Specifications c,
STORMWATER CALCULATIONS
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(EXPIRATION DATE: 41%/frSI
FOR
12665 SW 69TH AVE
TIGARD, OR
JOSEPH HUGHES
JOSEPH HUGHES CONSTRUCTION,INC.
CSA JOB#02-221
PRE-DEVELOPED CONDITIONS:
Impervious Area:
Asphalt concrete area=0.14 acres
Pervious Area:
Graveled area=0.24 acres
Total Area: 0.38 acres
POST-DEVELOPED CONDITIONS:
Impervious Area:
Asphalt concrete area=0.19 acres
Office building=0.08 acres
Pervious Area:
Meadow/Grass area=0.11 acres
Total Area: 0.38 acres
CFA Consulting Engineers PRE 09:33 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Pre-developed 5-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 5 years
storm duration = 24 hr.
total rainfall = 3.00 in.
pervious area = 0.24 A CN = 89 Gp C:gravel roads
impervious area = 0.14 A CN = 98
total site area = 0.38 A
hydrograph file: c:\mydocu-1\02-221\5-yrpre.hyd
peak flow = 0.23 cfs @ 10.00 hr.
runoff volume = 3, 062 cu.ft.
' CFA Consulting Engineers PRE 09:34 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Pre-developed 10-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 10 years
storm duration = 24 hr.
total rainfall = 3.50 in.
pervious area = 0.24 A CN = 89 Gp C:gravel roads
impervious area = 0. 14 A CN = 98
total site area = 0.38 A
hydrograph file: c:\mydocu-1\02-221\10-yrpre.hyd
peak flow = 0.28 cfs @ 10.00 hr.
runoff volume = 3,714 cu.ft.
•
CFA Consulting Engineers PRE 09:34 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Pre-developed 25-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 25 years
storm duration = 24 hr.
total rainfall = 4.00 in.
pervious area = 0.24 A CN = 89 Gp C:gravel roads
impervious area = 0.14 A CN = 98
total site area = 0.38 A
hydrograph file: c:\mydocu-1\02-221\25-yrpre.hyd
peak flow = 0.33 cfs @ 10.00 hr.
runoff volume = 4, 373 cu.ft.
•
CFA Consulting Engineers PRE 10:21 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Pre-developed 100-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 100 years
storm duration = 24 hr.
total rainfall = 4.50 in.
pervious area = 0.24 A CN = 89 Gp C:gravel roads
impervious area = 0.14 A CN = 98
total site area = 0.38 A
hydrograph file: c: \mydocu-1\02-221\100-pre.hyd
peak flow = 0.37 cfs @ 10.00 hr.
runoff volume = 5,038 cu.ft.
•
CFA Consulting Engineers PRE 09:31 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Post-developed 2-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 2 years
storm duration = 24 hr.
total rainfall = 2.50 in.
pervious area = 0.11 A CN = 85 Gp C:meadow
impervious area = 0.27 A CN = 98
total site area = 0.38 A
hydrograph file: c:\mydocu-1\02-221\2-yrdev.hyd
peak flow = 0.20 cfs @ 10.00 hr.
runoff volume = 2, 696 cu.ft.
•
CFA Consulting Engineers PRE 09:31 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Post-developed 5-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 5 years
storm duration = 24 hr.
total rainfall = 3. 00 in.
pervious area = 0. 11 A CN = 85 Gp C:meadow
impervious area = 0.27 A CN = 98
total site area = 0.38 A
hydrograph file: c:\mydocu-1\02-221\5-yrdev.hyd
peak flow = 0.24 cfs @ 10.00 hr.
runoff volume = 3,347 cu. ft.
' CFA Consulting Engineers PRE 09:30 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Post-developed 10-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 10 years
storm duration = 24 hr.
total rainfall = 3.50 in.
pervious area = 0. 11 A CN = 85 Gp C:meadow
impervious area = 0.27 A CN = 98
total site area = 0.38 A
hydrograph file: c: \mydocu-1\02-221\10-yrdev.hyd
peak flow = 0.29 cfs @ 10 .00 hr.
runoff volume = 4, 007 cu.ft.
' CFA Consulting Engineers PRE 09:28 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Post-developed 25-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 25 years
storm duration = 24 hr.
total rainfall = 4 .00 in.
pervious area = 0.11 A CN = 85 Gp C:meadow
impervious area = 0.27 A CN = 98
total site area = 0. 38 A
hydrograph file: c:\mydocu-1\02-221\25-yrdev.hyd
peak flow = 0.34 cfs @ 10.00 hr.
runoff volume = 4, 672 cu. ft.
' CFA Consulting Engineers PRE 10:22 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Post-developed 100-year storm event
total Time of Concentration = 5.0'
storm hyetograph: SCS Typel
return period = 100 years
storm duration = 24 hr.
total rainfall = 4.50 in.
pervious area = 0. 11 A CN = 85 Gp C:meadow
impervious area = 0.27 A CN = 98
total site area = 0.38 A
hydrograph file: c: \mydocu-1\02-221\100-dev.hyd
peak flow = 0.38 cfs @ 10 .00 hr.
runoff volume = 5, 341 cu. ft.
RESULTS OF SANTA BARBARA URBAN HYDROLOGY FOR WATER OUANTITY
STORM CALCULATIONS:
TABLE 1 -PEAK FLOWS(CFS)
I STORM EVENT PRE-DEVELOPED POST-DEVELOPED
Z.50 12-YEAR /0.18 ✓9.20 J
3, 601 5-YEAR V,0.23 t/0.24 1
3.7OI 10-YEAR ,/ 0.28 x/0.29 I
4'00 1 25-YEAR 0.33 1/'6.34
6-a), loo-\ha_ 0. 37 a. 3g
TABLE 2-PEAK FLOWS-WITH DETENTION
STORM EVENT PRE-DEVELOPED POST-DEVELOPED
I 2-YEAR 0.18 0.17
I 5-YEAR 0.23 0.21
I 10-YEAR 0.28 0.26
I 25-YEAR 10.33 0.30
Detention will be provided by a flow control manhole with 18 feet of 18-inch detention pipe.
The flow control manhole will have a 2-inch orifice,and the detention pipe will be sloped at 1%.
RESULTS OF SANTA BARBARA URBAN HYDROLOGY FOR WATER OUALITY
STORM CALCULATIONS:
TABLE 3 -PEAK FLOWS(CFS)*
CATCH BASIN PEAK FLOW(CFS) STRUCTURE CAPACITY(CFS)
CB NO. 1 0.07 1.0
CB NO.2 0.12 1.0
*Peak flows are based on a 25-year,24-hour storm event with a total rainfall of 4-inches. Structure capacity
is based on the structure specifications for a one-cartridge steel catch basin stormfilter,as provided by
Stormwater Management,Inc.
(t#
1�4 . TABLE 4-PEAK WATER OUALITY FLOWS(CFS)**
0 CATCH BASIN PEAK FLOW(CFS) CARTRIDGE CAPACITY(CFS)
1 CB NO. 1 0.02 0.033
y (} I CB NO.2 0.03 0.033
94- q
**Peak flows are based on a 1-year,4-hour storm event with a total rainfall of 0.36 inches. Cartridge
capacity is based on the structure specifications for a filter cartridge, as provided by Stormwater
Management,Inc.
STORMWATER SUMMARY
STORMWATER NARRATIVE:
The current conditions on this site allow stormwater to sheet across the lot from East to West.The
stormwater flows across a graveled area,then across an asphalt concrete area until it eventually runs off
into a small drainage ditch just West of the property.This drainage ditch also collects stormwater run-off
from properties to the North and carries this flow down to the south where it empties into the public
stormwater system through a ditch inlet.The drainage area was inspected during a small storm event and
no apparent signs of flooding were seen,upstream or downstream.
With the post-developed conditions,the impervious area will increase two-fold.The stormwater will be
collected by two(2) stormwater filter catch basins and then emptied into a flow control manhole with an
18-inch detention pipe spanning 18-feet.The stormwater will then be carried out to the drainage ditch by a
12-inch pipe and emptied into the ditch with additional riprap ditch protection.With the provided water
detention system the post-developed peak run-off flow during a 25-year storm event will be equal to or less
than the peak run-off flow for the respective storm event with the current pre-developed conditions.
STORMWATER OUALITY:
Water quality will be provided by stormwater filter catch basins manufactured by Stormwater
Management,Incorporated.These facilities will filter petroleum and oil products from the parking lot run-
off using perlite media or CSF leaf media.
STORMWATER OUANTITY:
Water detention control will be provided by a flow control manhole with a 2-inch orifice,with an attached
18-foot long, 18-inch detention pipe. This system will maintain the current run-off flows in the pre-
developed area(during a 25-year storm event)with the post-developed terrain conditions.
DET VLCUL
2 Nig-,
10
25
100
STORMWATER CALCULATION DATA
FOR PRE AND POST-DEVELOPMENT PEAK FLOW CONDITIONS
(AS SUMMARIZED IN TABLES 1 & 2 ON SHEET 3)
CFA Consulting Engineers PRE 09:32 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
Pre-developed 2-year storm event
total Time of Concentration = 5. 0'
storm hyetograph: SCS Typel
return period = 2 years
storm duration = 24 hr.
total rainfall = 2.50 in.
pervious area = 0.24 A CN = 89 Gp C:gravel roads
impervious area = 0. 14 A CN = 98
total site area = 0. 38 A
hydrograph file: c:\mydocu-1\02-221\2-yr-pre.hyd
peak flow = 0.18 cfs @ 10. 00 hr.
runoff volume = 2, 421 cu. ft.
' CFA Consulting Engineers PRE 09:58 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
DETENTION ROUTING
flow (cfs)
0.2
0.2
i
0.1
•
0.1
0.0
0 20 40 60 80 100
time (hr)
DETENTION TUBE (stage-volume .-lculated)
diameter = 1.50'; length = le' ope = 1.00%; invert = 237.90'MSL
STAGE VOLUME
237.9 0
238.2 3
238.5 9
238.7 16
239.0 23
239.3 28
239.6 32
OUTLET TYPE ELEVATION SIZE
circ. orifice 238.0 dia. (in) = 2.00
inflow hydrograph: c:\mydocu-1\02-221\2-yrdev.hyd
outflow hydrograph: c:\mydocu-1\02-221\2-yr-pre.hyd
peaks: inflow = 0.20 cfs @ 10.00 hr.
outflow = 0.17 cfs @ 10.17 hr.
stage: 2.79 ft. volume: 32 c.f.
' CEA Consulting Engineers PRE 09:57 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
DETENTION ROUTING
flow (cfs)
0.3
0.3
0.2
0.2
0.1
0.1
0.0
0 5 10 15 20 25 30
time (hr)
DETENTION TUBE (stage-volume calculated)
diameter = 1.50'; length = 18.00'; slope = 1.00%; invert = 237.90'MSL
STAGE VOLUME
237.9 0
238.2 3
238.5 9
238.7 16
239.0 23
239.3 28
239.6 32
OUTLET TYPE ELEVATION SIZE
circ. orifice 238.0 dia. (in) = 2.00
inflow hydrograph: c:\mydocu-1\02-221\5-yrdev.hyd
outflow hydrograph: c:\mydocu-1\02-221\5-yrpre.hyd
peaks: inflow = 0.24 cfs @ 10.00 hr.
outflow = 0.21 cfs @ 10.17 hr.
stage: 4.15 ft. volume: 32 c.f.
CFA Consulting Engineers PRE 09:56 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
DETENTION ROUTING
flow (cfs)
0.3
0.3
0.2
•
0.2
•
0.1
0.1
17-7-7-Y
0.0
0 5 10 15 20 25 30
time (hr)
DETENTION TUBE (stage-volume calculated)
diameter = 1.50'; length = 18.00'; slope = 1.00%; invert = 237.90'MSL
STAGE VOLUME
237.9 0
238.2 3
238.5 9
238.7 16
239.0 23
239.3 28
239.6 32
OUTLET TYPE ELEVATION SIZE
circ. orifice 238.0 dia. (in) = 2.00
inflow hydrograph: c:\mydocu-1\02-221\10-yrdev.hyd
outflow hydrograph: c:\mydocu-1\02-221\10-yrpre.hyd
peaks: inflow = 0.29 cfs @ 10.00 hr.
outflow = 0.26 cfs @ 10.33 hr.
stage: 6.32 ft. volume: 33 c.f.
CFA Consulting Engineers PRE 09:55 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
DETENTION ROUTING
flow (cfs)
0.4 •
0.3
0.2
0.1
0.0 \LI-1
0 20 40 60 80 100
time (hr)
DETENTION TUBE (stage-volume calculated)
diameter = 1.50'; length = 18.00'; slope = 1.00%; invert = 237.90'MSL
STAGE VOLUME
237.9 0
238.2 3
238.5 9
238.7 16
239.0 23
239.3 28
239.6 32
OUTLET TYPE ELEVATION SIZE
circ. orifice 238.0 dia. (in) = 2.00
inflow hydrograph: c:\mydocu-1\02-221\25-yrdev.hyd
outflow hydrograph: c:\mydocu-1\02-221\25-yrpre.hyd
peaks: inflow = 0.34 cfs @ 10.00 hr.
outflow = 0.30 cfs @ 10.33 hr.
stage: 8.25 ft. volume: 33 c.f.
-
•
' CFA Consulting Engineers PRE 10:23 20-Feb-03
Project 02-221
Joseph Hughes Office Building - 12665 SW 69th
DETENTION ROUTING
flow (cfs)
0.4
0.3
IISI
0.2
1
0.1
0.0
0 20 40 60 80 100
time (hr)
DETENTION TUBE (stage-volume calculated)
diameter = 1.50'; length = 18.00'; slope = 1.00%; invert = 237.90'MSL
STAGE VOLUME
237.9 0
238.2 3
238.5 9
238.7 16
239.0 23
239.3 28
239.6 32
OUTLET TYPE ELEVATION SIZE
circ. orifice 238.0 dia. (in) = 2.00
inflow hydrograph: c:\mydocu-1\02-221\100-dev.hyd
outflow hydrograph: c:\mydocu=1\02-221\100-pre.hyd
peaks: inflow = 0.38 cfs @ 10.00 hr.
outflow = 0.35 cfs @ 10.17 hr.
stage: 9.63 ft. volume: 33 c.f.
STORMWATER CALCULATION DATA
FOR CATCH BASIN CAPACITY IN PEAK FLOW CONDITIONS
(AS SUMMARIZED IN TABLE 3 ON SHEET 3)
CFA Consulting Engineers PRE 09:53 26-Aug-03
Project 02-221
ENYEART OFFICE BUILDING
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
CATCH BASIN NO. 1 - VOLUME AND FLOW
total Time of Concentration = 5 .0'
storm hyetograph: SCS Typel
return period = 25 years
storm duration = 24 hr.
total rainfall = 4.00 in.
pervious area = 0.00 A CN = 79
impervious area = 0. 07 A CN = 98
total site area = 0. 07 A
hydrograph file: d:\civilp-1\cb-no-l.hyd
peak flow .= 0.07 cfs @ 10 .00 hr.
runoff volume = 929 cu.ft.
CFA Consulting Engineers PRE 09:57 26-Aug-03
Project 02-221
ENYEART OFFICE BUILDING
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
CATCH BASIN NO. 2 - VOLUME AND FLOW
total Time of Concentration = 5.0 '
storm hyetograph: SCS Typel
return period = 25 years
storm duration = 24 hr.
total rainfall = 4 .00 in.
pervious area = 0.00 A CN = 79
impervious area = 0. 12 A CN = 98
total site area = 0. 12 A
hydrograph file: d:\civilp-1\cb-no-2.hyd
peak flow = 0.12 cfs @ 10 .00 hr.
runoff volume = 1,626 cu.ft.
STORMWATER CALCULATION DATA
FOR CATCH BASIN WATER QUALITY CAPACITY DURING
WATER QUALITY STORM CONDITIONS
(AS SUMMARIZED IN TABLE 4 ON SHEET 3)
CFA Consulting Engineers JSS 10: 02 26-Aug-03
Project 01-118
EATON ADDITION, SW 80TH AVE & SW CEDARCREST ST.
HYDROGRAPH
Hydrograph Al
load D:\CIVILP-1\CB-NO-I.HYD
1.00
0.80
0.60
0.40
0.20
10 20 30
peak flow = 0.07 cfs @ 10.00 hours
volume = 1, 026 cu.ft.
CFA Consulting Engineers JSS 10:02 26-Aug-03
Project 01-118
EATON ADDITION, SW 80TH AVE & SW CEDARCREST ST.
HYDROGRAPH
Hydrograph Al
load D:\CIVILP-1\CB-NO-2 .HYD
1.00
0.80
0.60
0.40
0.20
10 20 30
peak flow = 0.12 cfs @ 10.00 hours
volume = 1,578 cu.ft.
CFA Consulting Engineers PRE 10:15 26-Aug-03
Project 02-221
ENYEART OFFICE BUILDING
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
WATER QUALITY FLOW - CB NO. 1
total Time of Concentration = 5.0 '
storm hyetograph: SCS Typel
return period = 1 year
storm duration = 4 hr.
total rainfall = 0.36 in.
pervious area = 0.00 A CN = 79
impervious area = 0. 07 A CN = 98
total site area = 0. 07 A
hydrograph file: d:\civilp-l\cb-no-lq.hyd
peak flow = 0.02 cfs @ 1. 72 hr.
runoff volume = 47 cu.ft.
•
•
CFA Consulting Engineers PRE 10:19 26-Aug-03
Project 02-221
ENYEART OFFICE BUILDING
RUNOFF by the SANTA BARBARA URBAN HYDROGRAPH
WATER QUALITY FLOW - CB NO. 2
total Time of Concentration = 5.0 '
storm hyetograph: SCS Typel
return period = 1 year
storm duration = 4 hr.
total rainfall = 0.36 in.
pervious area = 0.00 A CN = 79
impervious area = 0.12 A CN = 98
total site area = 0.12 A
hydrograph file: d:\civilp-1\cb-no-2q.hyd
peak flow = 0.03 cfs @ 1.72 hr.
runoff volume = 82 cu.ft.
CFA Consulting Engineers PRE 10:19 26-Aug-03
Project 02-221
ENYEART OFFICE BUILDING
HYDROGRAPH
Hydrograph Al
load D:\CIVILP-1\CB-NO-1Q.HYD
1.00
0.80
0.60
0.40
0.20
,J
1 2 3 4 5
peak flow = 0.02 cfs @ 1.61 hours
volume = 29 cu.ft.
CFA Consulting Engineers PRE 10:19 26-Aug-03
Project 02-221
ENYEART OFFICE BUILDING
HYDROGRAPH
Hydrograph Al
load D:\CIVILP-1\CB-NO-2Q.HYD
1.00
0.80
0.60
0.40
0.20
1 2 3 4 5
peak flow = 0.03 cfs @ 1.67 hours
volume = 73 cu.ft.
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CSS PROJECT NAME: SCALEIHORI N/A DATE No. REVISION Br
ENYEART OFFICE BUILDING HORIZ:o3 10"
DATE: 7/28/03
Consulting Engineers SW 69TH AVENUE PROJECT #: 02-221
321 SW 4th AVE. j LEGAL DESIGNED: PRE SHEET OF
4th Floor
QUADRANT SECTION 1WP. GE DRAWN: PRE
PORTLAND, OREGON 97204 DRAINAGE PLAN I I IRAN
(CHECKED: AFC 5 9
(503) 228-3848 AD 1 ,2S 1 W APPROVED:AFC