HomeMy WebLinkAboutTED4001925.2O
REVISED STORM DETENTION CALCULATIONS
Based on a 25-year storm intensity
and a -year release rate to reduce
discharge from site.
Total site area = 3.60 acres
Average slope of site = 4.0%
Exist.'c'=0.15 & 'v'=1.3 ft/sec
Tc= 10.0 + 400/(1.3)(60)= 15.1 min.
i5= 1.1 in/hr (Renton/Seattle)
Exist. Q=ciA=(0.15)(1.1)(3.6)=0.59 cfs
= allowable release from site.
Note: use multiple orifices since allow.
release rate exceeds 0.3 cfs
DEVELOPED CONDITIONS
Total landscape area=28,920 s11=0.66 ac.@'c'=0.25
Balance of site=2.94 ac.@'c'=0.90
Developed 'c'=(2.94)(0.90)+(0.66)(0.25) =
0.78
3.60
Qo='0.59/(3.60)(0.78) = 0.21 cfs/ac-c
T =-25 + (85,500/29.9Q0)1. =-25+116.7 =
91.7 min.
Vs = 3420T - 29.9Q0 T = 2687.4-575.8 = 2111.6
cf/ac
T+25
Vt = VsAc = (2111.6)(3.60)(0.78) = 5929.4
cf
= total storage required
STORAGE PROVIDED TO OVERFLOW EL. 34.07
CB-1 to CB-2 = 32 1f-12" @ 0.79 cf/lf =
25.3 CF
CB-2 to CB-3 = 151 1f-54" @15.90 cf/If =
2400.9 cf
4 1f-36" @ 7.07 cf/If =
28.3 cf
CB-2 to CB-4 = 161 1f-54" @15.90 cf/lf =
2559.9 cf
4 if-36" @ 7.07 cf/If =
28.3 cf
CB-4 to CB-5 = 47 if-12" @ 0.79 cf/If =
37.1 cf
CB-5 to CB-6 = 34 1f-12" @ 0.79 cf/lf =
26.9 cf
CB-4 to CB-7 = 128 1f-24" @ 3.14 cf/lf =
401.9 cf
In CB-1 =5.57 1f-54" @15.90 cf/lf =
88.6 cf
In CB-2 =5.35 1f-54" @15.90 cf/lf =
85.1 cf
In CB-3 =4.55 if-54" @15.90 cf/If =
72.3 cf
In CB-4 =4.50 if-54" @15.90 cf/If =
71.6 cf
In CB-5 =4.03 1f-48" @12.57 cf/lf =
50.7 cf
In CB-6 =3.74 if-48" @12.57 cf/If =
47.0 cf
In CB-7 =3.22 1f-48" @12.57 cf/lf =
40.5 cf
Total storage provided =
5964.9 cf
Total storage required =
5929.5 cf
Excess storage provided =
35.5 cf
ORIFICE SIZING
h-5 57 ft • Q=0 3 cfs
A PORTION OF THE SW 1/47 OF THE SE 1/4 OF SEC. 29, TWP 24 N., RGE. 6 E.,W M.
KING COUNTY, WASHINGTON
I i
CB NO.3 -TYPE II-54" C.) JO.8-TYPE I
GRATE EL.=�B- 39.SL' 4-GRATE EL.=a81_ 35.03'
I.E.=��36" � 30. 1Z' I.E. = 3rr.31-12� 3`�. 37'
I 00
I 30' 5
� 1
1.8 % I ' \ 40.02 1.2% 1.2%-
�rn
39.3 t 40.33 GB 40.26 39.97 I I 0 L.F. - 12" C. M. P. S =1.0 % /37.80
� 39.78 \ � 38.16
(70
I o 9
o ° Clp \
J O N N
� I N
I` 40.59 40.16 40.05 38.54
\\\ \\ O
128 c _r - 24'CMR
-1.0 /�
EX. SAN._ EW. M.H. � �\ \ O/-,
2 � <, y \ 0
RIM EL. = 137.27
9� I.E.=33.6 -12 ,
39.64 /
�� A\ 4C'.'_F �9.8 \ GB
\ . o
k2. 40.26 �\ \
FIN. FLR. EL.= 40.3
38
Bottom orifice - - •� � - C
1 1 �\ \ . `\\ \ /
Area (a)=0.3/0.62(64.4x5.57) z = 0.0255 sf \ 39.74 39.74 39.74 39.50
Diameter (d) _ (4a/ )2 = 0.1804 ft x 12 = 2.16" dia. N \ \
�\ \ o
Top orifice - h=2.79 ft.; Q=0.29 cfs
N 1
Area (a) = 0.29/0.62(64.4 x 2.79)z = 0.0349 sf
\\\ \ 38.98
Diameter (d) _ (4a/ ) 2 = 0.2108 ft x 12 = 2.53" dia. \\\ \ \39.91 170 CTR.-CTR. S -0.5% 38.98 .38.74 38.46 37.90
2. �`\ \ 54"CMP w/ 36" MP ENDS
1 \ \\ `` 38.83 38.62 G.B. 39.15 G.B. O 12 GA') M 38.62 '" 38.38 GB
�-- 1.0 % � � 1.0 % 2.82 %
Ij SAN.or- W.I.E.=33.19-12" � \ \ �� � - o ---
a°'�2 Z STM. I.E. = 28.54
\ \ \ 1 39.08 38.26 --i = - - - -- 38.79 - _ - - _ _ _ -
39.46j-
THE GEOTECHNICAL REPORT, AND RECOMMENDATIONS
CONTAINED THEREIN, PREPARED BY EARTH CONSULTANTS, _ -�
INC., DATED 11-5-87, ARE TO BE CONSIDERED PART 44 ?2LF-12't�IP N o 34 "' o�
\ r S 1 ° 0 .11
' / + M
OF THE SPECIFICATIONS FOR THIS PROJECT DUE TO -- \ 39.0638.58 38,31 37.78 r32
THE SENSITIVE NATURE OF THE UNDERLYING SOILS
CONDITIONS ON THE SITE. ALL ITEMS OUTLINED IN \ + _+ _
THE GEOTECHNICAL REPORT SHALL BE MONITORED &
TESTED BY EARTH CONSULTANTS, INC., TO VERIFY 30 LF-.3 %
WITH THE RECOMMENDATION CONTAINED \
CB-NO.7-TYPE II -4'� .I '2l
GRATES EL. = 3: �89 38.0v'
I.E. _ �-2-F - I _,3q•. � v'
2
- 4.3?
I
I
38.55 38.79 GB 39.0
I 2%
I °
M
M
N I
I
I a \
I i
I ,
p/O~ I ~ 2s r - _
2 47LF-12 CMF
y - 8 2 `Y° - - 1.0%
36.46 35.81 G.B.
COi�1PLIA6
NCE N. (01 30.15-1=
THEREIN °` \� i--- -°.C°- /
° ° °
0
I. I - 24 I 28 -0-
DC OUTLET CONTROL TRUC_TURE %� 28 -- _� °-
C6 N0.1 -TYPE-1 I 4 w/ SOLID LOC LID_
37.2S' RIM EL.=3�6 OVERFLv�V EL.= .G ��
EX. 24"coop I.E. _ -i^'� a 18" 28.2n � � � 30 C8 N0, 2-TYPE II-54H
_SEE DETAIL- - SHEET I.E.=i�-99.18f32 GRATE EL.= 38-86 uoT ` -�
__ _ I.E.�-12" >3� 36"_--ZA -8r7 CB_ NCB. 4- YPE II- 4 1 � \
_ _ 30 �\
L E. 25s - 2�__ 34 - f, GRN_�E .6 - AL 3 - o'
I.E. -ALL 30:�
36 EX. SAN. SEW. M.H.
3ga - - --- ,�-
_� RIM EL.=36.88
46 - 40- "CB N0.6-TYPE _ll 48��
%
J ADJ. TO EL.38.74 GRATE
016. INST. BEVELED ENDS N 42 I.E.=3GA -12"
& RIP -RAP OUTFALL. 6 44 - ¢ L_ R r
qs �2 NOTE EX. 24�� FiPE.. SHALL F CAFt=E.r-- \\
AND FILLED w/ LIGHT WEIGHT CONC.-
.1NX. DENSITY = 70 LBSlC.F. \
® INST. 6" PERF. PIPE ADJ. TO & AT SAME
I.E. AS SHOWN.
MATCH LINE TO SHEET
F I N. FLR. E L. = 40.2
GRATE EL.= \ 35.81 I.E.= 30.04-12
°
NOTE: ALL CATCH BASINS LOCATED IN AREAS DESIGNIATED BY THE GEOTECHNICAL
ENGINEER AS BEING UNDERLAYED BY COMPRESSIBLE SOILS SHALL HAVE TENSAR
SS-1 GEOGRID PLACED ON RECOMPACTED STRUCTURE SUBGRADE IN ACCORDANCE
WITH THE GEOTECHNICAL REPORT. ADDITIONALLY, TRENCH EXCAVATION, BACK -
FILLING, COMPACTION AND PLACEMENT OF MIRAFI FABRIC SHALL BE IN STRICT
CONFORMANCE WITH THE RECOMMENDATIONS AND METHODS SUGGESTED IN THE REPORT.
NOTE: ALL EXISTING BOUNDARY AND TOPOGRAPHIC INFORMATION
SHOWN ON THIS DRAWING IS FROM A SURVEY PERFORMED
BY BARGHAUSEN CONSULTING ENGINEERS INC. DATED
JUNE i4, 1986. (THEIR JOB NO. 2097)
BASIS OF BEARING
WASHINGTON STATE COORDINATE SYSTEM, NORTH ZONE.
BENCHMARK DATUM
WASHINGTON STATE DEPARTMENT OF TRANSPORTATION.
APPROVED BY
-4-
92
STORM OHAINAGE
AS-BUII-T PER SECTION
7-4 CONSTRUCTION
MANUAL FOR MUNICIPAL
PUBLIC WORKS
CONSTRUCTION 1973 BY
C G C SURVEYING MAY
19. 1988.
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SHEET? -OF 5-
O REV. 10-24 -87 PER CITY REVIEW JOB NO. 87-015
GRACING & DRAINAGE PLAN PREPARED BY:
4%5 EXIT!3Y ST E MI N C
.
rr%ENTC N WA6ri. 775 IOYLWOOO DRIVE S.W. ISSAQUAH, WA. 98027
C 206 1 392 1471
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