9 Calculate the Post-Development peak discharge(QPeak) O"A L14 cfs
10 Calculate total runoff vol(V)(for sizing primary storage) V 2,497 Aft
V-Ci(fcr:60)Ax3600
11 Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm I(9Sth percentile a 0.60 in) 95th 0.60 In
Enter Runoff Reduction Vol(95th Percentile=0.Wln xArea xC) V. 1,561 ft,
12 Detention:Approved Discharge Rate to Surface Waters jif applicable) Wcfs
13 Volume Summary unimproved areas v 10-0.30
Surface Storage:Basin streets
c
Basin Forebay V 2SO ft` Concrato 0.95
Pdmary Treatment/Storage Basin V 4247 ft' Brick 0.95
Subsurface Storage Roofs 0.95
Gravel
Volume Without Sediment Factor(See BMP 20 Tab) V 24� 97 ft` Fields:Sandy soft soil
SoYl Typo
Slope A B +C D
flat:0-2% O.oa 0.07 0.11 0.
Avera8e:2fi% 0.09 0.12 0,15 0-
Steep:a6% 0.13 0.18 0.23 O-
Adopted from ASCE
D:\KB Homes\Greyckff Sub\DOCUMENTS\PHASE 4,DRAINAGE CALCS\GRYCLFR4 SEEPAGEBED n1_6-2 23 x sm 6/27/2023,5:43 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 flows,Increase number of storage facilities to create new tab)
User input In yellow cells.
1 Project Name Graycliff Estates Subdivision#4-Seepage Bed#1
2 Enter number of Seepa6e Beds.25 maxi 1
3 Design Storm 100
4 Weighted Runoff Coefficient C 0.S8 Link to: ro—v�
QV 7RSS
5 Area A(Acres) 1.45 acres
6 Approved discharge rate(if applicable) MOD cis
7 Is Seepage Bed in Common Lot? No V 3,121 ft' 25%Sediment
8 Set Total Design Width of All Drain Rock W 12.0 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 Rods Voids OA
0.4 for 1.5".2"drain rock and 3/4'Chips
11 Design infiltration Rate IS In/hr max) Perc 8.00 fn/hr
12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in
13 She of Overflow Perf Pipe(Perfs 3",READ if Q100>3.3 cfs •n
14 Calculate Total Storage per Foot Spf 57.0 Oft
15 Calculate Design Length L 55 ft
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 55 ft
17 Variable infl'tration Window W SWW 12.0 ft
18 Time to Drain 6.4 hours
90%volumo in 48-hours m:nlmum
19 Length of WQ&Overflow Perf Pipes 55 ft
20 Perf Pipe Checks.Qperf>=Clpeak;
where Qperf=CdxAxV(2xgxH)
Note:This assumes chambers are organ:zed ins rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ft'
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 250 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 W/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft'/Unit
7 Total Number of Un is Required 0 ea
8 Area of Infiltration Aperc ft,
9 Volume mfiltratlon Vperc 0 ft}/hr
10 Time to Drain hours
90%volume in 48-hours minimum
D:\KB Homes\Greychff Sub\DOCUMENTS\PHASE 4\DRAINAGE CAtCS\GRYCLF#4 SEEPAGEBED#1 6 2 23.x sm 6/27/2023,5 43 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#4-Seepage Bed#1
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
Vault Size Spacing width Area(fe) 0.5 fps Velocity
SIG Traps Q-cfs inch inch max. ok?
1000 G 1 1.14 20 48 6.67 0.17
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
D:\KB Homes\Greycliff Sub\DOCUMENTS\PHASE 4\DRAINAGE CALCS\GRYCLF#4 SEEPAGEBED#1_6-2-23.xism 6/27/2023,5:43 PM
Version 10.0, May 2018
TIME OF CONCENTRATION
PROJECT: Dry Creek Ranch Village Subdivision #4
BASIN: Seepage Bed#2 (D.A.s#3-5)
OVERLAND SHEET FLOW(T1):
p 007(nL)°_A , WHERE: n= 0.24
Tt = (P2)n.5sa.a L1= 106
P2= 1.2
where:
s= 0.01
Tt = travel time(hr),
n = Mannittg's roughness coefficient
L = flow length(ft) Tl (hrs}= 0.537
P2 = 2-year,24-hour rainfall(in) T1 (min)= 32.22
s = slope of hydraulic grade line
(land slope,ft/ft)
GUTTER CONCENTRATED FLOW:
s2= 0.004
V =20.3 69)" , WHERE: V2= 1.29
L2= 600
T2= L2/V2 T2 (s)= 466.688
T2(min)= 7.78
CHANNEL/PIPE FLOW: M)
Pipe D(in)= 12
2 1
V _ 1.49r3s2 , WHERE: Ac(ft)= 0.79
n Pw(ft)= 3.14
where: r= 0.25
V = average velocity(ft/s) s= 0.0050
r= hydraulic radius(ft)and is equal to a/p,w n= 0.012
a= cross sectional flow area(ft.!) V3= 3.47
py,.= wetted perimeter(ft)
s= slope of the hydraulic grade line(channel L3= 32
slope,ft/ft)
n= Manning's roughness coefficient for open
channel flow. T3(s)= 9.23
T3(min)= 0.15
T3 = L3N3
TOTAL TIME OF CONCENTRATION (Tl+T2+T3)
Tc= 40.15 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
40.15 MIN :1�(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#3 79111 1.816 1.15 0.5 1.04 cfs CB#3
DA#4 76010 1.745 1.15 0.5 1.00 cfs CB#4
DA#5 21292 0.489 1.15 0.5 0.28 cfs CB#5
TOTAL: 176413 4.050 1.15 0.5 2.33 cfs
25 YR STORM INTENSITY GIVEN WITH TIME OF CONCENTRATION
50.1 M N— 082 (IN/HR)
WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF
C= 10S C!=c(1)(A)
DRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN
DA#3 79111 1.816 0.82 0.5 0.74 cfs CB#3
DA#4 76010 1.745 0.82 0.5 0.72 cfs CB#4
DA#5 21292 0.489 0.82 0.5 0.20 cfs CB#5
TOTAL: 176413 4.050 1.15 0.5 1.66 cfs
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to he a guideline to standardize ACRD 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.
g
User Input In yellow cells.
1 Project Name GraydHfEmtes Subdivision g4-Seepage Bed#2
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[
:Ircx io Show More Su6basins
Subbasin Subbasin Subbasin Subbasin Subbaskt Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 S. Subbasin 6 7 B 9 10
5 Area of Drainage Subbasin(SF or Acres[ SF 79,111 76,010 21,292
Acre 4.05
6 Determine the Weighted Runoff Coefficient(C) OR O.SO O;"
C=[(CJxA1)+(C2xA2)+[CnxAn)]/A Weighted 0.S0
7 [user takulare"�`�'r
Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 30 min 10 M.n Estimated Runoff Coefficients for Various Surfacr
- Type of Surface Runoff Coefficients^l
eusiness
Downlownareas 0.70-0.95
Hydraulic urban neighborhoods 0.50-0.70
Radius Flow Residential
Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50
ID pipe size in Sto a ft/ft Coeff. Len h Mannin n Perm s min MunMfamfly 0.6o-0.75
Residential rural 0.25-0.da
Segment 1-.Pipe Flow Apartment Dwelling Areas 0.70
a 12 0.005 32 1 0.022 1 0.25 3.5 0.2 Industrial and commercial
Light areas oleo
He araaa 0.90
Segment 2:Gutter Shallow Concentrated Flaw J' Parr C.meteriez 0-10-0.25
b 0.004 0.619 600 1.3 7.6 Playgrounds a.2D 0.35
Railroad yard areas
Segment 3:Overland Sheet flow B .TRSS<30O-tt
c 0.010 106 0.240 3.3 32.2
Computed Tca 40.0
User-Entered Tc= 40.0
B Determine the average rainfall Intensity(1)from IDF Curve based on Te I yu I hr
9 Calculate the Post-Development peak discharge(QPeak) Line y33 cis
10 Calculate total runoff vol(V)(for sizing primary storage) V 61998 ft
V-Ci(rce60K0600
11 Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm I(95th percentlle-0.60 In) 95th L60 in
Enter Runoff Reduction Vol(95th Percentile-0.60-In xArea x C) Vrr 4,374 ft*
12 Mention:Approved Discharge Rate to Surface Waters(If applicable) 0.00kfs
13 Volume Summary _un_ ImFroved areas 0.10-0."
Surface Storage:Basin streets
Basin Foreba V 700 It Asphalt ass
Y Concrete 0.95
Primary Treatment/Storage Basin V 61298 its Brick 0.95
subsurface Storage Ranh 0.95
Gravel 0.75
Volume Without Sediment Factor(See GMP 20 Tab) V 6,"S ft. Fields:sandy call Sall Type
Slope A It
Flat:0.2% O.DA 0.07 0.11 0.
Average:2-fi% 0.09 0.12 0-15 0.
Ste. :N% 0.13 a t. 0.23 a.
Adapted from ASCE
D:\KB Homes\Greycliff Sub\DOCUMENTS\PHASE 4\DRAINAGE CALLS\GRYCLF94 SEEPAGESED 42 6.2,23.xlsm 6/27/2023,5:44 PM
Version 10.0,May 2019
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE:This worksheet is intended to he 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.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab(
User input in yellow cells.
1 Project Name Goonfiff Estates Subdivision M4-Seepage Sect fit
2 Enter number of Seepage Beds 125 maxi 1
3 Design Storm 100
4 Weighted Runoff Coefficient C 0.50 Link to:
5 Area A(Acres) 4,05 acres
6 Approved discharge rate(if applicable) 0.00 cis
7 Is Seepage Bed in Common Lot? No V 8,749 ft} 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 Vold Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4'Chips
It Design Infiltration Rate(a in/hr max) Perc 8.00 In/hr
12 Size of WQ Pert Pipe(Pert 1800) Dia pipe 18 In
13 Size of Overflow Perf Pipe(Perfs 3600),REQD if Q100>3.3 cfs in
14 Calculate Total Storage per Foot Spf 71.2 ft;/ft
15 Calculate Design Length L 123 ft
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 123 It
17 Variable Infiltration Window W SWW 25.0 ft
18 Time to Drain 6.4 hours
90%volume in 48-hours minimum
19 Length of WO&Overflow Perf Pipes 123 ft
20 Perf Pipe Checks.Qperf>-Qpeak;
where Qpert=CdxAx JZWH)
Note:This assumes chambers are organized in a rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ft3
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 2.50 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Vold Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft;/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft;/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ft2
9 Volume Infiltration Vperc 0 ft3/hr
10 Time to Drain hours
90%volume In 48-hours m-nimum
D\KB Homes\Greydiff Sub\DOCUMENTS\PHA5E 4\DRAINAGE CALCS\GRYCLF#4 SEEPAGEBED 02 6.2 23.xism 6/27/2023,5:44 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 44-Seepage Bed#2
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat LO.3
Is the
Vault Size Spacing width Area(le) Velocity
5!G Traps Q-cfs inch inch ok?
1000 G 1 2.33 20 48 6.67
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
Q U 1000 n/a n/a 60
Q U 1500 n/a n/a 60
D:\KB Homes\Greydiff Sub\DOCUMENTS\PHASE 4\DRAINAGE CALCS\GRYCLF#4 SEEPAGEBED#2_6-2-23.xlsm 6/27/2023,5:44 PM
Version 10.0, May 2018
21
N1` GRAYCLIFF SUBDIVSION PHASE 3
2 BLOCK3 \\ A T �\\ DRAINAGE BASIN MAP
q
1C 2 3
2
BLOCK 2 3 5 \ \\\
�I 5 8 \�
\ 22
28 27 26 25 6 \ 9 \
24 �
� 8 10
23
22 l{{ / 10 BASIN 1 12 \ \\
- - - 21 11
E 1 2 3 4 20 12 14
19 13 \
14 BLOCK 3
18 \
BLOCK 2 15 15 17
S7
FUTURE
k BASIN 2 PHASE
3� NORTH 2 I 1 2 3 4 K fi ,r 4Tt I 1 \\ \
--- - BL
3 35 - - -- r � err
� BLOCK 4
2T 1 26 25 1 24 I 23 22 21 20 19 18 I 17 16 I 15 14 7
GRAPHIC SCALE IN FEET 4 36 _ B
0 75 150 300 !!!
5 37 i - - 5
., 14-7
Kimley)))Horn