HomeMy WebLinkAboutAJ Inc. Drainage CalculationsWHPacific
DRAINAGE CALCULATIONS
FOR
NEW BUILDING, AJ INC.
MERIDIAN, IDAHO
DECEMBER 2014
3130 SOUTH OWYHEE STREET - BOISE, IDAHO - 83705 PHONE: (208) 342-5400 FAX: (208) 342-5353
DRAINAGE CALCULATION SUMMARY
Project: New Building - AJ Inc.
Project #: 0005917W
Date: 12/12/2014
The stormwater runoff on the project site will be collected and treated via sand/ grease
traps. The stormwater will then be treated by sand filtration prior to discharging into
the receiving soils.
The runoff was calculated using a 100yr, 1 h design storm (1" runoff), for volume and
a 50 yr storm for sizing the sand/ grease traps.
The "c" value used in calculating the runoff is based upon the hardscape due to the
lack of landscaping draining to the system. Roof runoff from the building is assumed
to drain to the system.
SYSTEM AREA "C" Value
1 20, 970.00 0.9
2 57;490.00 0.9
3 2,870.00
DrnCalcs-AJ Building.xls Summary
0.9
4
20, 890.00
0.9
DrnCalcs-AJ Building.xls Summary
New Building - AJ Inc.
Drainaqe Area # 1
C value: 0.90
Initial Trench Volume = 1 in x (Area (ac) x 43560cu.ft./ac) x 1ft./12in. x "C"
Volume = 1572.75 cu. ft.
Req'd Storage Vol. = 1573 ft'
Trench Dimensions = 8 Depth (ft)
10 Width (ft)
42 Length (ft)
Storage/ft = (Vr)(D)(W)
D =
8 ft
Depth
= 32 ft2
W=
10 ft
Width
Bottom Perc/ft = (W)(Pr)(1ft/12")
Vr =
40 %
Drain Rock Void Ratio
= 6.67 ft2
Pr =
8 in./hr
Percolation Rate
Trench Volume = (Length)(Storage/ft + Bottom perc/ft)
Trench Volume = 1624 ft'
Velocity in throat
Flow = Q21 =C*i25*a 62 3.1 time of concentration < 5min
(in/hr)
Q25= 1.3 cfs
Velocity = Q25/A A= area of throat in box'
A= W*T
A= 4.17 sq. ft. A= width of box . throat o
W= 4.17 1000 gal s/g trap
T= 1.00
Velocity = 0.32 ft/ sec
DmCalcs-AJ Building.xls System #1 2
New Building - AJ Inc.
Drainaae Area # 2
Area (acres): 1.32
C value: 0.90
Initial Trench Volume = 1 in x (Area (ac) x 43560cu.ft./ac) x 1ft./12in. x "C"
Volume = 4311.75 cu. ft.
Req'd Storage Vol. = 4312 W
Trench Dimensions = 8 Depth (ft)
12 Width (ft)
95 Length (ft)
Storage/ft = (Vr)(D)(W)
D =
8 ft
Depth
= 38.4 ft2
W=
12 ft
Width
Bottom Perc/ft = (W)(Pr)(1ft/12")
Vr =
40 %e
Drain Rock Void Ratio
= 8.00 ftz
Pr=
8 in./hr
Percolation Rate
Trench Volume = (Length)(Storage/ft + Bottom perc/ft)
Trench Volume = 4408 ftp
Velocity in throat
Flow= Q21=C*i25*a i25= 3.1 time of concentration < 5min
(in/hr)
Qts= 3.7 cfs
Velocity = Q25/A A= area of throat in box
A= W*T
A= 7.69 sq. ft. A= width of box . throat o
W= 5.13 1500 gal s/g trap
T= 1.50
Velocity = 0.48 ft/ sec
DmCalcs-AJ Building.xls System #2 3
I New Buildina - AJ Inc. I
Area (acres): 0.07
C value: 0.90
Initial Trench Volume = 1 in x (Area (ac) x 43560cu.ft./ac) x 1ft./12in. x "C"
Volume = 215.25 cu. ft.
Req'd Storage Vol. = 215 ft'
Trench Dimensions = 4 Depth (ft)
6 Width (ft)
18 Length (ft)
Storage/ft = (Vr)(D)(W)
D =
4 ft
Depth
= 9.6 ft2
W =
6 ft
Width
Bottom Perc/ft = (W)(Pr)(1ft/12")
Vr =
40 %
Drain Rock Void Ratio
= 4.00 ft2
Pr=
8 in./hr
Percolation Rate
Trench Volume = (Length)(Storage/ft + Bottom perc/ft)
Trench Volume = 245 ft'
Velocity in throat
Flow = Q25 =C*its*a i25= 3.1 time of concentration < 5min
(in/hr)
Q25= 0.2 cfs
Velocity = Q25/A A= area of throat in box
A= W*T
A= 1.50 sq. ft. A= width of box . throat o
W= 3.00 350 gal s/g trap (DB1)
T= 0.50
Velocity = 0.12 ft/ sec
DrnCalcs-AJ Building.xls System #3 4
New Building - AJ Inc.
Drainaae Area # 4
Area. (acres): 0.48
D =
C value: 0.90
Depth
Initial Trench Volume = 1 in x
(Area (ac) x 43560cu.ft./ac) x 1ft./12in. x "C"
Volume =
1566.75 cu. ft.
Req'd Storage Vol. =
1567 ft'
Trench Dimensions =
6 Depth (ft)
= 6.67 ft2
10 Width (ft)
8 in./hr
55 Length (ft)
Storage/ft = (Vr)(D)(W)
D =
6 ft
Depth
= 24 ft2
W =
loft
Width
Bottom Perc/ft = (W)(Pr)(1ft/12")
Vr =
40 %
Drain Rock Void Ratio
= 6.67 ft2
Pr =
8 in./hr
Percolation Rate
Trench Volume = (Length)(Storage/ft + Bottom perc/ft)
Trench Volume = 1687 ft'
Velocity in throat
Flow = Q21 =C`izs*a i25= 3.1 time of concentration < 5min
(in/hr)
Q25= 1.3 cfs
Velocity = Q2s/A A= area of throat in box
A= W'T
A= 1.50 sq. ft. A= width of box . throat o
W= 3.00 (3)-350 gal s/g trap (DB1)
T= 0.50
Velocity = 0.30 ft/ sec
DmCalcs-AJ Building.xls System #4 1
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