534 DAYTON ST.PDFiiiiiiiiiiiiii
13881
534 DAYTON ST
IST PILE
DONNA L. BRESKE, P.E.
14712 Meadow Rd. Lynnwood, WA 98037
Phone: 425-742-6386 Fax: 425-787-9330
STORM DRAINAGE DETENT10N REPORT
WSIR
MICHEL CONSTRUCTION, INC.
DATE: OCTOBER 31, 2.001
JANUARY 9, 2002 (REVISION # 1)
SITE: 532
EDMONDS, WA
0 k' j S t cill-) I - -
Joe rp
27 7
- . �11� lov. - . V
R F- C =- U V E D
FEB - 1 2002
DEVELOPMENT SERVICES CTR.
CITY OF EDMONDS
DRAINAGE — DETENTION — INSPECTION — GRADING & TESC — SEWER & WATER
FEASIBILITY SITE DEVELOPMENT
Revision #1
January 9, 2002
'C
532 & 534 DAYTON.STREET
REVISION #1 -(Use CN=73 for second growth forest per city of Edmonds)
OVERVIEW:
Condominiums are proposed for construction at 532 & 534 Dayton Street. The
sitearea to be developed is 11 .000 square feet. Currently, there are two houses and
outbuildings located on the property. Both houses and the outbuildings are proposed for
removal.
DETENTION CALCULATIONS DISCUSSION:
Attached are calculations that result in a storm water detention pipe of 4 feet in
diameter and 94 feet long. Required detention volume is 1, 181 cubic feet. For
calculation purposes, it was assumed that there is no existing impervious area, and a
CN=73 for second growtb.forest was used. The developed impervious area is 6,675
square feet.
The SCS method was used for calculation purposes. In accordance with the
Washington State Department of Ecology Manual, the pipe is designed to detain flows -
from the 2-, 10- and I 00-yr 24-hr storm events." Per the Washington State DOE Manual,
flows released from the detention structure areto match one-half of the calculated flow
from the pre -developed 2-yr storm, and to match the pre -developed flows of both the 10-
and I 00-yr storms. However, due to the conservative value of CN=73, the calculated
pre -developed 2-year flow is 0.00 cfs. Some flow must be released for the 2-year storm,
or the pipe will never completely drain. Therefore, the controlled released for the 2-year
storm is set at 0.01 cfs. A chart of the pre -developed, developed and controlled
developed release flows is shown below:
DESCRIPTION
PRE -DEVELOPED
FLOWS
DEVELOPED
FLOWS
CONTROLLED
RELEASE DEV FLOWS
2-YR, 24 HR
0.00
0.05
0.01
10-YR, 24 HR
0.01
0.08
0.01
100-YR, 24 HR
0.02
0.13
0.02
REC r=ivED
Revision #1
FEB - i 2V12 January 9,2002
DEVELOPMENT SERVICE8 CTA:
.CITY OF EDMONDS
C.10
G32 9, 531 %bil 5t/ Drawagc ca cs -OA
d
J-0
Z,15-3
Sod T-pe AlderWood Urba'n' Lar�d-:complex
Gro up , c-
P �2, 0
10
100..
EXISTIK(:� -CoND(TIONS - T" ho'use-s 9- ----hed-s e A-(S^t
oti +he propesly. i4oweLettj +h&y wil/ I e V-e'moued,
Hetir-e. assume rio ext�f,(n_q imperv('ous
Perul'oos, /1000 SF A e-
6ross couer so - -7.5% -�he arm 1'73
DaVEL-OP&D
)mpervious
Dr�ve. &'-Walks
6�(a 7 5- S F
- 15- S tqC
Pe vlo o S 2- 5-3 ,q /,53 A
I-afld5copiA3 w I+h rass CN = q0
- cover on so - s-% o� 4hearft
..RECEIVED
FEB - 1 2002
DEVELOPMENT SERVICES CTR.
CITY OF EDMONDS
l/ 8/02 page
JANUARY 8., 2002
532 '& 534 DAYTON ST.
BASIN SUMMARY
BASIN ID: A10OX
SBUH METHODOLOGY
TOTAL AREA .......
RAINFALL TYPE ....
PRECIPITATION.....:
TIME INTERVAL .... :
TIME OF CONC ..... :
ABSTRACTION COEFF:
NAME: 100 YR 24 HR
0.25 Acres BASEFLOWS: 0.00 cfs
TYPElA PERVIOUS AREA
3.00 inches AREA..: 5 cres.
(:��A
10.00 min CN.... 73.00
_7_
23.35 min IMPERVIOUS AREA-
0.20 AREA..:' 0.00 Acres
PEAK RATR: 0.02 cfs VOL:
CN.... : 98.00
0.02 Ac-ft TIME: 490 min
BASIN ID.: AlOX
NAME: 10 YR
24 HR EXISTING
SBUH METHODOLOGY
TOTAL AREA .........
0.25 Acres
BASEFLOWS:
0.00
cfs
RAINFALL TYPE ....
TYPEIA
PERVIOUS AREA
PRECIPITATION ....
TIME INTERVAL.....:
2.00-inches
10.00 min
AREA..:
CN....
-25
73.0
Acres
TIME OF-CONC .....
23.35 min
IMPERVIOUS
ABSTRACTION COEFF.:
0.20
AREA..:
0.00
Acres
CN....
98.00
PEAK RATR: 0.01
cfs. VOL: 0.01
Ac-ft TIME:
960
min
BASIN ID: A2X NAME: 2 YR 24 HR EXISTING
SBUH METHODOLOGY
TOTAL AREA ....... 0.25 Acres BASEFLOWS: 0.00 cfs
RAINFALL TYPE .... TYPElA PERVIOUS AREA
PRECIPITATION .... 1.30 inches AREA..: cres
TIME INTERVAL .... 10.00 min CN.... 73.00
TIME OF CONC ...... 23.35 min IMPERVIOUS
ABSTRACTION COEFF: 0.20 AREA..: 0.00 Acres
CN.... : 98.00
TcReach - Sheet L: 100.00 ns:0.4000 p2yr: 1.30.s:0.0500
PEAK RATE.: 0.00 cfs VOL: 0.00 Ac-ft TIME: ' 1320 min
REECEIV ED
FEB - 1 20`32
DEVELOPMENT SERVICES CTR,
CITY OF EDMONDS
11 8/02
page 2
JANUARY 8, 2002
532 & *534 DAYTON ST.
BASIN
SUMMARY
BASIN ID: B100D
NAME: 100 YR
24 HR DEVELOPED
SBUA METHODOLOGY
TOTAL AREA ........ :
0.25 Acres..
BASEFLOWS:
0.00 cfs
RAINFALL TYPE .... :
TYPElA
PERVIOUS AREA
PRECIPITATION .... :
3.00 inches
AREA...:
0.10 Acres
TIME INTERVAL .... :
10.00 min
CN.....:
90.00
TIME OF CONC ..... : 10-00
min
IMPERVIOUS
AREA
ABSTRACTION COEFF
0.20
AREA...:
0.15 Acres
PEAK RATE: 0.13 cfs
VOL: 0.05
CN.... :
Ac-ft TIME:
98.00
480 min
BASIN ID: B10D
NAME: 10 YR
24 HR DEVELOPED
SBUH METHODOLOGY
TOTAL AREA ... .... :-
0.25 Acres
BASEFLOWS: 0.00 cfs
RAINFALL TYPE ....
TYPElA
PERVIOUS AREA
PRECIPITATION ...
2-.00 inches
AREA..: 0.10 Acres
TIME INTERVAL.....:
10-00 min
CN....: .90.00
,TIME OF CONC .....
10-00 min
IMPERVIOUS AREA
ABSTRACTION COEFF:
0.20
AREA..: 0.15 Acres
PEAK.RATE: 0. 08
- -
cf s- - VOL-: 0.03
CN.... 98-.00
Ac-ft TIME.: 480 min
BASINID: B2D
SBUH METHODOLOGY
TOTAL AREA .......
RAINFALL TYPE ....
PRECIPITATION ....
TIME INTERVAL ....
TIME OF CONC .....
ABSTRACTION COEFF:
NAME: 2 YR 24 HR DEVELOPED
0.25 Acres
BASEFLOWS: 0.00 cfs
TYPElA
PERVIOUS AREA
1.30 inches
AREA..: 0.10 Acres
10-00 min
CN.... : 90.00
10-00 min
IMPERVIOUS AREA
0.20
ADVA A
. . o - 15 ticres
CN.... : 98.00
PEAK RATE: 0.05 cfs VOL: 0.02 Ac-ft TIME: 480 min
R F. CE5 I V E D
FEB - 1 2002
DEVELOPMENT SERVICES CTR.
CITY OF EDMONDS
1/.8/02 'page 3
JANUARY 8, 2002
53:2 & 534 DAYTON ST.
HYDROGRAPH SUMMARY
PEAK
TIME
VOLUME
HYD
RUNOFF
OF
OF
Contrib.
NUM
RATE
PEAK
HYDRO
Area
cfs
min.
cf\AcFt
Acres
1
0.002
1320
67 cf
0.25
2
0.006
960
291 cf
0.25
3
0.024
490
778 cf
0.25
4
0.046
48 " 0
783 cf
0.25
5
0.081
480
.1363 cf
0.25
0.134
480
2228 cf
0.25
.0.008'
980
783 cf
d.25
12
0.011
1340
1363 cf
0'.25
13
0.025
800
2099 cf
0.25
I
RECi=-jvEj)
FEB - I M 2
DEVELOPMENT SERVICES CTR.
CITY OF EDMONDS
1], 8/02
page 4
JANUARY 8, 2002
532 & 534 DAYTON.ST.
STORAGE STRUCTURE LIST
UNDERGROUND PIPE ID No. Pi
Description: UNDERGROUND PIPE
Diameter: 4.00 ft. Length: 94.0 1/ 8/02
MICHEL CONST.
JANUARY 8, 2002
532 & 534 DAYTON 8T..
STORAGE STRUCTURE LIST
UNDERGROUND PIPE ID No. Pi
Description: UNDERGROUND PIPE
Diameter: 4.00 ft. Length: 94.00 ft.
Slope....: 0.0050 ft/ft
RECEWED
FEB - 1 2002
DEVELOPMENT SEFIV16ES CTR.
CITY OF EDMONDS
-1/ 8/02
page 2
JANUARY 8, 2002
532 & 534 DAYTON ST.
DISCHARGE STRUCTURE LIST
COMBINATION DISCHARGE ID No. C1
Description: COMBINATION DISCHARGE
Structure: 01 Structure:
Structure: N1 Structure:
Structure:
NOTCH WEIR ID No. N1
Description:- NOTCH WEIR
Weir Length: 0.0830 ft. Weir height (p): 2.0000 ft.
Elevation 103.40 ft. Weir Increm: 0. 10*
MULTIPLE ORIFICE ID No. 01
Description: ORIFICE
Outlet Elev: 100.00
.Elev:- 99.00 ft. orifice Diameter: 0.5000 in.
REECEEIVEED
FEB - I 2CT2
DEVELOPMENT SERVICES CTR.
CITY OF EDMONDS
1/ 8/02
page 3
.JrANUARY 8, 2002
532 & 534 DAYTON ST.
LEVEL
POOL TABLE SUMMARY
MATCH
INFLOW
-STO-
-DIS-
-PEAK->
STORAGE
t46+Ch
< -------- DESCRIPTION --------- >.
(cfs)
(cfs)
--id-
--id-
<-STAGE>
id
VOL (cf)
Pfq
2 YR 24 HR ....................
0.00
0.05
P 1
Cl
101.39
11
283.99
vol
10 YR 24 HR ..................
0.01
0.08
pl
C 1
102.45
12
669.34
100 YR 24 HR ...................
0.02
0.13
P1
Cl
103.59
13
1052.'04
RECEAYIED
FEB - 1 2PUZ9
DEVELOPMENT SERVIdES CTR.
CITY OF EDMONDS
Table 2.3
Runoff -Curve Numbers for Selected Agricultural, Suburban, and Urban Areas
(Sources: TR 55, 1986, and Stormwater Management Manual, 1992. See Section 2. 1.1 for explanation)
CNs for hydrologic S
Cover type and hydrologic condition.
A B ( C
D'd
Curve Numbers for Pre -Development Conditions
..Or
Pasture, grassland, or range -continuous forage for grazing:
'Fair condition (ground -cover 50% to 75% and not heavily grazed).
49 69 79
84
Good condition (ground cover >75% and lightly or only occasionally grazed)
39 61 74
80
Woods:
Fair (Woods are grazed but not burned, and some forest litter covers the soil).
36 60
PO
79
Good (Woods are protected from'grazing, and litter and brush adequately cover the soil).
30 55
77
Curve Numbers for Post-DeveloRment Conditions
Open space (lawns, parks, golf courses, cemeteries, landscaping, etc.)'
Fair condition (grass cover on 50% -� 75% of the area).
77 85
92
Good condition (grass cover on >75% of the area)
68 80 86
90
Impervious areas:
O�en water bodies: lakes, wetlands, ponds etc.
100 100 J�Lo.
100
Paved parking lots, roofs�, driveways; etc. (excluding right-of-way)
98 98 n9
98
Porous Pavers and Permeable Interlocking Concrete (assumed as 85% impervious and 15%'Iawn) -
Fair lawn condition (weighted average CNs).
95 96 97
97
Good lawn condition (weighted. average CNs).
94 95 96
97
Paved
:98 -98. _ 98
98
Gravel (including right-of-way)
.76 ..',85
Dirt (including right-of-way)
82. -__87 -_'89
Pasture, grassland, or range -continuous forage For grazing:
__--72
Poor �ondition (ground cover <50% or heavily grazed with no mulch�
68 19': '96
80
Fair condition (ground cover 5001. to 75% and not heavily grazed).
49 69 '79
�94
Good condition (ground cover >75% and lightly or only occasionally grazed)
39 61 74
80
Woods:
Poor (Forest litter, small trees, and brush are destroyed by heavy grazing or regular burning).
45 66 77
83
Fair (Woods are grazed but not burned, and some forest litter covers the soil).
36 `60 -13
79'
Good (Woods are protected from grazing, and litter and brush adeg6ately cover the soil).
-30* 55' __-10
77
Single family residential':. . Should only be used for Average Percent
' 3.4
Dwelling Unit/Gross Acre subdivisions > 50 acres impervious area
1.0 DU/GA 15
Separate curve number
1.5 DU/GA 20
shall be selected for
2.0 DU/GA 25
pervious & i;n-pervious
2.5 DU/GA 30
portions of the site or.
3.0 DU/GA 34
basin
3.5 DU/GA 38
4.0 DU/GA 42
4.5 DU/GA 46
5.0 DU/GA 48
5.5 DU/GA 50
6.0 DU/GA 52
6.5 DU/GA 54
7.0 DU/GA 56
7.5 DU/GA 58
PUD's, condos, apartments, commercial %impervious Separate curve numbers shall
businesses, industrial areas & must be be selected for pervious and
& subdivisions < 50 acres computed impervious portions of the site
For a more detailed and complete description of land use curve numbers refer to chapter two (2) of the Soil Conservation Service's Technical
�'el �seNo. 55.(210-VI-TR-55, Second Ed., June 1986).
'Where roof runoYa�d driveway runoff are infiltrated or dispersed according to the requirements in Chapter 2,.the average percent impervious
area maybe adjusted in accordance with the procedure described*under "Flow Credit for Roof Downspout Infiltration" and "Flow Credit for Roof
Downspout Dispersion".in Chapter 2.
iAssumes roof and driveway runoff is directed into street/storm system.
4AII the remaining pervious area (lawn) arr considered to be in good'condition for these
curve numbeis.�
TED':
August 2001 -Volume 1/1 - Hydrologic. Analysis an
d Flow Control
DEVELOPMBi2
D&
CES. CTR...
-OF EDMOI DS
CITY