Specifications (3) r
LEWIS &
VAN VLEET
Incorporated
principals
cihris c. van vleet. p.e.
Bary j. Lewis. p.a
STORM WATER CALCULATIONS
FOR
SOUTHWEST
CHURCH OF CHRIS T
9725 S.W. Durham Road
Tigard, Oregon
Client:
Lane Brown, Architect
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EXPIRES: /
Lewis &Van Vleet, Inc. Job Number 03250
consulting engineers
18660 s.w. boones ferry road
tualatin, oregon 97062
[503] 885.8605 phone
[503] B85.1206 fax
Table of Contents
Site Areas 1
Narrative 1
Water Quality 1
Detention 2
Provided Pond Volume 3
Pipe Size Calculations Worksheet 4
Appendices
Appendix A—SBUH Printouts
Appendix B—Existing Pond Calculations
(From 1995)
CIVIL CALCULATIONS
Job SOUTHWEST CHURCH OF CHRIST
Client LANE BROWN
Job No. 03250 By BSD
Date 08/16/03 Sheet 1
SITE AREAS
Total Site Area: 138,000 sf= 3.17 ac
Total Existing Imp. Area: 90,000 sf = 2.07 ac
Existing Impervious Area
draining to pond: 33,025 sf= 0.76 ac
Proposed Impervious Area: 10,000 sf= 0.23 ac
NARRATIVE
The existing pond is only sized for water quality for 33,025 sf of existing impervious area
from the north side of the parking lot. We are proposing the drainage from the new
10,000 sf addition to connect into the existing storm piping and flow to the existing pond.
We will reg rade the pond to hold the required volume for both water quality and detention
for the new impervious area as well as the water quality volume for the existing impervious
area. The existing control structure meters the flow for water quality prior to discharge to
the pond. We are proposing to modify the orifice in the existing flow control structure to
control the total water quality flow and add a new control structure in the pond for detention.
WATER QUALITY(Extended Dry Detention Pond - Per CWS Standards)
Required W.Q. Volume = (Impervious Area) x(0.03)
(33,025 + 10,000)x (0.03) = 1,291 cf
Water Quality Flow = 1,291 cf = 0.090 cfs
(4 Hr)x(60 min/hr)x(60 sec/min)
Orifice Formula: Q = CA(2gh)o.s
Given:
C = 0.61
g = 32.2
Design:
Q = 0.090 cfs
h = 1.5 feet of head
Solve for A:
A= Q/[ C (2gh)osI
A= 0.089635 /[0.62 (2 2
(c.f.s.) (head)
A= 0.015 sq. ft. (orifice area)
Solve for D:
A= pixR2
R = (A/pi)o.s
R=( 0.015 /3.14 )o.5
(area)
R = 0.069 ft
D = 2xRx12
D= 1.66 inches
CIVIL CALCULATIONS
Job SOUTHWEST CHURCH OF CHRIST
Client LANE BROWN
Job No. 03250 By BSD
Date 08/16/03 Sheet 2
DETENTION (CWS Standards: 2-10-25 Year, 24 Hour Storm - SBUH Method)
- From CWS Design Storm Distribution Chart: P2 =2.50 inches
(P, = Rainfall Depth for'n' year storm) Plc)= 3.45 inches
P25= 3.90 inches
- SCS Type 1 Soil (Aloha)*
Hydrologic Soil Group = C
Existing Conditions:
Impervious Area = 0 sf= 0.00 ac CN = 98 (Paved Surfaces, Roofs, etc...)
Pervious Area = 10,000 sf= 0.23 ac CN = 86 (Open Space, Poor Condition)-
Time of Concentration (Tc):
Te= [/0.42*(nsL)08] (Sheet Flow up to 300 feet.)
[\ 2)u.b21(So)ul
where: ns= 0.15 (Sheet flow Manning's effective roughness coefficient)
L = 120 ft. (Length of Flow)
P2= 2.50 in (2-year, 24 hour rainfall)
So= 3.3 % (Slope of hydraulic grade line-land slope)
T, = 10.2 minutes
Storm 2-Yr 10-Yr 25-Yr
Peak-Q 0.07 0.12 0.14 < See Printouts
Proposed Conditions:
Impervious Area= 10,000 sf= 0.23 ac CN = 98 (Paved Surfaces, Roofs, etc...)
Pervious Area = 0 sf= 0.00 ac CN = 86 (Open Space, Poor Condition)**
Time of Concentration (Ta):
Tc= Use 5.0 minutes, minimum
Storm 2-Yr 10-Yr 25-Yr
Peak-Q 0.15 0.21 0.23 < See Printouts
Detention Volume Required = 308 cf < See Printouts
* Per Washington County SCS Manual
Per CWS Design Manual
CIVIL CALCULATIONS
Job SOUTHWEST CHURCH OF CHRIST
Client LANE BROWN
Job No. 03250 By BSD
Date 08/16/03 Sheet 3
PROVIDED POND VOLUME
Take larger volume of Water Quality and Detention.
Water Quality Volume= 1,291 cf
Detention Volume = 308 cf
Total pond volume required = 1,291 cf
Existing pond volume = 990 cf
Additional pond volume required = 301 cf
Widening the pond approximately 6' to the west and 10'to the south, the new pond
volume is:
Elev (ft) Area (sf) Volume (cf)
207 450
550
208 650
765
209 880
Total = 1,315 > 1,291 --OK
PIPE SIZE CALCULATIONS
Project No. 03250 Designed by: BSD Date: 03/30/04 Checked by: BSD Date:
Project Name: SOUTHWEST CHURCH OF CHRIST Page: 1 of 1
DESIGN DESIGN CALCULATIONS DESIGN INVERT
SECTION ELEVATIONS
INCR. TOTAL INTEN- INCR. RUNOFF EQUIV. TOTAL CAPA-
MH to MH TIME TIME SITY AREA COEFF. INCR. EQUIV. RUNOFF SLOPE DIA. CITY VELOC. LENGTH UPPER LOWER
OR AREA AREA
ST to ST T T, I A C CA ECA Q S d Qf Vf L
minutes minutes in./hr. acres coeff. acres acres cfs % inches cfs fps feet
Existing Configuration
CB1 -CB2 5.0 5.0 3.00 0.356 0.9 0.320 0.320 0.96 1.80% 6 0.98 4.99 100 213.40 211.60
CB2 -C.O. 0.3 5.3 2.95 0.402 0.9 0.362 0.682 2.01 1.13% 10 3.03 5.55 118 211.43 210.10
C.O. -STRUCTURE 0.4 5.7 2.89 0.000 0.9 0.000 0.682 1.97 1.13% 10 3.03 5.55 . 124 210.10 208.70
Proposed Configuration
CB1 -CB2 5.0 5.0 3.00 0.356 0.9 0.320 0.320 0.96 1.80% 6 0.98 4.99 100 213.40 211.60
CB2 -NORTH ROOF 0.3 5.3 2.95 0.402 0.9 0.362 0.682 2.01 6.00% 10 6.98 12.80 10 211.43 210.83
N. ROOF -S. ROOF 0.0 5.3 2.95 0.145 0.9 0.130 0.812 2.40 1.00% 10 2.85 5.22 105 211.15 210.10
S. ROOF-C.O. I 0.3 5.7 2.89 0.145 0.9 0.130 0.942 2.72 11.00% 10 2.85 5.22 3 210.10 210.07
C.O. -STRUCTURE I 0.0 5.7 2.87 0.000 0.9 0.000 0.942 2.70 1.13% 10 3.03 5.55 124 210.07 208.67
EXIgirING 10" Pt PE rtY 15��
ti .F=tcl E rr- A--AD I-noIJ
NW ROOF- 10"STS 5.0 5.0 3.00 0.075 0.9 0.068 0.068 0.20 0.40% 6 0.46 2.35 70 211.65 211.37
NE ROOF- 10"STS 5.0 5.0 3.00 0.075 0.9 0.068 0.068 0.20 10.40% 6 0.46 2.35 70 211.65 211.37
SW ROOF- 10"STS 5.0 5.0 3.00 0.075 0.9 0.068 0.068 0.20 11.00% 4 0.25 2.84 70 1211.65 210.95
SE ROOF- 10"STS 5.0 5.0 3.00 0.075 0.9 0.068 0.068 0.20 1.00% 4 0.25 2.84 70 211.65 210.95
NOTE: PIPE SIZES ARE CALCULATED USING THE RATIONAL METHOD FOR A 10 YEAR, 24 HOUR STORM EVENT PER CLEAN WATER
SERVICES RAINFALL INTENSITIES WITH 5 MINUTES TIME OF CONCENTRATION, MINIMUM. i,o= 3.0 in/hr.
r
APPENDIX A
SBUH Printouts
1
KING COUNTY DEPARTMENT OF PUBLIC WORKS
Surface Water Management Division
HYDROGRAPH PROGRAMS
Version 4 . 21B
R/D FACILITY DESIGN ROUTINE
SUMMARY OF INPUT ITEMS
1) TYPE OF FACILITY: POND (3 . 0 : 1 SIDE SLOPES)
2) STORAGE DEPTH (ft) : 2 . 00
3) VERTICAL PERMEABILITY (min/in) : . 00
4 ) PRIMARY DESIGN HYDROGRAPH FILENAME: 25NEW
5) PRIMARY RELEASE RATE (cf s) : . 14
6) NUMBER OF TEST HYDROGRAPHS: 2
TEST HYD 1 FILENAME: 10NEW TARGET RELEASE (cfs) : . 12
TEST HYD 2 FILENAME: 02NEW TARGET RELEASE (cfs) : . 07
7) NUMBER-OF-ORIFICES, RISER-HEAD (ft) , RISER-DIAM (in) : 2, 2 . 00, 8
8) ITERATION DISPLAY: NO
ENTER ITEM NUMBER TO BE REVISED (ENTER ZERO IF NO REVISIONS ARE REQUIRED) :
0
INITIAL STORAGE VALUE FOR ITERATION PURPOSES: 1200 CU-FT
BOTTOM ORIFICE: ENTER Q-MAX (cfs)
. 07
DIA. = 1 . 35 INCHES
TOP ORIFICE: ENTER HEIGHT (ft)
1 . 55
DIA. = 1 . 96 INCHES
PERFORMANCE : INFLOW TARGET-OUTFLOW ACTUAL-OUTFLOW PK-STAGE STORAGE
DESIGN HYD: . 23 . 14 . 14 2 . 00 308
TEST HYD 1 : . 21 . 12 . 12 1 . 85 260
TEST HYD 2 : . 15 . 07 . 07 1 . 56 180
SPECIFY: D - DOCUMENT, R - REVISE, A - ADJUST ORIF, E - ENLARGE, S - STOP
SOUTHWEST CHURCH OF CHRIST DETENTION
KING COUNTY DEPARTMENT OF PUBLIC WORKS
Surface Water Management Division
HYDROGRAPH PROGRAMS
Version 4 . 21B
SBUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH
STORM OPTIONS :
1 - S . C. S . TYPE-1A
2 - 7-DAY DESIGN STORM
3 - STORM DATA FILE
SPECIFY STORM OPTION:
1
S . C. S . TYPE-1A RAINFALL DISTRIBUTION
ENTER: FREQ (YEAR) , DURATION (HOUR) , PRECIP (INCHES)
2, 24, 2 . 5
******************** S . C. S . TYPE-1A DISTRIBUTION ********************
********* 2-YEAR 24-HOUR STORM **** 2 . 50" TOTAL PRECIP. *********
ENTER: A (PERU) , CN (PERV) , A (IMPERV) , CN (IMPERV) , TC FOR BASIN NO. 1
. 23, 86, 0, 98, 10
DATA PRINT-OUT:
AREA (ACRES) PERVIOUS IMPERVIOUS TC (MINUTES)
A CN A CN
. 2 . 2 86. 0 . 0 98 . 0 10 . 0
PEAK-Q (CFS) T-PEAK (HRS) VOL (CU-FT)
. 07 7 . 83 1037
ENTER [d: ] [path] filename [ . ext] FOR STORAGE OF COMPUTED HYDROGRAPH:
02EXIST
KING COUNTY DEPARTMENT OF PUBLIC WORKS
Surface Water Management Division
HYDROGRAPH PROGRAMS
Version 4 . 21B
SBUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH
STORM OPTIONS :
1 - S. C. S . TYPE-1A
2 - 7-DAY DESIGN STORM
3 - STORM DATA FILE
SPECIFY STORM OPTION:
1
S. C. S . TYPE-1A RAINFALL DISTRIBUTION
ENTER: FREQ (YEAR) , DURATION (HOUR) , PRECIP (INCHES)
10, 24, 3 . 45
******************** S.C. S. TYPE-1A DISTRIBUTION ********************
********* 10-YEAR 24-HOUR STORM **** 3 . 45" TOTAL PRECIP. *********
ENTER: A (PERV) , CN (PERV) , A (IMPERV) , CN (IMPERV) , TC FOR BASIN NO. 1
. 23, 86, 0, 98 , 10
DATA PRINT-OUT:
AREA (ACRES) PERVIOUS IMPERVIOUS TC (MINUTES)
A CN A CN
. 2 . 2 86 . 0 . 0 98 . 0 10 . 0
PEAK-Q (CFS) T-PEAK (HRS) VOL (CU-FT)
. 12 7 . 83 1713
ENTER [d: ] [path] filename [ . ext] FOR STORAGE OF COMPUTED HYDROGRAPH:
10EXIST
KING COUNTY DEPARTMENT OF PUBLIC WORKS
Surface Water Management Division
HYDROGRAPH PROGRAMS
Version 4 . 21B
SBUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH
STORM OPTIONS:
1 - S . C. S . TYPE-1A
2 - 7-DAY DESIGN STORM
3 - STORM DATA FILE
SPECIFY STORM OPTION:
1
S . C. S . TYPE-1A RAINFALL DISTRIBUTION
ENTER: FREQ (YEAR) , DURATION (HOUR) , PRECIP (INCHES)
25, 24, 3 . 9
******************** S . C. S. TYPE-1A DISTRIBUTION ********************
********* 25-YEAR 24-HOUR STORM **** 3 . 90" TOTAL PRECIP. *********
ENTER: A (PERV) , CN (PERV) , A (IMPERV) , CN (IMPERV) , TC FOR BASIN NO. 1
. 23, 86, 0, 98, 10
DATA PRINT-OUT:
AREA(ACRES) PERVIOUS IMPERVIOUS TC (MINUTES)
A CN A CN
. 2 . 2 86. 0 . 0 98 . 0 10 . 0
PEAK-Q (CFS) T-PEAK (HRS) VOL (CU-FT)
. 14 7 . 83 2049
ENTER [d: ] [path] filename [ . ext] FOR STORAGE OF COMPUTED HYDROGRAPH:
25EXIST
KING COUNTY DEPARTMENT OF PUBLIC WORKS
Surface Water Management Division
HYDROGRAPH PROGRAMS
Version 4 . 21B
SBUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH
STORM OPTIONS:
1 - S.C. S. TYPE-1A
2 - 7-DAY DESIGN STORM
3 - STORM DATA FILE
SPECIFY STORM OPTION:
1
S . C. S . TYPE-1A RAINFALL DISTRIBUTION
ENTER: FREQ (YEAR) , DURATION (HOUR) , PRECIP (INCHES)
2, 24, 2 . 5
******************** S . C. S . TYPE-1A DISTRIBUTION ********************
********* 2-YEAR 24-HOUR STORM **** 2 . 50" TOTAL PRECIP. *********
ENTER: A(PERV) , CN (PERV) , A (IMPERV) , CN (IMPERV) , TC FOR BASIN NO. 1
0, 86, . 23, 98 , 5
DATA PRINT-OUT:
AREA(ACRES) PERVIOUS IMPERVIOUS TC (MINUTES)
A CN A CN
. 2 . 0 86 . 0 . 2 98 . 0 5 . 0
PEAK-Q (CFS) T-PEAK (HRS) VOL (CU-FT)
. 15 7 . 67 1895
ENTER [d: ] [path] filename [ . ext] FOR STORAGE OF COMPUTED HYDROGRAPH:
02NEW
KING COUNTY DEPARTMENT OF PUBLIC WORKS
Surface Water Management Division
HYDROGRAPH PROGRAMS
Version 4 . 21B
SBUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH
STORM OPTIONS :
1 - S . C. S . TYPE-1A
2 - 7-DAY DESIGN STORM
3 - STORM DATA FILE
SPECIFY STORM OPTION:
1
S . C. S. TYPE-1A RAINFALL DISTRIBUTION
ENTER: FREQ (YEAR) , DURATION (HOUR) , PRECIP (INCHES)
10, 24, 3 . 45
******************** S. C. S . TYPE-1A DISTRIBUTION ********************
********* 10-YEAR 24-HOUR STORM **** 3 . 45" TOTAL PRECIP. *********
ENTER: A(PERV) , CN (PERV) , A (IMPERV) , CN (IMPERV) , TC FOR BASIN NO. 1
0, 86, . 23, 98 , 5
DATA PRINT-OUT:
AREA(ACRES) PERVIOUS IMPERVIOUS TC (MINUTES)
A CN A CN
. 2 . 0 86. 0 . 2 98 . 0 5 . 0
PEAK-Q (CFS) T-PEAK (HRS) VOL (CU-FT)
. 21 7 . 67 2685
ENTER [d: ] [path] filename [ . ext] FOR STORAGE OF COMPUTED HYDROGRAPH:
10NEW
KING COUNTY DEPARTMENT OF PUBLIC WORKS
Surface Water Management Division
HYDROGRAPH PROGRAMS
Version 4 . 21B
SBUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH
STORM OPTIONS :
1 - S .C. S . TYPE-1A
2 - 7-DAY DESIGN STORM
3 - STORM DATA FILE
SPECIFY STORM OPTION:
1
S . C. S . TYPE-1A RAINFALL DISTRIBUTION
ENTER: FREQ (YEAR) , DURATION (HOUR) , PRECIP (INCHES)
25, 24, 3 . 9
******************** S . C. S. TYPE-1A DISTRIBUTION ********************
********* 25-YEAR 24-HOUR STORM **** 3 . 90" TOTAL PRECIP. *********
ENTER: A (PERV) , CN (PERV) , A (IMPERV) , CN (IMPERV) , TC FOR BASIN NO. 1
0, 86, . 23, 98 , 5
DATA PRINT-OUT:
AREA (ACRES) PERVIOUS IMPERVIOUS TC (MINUTES)
A CN A CN
. 2 . 0 86 . 0 . 2 98 . 0 5 . 0
PEAK-Q (CFS) T-PEAK (HRS) VOL (CU-FT)
. 23 7 . 67 3060
ENTER [d: ] [path] filename [ . ext] FOR STORAGE OF COMPUTED HYDROGRAPH:
25NEW
APPENDIX B
Existing Pond Calculations
I-
EXTENDED DRY DETENTION PONDS
DESIGN CRITERIA
Phosphorous Removal Efficiency.
The information on page 3.11 and Figure 3.6 on page 3.12 in (MCG) above provide
evidence that "extended dry detention ponds" designed to the criteria herein listed will
have a phosphorous removal efficiency of 50%, (Figure 3.6 dr page 3.11 attached)
Design Storm.
The design storm for surface water quality facilities to meet the phosphorous removal
standard is the mean summertime storm event totaling 0.36 inches of precipitation
falling in 4 hours with an average return period of 96 hours. (USA, Section 7.08)
Pond Volume (PV).
Determine the required pond volume(PV)by computing the runoff volume from 100%
of the proposed new Impervious area during the 0.36 inch,4 hour storm event.
PV = (0.36 in.) (1 ft./12 in.) ( 33► OZ-S sq. ft.) = ',O cu. ft,
impervious area • pond volume
Outlet Release Rate (Qout).
Calculate the outlet release rate needed to release the pond volume over a 48 hour
period.
Qout ( cu. ft.) /'(48 hrs. X 60 min.X 60 sec.) - C)°57c.f.s.
pond volume o
Outlet Orifice Diameter. v " &57 I 5
Determine the orifice diameter needed for the outlet release rate. : /
Orifice Equatio • Q = C`A''(2gh)SQRT
\ W I C 0:62, g = 32.20
h ' feet
Q cf.s. p‘= 1't' r
c.,0241)-))-) Area: A = Q/C*(2gh)SQZT r 'n
A = • 000 sq. ft. A a pi(R)SQ
Radius: R 4 . 0)er 9 ft. R = SQRT(A/pl)
Diameter: D _ ft.
D .40(0 inches
(131 ---_Page 6
-- C. A, A C = . ,O = S,(.70
(7°) .O a) 15 7e3 43 c5Z.o -- o ,77 G tis
v /n 96!(a.0 0.) 7 �J4 /o 0 Co ! GFS
07 ���5 !`977 c--1
'
QTY ,of" l0/1 w/ f o f Z5 7 .Lop.e
3. 02 > (,,,77-t /.0179) - Z, 64.6
PROJECT 4
PREPARED BY ,1 DATE I JOB NO.
DAM" din nc
• FROM` : LANE BROWN ARCHITECT FAX NO. : 503-248-1088 Sep. 03 2003 12:49PM P5
D4 : U 0 . 018 READY
A B C D E F G H
1
2 Pipe Diameter - 6 in
3 Roughness Coefficient - 0 . 01
4 Slone - 0 . 018 (percent divided by 100 )
5
6 Calculates maximum capacity
7 of pipe based on size, roughness ,
8 and slope_
9
10 A = 0 . 196 sq . ft .
11 R = 0 . 125 (hydraulic radius )
12
13 0 = 0 . 979 cfs
14
15
16
17
18
19
20
25-Oct-95 10 : 32 AM NUM
FROM :' LANE BROWN ARCHITECT FAX NO. : 503-248-1088 Sep. 03 2003 12:49PM P6
04 : U . 0 . 01125 READY
A B C 0 E P G H
1
2 Pipe Diameter = 10 in
3 Rouahness Coefficient = 0 . 01
4 Slope = 0 . 01125 (percent divided by 100)
5
6 Calculates maximum capacity
7 of pipe based on size, roughness ,
8 and slope.
9
10 A = 0 . 545 sct . ft .
11 R = 0 . 208 (hydraulic radius)
12
13 0 - 3 . 021 cfs
14
15
16
17
18
19
20
25-Oct-95 11 : 25 AM NUM