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DONNA L. BRESKE, P.E. 6621 Foster Slough Rd. Ph: 425-334-9980
Snohomish, WA 98290 Fax: 425-334-7380
0",
OEM
DATE: January 13, 3006
Revised May 30, 2006 — Add Water Quality Calculations and
Design Detention System to release the 2 -year storm at the pre -
developed peak runoff rate.
SITE: 7425 210' ST. S.W.
EDMONDS, WA 98026
ELP 7-A E 271 1�
A:e7=
DRAINAGE - DETENTION -- INSPECTION - GRADING &TESC'
SEWER & WATER -- FEASIBILITY - SITE DEVELOPMENT
rea
"JOV
GOODNIGHT 1
1 1 1i
OVERVIEW:
An 11 -unit townhome project is proposed for the site located at 8610 202ND St.
S.W. Currently a house and garage are present on the site. The house and garage are to
be removed. Eleven new townhouses will be constructed
The site slopes downward from north to south at approximately 3.7%. A total
impervious area, (rooftop and driving surface) used for calculating the detention system
is 13,902 sf. A total of 6,385 sf of pollution generating impervious area is proposed.
DETENTION SYSTEM & WATER QUALITY DESIGN:
The site area is 18,759 square feet. The site is less than one acre in size and
drains to Lake Ballinger. The storm water detention system is designed in accordance
with the SBUH method and the ECDC 18.30.060.A.1.a for the 2, 10, and 100 -year 24-
hour storm events. The release structure is designed to release flows for the three storms
events at the pre -developed peak flows for the corresponding 2, 10, and 100 -yr, 24-hour
design storms. A chart of the pre -developed and post -developed flows is shown below:
DESCRIPTION
PRE -DEVELOPED
FLOWS
DEVELOPED CONTROLLED
FLOWS RELEASE DEV FLOWS
2 -YR, 24-1-111D,
.02 cfs
.10 cis .02 cfs
10 -YR, 24 -HR
.05 cfs
.15 cfs .05 cfs
100 -YR, 24 -HR
.11 cfs
.24 cfs .11 cfs
The detention system consists of 63 LF of 5' diameter detention pipe coupled
together with one Type 2-48" CB and one Type 2-54" CB. The lower 1.65' of the 5'
diameter pipe is designed to provide water quality control dead storage. The water
quality volume is determined by using the runoff volume from the pollution generating
impervious area, (6,385 sf of driving surface), for the 6 -month storm. The water quality
volume provided is 404.45 cubic feet. The calculated detention volume is 977.31 cf.
DRAINAGE - DETENTION - INSPECTION - GRADING & TESC
SEWER & WATER - FEASIBILITY - SITE DEVELOPMENT
b-) %
19-
m
I-
1-71
w x m g ��
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.
1-71
I
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co
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CCDO
zLU
Dra-iaaye CctI66 � 7V57 colh S -t, 5c)l Ecimonds, IAlA Zz-q)y,
(ovvs fowl -the S rhe r-elea se La Ba llt(-
The 51 J,6 is vqt`+hin H q 11,5 Ct'k. D r'ainaye as -"i
5 /TE /q rea 75,-cl 5 F = 0 ® +3 A
Tc = 6,5 rn►n
P.2 1®5 -,r®m Wafer Works
P,o ® 2,0
100
F I S T IA(G SITE (OND TIONS m
Per E cIDG 1 , 30, 060, assn meadow
•► •
Per Ecpc 1, 3a 0®, 1® a, 1 i m i e peak Yako
off' runoC� to A& pre-deoelop corldrf-ids Iwo -year
" hr-de�In s YiV?� W�'ja 1'VIGI(ni-oItn (113 i�rle
Pre -deve) cped condrfi`vn peak. runo q �6r
4 -he- 10 -year) -I--h►' I®O -yam 2 - ,f -hour
mpervl' o v5 f -req 131 ?02 = / c
c (q
Pe r (r® os Prey = 19, 7 - 131 qOZ
LC
Ac
m
5/lf/06 page 1
MAGNOLIA LANE
GOODNIGHT BROTHERS
BASIN SUMMARY
BASIN ID: A100X NAME: 100 YR, 24 HR EXISTING
SBUH METHODOLOGY
TOTAL AREA.......:
0.43 Acres
BASEFLOWS:
0.00 cfs
RAINFALL TYPE....:
TYPEIA
PERVIOUS AREA
PRECIPITATION....:
3.00 inches
AREA..:
0.43 Acres
TIME INTERVAL....:
10.00 min
CN....:
85.00
TIME OF CONC.....:
26.50 min
IMPERVIOUS
AREA
ABSTRACTION COEFF:
0.20
AREA..:
0.00 Acres
AREA..: 0.00 Acres
CN.....
98.00
TcReach - Sheet
L: 295.00 ns:0.1500 p2yr: 1.50
s:0.0373
PEAK RATE: 0.11
cfs VOL: 0.06
Ac -ft TIME:
490 min
BASIN ID: AlOX
NAME: 10 YR
24 HR EXISTING
SBUH METHODOLOGY
PERVIOUSTYPElA AREA
inches1.50
TOTAL AREA.......:
0.43 Acres
BASEFLOWS: 0.00 cfs
RAINFALL TYPE....:
TYPEIA
PERVIOUS AREA
PRECIPITATION....:
2.00 inches
AREA..: 0.43 Acres
TIME INTERVAL....:
10.00 min
CN....: 85.00
TIME OF CONC.....:
26.50 min
IMPERVIOUS AREA
ABSTRACTION COEFF:
0.20
AREA..: 0.00 Acres
CN..... 98.00
TcReach - Sheet
L: 295.00 ns:0.1500
p2yr: 1.50 s:0.0373
PEAK RATE: 0.05
cfs VOL: 0.03
Ac -ft TIME: 490 min
BASIN ID: A2X
SBUH METHODOLOGY
TOTAL AREA.......:
RAINFALL TYPE....:
PRECIPITATION....:
TIME INTERVAL....:
TIME OF CONC.....:
ABSTRACTION COEFF:
NAME: 2 YR 24 HR EXISTING
0.43 Acres
;. •
0.00 cfs
PERVIOUSTYPElA AREA
inches1.50
■
0.00
.:
85.00
26.50 min
IMPERVIOUS
AREA
SheetTcReach - OA
PEAK 0.02 cfs VOL:
CN..... 98.00
ns:0.1500 p2yr: 1.50 s:0.0373
0.02 Ac -ft TIME: 490 min
5/2/06 page 2
MAGNOLIA LANE
GOODNIGHT BROTHERS
BASIN SUMMARY
BASIN ID: B100D
SBUH METHODOLOGY
TOTAL AREA.......:
RAINFALL TYPE....:
PRECIPITATION....:
TIME INTERVAL....:
TIME OF CONC.....:
ABSTRACTION COEFF:
NAME: 100 YR, 24 HR DEVELOPED
0.43 Acres
BASEFLOWS:
0.00 cfs
TYPEIA
PERVIOUS AREA
3.00 inches
AREA..:
0.11 Acres
10.00 min
CN....:
86.00
10.00 min
IMPERVIOUS
AREA
0.20
AREA..:
0.32 Acres
CN..... 98.00
PEAK RATE: 0.23 cfs VOL: 0.09 Ac -ft TIME: 480 min
BASIN ID: B10D
SBUH METHODOLOGY
TOTAL AREA.......:
RAINFALL TYPE....:
PRECIPITATION....:
TIME INTERVAL....:
TIME OF CONC.....:
ABSTRACTION COEFF:
NAME: 10 YR, 24 HR DEVELOPED
0.43 Acres
BASEFLOWS:
0.00 cfs
TYPEIA
PERVIOUS AREA
2.00 inches
AREA..:
0.11 Acres
10.00 min
CN....:
86.00
10.00 min
IMPERVIOUS
AREA
0.20
AREA..:
0.32 Acres
PEAK RATE: 0.14 cfs VOL:
BASIN ID: B2D
SBUH METHODOLOGY
TOTAL AREA.......:
RAINFALL TYPE....:
PRECIPITATION....:
TIME INTERVAL....:
TIME OF CONC.....:
ABSTRACTION COEFF:
CN..... 98.00
0.06 Ac -ft TIME: 480 min
0.43 Acres
BASEFLOWS:
0.00 cfs
TYPEIA
PERVIOUS AREA
1.50 inches
AREA..:
0.11 Acres
10.00 min
CN....:
86.00
10.00 min
IMPERVIOUS
AREA
0.20
AREA..:
0.32 Acres
CN..... 98.00
PEAK RATE: 0.10 cfs VOL: 0.04 Ac -ft TIME: 480 min
5/24/06 page 1
MAGNOLIA LANE
GOODNIGHT BROTHERS
6 MONTH STORM WATER QUALITY TREATMENT VOLUME
BASIN SUMMARY
BASIN ID: B6MO
SBUH METHODOLOGY
TOTAL AREA........
RAINFALL TYPE....:
PRECIPITATION....:
TIME INTERVAL....:
TIME OF CONC.....:
ABSTRACTION COEFF:
NAME: 6 -MONTH
24 -HR DEVELOPED P®LLUTION 6ENERFiou6
SURFACE 6MLY
0.15 Acres
BASEFLOWS: 0.00
cfs
TYPEIA
PERVIOUS AREA
0.96 inches
AREA..: 0.00
Acres
10.00 min
CN....: 86.00
10.00 min
IMPERVIOUS AREA
0.20
AREA..: 0.15
Acres
PEAK RATE: 0.02 cfs
CN..... 98.00
VOL: 0.0(1 Ac -ft TIME: 480 min
o®q2 14c-�t
Ro llu-hoyl soy -f Ce
.147 lqc(-es
P(�, y Y) 0 (o (PZ)
Volome .002 Ate® x 4 -3,5 -(bo'
A
Wa Q ualt
0.4' (TYP.,
3.35' -F
5' EL=195.0'
1.615'
1
S TA GE S I.,
GOODNIGHT'I
MAY l 2006
VJ - n —.—
ADDITIONAL LIVE & DEAD STORAGE
IN TYPE 2 CATCH BASINS
63 LF- 5' DIA PIPE
'-<----WATER QUALITY DEAD STORAGE 358.5 CF
WATER QUALITY DEAD STORAGE IN 48" CB 20.72 CF
WATER QUALITY DEAD STORAGE IN 54" CB 25.23 CF
VOLUME OF 0.4' "SLICE" OF TOTAL DEAD STORAGE 404.45 CF
LIVE STORAGE IN 4.5 DIA
TYPE 2 CB = 6.35 CF
CORRESPONDING
VOLUME
IN 63 LF OF PIPE
0.17 SF 10.71 CF
1.0 SF 63.0 CF
1.42 SF
89.46 CF
1.68 SF
105.84 CF
1.85 SF
116.55 CF
1.94 SF
122.22 CF
2.0 SF
126.0 CF
1.98 SF
124.74 CF
1.9 SF
119.7 CF
CUBIC FEET
VOLUME OF 0.4' "SLICE" OF
LIVE STORAGE IN 4' DIA
TYPE 2 CB = 5.02 CF
5/29/06 page 1
MAGNOLIA LANE
GOODNIGHT BROTHERS
5' DIA PIPE WITH WATER QUALITY DEAD STORAGE
STAGE STORAGE TABLE
CUSTOM STORAGE ID No. P563
Description: 5' PIPE 63 FEET LONG
STAGE <---- STORAGE ---- > STAGE <---- STORAGE ---- > STAGE <---- STORAGE ---- > STAGE <---- STORAGE ---- >
(ft) ---cf--- --Ac-Ft- (ft) ---cf-----Ac-Ft- (ft)---cf--- --Ac-Ft- (ft)---cf--- --Ac-Ft-
195.00 131.07 0.0030 195.90 437.95 0.0101 196.80 724.67 0.0166 197.70 939.88 0.0216
195.10 165.10 0.0038 196.00 471.35 0.0108 196.90 753.97 0.0173 197.80 958.47 0.0220
195.20 199.13 0.0046 196.10 504.74 0.0116 197.00 783.27 0.0180 197.90 963.99 0.0221
195.30 233.15 0.0054 196.20 538.14 0.0124 197.10 808.48 0.0186 198.00 969.51 0.0223
195.40 267.18 0.0061 196.30 570.12 0.0131 197.20 833.69 0.0191 198.10 975.03 0.0224
195.50 301.52 0.0069 196.40 602.10 0.0138 197.30 858.89 0.0197 198.20 980.55 0.0225
195.60 335.87 0.0077 196.50 634.08 0.0146 197.40 884.10 0.0203
195.70 370.21 0.0085 196.60 666.06 0.0153 197.50 902.69 0.0207
95.80 404.55 0.0093 196.70 695.36 0.0160 197.60 921.29 0.0211
2 7, 19 57.02 ¢.5--5-
13 1,0'7
--131,®7 4-. 12 f. 7 -f- 35 -/-.; . 02 = 2.,6 7. /
I�T-7 S, 02 = 131.07
Volume of U®line 6-( Vo/
/',h'ce
5/29/06 page
MAGNOLIA LANE
GOODNIGHT BROTHERS
5' DIA PIPE WITH WATER QUALITY DEAD STORAGE
DISCHARGE STRUCTURE LIST
MULTIPLE ORIFICE ID No. 01
Description: ORIFICE
Outlet Elev: 195.00
Elev: 193,00 ft Orifice Diameter: O.9000 in.
Elev: 196.55 ft Orifice 2 Diameter: 1.4500 in,
5/29/06 page 3
MAGNOLIA LANE
GOODNIGHT BROTHERS
5' DIA PIPE WITH WATER QUALITY DEAD STORAGE
LEVEL POOL TABLE SUMMARY
MATCH INFLOW -STO- -DIS- <-PEAK-> STORAGE M 1�rCM
<-------- DESCRIPTION --------- > (cfs) (cfs) --id- --id- <-STAGE> id VOL (Cf) PZA
--------------
2 YR 24 HR ................... 0.02 0.10 P563 o1 196.25 11 555.61 O.�Z
10 YR 24 HR .................. 0.05 0.14 P563 01 196.73 12 704.22 0.05-
100 YR 24 HR ................. 0.11 0.23 P563 o1 198.14 13 977.31 0. f(