20070684 Columbia Rim _Storm Calc Comments.pdfI -F
100.2300 ft 105.7800 ft
0.10
Orif Coeff: 0,62
Bottom El:
93.23 ft
Lowest Diam:
0.6250 in
out to 2nd: 4.4000 fl
Diam:
2.0000 in
IN"j
Ij
J
20
j o
BIOSWALE CALCULATIONS
21
Project: Columbis data Bu ilding_C�ny- 8128 240th Street Southwest Site
METHOD OF ANALYSIS
Step 1) Calculate design flows
Biofiltration swales generally precede other water quality facilities
If DO high flow bypass
Water Quality Design Flow
Rainfall Zone:
Soil Type: Till or Outwash?
Forest
Pasture
Grass
Wetland
Impervious
IM
FA
0.105 (cfs)
„...09750
0.000
044
Q1,
0.0,31 cfs)
IM
FA
Required "15
Time Step: Hourly or 15 -min?
Areas
draining to
0.000
^ (acres) Swale
0.000
(acres)
0,000
(acres)
0.000
(acres)
0.120
(acres)
Required "15
Time Step: Hourly or 15 -min?
15 -min
min"
Recommend
Data Type: Reduced or Historic?
Reduced
"Reduced"
Step 2) Calculate Swale bottom width
Simplified
Manning's
67*
b *-n,)/(IA9*y' so,S)
2.00
(R)
formula
Calculated in
Q"A water quality design flow
0.031
(cfs)
Step I
Required
ttMn Manning's roughness coefficient
020
0.20
Mowed 2 in.
(0. l7ft),
Rural 4
y= design flow depth
0.080
(ft)
im(0-33ft)
S-- longitudinal slope along path
0.0150
(ft/ft)
If the bottom width is calculated to be between 2 and 10 feet, proceed to Step 3.
If bottom width is less than 2 feet, increase width to 2 feet and recalculatc the design flow depth (y)
If bottom width is More than 10 feet: increase longitudinal slope (s), increase design flow depth (y),
install flow divider
and flow spreader, or relocate Swale after detention facility.
Step 3) Determine design flow velocity
22
If the length is less than 100 feet, increase the length to 100 feet, Beaving the bottom width unchanged.
If the swale length can be accommodated on th�W site, proceed to Step 6.
If the length is too long for the site, proceed to ;Step 5
Step 6) Provide conveyance capacity for Rows higher than Q,
Meet conveyance requirements of STAMEW Section 5.5 3 and check conveyance and velocity of high
flows aganist erosion requirements.
(o
A)
n,;:,- Manning's toughness coefficient
A� by,+Zyea
R, A/(b-i-2y�(Zl+l '11)
s -n. longitudinal slope, along flow
Y� =
I 00 -yr flows
13) vK)o�-,Q,00/Amo
If vjGf, exceeds 2.0 feet per second, return to Step 2 and increase the bottom width or flatten slope.
Size ummary
Land area is needed for the channel, access, setbacks, and, if necessary, area to
convey high flows.
A,= Water surface at conveyance depth
Cross, Section includes depth, channel slope x length, and, if necessary,
underdrain and high flows.
Slope times length =
23
Mannines,
Flow
Continuity
v,
design flow velocity
0.18
(fps)
Eq.
Manning's
In"
0.2001/
Cross-
V e
Cross
0.427 (ftp)
sectional area
(olf�
J 2,
Hydraulic
at design
Radius
by + ZY
0.1792
(f1l)
depth
0.01.50'1 (ft/ft)
side slope length per unit height
(ft/ft)
Select now
if the velocity exceeds 1.0 foot per second, go back to Step 2 and modify longitudinal slope, bottom
now, from
Width, or depth.
Flow Master
1f the velocity is less than 1,0 foot
per second, proceed Step 4.
----.0.25
Step 4) Calculate s,wale length
L = 540*Vl,
swale length
100
(fl)
Required 9
540
hydraulic residence time
540
(s)
minutes
Calculated
design flow velocity
0-175_.
(fps)
from Step 3
If the length is less than 100 feet, increase the length to 100 feet, Beaving the bottom width unchanged.
If the swale length can be accommodated on th�W site, proceed to Step 6.
If the length is too long for the site, proceed to ;Step 5
Step 6) Provide conveyance capacity for Rows higher than Q,
Meet conveyance requirements of STAMEW Section 5.5 3 and check conveyance and velocity of high
flows aganist erosion requirements.
(o
A)
n,;:,- Manning's toughness coefficient
A� by,+Zyea
R, A/(b-i-2y�(Zl+l '11)
s -n. longitudinal slope, along flow
Y� =
I 00 -yr flows
13) vK)o�-,Q,00/Amo
If vjGf, exceeds 2.0 feet per second, return to Step 2 and increase the bottom width or flatten slope.
Size ummary
Land area is needed for the channel, access, setbacks, and, if necessary, area to
convey high flows.
A,= Water surface at conveyance depth
Cross, Section includes depth, channel slope x length, and, if necessary,
underdrain and high flows.
Slope times length =
23
In
Mannines,
Eq.' - 100 -yr
or 25 -yr flow
0.l 05 (Cfs)
in Step I
Manning's
In"
0.2001/
V e
Cross
0.427 (ftp)
sectional area
Hydraulic
0.13V (ft)
Radius
Selected in
0.01.50'1 (ft/ft)
Step 2
Calculate
now, from
0,170 41)
Flow Master
(fps)
----.0.25
248 (W)
From Steps
1.50 (ft)
3, 4, and 6
In