HomeMy WebLinkAbout03115 - Technical Information Report - Drainage �
�� Core Design,Inc. I,I
CORE 1471 1 N E 29th Place Suite #101 I
Bellewe,Washington 98007
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`I 425.885.7877 Fax 425.885.7963
FINAL STORM DR.AINAGE REPORT
FOR
HONEY BROOKE - PHASE III
REV'TON, ��'ASHINGTON
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Prepared by: Stacia l�. Schroe�ier, P.E. �-����� °����o�
Reviewed b��: Davi�d �. Cayton, P.E. g_z 7_�
Date: �Iay 2003
Revised: August z003
Core No.: 02U09
ENGINEERING P(ANNING SURVEYING
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HONEY BROOKE - PHASE III '
TABLE OF CONTENTS
I. Project Overview
II. Existing Conditions Summary
III. Off-site Analysis
A. Upstream Tributary Area '
B. Downstream Analysis
IV. Developed Conditions Summary
A. Hydraulic Analysis '
B. Detention Routing Calculation I
C. Water Quality Volume Calculation '
V. Conveyance Calculations '�
VI. Temporary Sediment Trap ,
Core Design,Inc. Page 2
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I. PROJECT OVERVIEW
The Honey Brooke—Phase III project consists of 4 separate parcels located near the
intersection of SE 128`h Street and 142nd Avenue SE in Renton, Washington. (See the
attached vicinity map.) The 4 parcels cover a total area of 4.46 acres. The existing
g�-ound slopes gently from west to east and is�covered by a combination of landscaping,
grass, pasture and some trees. Each parcel is currently occupied by a single-family
residence and associated outbuildings. However, only two existing houses with new lot
perimeters, and no outbuildings, will remain as part of the development. In all, the
developer proposes to construct 22 single-family lots with associated roadway and
utilities. The new ground cover will be mostly impervious surface with some
landscaping. A wetland with a 25' buffer will remain undisturbed near the site's southern
border.
Half street roadway improvements�vill extend Jericho Avenue NE and Ilwaco Place NE
in the north-south direction, and NE 5`h Street and NE 5`h Place in the east-west direction.
Full width roadway improvements will extend Il�vaco Avenue NE to the north 300+ feet.
The developer will install over 1,400LF of roadway, including curb, gutter and sidewalk
as needed to connect to existing residential areas. Also, per the City of Renton's request,
a 21' section of right-of-way was allotted along the site's northern boundary for the future
extension of NE 6`h Street. Ho«ever, no street improvements are called out in this area.
L"tilities are called out to service each of the 22 single-family lots. The developer
proposes to install 1,4�0+/- LF of 12" CPEP, 5 concrete inlets, 12 Type I catch basins,
and 3 Type II-48" diameter catch basins far storm drainage purposes. The City of Renton
requires Leve12 Flow Control and Basic Water Quality for the site. The on-site
generated runoff will be directed through the pipe/catch basin system to a combination
detention/water quality vault (40'x175'x9') to be installed in a storm drainage easement
along the rear of lots 7 through 16. All drainage discharging from the vault will be routed
to an existing wetland east of the site, which is the natural downstream drainage course
for this area. No bypass of flow is necessary for this project. See the attached site plan.
Core Design,Inc. Page 3
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FIGURE 1: VICINITY MAP
DATE MAY 2003 l47)l NE29rh Plaos Suife l07
Belkwe,Woshingron 98007
DRAWN SKS 425.885J877 Fox425.885J963
APPROVED DEC DESfGN
PROJECT MANAGER ENGINEER/NG • PLANNING • SURVEYfNG
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F I GURE 2� SITE PLAN
DATE MAY 2003 1471 1 NE 29th Place Suite 101
Bellevue, Washington 98007
DRAWN SKS
425.885.7877 Fax 425.885.7963
APPROVED DEC DESIGN
PROJECT MANAGER FNGINEERING • PLANNING • SURVEYlNG
II. EXISTING CONDITIONS SUNTMr�RY
The existing site is covered by a combination of impervious surfaces (houses and
outbuildings), miscellaneous landscaping, pasture, and few trees. A small wetland grazes
the site's southern boundary. The site soils are classified as Alderwood Series (AgB and
AgC), hydrologic �oup C (see the attached soils map). Drainage currently sheet flows to
the southeast across the property at a slope of 0-5%. Near the wetland however, a small
portion of the site slopes at approxunately 15+/-%. Under the existing condition the site
has no curb and gutter or sidewalk, and no drainage system.
Core Desigii. Inc. Page d
SHEET NO. 11
KING COUNTY AREA, WASHINGTON
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III. OFF-SITE ANALYSIS
I
A. UPSTREAM TRIBUTARY AREA
There is no upstream area tributary to the subject site:
B. DOWNSTREAM ANALYSIS
Draina e from the site naturall sheet flows in the southeasterl direction across the
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property and onto the adjacent property to the east and the existing pond along the south
property line. The existing surface drainage is split between two basins, however, this
analysis will utilize one detention system based on the following:
1. Historically, the pond along the south property line, which is located mostly in the
Honey Brooke Phase I project, a.k.a. 4.77 Court was connected to the existing
wetland east of the site. Fill material has been placed on-site by the original
property owner during the past few years, which has cut-off the hydraulic
connection. This proposed project would reestablish the original surface water
runoff course.
2. The Honey Brooke Phase I project did not include the offsite tributary area to the
north in the storm drainage vault design. Therefare,routing additional tightline
runoff to the existing vault will have adverse effects on the Phase I detenrion
system.
i3. The Honey Brooke Phase I project did not construct an emergency outfall
structure for the pond. Flooding of this pond will overflow onto rear yards of
adjacent lots and eventually overflow onto the roadway surface south on the pond.
Based on the above information, this project proposes to match the natural runoff
characteristics of the parcel and reduce the potential flooding risk associated with the
existing pond.
The outfall of the proposed detention/water quality vault will be directed to a point near
the existing offsite wetland located approximately 125 feet north of the southeast property
Core Design,Inc. Page 5
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, - � - II
c�rn�r. �t�,rm���at�r t1o���s tlu-ou��h the �t��tlan� 1or appr��si�uat�l�� �,�� i:ct in an eastcrl�� �
direcrion where it enters a 5-10 feet wide manmade ditch that drains south for
approximately 600 feet and enters an 18" intake. This intake drains to a catch basin/pipe
system that flows east along the north side of NE 4�'street for approximately 100 feet
where it enters a Type II catch basin. From this catch basin, stormwater flows south
underneath NE 4`� Street via a 36"storm pipe for approximately 85 feet and into another
Type II catch basin in private property. The outfall of this catch basin drains south
through a 48"diameter concrete pipe for approximately 80 feet where it daylights into an
existing 2—3 feet wide ditch. This ditch eventually meanders in a southerly direction for
approximately 200 feet where it enters the Sienna Plat, which is currently under
construction.
The remaining downstream has been described by Triad Associates in their T.I.R. for the
� Sienna Plat and verified by this office. A copy of their downstream analysis and map
I follows.
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Core Design,Inc. Page 6
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. Sienna Level 1 Downstream Analysis
With the exception of the existing houses and associated driveways, the site is covered
predominately with second growth forest of alder, fir, cedar, maple, scrub trees and bramb
under story. The site contains mild slopes ranging from 1% to 3% sloping from the n to
the south. A drainage swale meanders through the middle of the site, flowing no o south.
A 0.19 —acre wetland lies at the northeast corner of the site. The wetland w' � remain.in a
sensitive area tract.
2 UPSTREAM DRAINAGE ANALYSIS
A site visit was performed on July 2, 99 bserve upstream, site and downstream
drainage conditions. The following ana , sis` sed that site visit and related research of
available records. ;
2.1 Upsfream Basin
There are approximately 160 acres. upstream area tributary to the site as delineated on the
Upstream Tributary Map. ' area consists mainly of existing nursery, single-family
residences, roadway and ' cellaneous wetlands. Storm water tends to sheet flow over the
yard and roadway are where it is picked up by ditches and pipes. A 42-inch storm line
carries the flow s � under SE 128`� St. where it discharges into a ditch behind a residence
at 14415 SE- � 8`h St. The ditch ranges from 2 to 3 feet deep and then travels under a
driveway, a an 18-inch culvert. The storm water enters the north property line of the site •
via ditch and meanders through an existing swale in a southerly direction.
3 DOWNSTREAM DRAINAGE ANALYSIS
Refer to the Downstream Drainage Map to aid in the following summary of the downstream
drainage system.
3.1 Site Runoff
In the existing condition, the storm water sheet flows to the onsite swale_ The storm water
then flows in a southerly direction where it leaves the site approximately 400 feet east of the ',
Februa 13,2002 p �' �
ry � age
Job#01-108 /TnT�n �
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� Sienna Level 1 Downstream Analysis
intersection of SE 132"d St. and 144`h Ave SE. At this point the storm water flows for a few
feet in a ditch and then under SE 132"d St. in an 18-inch concrete culvert.
3.2 Downstream Runoff
The site runoff flows through the 18-inch culvert to a catch basin located on the south side of
SE 132°d St. The storm water is then piped south approximately 350 feet where it outfalls
into a graveUhard packed ditch/swale. The water continues to flow in a southerly direction
for approximately 100 feet where it splits west and east. The easterly channel conveys flow
from a 12-inch culvert where it picks up storm water on the east side of the unopened right-
of-way of 164�' Ave. SE. The westerly channel flows through a heavily vegetated area into a .
property at 13224 144th Ave SE. The water is transported through a manmade rocked
channel, under a footbridge and then into a 24-inch concrete culvert where it crosses under
14��' Ave SE. The water discharges on the west side of 144`h Ave SE into a seasonal stream
called Maplewood Creek. The creek bed was dry at the time of the site visit. It is well
vegetated with grass and meanders through a pasture. The stream flows in a west-
southwesterly direction to 142"d Ave SE where it then flows south. There were no appazent
signs of flooding outside of the ditch/swale streambed.
3.3 Downstream Drainage Prob/ems
According to complaints compiled by the King County Water and Land Resources Division,
flooding has occurred between the project site and the one-quarter mile point. Specifically,
complaints #86-0739 and #90-OSSb reported of flooding of private property at 13323 14b�'
Ave SE. (See the Drainage Complaints exhibit located in the appendix).
The first enclosed complaint was received on July 23, 1986. The complaint was of water
flowing from Maplewood Heights Elementary School onto the property. The investigation
narrated that the school property is 3-6 feet lower than the complainants' property. Therefore
the complaint was closed. The second complaint was received on February 6, 1990. It
appears that a neighbor filled a low area in their yard that forced drainage to pond in an
adjacent yard. The action taken by King County Department of Public Works was not
included in the report. At the time of the site visit performed on July 2, 2001, the drainage
February 13,2002 Page �
Job#01-108 /TT�T�
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� Sienna Level 1 Downstream Analysis �,
swale at this location was ill defined for approximately 100 feet. At this point, the drainage ,
converges with the outflow of the 18-inch pipe from the north. The channel is well defined '
at the convergence point.
The ditches along NE 2"d St and 146`� appear to have not been maintained in several years.
There are numerous alder saplings along with heavy growth of vegetation. The resident at
the comer of NE 2"a St. and 146`h Ave SE stated that he has not seen a maintenance crew in
over 5 years. He also stated that the ditches have not overflowed but have come close to the
top. No flow was observed on the day of the site visit.
February 13,2002 Page 4
Jab#01-108 /TT�T A Tl
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IV. DEVELOPED COnDITIOVS SU1�I��IARY
A. HYDR.�ULIC :�NALYSIS
The hydraulic analysis was conducted using the King County Runoff Time Series
software (KCRTS) methodology. The site soils, identified as Alderwood Series (a�B
and AgC), correlate to the KCRTS group Till. The SeaTac rainfall region was used. �.��:t h
a regional scale factor of 1.0. Using the predeveloped impervious and pervious area�
shown in the table below, a predeveloped time series was generated. (The imper�
area was measured directly from the existing site plan using a planimeter.) Upon
completion of the final improvements, the developed timeseries was manufacture,.
much the same way. The developed site's impervious area was arrived at using the '
King County Surface Water Drainage Manual (KCSWDM), Section 3.2.2. Using tl:
criteria and applying it to King County Code (K.C.C. 21A.12.03) for R-5 zoning, th�
maximum impervious coverage is interpolated to be about 62.5% for the lots.
Pre-Developed Area Developed Area
(Acres) (Acres)
Till Pasture 3.99 -
Till Grass - 1.15
Impervious 0.39 3.23
Undisturbed Wetland 0.08 0.08
(Including Buffer)
Total 4.46 4.46
Core Design,Inc. Page 6
3.2.2 KCRTS/RUNOFF FILES ME'I'HOD—GENERATING TfME SERIES
. ,_ -
TABLE 3�...._.'B.EQUIVALENCE BET`WEEN'SCS SOII.TYPES AND KCRTS SOIL TYPES
SCS Soil Type SCS KCRTS Soil Notes
Hydrologic Group
Soii Group
Aiderwood (AgB,AgC,AgD) C Till
Arents, Alderwood Material (Am6, AmC) C Till
Arents, Everett Material(An) B Outwash 1
Beausite (BeC, BeD, BeF7 C Till 2
Bellingham (Bh) D Till 3
Briscot (Br} D Till 3
Buckley (Bu) D Till 4
Earlmont (Ea) D Till 3
Edgewick(Ed) C Till 3
Everett(EvB, EvC, EvD, EwC) A/B Outwash 1
Indianola (InC, InA, InD) A Outwash 1
Kitsap (KpB, KpC, KpD) C Till
Klaus (KsC) C Outwash 1
Neilton (NeC) A Outwash 1
Newberg (Ng) B Till 3
Noaksack (Nk) C Till 3
Norma (No) D Till 3
Orcas (Or) D Wetland
Oridia (Os) D Tifi 3
Ovall (OvC,OvD,OvF) C Till 2
Pilchuck(Pc) C Till 3 �
Puget (Pu) D Till 3
Puyallup (Py) B Till 3
Ragnar(RaC, RaD, RaC, RaE) B Outwash 1
Renton (Re) D Till 3
Salal (Sa) C Till 3
Sammamish (Sh} D Till 3
Seattle (Sk) D Wetland
Shalcar(Sm) D Till 3
Si(Sn) C Til! 3
Snohomish (So, Sr) D Till 3
Sultan (Su) C Till 3
Tukwila (Tu) D Till 3
Woodinville(VVo) D Till 3
Nofes:
1. Where outwash soifs are saturated or underlain at shallow depth(�5 feet) by glacial till,they should
be treated as till soiis.
2. These are bedrock soils, but calibration of HSPF by King County DNR shows bedrock soils to have
similar hydrologic response to till soils.
3. These are allwial soils,some of which are undertain by glacial till or have a seasonally high water
table. In the absence of detailed study,these soils should be treated as till soils.
4. Bucldey soils are formed on the low-permeability Osceola mudflow. Hydrologic response is
assurned to be similar to that of till soils.
1998 Surface Water Design Manual 9/1/98
3-25
SEC'ITON 3.2 RUNOFF COMPUTATION AND ANALYSIS MEIHODS
FIGURE 3?.Z.A RAINFALL REGIONS AND REGIONAL SCALE FACTORS I
ST 1.0/
. 1 ST 1.0 LA p,g LA 0.9 LA 1•0 LA 1.2
ST 1�■ SMOMOMISM COUNT♦
��,,a'�
�� �� X1MG COYNiY �
l,P� � �
l.:{`vLc-• r_
�- � � '''�;i--�� ,-�
� :; '��r'�, �� '� 4L .:,
'S T�, .i` �- � 'e ! i,
_� � 'i. �' ,� "�.,,1�.J � _ - .
� , .�, ;. _ � $y
:� 1"'.+i oNo�;
,� � , ,
f � '` � \
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., . . e
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-� �� i' � s;. - �. ,� �a
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i
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searr�- " ?-+ � � �; r ���C�.o�.�:
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� �ti � . . �� ,.j ���-.
r : n -
r.� wa }
. ��� �; I �' Knw .( � . �: -! ��I
, .. f �', y1 ;•'. !. ��_.
- 3_4, -1� �:` _ Q� �,. �� .r:
nni� �' s� '. — 4 /�)., � �� .
.o - r
� � / .� �:� �.1�r � 1 ~ / �atow
� " � ���� " � � LANDSBURG
� ,, � Q
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' "°' � a�,t � •:� q
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_ �
.,l+ei+ ,� `- ,� .:�-, :, � u�,e..,., � . . : .
: .s�.� Q �,,' 1 .y, '' _
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.-i . �� >�ru��� ��1� �D� `:.�. _
ST 1.1 °""`' � ����' � ,
e� `: - . '; g .
;:
� � -"'wna eourir �
nenac eouwrr \
I
ST '1.0 �
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i�.
� -
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ST 1.0/ �" `�
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- Rainfall Regions and �a o.s `` �.. - � -
�
Regional Scale Factors �a o.s
LA 1.2
�
� Incorporated Area LA 1.0
�� RivedLake
Major Road
9/1/98 1998 Surface Water Design:vlanual
3-22
21A.12.030 ZONING
29A.'f 2.030 A Densities and dimensions -residential zones.
RESIDENTIAL �,
Z Ruwu. u�w � u�w
0
N RE- �� RESIDENTUIL
E
g SHtYE {I =`i fJ �
ST/WDqRpS R/42.5 R/43 R/1r10 RA-20 UR R-1 R-� R�'i R-8 R-12 R-18 R-24 Rr8
(�T)
eas.oe�sKy: 01 o.z o.a o.o� o� � a s a �z �s s4 �a
Dwslling du/x du/ac dWx dufae dulu dulae dulac dulx dufae dWac du/ac dulac du/ac
UrdfUcn (21) (6)
('s,
w�nwm oensny: o.a a.a a e �z �a 2� ae n
Dws�lny UnWAcrs du/ac du/ae dufae dWae du/ae du/ae dWac du/ac du/ae
l�) (�01 !Zo) (�I
MlNmum Wmity: 8594 85X 85% 80X 73% 70X 65%
�� ('12) (�2) (12) (18) (18) (18) ('IS)
(�8) ��8) ��8�
(23)
YtNmum Lot/vea 1975 3.73 ac 7.3 ae 1 S ac
(13) ae
Minimun Lot 135 R 135 R 130 ft 135 ft 3�R 35 R 30 R 30 it 30 R 30 R 30ft 30 ft 30 R
VNdth (� (7)
(3)
MlNmunStreet 30R 30ft 30ft 30R 30tt 20R 10R 10ft �Oft 10R 10ft �OQ �OR
Sewack (9) (9) (9) (9) (�) (� (s) (81 I8) (8) (8) (8) (8)
(3)
MiNmumlrHerior SR �Oft 10R 108 SR 5ft Sft Sft SR SR SS 3tt Sft
sowxk (9) {91 (91 (9) (� C/) f�ol (�a1 (�o) (�a)
(3)('IB)
Baae Hsight 40 R 40 R 10 ft 40 R 3S R 33 ft 3�R 35 ft 33 h 60 ft 60 ft 60 ft BO it
(4) 45 R 45 R 80 R 80 ft 80 ft
(14) (14) (�4) (�4) (14)
Maximum 23% 20% 15% 12396 30X 30Y. SSX 70X 73% 85% 85% 83X 90%
ImpwWous -- (1't) ('11) (11) ('11) (11) (11)
Surfacs: (19) (�9� ('19) (�9) •
2�
Peres�Yage(S) �y
B. Development conditions.
1. This maximum density may be achieved only through the application of residential density
incentives in accordance with K.C.C. chapter 21A.34 or transfers of density credits in accordance with
K.C.C. chapter 21A.36 or 21A.55, or any combination of density incentive or density transfer. Maximum
density may only be exceeded in accordance with K.C.C. 21A.34.040F.1.g.
2. Also see K.C.C. 21A.12.060.
3. These standards may be modified under the provisions for zero-lot-line and townhouse
developments.
(King County 3-2001)
21A-105
Tin, _
Pro
Flow Rate Ranic Time cf Peax - - Peaks - - Rank Return Pr�
(CFS) (CFS) Period
0.361 3 2/09/O1 15 :00 0.702 1 100.00 0 . 5.
0.204 7 1/05/02 16:00 0.378 2 25.00 0.960
0.378 2 2/27/03 7:00 0.361 3 10.00 0.900
0.133 8 S/26/04 2 :00 0.360 4 5.00 0.800
0.216 6 1/05/05 8:00 0.341 5 3 . 00 0.667
0.360 4 1/18/06 16:00 0.216 6 2.00 0.500
0.341 5 11/24/06 3 :00 0.204 7 1.30 0.231
0.702 1 1/09/08 6:00 0.133 8 1.10 0.091
Computed Peaks 0.594 50.00 0. 980
Flow Frequency Analysis
Time Series File:dev.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.897 6 2/09/O1 2:00 1.77 1 100.00 0.990
0.744 8 1/OS/02 16:00 1.20 2 25.00 0.960
1.07 3 2/27/03 7:00 1.07 3 10.00 0.900
0.826 7 8/26/04 2 :00 0.989 4 5.00 0.800
0.989 4 10/28/04 16:00 0.943 5 3 .00 0.667
0.943 5 1/18/06 16:00 0.897 6 2 .00 0.500
1.20 2 10/26/06 0:00 0.826 7 1.30 0.231
1. 77 1 1/09/08 6:00 0.744 8 1. 10 0.091
Computed Peaks 1 . 58 50 . 00 0 . 990
B. DETENTION ROUTING CALCULATION
The detention routing calculation, a continuation of the hydraulic analysis, uses KCRTS
to match the pre-developed outflow to the developed outflow by providing a site-specific
amount of detention. The following printout shows a vault 40' wide by 168' long and 5'
deep (33,600c fl in conjunction with the documented control structure will provide
enough live storage (detention) to satisfy this requirement.
II
Core Design. Inc. Page 7
-
Retention/Detention Facility �I
e of Facilit : Detention Vault I��
TYP Y
Facility Length: 168.00 ft
Facility Width: 40.00 ft
Facility Area: 6720. sq. ft
Effective Storage Depth: 5.00 ft
Stage 0 Elevation: 0.00 ft
Storage Volume: 33600. cu. ft
Riser Head: 5.00 ft
Riser Diameter: 12.00 inches
Number of orifices : 3
Full Head Pipe
Orifice # Height Diameter Discharge Diameter
(ft) (in) (CFS) (in)
1 0.00 1.67 0. 169
2 2 .40 1.55 0. 105 4 .0
3 3 .25 1.55 0. 086 4 .0
Top Notch Weir: None
Outflow Rating Curve: None
I� Stage Elevation Storage Discharge Percolation
; (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs)
� 0.00 0.00 0. 0.000 0.000 0.00
I�i 0.02 0.02 134. 0.003 0.010 0.00
0.03 0 .03 202 . 0.005 0.014 0.00
� 0.05 0 .05 336. 0.008 0.017 0.00
� 0.07 0 .07 470. 0.011 0.020 0.00
I 0.09 0 .09 605. 0.014 0.022 0.00
0 .10 0 .10 672 . 0.015 0.024 0.00
0 .12 0.12 806. 0.019 0.026 0.00
0.14 0 .14 941. 0 .022 0.028 0.00
0.24 0.24 1613 . 0.037 0.037 0.00
I 0.34 0.34 2285. 0.052 0.044 0.00
0.44 0.44 2957. 0.068 0.050 0.00
0 .54 0 .54 3629. 0 .083 0.056 0. 00
0.64 0 .64 4301. 0.099 0.060 0.00
0.74 0 .74 4973 . 0 .114 0.065 0.00
0.84 0.84 5645. 0 . 130 0.069 0.00
0.94 0.94 6317. 0 .145 0.073 0.00
1.04 1.04 6989. 0 . 160 0.077 0.00
1.14 1.14 7661. 0.176 0 .081 0.00
1.24 1.24 8333 . 0 .191 0 .084 0.00
1.34 1.34 9005 . 0 .207 0 .088 0.00
1.44 1.44 9677. 0 .222 0 .091 0 .00
1.54 1.54 10349. 0.238 0 .094 0 . 00
1.64 1.64 11021. 0.253 0 .097 0 .00
1.74 1.74 11693. 0 .268 0 .100 0 .00
1.84 1.84 12365. 0.284 0.103 0 .00
1.94 1.94 13037. 0.299 0.105 0 .06
2.04 2 .04 13709. 0 .315 0.108 0 .00
2 .14 2 .14 14381. 0 .330 0.111 0 .00
2 .24 2 .24 15053. 0 . 346 0.113 0 .00
2 .34 2 .34 15725. 0 . 361 0.116 0 . 00
-- -
, � , - �I
� . 40 � .4'„ _5��� . � . � , ., J . 1= 0 . 00
2 .42 2 .42 16202 . 0.373 0 . 118 0 .00 I
2 .43 2 .43 16330. 0.375 0.120 0 .00
2 .45 2 .45 16464. 0.378 0.123 0 .00 '
2 .46 2 .46 16531. 0.380 0 .127 0 .00
2 .48 2 .48 16666. 0.383 0 .131 0 .00 �
2 .50 2 .50 1680�. 0.386 0.137 0 .00
2 .51 2 .51 16867. 0.387 0.142 0 .00
2 .53 2.53 17002. 0.390 0.144 0.00
2 .63 2 .63 17674. 0.406 0.154 0.00
2 .73 2 .73 18346. 0.421 0. 162 0.00
2 .83 2 .83 19018. 0.437 0. 170 0. 00
2 . 93 2 .93 19690. 0.452 0. 177 0. 00
3 . 03 3 .03 20362. 0.467 0. 183 0. 00
3 . 13 3 .13 21034. 0.483 0.189 0. 00
3 .23 3 .23 21706. 0.498 0.195 0. 00
3 .25 3 .25 21840. 0.501 0.196 0. 00
3 .27 3 .27 21974. 0.504 0.198 0. 00
3 .28 3 .28 22042. 0.506 0.200 0 . 00
3 .30 3 .30 22176. 0.509 0.204 0 . 00
3 .31 3 .31 22243 . 0.511 0.208 0 .00
3 .33 3 .33 22378. 0.514 0.213 0 .00
3 .35 3 .35 22512 . 0.517 0.219 0 .00
3 .36 3 .36 22579. 0 .518 0.225 0 .00
3 .38 3 .38 22714. 0.521 0.227 0 .00
3 .48 3 .48 23386. 0.537 0.240 0.00
3 .58 3 .58 24058. 0.552 0.251 0 .00
3 .68 3 .68 24730. 0.568 0.261 0 .00
3 .78 3 .78 25402. 0 .583 0.271 0 .00
3 . 88 3 .88 26074. 0 .599 0 .280 0 .00
3 .98 3 .98 26746. 0 .614 0 .288 0 .00
4 . 08 4 .08 27418. 0 .629 0.297 0 .00
4 .18 4.18 28090. 0.645 0.304 0.00
4 .28 4.28 28762. 0.660 0.312 0 .00
4 .38 4 .38 29434. 0.676 0.319 0. 00
4 .48 4 .48 30106. 0.691 0.326 0.00
4 .58 4 .58 30778. 0.707 0.333 0.00
4 .68 4.68 31450. 0.722 0.340 0.00
4 .78 4.78 32122 . 0.737 0.346 0 .00
4 .88 4.88 32794. 0.753 0.353 0. 00
4 . 98 4 .98 33466. 0.768 0 .359 0. 00
5 .00 5.00 33600. 0.771 0.360 0. 00
5 .10 5.10 34272 . 0.787 0.675 0 . 00
5 .20 5 .20 34944. 0.802 1.240 0 .00
5 .30 5.30 35616. 0.818 1.980 0 .40
5_40 5.40 36288. 0.833 2 .780 0.00
5.50 5.50 36960. 0 .848 3 .060 0 .00
5.60 5.60 37632 . 0 .864 3 .330 0 .00
5. 70 5.70 38304. 0 .879 3 .570 0 .00
5.80 5. 80 38976. 0 .895 3 .790 0 .00
5.90 5.90 39648. 0 .910 4.000 0 .00
6.00 6.00 40320. 0 .926 4 .200 0.00
6.10 6.10 40992. 0.941 4 .390 0.00
6.20 6.20 41664. 0.956 4 .570 0.00
6.30 6.30 42336. 0.972 4 .740 0.00
6.40 6.40 43008. 0.987 4 . 910 0.00
6.50 6 .50 43680. 1. 003 5 . 070 0 .00
6.60 6.60 44352. 1.018 5.230 0.00
6.70 6.70 45024. 1. 034 5 .380 0.00
6.80 6.80 45696. 1.049 5.530 0.00
6.90 6.90 46368. 1.064 5 .670 0.00
7.00 7.00 47040. 1.080 5 . 810 0 .00
Hyd Inflow Outflow Peak Storage
Target Calc Stage Elev (Cu-Ft) (Ac-Ft)
1 1.77 0.70 1.49 5.23 5.23 35169. 0 . 807
2 1.20 ******* 0.20 3 .30 3 .30 22163 . 0 .509
3 1.07 ******* 0.29 3 .97 3 .97 26655. 0 .612
4 0.99 ******* 0.11 2.09 2 .09 14017. 0 .322
5 0.94 ******* 0.33 4.49 4 .49 30185. 0.693
6 0.90 ******* 0.55 5.06 5 .06 34004 . 0.781
7 0.83 ******* 0.11 1.99 1.99 13362 . 0.307
8 0.74 ******* 0.12 2.36 2 .36 15826. 0 .363
--------------------------------- I�
Route Time Series through Facility
Inflow Time Series File:dev.tsf
�utflow Time Series File:rdout
Inflow/Outflow Analysis
Peak Inflow Discharge: 1.78 CFS at 6 :00 on Jan 9 in Year 8
Peak Outflow Discharge: 1.49 CFS at 9:00 on Jan 9 in Year 8
Peak Reservoir Stage: 5.23 Ft
Peak Reservoir Elev: 5 .23 Ft
Peak Reservoir Storage: 35169. Cu-Ft
. 0 .807 Ac-Ft
Flow Duration from Time Series File:rdout.tsf
Cutoff Count Frequency CDF Exceedence_Probability
CFS °s � %
0 .008 43107 70.298 70.298 29.702 0.297E+00
0 .023 4885 7.966 78.265 21.735 0.217E+00
0 .039 4583 7.474 85.739 14.261 0.143E+00
0 .054 3481 5.677 91.416 8 .584 0.858E-01
0 .070 2265 3 .694 95.109 4.891 0.489E-01
0 .085 1381 2.252 97.361 2 .639 0.264E-01
0.100 780 1.272 98.633 1.367 0.137E-01
0. 116 466 0.760 99.393 0.607 0.607E-02
0 . 131 53 0.086 99.480 0.520 0 .520E-02
Q.147 25 0.041 99.521 0 .479 0 .479E-02
0.162 44 0.072 99.592 0.408 0.408E-02
�.178 43 0.070 99.662 0.338 0.338E-02
0 .193 82 0.134 99.796 0.204 0 .204E-02
0 .209 21 0.034 99.830 0.170 0.170E-02
0.224 6 0.010 99.840 0.160 0.160E-02
0.239 17 0.028 99.868 0.132 0.132E-02
0.255 11 0.018 99.886 0 .114 0. 114E-02
0 .270 10 0.016 99.902 0 .098 0.978E-03
0 .286 14 0.023 99.925 0.075 0.750E-03
0 .301 9 0.015 99.940 0.060 0.603E-03
0 .317 10 0.016 99.956 0.044 0.440E-03
0.332 9 0.015 99.971 0 .029 0.294E-03
0 .347 9 0.015 99.985 0 .015 0. 147E-03
0.363 4 0.007 99.992 0. 0a8 0 .815E-04 II
0.378 0 0.000 99.992 0.008 0.815E-04
0.394 0 0.000 99.992 0.008 0.815E-04
0.409 0 0.000 99.992 0.008 0.815E-04
0.425 1 0.002 99.993 0.007 0.652E-04
0.440 0 0.000 99.993 0.007 0.652E-04 I
0.456 0 0.000 99.993 0.007 0.652E-04 I
0.471 0 0.000 99.993 0.007 0.652E-04 ���
0.486 2 0.003 99.997 0.003 0.326E-04 I
0.502 0 0.000 99.997 0.003 0.326E-04
0.517 1 0.002 99.998 0.002 0.163E-04
0.533 0 0.000 99.998 0.002 0.163E-04
0 .548 0 0.000 99.998 0 .002 0 .163E-04
� � � �
.
� � � : • 1 1 1 '
� � r����_��,�t.z.��_�r ;-
tc�rg�t,dur x.
_ , .
' - o
c�
0
�'; � < ;
''��dt .. 3 ' tL .. . � .
-`�t` � -� "!'� '"��ra z �;
.,.,.r.-' O�. _ . . . . � .
R
o .
_ � ,
.-, .
cr�a
�
V
w
, � oao �
- C7�
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t�
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� -: ��
� Probability Exceedence ���i.�
'i-
1�� . ' � 10�` 10�' 10 Z 10 ' 1
Base Fiie: predev.t�
New File: rdout.ts:
Cutoff Units: Discharge __ -_ _
I
-----Fraction of Time---- ---------Checx of Tolera:
Cutoff Base New �Change Probability Base Ne:�; ��ha__
0.109 � 0. 91E-02 0.87E-02 -4.0 I 0.91E-02 0.109 0.108 -0
0.146 � 0.51E-02 0.49E-02 -4.8 � 0.51E-02 0.146 0.136 -6 .
0.182 � 0.30E-02 0.30E-02 -2 .2 I 0.30E-02 0 .182 0.182 -0.4
0.219 � 0.18E-02 0.16E-02 -10.0 � 0.18E-02 0 .219 0.199 -9.2
0.256 � 0.12E-02 0.11E-02 -4.1 I 0.12E-02 0.256 0.253 -0.9
0.292 � 0.77E-03 0.70E-03 -8.5 � 0.77E-03 0.292 0.285 -2 .5
0.329 � 0 .47E-03 0.31E-03 -34 .5 � 0.47E-03 0.329 0.315 -4 .2
0.366 I 0 .29E-03 0.82E-04 -72 .2 � 0.29E-03 0.366 0.332 -9.2
0.402 I 0.21E-03 0. 82E-04 -61.5 � 0.21E-03 0.402 0.341 -15.2
0.439 � 0.11E-03 0.65E-04 -42 .9 I 0.11E-03 0.439 0.353 -19.6
0.476 � 0.65E-04 0.65E-04 0.0 I 0.65E-04 0.476 0.482 1.2
0 .513 � 0.33E-04 0.16E-04 -50.0 � 0 .33E-04 0.513 0.511 -0.2
0 .549 � 0. 16E-04 0.16E-04 0.0 I 0.16E-04 0.549 0.549 0.0
Maximum positive excursion = 0.025 cfs ( 5.2%)
occuring at 0.486 cfs on the Base Data:predev.tsf
and at 0.511 cfs on the New Data:rdout.tsf
' Maximum negative excursion = 0.097 cfs (-21.5�)
occuring at 0.454 cfs on the Base Data:predev.tsf
and at 0.357 cfs on the New Data:rdout.tsf
I
I� .
C. WATER QUAI.ITY VOLUNIE CAI.CULATION
'The water quality volume for Honey Brooke—Phase III was calculated using the King
County Surface Water Design Manual (KCSWDM), 1998 Edition, pages 6-68 to 6-71.
Vb = f*(0.9A; + 0.25Atg+ O.lOA�+ O.lOAo)*(R/12)
Where, Vb =wetpool volume (c fl
f=volume factor
A; =area of impervious surface (s�
Atg= area of till soil covered with �ass (s fl
Atf= area of till soil covered�vith forest (s fl
Ao= area of outwash soil covered with grass or forest
i
R=rainfall from mean annual storm (inches)
(refer to the attached precipitation graph)
Thus,
�� Vb = 3[(0.9(140,699) + 0.25(50,094))(0.47/12)]
i
Vb = 16,350cf
Taking into account the detention/water quality vault footprint as derived in the previous
section of this report, the depth of storage needed to satisfy the requirements is shown
below:
Depth of
Dead Storage= 16,350/(175*40) = 2.44ft
Core Design,I�ic. Page 8
6.4.1 WETPOI�IDS—BASIC r1ND LARGE—METHODS OF ANALYSIS
FIGL'RE 6.4.1.A PRECIPITATION FOR VIE;��i ANNUAL STORM IN INCHES(FEET�
ST 1.0/ I,A 1.2
ST 1.1 - ST 1.0 � 0.8 LP,. 0.9 � 1.0
' `�: ..��.. ...-r
�'^�I' �.� l0 .:� .'.:5 �
.'/; M1, r� � � `^\' -
_ � `�" �Y } A:
� � �y.
_ ���� , �i -1—_� �Q G'�..� ,-
- ,� `.. -�.' ��� i � $�Vi
l �` � \
� ,� �p _d� �, -� �-~���� `� i
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— r `�` � '
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,! d' �� . � b
(0.045` ) :
i::_._ - «»:,
�.xx_. .oe.,t \
0.47' .
(0.039') �, .. " .
. ��
� ;�_ _--=�i
� incorporated Area --- �
�., J _ e
...� RivedLake 0.47' �
.--.
— Major Road (0.Q 3 9' ) 0.5 2" �--.���
(0.043' 0.65" �
NOTE:Areas east of the eastemmost isoplwial should use 0.65 �.5 6° (0.O S 4' )
inches unless rainfall data is available for the location of irnerest (0.047' )
�The mean annual storm is a�ual stortn faud
by dividng Cee annuat predpNation by fhe totai number
_ sfortn events per year
— ---_ _ _
result,generates lar�e amounu of runoff. For this applica[ion, till soil types include Buckley and
bedrock soils,and alluvial and outwash soils that have a seasonally high water table or are underlain at
� a shallow depth(less than�feet)by glacial tiIl. U.S. Soil Conservation Service (SCS)hydrolo�ic soil
groups that are classified as till soils include a few B,most C,and all D soils. See Chapter 3 for
classification of specific SCS soil types.
1998 Surface Water Design vlannal 9/1/98
�-s9
V. CONVEYANCE CALCULATIONS
The conveyance calculations were performed utilizing the methodologies set forth in the
KCSWDM, 1998 Edition, Sec. 4. The storm drain system, shown in the attached site
plan and on sheet C4.01 of the plan set, was designed to accommodate the 100-yr storm
event; no overtopping of any catch basins will occur using this analysis. See the attached
storm conveyance design and backwater calculations spreadsheets for more information.
Core Design, Inc. Pa�e 9
3.2.1 RAT'IONAL METHOD
FIGURE 3.2.1.D 100-YEAR 24-HOUR ISOPLLTVIALS
3 0��� � ��� ��.�� ��� ���� ��� �� �� � CO�N��T
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P�E CC COUKT7
1NESTERN �° � '�''
� � �`� s.�
K1NG COUNTY �o ,� .�:�' - _ .: s.o
N p�• �, _ �� 5.5
�
100-Year 24Hour °� �:� �.� � _ ,f-,=; -
Prec�pitation °`��,h --� ,--,,�-.� ' '
yo � �.
in Inches ° -�"�� y �
h•
1998 Surface Water Design Manual 9/1/98
3-17
_ _ _ _
�T4I2�VI �ONY�Y.h:NC�:�Y`STF1�I I)��I+�N....
LO('A'17ON: NF:N'1'C)N,WA 24-HR RAINFALL: 3.9 INCHES
106 NA114F.: I'IN:Lb;1',11tCEf. JOR Ni1hiBER: 02009 PREPARED BY: SKS OS-09-03 llESIGN STORM: l0U YEAR
:�{ .�:: �N(7tBM11t,NIAt !i; RI1N/3FF... ..IMPFRlIfDf1Y:; ..,..:�j 3'IMh::fiN e,�i�ur:t1.L ;fH(xUP,�uv�:... .'� jriva .:;:'eire. :� .,:NiNw�..�.ac['vA.r. ,;.r�lav�,i,: ��.:YLI'h CANA�:LLY�SU3Y1MAItY�..;;;
Pq'F.,4FfMF.�P::. . ..RRF.A �i'l'OFFM3:CF�'�17" �.- ..'�,A£A�-.: RUM�" [YINC. INTF.NSITV <-. F60W '. h1ANNlnf'S DIAA1FlF,K -��$LIN'h -'I,BIVGIH.:YhJLOCIYY 11hFL�:' Yj(E131;4! Y(l!'U44j �. ��(ACly4(fU44)��.
hK.fiPf ., t0���� iAl'!ik�l ,'C';;' ', :;(.�y� � (A. Cj:; dc�INU"iC5} �tvn�a� ':,� (CFS� . ^n'�: (fNCHFS). ;(P�RCRnr) ���E��r). -.�:(ee�S�C). :(MINI�7,k�5j � {4�S?�, �.(IrP!,�i�I'):.:'�''(N�iRte.3�"�):��::
C'B 3 VOI1T 0.000 0.65 0.000 0.000 10.08 U.61 2.1I4 O.U12 12 59.400 5 21.40 0.00 29J47 3Z8R 7.49�
CI3 4 CB 3 0.000 O.tSS 0.000 0.000 10.01 0.61 1.709 0.012 12 4.530 32 8.11 0.07 8.215 10.46 20.8°/
('F3 5 CR 4 0360 0.65 0.234 0.234 9.49 0.63 1.709 OAl2 12 U.SUU 124 3.96 0.52 2J29 3.47 (i2.6'%
6SA CR5 0.440 0.(,5 0.286 0.286 6.30 0.82 0.234 Q012 12 4.400 38 3.92 0.16 8.096 10.31 2.9'%
C6 6 C'B 5 0300 QCS 0.195 O.195 894 0.66 1327 0.012 12 U.SUU 127 3.8G U.SS 2J29 3.47 48.6'%
L6A C136 0._>80 0.65 0.182 0.182 (330 0.82 O.149 OAl2 L2 12.000 29 5.19 0.09 13370 17.02 1.1% I
CL7 7 C13 6 0.160 0.65 0.104 0.104 R39 0.G8 1.050 OAl2 12 0.500 125 3.75 0.56 2.729 3.47 38.5%
CB 8 CB 7 0.180 0.65 0.117 0.I17 8.29 0.69 0.97) OAl2 12 2.(10O 3(1 5.04 0.10 5.458 6.95 17.9%
CI3 9 CI�k 0.000 0.65 0.000 0.000 8.07 0.70 0.898 0.012 12 0.500 48 3.67 0.22 2.729 3.47 329%
CIi15 ('h39 0.140 O.GS 0.091 0.091 G.52 0.80 0.318 0.012 12 2.000 121 3.51 0.57 5.458 6.95 5.8%
IIS� CI315 0.460 0.65 0.299 0.299 630 0.82 0.245 OAl2 l2 0.700 30 2.32 0.?2 3.229 4.11 7.6%
CB14 CB9 0.280 0.65 0.182 0.182 6.30 0.82 0.176 OAl2 12 8.300 46 4.32 O.1R 11.120 14.16 Lfi°/
114A CB14 OA50 0.65 Q033 0.033 630 0.82 0.027 OAl2 12 2A00 24 0.00 0.00 5.458 G.95 0.5%�
CB 10 CB 9 0.340 0.65 0.221 0.221 7.24 OJS 0.405 0.012 12 0.500 120 2.42 0.83 2.729 3.47 14.8%
C:Bll CB10 0.090 0.(5 0.059 0.059 G35 0.81 0.239 0.012 12 0.500 110 2.05 0.89 2.729 3.47 8.8%�
IIIA CB11 0.360 0.G5 0.234 0.234 6.30 0.82 0.1)2 U.U12 12 3.500 10 3.49 0.05 7.221 9.19 2J%
CF312 CB3 O.SRO 0.65 0377 0.377 6.A1 0.78 0.4A5 0.012 12 0.500 l30 2.52 0.86 2.729 3.47 17.R%
C'B13 CB12 0.360 0.65 0.234 0.234 6.30 0.82 0.192 0.012 12 3.400 105 3.44 0.51 7.117 9.Oti 2.7%
CB 1 O-lA 0.000 0.65 0.000 0.000 0.50 0.00 2.I94 0.012 12 0.500 44 3.93 Ql9 2.729 3.47 80.4%
C132 Cf31 0.000 0.65 OAOU 0.000 O.UU O.UO 2.194 O.U12 12 U.500 117 3.93 OSO 2.729 3.47 80.4%
VOUT CR2 0.000 0.65 0.000 0.000 0.00 0.00 2.194 0.012 12 o.non IS 0.00 0.00 0.000 Q.00 0.0'%
CORE DES[GN, INC.
PR0.IECT NO. 02009
llATE: OS/12/03 I,
s�cx��-.arEt�C:�t,cti��a�rio�s :
OB VAM1iE:PIELE PARCEL OPERATOR:SKS � I
OB NG�IBER:02009 �I.�YU:�L: 1998 KCS�i'DM&2001 D.O.E. STORYI FREQCEVCY: 100-vr DATE:OS-09-03
ENTRAIVCE ENTR4NCE E�CI�f OUTLET INLET APPROACH BEND JL'nCTION
PIPE PIPE �iANNIVG'S OUTLET INLET PIPE FLOW VELOCITY TAILWATER FR;CTIOv HGL HEAD HEAD COnTROL CO�TROL VELOCiTY HEAD HEAD HEADwATER
FRO�I TO FLOW LEVGTH DIA. n ELEVATION ELEVATION AREA �'ELOCITY HE:�D ELEVATIO:� LOSS ELEV:�TION LOSS LOSS ELEVATION ELEVATIOn HEAll LOSS LOSS ELEVArIOV
CB CB (CFS) (FEET) (1�) VALUE (FEE� (FEE'1� (SQ F� (FI'/SEC) (FEE1� (FEET) (FEET) (FEET) (FEET) (FEET) (FEET) (FEE'1� (FEET) (FEET) (FEET) (FEET) RINI EL
CB 3 VOLT 2.194 5 12 0.012 441.80 444J7 0.79 2.79 0.12 �147.80 0.02 447.82 0.06 O.12 �t8.00 445.77 0.0? 0.00 0.03 447.96 4�2.50 4.�d
CB 4 CB 3 1.?09 32 12 OAl2 444.77 446.22 0.79 2.18 a.07 447.96 0.06 448.02 0.04 0.07 4�38.13 447.22 0.07 0.00 0.00 448.06 449.25 1.19
CB� CB 4 1.?09 124 12 0.012 446.22 �146.84 0.79 2.18 O.Oi 448.06 0.24 448.30 0.04 0.07 448.41 447.84 �.00 OAS 0.02 448.48 451.37 2.89
I-SA CB 5 0.234 38 ]2 0.012 446.84 448.�1 0.79 0.30 0.00 4d8.48 0.00 �34951 0.00 0.00 �349.51 �49.51 0.04 0.00 0.00 449.�7 451.50 2.03
CB 6 CB� 1.327 l27 12 0.012 446.84 447.47 OJ9 1.69 0.04 448.48 O.IS �8.63 0.02 0.04 �348J0 448.4i 0.00 0.06 0.01 438.77 453.99 SZ2
I-6A CB 6 0.149 29 12 0.012 4�7.47 450.95 0.79 0.19 0.00 448.77 0.00 451.95 0.00 0.00 451.95 451.95 Q03 0.00 0.00 451.92 453.99 2.07
CB 7 CB G I.O50 125 12 OAl2 �47.47 448.09 0.79 1.34 0.03 448.77 0.09 449.49 OA1 0.03 4=t9.13 449.09 0.02 OA� 0.00 449.11 454.35 5.24
CB 8 CB 7 0.979 30 12 0.012 448.09 448.69 0.79 1.2� 0.02 449.11 0.02 449.69 0.01 0.02 449.73 449.69 0.02 0.03 0.00 449.74 454.35 4.61
CB 9 CB 8 0.898 48 12 0.012 448.69 448.93 0.79 1.14 0.02 449.74 0.03 �349.93 0.01 0.02 449.96 449.93 0.00 OA1 0.00 449.97 455.5i 5.60
CB1� CB 9 0.318 121 l2 0.012 448.93 451.35 0.79 0.40 0.00 449.97 OA1 452.35 0.00 0.00 4�2.35 452.3� 0.00 0.00 0.00 452.36 454.66 2.30
I15A CB1� 0.245 30 12 dAl2 451.3� 451.6� 0.79 0.31 0.00 452.36 0.00 4�2.65 0.00 0.00 452.65 452.6� U.00 0.00 0.00 452.6� 454.66 2A1
CB14 CB 9 O.176 46 12 0.012 448.93 452.75 0.79 0.22 0.00 449.97 0.00 353.75 0.00 0.00 453.75 453.75 0.00 0.00 0.00 4�3J6 456.12 2.36
114A CB14 0.027 24 12 0.012 452.75 453.23 OJ9 0.03 0.00 453.76 0.00 454.23 0.00 0.00 454.23 454.23 0.00 0.00 0.00 454.23 456.22 1.99
CB10 CB 9 0.405 120 l2 0.012 448.93 449.53 0.79 0.52 0.00 449.97 0.01 450.53 0.00 0.00 450.�4 450.53 0.00 0.00 0.00 450.54 454.43 3.89
CB11 CB10 0.239 110 12 0.012 449.53 450.08 0.79 0.30 0.00 4�0.54 0.00 4�1.08 0.00 0.00 4�1.08 451.08 0.00 0.00 0.00 451.08 454.91 3.83
I11A CB11 O.192 10 12 0.012 450.08 450.43 0.79 0.24 0.00 451.08 0.00 451.43 0.00 0.00 451.43 451.43 0.00 0.00 0.00 451.43 4�5.33 3.90
CB12 CB 3 O.d85 130 12 0.012 444.77 445.42 OJ9 0.62 OAl 447.96 0.02 4�7.98 0.00 0.01 447.98 446.42 0.00 0.01 4.01 448.00 �48.42 0.42
CB13 CB12 0.192 10� 12 0.012 445.42 348.99 OJ9 0.24 0.00 448.00 0.00 449.99 0.00 0.00 �49.99 449.99 0.00 0.00 0.00 449.99 452.30 2.31
CB 1 O-lA Z.194 44 12 0.012 442.00 442.22 0.79 2.79 0.12 443.00 0.37 �3.37 0.06 0.12 �13.i6 443.22 0.12 0.00 0.00 443.43 44839 4.96 '
CB 2 CB 1 2.194 117 12 O.Ol2 �M12.22 442.80 0.79 2.79 0.12 443.43 0.05 443.80 0.06 0.12 �1=13.98 443.80 O.12 0.16 0.00 444.02 452.20 8.18
VOUT CB 2 2.194 l5 12 OAl2 �12.80 442.80 0.79 2.79 0.12 �344.02 0.00 44d.02 0.06 0.12 444.20 443.80 0.00 0.06 0.00 444.27 448.30 4.03
CORE DESIG�1, INC.
PROJECT NO. 02009
DATE: OS/12/03
VI. TE�TPOR=�RY SEDINTENT POND
A sediment pond is required for all development sites in excess of 3 acres. The sediment
pon for this site was designed per KCSWDM, 1998 edition,pages D-28 to D-31. The
required surface area of the sediment pond at the riser overflow elevation was 1,667sf.
The current sediment pond design proposes 2,297sf at this elevation. The 12"riser pipe
was sized to pass the 10-year flow (lcfs), and the 6' wide emergency spillway with 0.2ft
of depth,was designed to pass the 100-yr flow (1.62cfs). Both points of discharge match
the final design discharge point.
Core Design, Inc. Page 10
SECI70N 5.3 DETENTION FACILITIES
Riser Overtlow
, The nomo�raph in Fiwre 5.3.4.H can be used to determine the head(in feet)above a riser of given
diameter and for a given flow(usually the 100-year peal:flow for developed conditions).
FIGURE 5.3.4.H RISER INFLOW CURVES
�oo � � 72 54 48 `
I �
42 ,
. I � I �
� 36
� 33 ,
I ,
30
i
i 27
� ,
24 (
�t I i '
2 1 �� �
� ��° w
c � I ,
m 18 � i
� � ,
`m �a
m 10 15 w I
� — I i
3 '
Q 12 i � � �
10 �
� �
I I �
f
� j
i - � �
��� HEAD IN FEET (measu�red from crest of riser) ��
�rreir=9.739 OH��Z
2 t/2
�o�i���.=3.782 D H ,
0 in cfs, D and H in feet
Slope change occurs at weir-orifice transifion
9/1/98 1998 Surface Water Desian Manual
5-50
„ . � 'F(t-0 �''( �'E �W EY a(T—o o{c � ��E L l Y`f 1 W J�R--y
,.-t-o {��z 2 E P��T
I
IV. FLOW CO�TROL ��iD �'4:ATER QliALITY FACILITY ��ALYSIS AND
DESIGN
A. HYDROLOGIC ��1ALYSIS
The developed Honey Brooke—Phase V site (0.8�7ac) will combine its runoff«�ith that
�
from the developed Honey Brooke—Pha�III site (4.423ac) to the east. One
detention/wet vault faciliry will serve both projects. For this reason the vault will be
sized based on the combined existing and developed conditions for both projects.
The hydrologic analysis for the following vault was conducted based on the 1998
KCSWDM and the King County Runoff Time Series (KCRTS) software. The site soils,
identified as Alderwood Series (AgB and AgC), conelate to the KCRTS group Till. The
SeaTac rainfall region was used, with a regional scale factor of 1.0. Using the pre-
developed impervious and pervious areas shown in the table below (for both the Hone�,
Brooke —Phase V site and the Honey Brooke—Phase III site), a single pre-developed
time series ��as generated.
The developed site's impen�ious areas «�ere amved at using the 1998 KinQ County
Surface Water Drainage�Ianual (KCSWDl�1), Section 3.2.2. Using the criteria and
applying it to King County Code (K.C.C. 21A.12.03) for R-8 zoning, the maximum
impervious coverage is interpolated to be about 75% for the lots, or 4,OOOsf/lot
(whichever is less). Please refer to the attached Site Statistics spreadsheet for a
breakdo«�n of developed pervious and impen�ious areas.
Pre-Developed Area (.=�cres) Developed Area (.�cres)
H.B.—III H.B. —V H.B.—III H.B. —V
Till Pasture 3.948 - - -
Till Grass - 0.687 1.040 0.306
Impervious 0.390 0.170 3.298 0.5�1
Subtotal 4.338 0.857 4.338 0.857
L"ndisturbed Wetland 0.085 - 0.085 -
Total Gross Area 4.423 0.857 4.423 0.857
Core Design.Lic. Hone�� Brooke—Phase �' Page 6
� ' lO' '^ :680000 FE�T 1Z2°0��.
� 3EATTC£(C1TY P OJ !0 �UJ.l'IL'��i�� 5 Ml. TO /NTERSTATE 90��`�'AI<P (Joms sheet 5) ATC lSSAQUAH'?Ml. �
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Scale 1:24 000
D ATE APR/L 2004 S H EET O F
�4 �z �' o ' ' '�'�'S DESIGNED DEC 1 1
i -
�� —
SOCC �toGo Co 2Co0 �000 0 SCtJo l0000 �eei DRAWN $!(S PROJECT NUMBER
0.3044
• r DESCRIPTIONS OF THE SOILS
This section describes the soil series and map- Alderwood soils are used for timber, pasture,
ping units in the King County Area. Each soil berries, row crops, and urban development. They
series is described and then each mapping unit in are the most extensive soils in the survey area.
that series. Unless it is specifically mentioned '
otherwise, it is to be assumed that what is stated .Aldexwood gravelly sandy loam, 6 to 15 percent
about the soil series holds true for the mapping slopes (�gC) .--This soil is rolling. areas are
units in that series. Thus, to get full information irregular in shape and range from 10 to about 600
about any one mapping unit, it is necessary to read acres in size.
both the description of the mapping unit and the Representative profile of Alderwood gravelly
description of the soil series to which it belongs. sandy loam, 6 to 15 percent slopes, in woodland,
An important part of the description of each 450 feet east and 1,300 feet south of the north
soil series is the soil profile, that is, the quarter corner of sec. 15, T. 24 N. , R. 6 E. :
sequence of layers from the surface downward to
rock or other underlying material. Each series AI--O to 2 inches, very dark brown (lOYR 2/2)
contains two descriptions of this profile. The gravelly sandy loam, dark grayish brown
�first is brief and in terms familiar to the layman. (14YR 4/2) dry; weak, fine, granular struc-
"' The second, detailed and in technical terms, is for ture; slightly hard, friable, nonsticky,
. scientists, engineers, and others who need to make nonplastic; many roots; strongly acid;
thorough and precise studies of soils. Unless it abrupt, wavy boundary. 1 to 3 inches thick.
is otherwise stated, the colors given in the B2--2 to 12 inches, dark-brown (lOYR 4/3) gravelly
descriptions are those of a moist soil. sandy Zoam, brown (lOYR 5/3) dry; moderate,
As mentioned in the section "How 'Ihis Survey Was mediwn, subangular blocky structure; slightly
�1ade," not all mapping units are members of a soil hard, friable, nonsticky, nonplastic; many
series. Urban land, for example, does not belong roots; strongly acid; clear, wavy boundary.
to a soil series, but nevertheless, is listed in 9 to 14 inches thick.
alphabetic order along with the soil series._ B3--12 to 27 inches, grayish-brown (2.5Y S/2)
Following the name of each mapping unit is a gravelly sandy loam, light gray (2.SY 7/2)
symbol in parentheses. This symbol identifies the dry; many, mediwn, distinct mottles of light
mapping unit on the detailed soil map. Listed at olive brown (2.5Y 5/6) ; hard, friable, non-
tne end of each description of a mapping unit is the sticky, nonplastic; many roots; mediwn acid;
capability unit and woodland group in �,rhiCh the abrupt, wavy boundary. 12 to 23 inches thick.
mapping unit has been placed. The woodland desig- IIC--27 to 60 inches, grayish-brown (2.5Y 5/2) ,
nation and the page for the description of each weakly to strongly consolidated till, light
capability unit can be found by referring to the gray (2.5Y 7/2) dry; common, medium, distinct
"Guide to Mapping Units" at the back of this survey. mottles of light olive brown and.yellowish
The acreage and proportionate extent of each brown (2.5Y 5/6 and lOYR 5/6) ; massive; no
mapping unit are shown in table 1. Many of the roots; medium acid. �Iany feet thick.
terms used in describing soils can be found in the
Glossary at the end of this survey, and more de- The A horizon ranges from very dark brown to
tailed information about the terminology and methods dark brown. The B horizon is dark brown, grayish
of soil mapping can be obtained from the Soil Survey brown, and dark yellowish brown. The consolidated
�1anua1 (191 . C horizon, at a depth of 24 to 40 inches, is mostly
grayish brown mottled with yellowish brown. Some
�Alderwood Series layers in the C horizon slake in water. In a few
areas, there is a thin, gray or grayish-brown r12
Tne Aldenaood series is made up of moderately horizon. In most areas, this horizon has been
�.,�ell drained soils that have a weakly consolidated destroyed through logging operations. .
to strongly consolidated substratwn at a depth of Soils included with this soil in mapping make up
24 to 40 inches. These soils are on uplands. They no more than 30 percent of the total acreage. Some
formed under conifers, in glacial deposits. Slopes areas are up to 3 percent the poorly drained Vorma,
are 0 to 70 percent. The annual precipitation is Bellingham, Seattle, 'hikwila, and Shalcar soils;
35 to 60 inches, most of which is rainfall, between some are up to 5 percent the very gravelly Everett
October and btay. The mean annual air temperature is and Neilton soils; and some are up to 15 percent
about 50° F. The frost-free season is 150 to 200 Alderwood soils that have slopes more gentle or
days. Elevation ranges from 100 to 800 feet. steeper than 6 to 15 percent. Some areas in New-
In a representative profile, the surface layer castle Hills are Z5 percent Beausite soils, some
and subsoil are very dark brown, dark-brown, and northeast of Duvall are as much as 25 percent Ovall
grayish-brown gravelly sandy loam about 27 inches soils, and some in the vicinity of Dash Point are
thick. The substratum is grayish-brown, weakly 10 percent Indianola and Kitsap soils. Also
consolidated to strongly consolidated glacial till included are small areas of Alderwood soils that
that extends to a depth of 60 inches and more. have a gravelly loam surface layer and subsoil.
8
• Permeability is moderately rapid in the surface Arents, Alde:-wood Material
layer and subsoil and very slow in the substratum.
Roots penetrate easily to the consolidated substra-
tum where they tend to mat on the surface. Some arents, Alderwood material consists of Alderwood
roots enter the substratum through cracks. Water soils that have. been so disturbed through urban-
moves on top of the substratum in winter. Available ization that they no longer can be classified with
water canacity is low. Rimoff is slow to medium, the Aldertaood series, These soils, however, have
and the hazard of erosion is moderate. many similar features. The upper part of the soil,
This soil is used for Limber, pasture, berries, to a depth of 20 to 40 inches, is brown to dark-
and row crops, and for urban development. Capability brown gravelly sandy loam. Below this is a grayish-
unit IVe-2; woodland group 3d1. brown, consolidated and impervious substratum.
Slopes generally range from 0 to 15 percent.
Alderwood gravelly sandy loam, 0 to 6 percent _ Z'}lese soils are used for urban development.
slopes (AgB) .--This soil is nearly level and
undulating. It is similar to Alderwood gravelly
sandy loam, 6 to 15 percent slopes, but in places ,�ents, Alderwood material, 0 to 6 percent slopes
its surface layer is 2 to 3 inches thicker. Areas
(AmB) .--In many areas this soil is level, as a
are irregular in shape and range from 10 acres to result of shaping during construction for urban
slightly more than 600 acres in size. facilities. Areas are rectangular in shape and
Some areas are as much as 15 percent included range from 5 acres to about 400 acres in size.
Norma, Bellingham, Tukwila, and Shalcar soils, al2
of which are poorly drained; and some areas in the Representative profile of Arents, Alderwood
vicinity of Enumclaw are as much as 10 percent �aterial, 0 to 6 percent slopes, in an urban area,
1,300 feet west and 350 feet south of the northeast
Buckley soils. corner of sec. 23, T. 25 N., R. 5 E. :
Runoff is slow, and the erosion hazard is
slight. 0 to 26 inches, dark-brotim (lOYR 4/3) gravelly
This Alderwood soil is used for timber, pasture, sandy loam, pale brown (lOYR 6/3) dry;
berries, and row crops, and for urban development.
Capability tmit IVe-2; woodland group 3d2. massive; slightly hard, ver/ friable, non-
sticky, nonplastic; �nany roots; medium acid;
Alderwood gravelly sandy loam, 15 to 30 percent abrupt, smooth boundary. 23 to 29 inches
slopes (AgD) .--Depth to the substratum in this soil thick.
varies within short distances, but is commonly 26 to 60 inches, grayish-brown (2.5Y 5/2) weakly
about 40 inches. r�reas are elongated and range consolidated to strongly consolidated glacial
from 7 to about 250 acres in size. till, light brownish gray (2.SY 6/2) dry;
Soils included with this soil in mapping make comrnon, medii,un, prominent mottles of yellowish
up no more than 30 percent of the total acreage. brown (lOYR 5/6) moist; massive; no roots;
Some areas are up to 25 percent Everett soils that medium acid. Many feet thick.
have slopes of 15 to 30 percent, and some areas are
up to 2 percent Bellingham, Norma, and Seattle soils, The upper, very friable part of the soil ex:�nds
which are in depressions. Some areas, especially to a depth of 20 to 40 inches and ranges from dar�
on Squak Mountain, in Vewcastle Hills, and north of grayish brown to dark yellowish brown.
Tiger Mountain, are 25 percent Beausite and Ovall � Some areas are up to 30 percent included soi1=
soils. Beausite soils are underlain by sandstone, that are similar to this soil material, but either
and Ovall soils by andesite. shallower or deeper over the compact substratum;
Runoff is medium, and the erosion hazard is and some areas are S to 10 percent very gravelly
severe. The slippage potential is moderate. Everett soils and sandy Indianola soils.
This Alderwood soil is used mostly for timber. This Arents, Alderwood soil is moderately well
Some areas on the lower parts of slopes are used drained. Permeability in the upper, disturbed soil
for pasture. Capability unit VIe-2; woodland group material is moderately rapid to moderately siow,
3d1. depending on its compaction during construction.
The substratum is very slowly permeable. Roots "
Alder,aood and Kitsap soiis, ver;r steep (t1kF) .-- Penetrate to and tend to mat on the surface of the
This mapping unit is about �0 percent Alderwood consolidated substratum. Some roots enter the
gravelly sandy loam and 25 percent Kitsap silt substratum through cracks. Water moves on top of
loam. Slopes are z5 to 70 percent. Distribution �e substratwn in winter. Available water capacity
of the soils varies greatly within short distances. is low. Runoff is slow, and the erosion hazard is
About 15 percent of some mapped areas is an slight.
included, unnamed, very deep," moderately coarse 'I'his soil is used for urban development. Ca-
textured soil; and about 10 percent of some areas Pability unit IVe-2; woodland group 3d�.
is a very deep, coarse-textured Indianola soil.
Drainage�and permeability vary. Runoff is rapid
to very rapid, and the erosion hazard is severe to arents, �.lde naood material, 6 to 15 percent
very severe. The slippage potential is severe. slopes (AmC) .--This soil has convex slopes. ..Lreas
These soils are used for timber. Capability are rectangular in shape and range from 1Q acres to
unit VIIe-1; woodland group 2d1. about 450 acres in si�e.
10
3.2.2 KCRTS/RUNOFF FII.ES METHOD—GENERATING TIME SERIE:;
TABI.E 3.2?B EQUIVALENCE BETWEEN SCS SUIL TYPES:4ND`KC1tTS SQIL TYPES'<_:'
SCS Soil Type SCS KCRTS Soil Notes
Hydrologic Graup
Soit Group
Alderwood (AgB,AgC,AgD} C Till
Arents, Alderwood Material (AmB,AmC) C Till •
Arents, Everett Materiai (An) B Outwash 1
Beausite (BeC, BeD, BeF' C Till 2
Bellingham(Bh) D Tiil 3
Briscot (Br) D Till 3
Buckley{Bu) D Tilf 4
Earlmont(Ea) D Till 3
Edgewick (Ed) C Till 3
Everett {EvB, EvC, EvD, EwC) A/B Outwash 1
Indianola(InC, InA, InD) A Outwash 1
Kitsap (KpB, KpC, KpD) C Til[
Klaus (KsC) C Outwash 1
Neilton (NeC} A Outwash 1
Newberg (Ng) B Till 3
Nooksack (Nk) C Till 3
Norrna (No) D Till 3
Orcas (Or) D Wetland
Oridia (Os) D Till 3
Ovall (OwC, OvD,OvF) C Till 2
Pilchuck(Pc) C Till 3 '
Puget (Pu) D Till 3
Puyallup (Py) B Till 3
Ragnar(RaC, RaD, RaC, RaE) B Outwash 1
Renton (Re) D Till 3
Salal (Sa) C Till 3
Sammamish (Sh} D Till 3
Seattle (Sk) D Wettand
Shalcar(Sm) D Till 3
Si (Sn) C Till 3
Snohomish (So, Sr} D Till 3
Sultan (Su) C Till 3
Tukwila (Tu) D Tili 3
Woodinville (Wo) D Till 3
Nofes:
1. Where outwash soils are saturated or underlain at shallow depth (<5 feet) by glacial till, they should
be treated as till soils.
2. These are bedrock soils, but calibration of HSPF by King County DNR shows bedrock soils to have
similar hydrologic response to till soils.
3. These are aNuvial soils,some of which are underiain by glacial till or have a seasonally high water
table_ In the absence of detailed study,these soils should be treated as till soils.
4. Buckley soiEs are formed on the low-permeability Osceola mudflow. Hydrologic response is
assumed to be similar to that of 611 soiis.
1998 Surface Water Design Manual 9/1/98
3-25
� SECTION 3.2 RUNOFF COMPUTATION AND ANALYSIS METHODS
FIGL'RE 3.2.2.A R�iINFALL REGIONS AND REGIONAL SCALE FACTORS
ST 1.0/
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�`�'�J Incorporated Area
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Major Road
9/1/98 1998 Surface Water Design!vlanual
3-22
21A.12.030 ZONING
29Al2.U30 A. Densities and dimensions -residential zones.
RESIDE�ITIAL
Z RURAL URBAN URBAN
O
N RE- RESIDENTUIL
E
S S� =`-1�J �
• STIWDARDS RA-2.5 R/45 R/410 R/420 UR R-1 R-4 R6 R.8 R-12 R-1H R-24 R�8
(��
Base Density: 02 02 0.� 0.05 02 1 4 6 8 12 18 24 48
Dweiling dulac dulac dWac du/ac du/ac dWac dWac du/ac du/ac dWac dWac dulac dulac
UniUAcra (2'1) (6)
(,5,
Ma�drtwm Density: Od OA 6 9 12 18 27 36 72
Dwe9ing UrrtlAcre dWac du/ac du/ac dufac dWac du/ac dWac dulac du/ac
(�) (20) (Zo1 (�)
Minimum Ds�ity_
859G 85X 85X. 809G 759G 709L 657b
(Z) ��2� ��z� ��z� ��s� ��a� ��s� ��s�
l�$) (�8) (�81
(23)
Minimum Lot Aroa �874 3.75 ac 7.S ac 1 S ac
(13) ac
Ninimum Lot 135 ft '135 ft 133 ft 135 k 35 ft 35 R 30 ft 30 ft 30 ft 30 it 30ft 30 ft 30 it
YNdth (7) m
(3)
Mirrmun Streat
30 ft 30 ft 308 30 R 30 ft 20 ft '10 ft 10 R �0 R 10 R 10 ft �Ott 10 ft
Setback I9) (9f (91 (9) (n �') (8) (e) ($1 (8) (8) (81 ($)
(3)
iJllnimum IMerior 51t 108 10 ft 10 ft 5 ft 5 ft 5 R S R S R S ft 3 ft S Q S ft
Setback (9) (9) (9) (9) (7) (� (�0) (��) (��) (�a)
(3){16)
Base HeigM 40 R 40 B 40 ft 10 R 35 R 35 R 35 R 35 ft 35 ft 60 ft 60 ft 60 R 60 tt
(4) 45 it 45 ft 80 R 80 R 80 ft
(14) ('14) ('!4) ('14) ('14)
Ma�dmum 25X 20% �SX 12.5% 30X 30% 555L 70% 759G . 85% SSX 8S%. 90%
i�y,ervia,s ' ���� ���� �»� ���� ���� ����
Surface: (19) (�9) (19) ('19}
Percertage(5)
B. Development conditions.
1. This maximum density may be achieved only through the application of residential density
incentives in accordance with K.C.C. chapter 21A.34 or transfers of density crediis in accordance with
K.C.C. chapter 21A.36 or 21A.55, or any combination of density incentive or density transfer. Maximum
density may only be exceeded in accordance with K.C.C. 21A.34.040F.1.g.
2. AI so see K.C.C. 21 A.12.060.
3. These standards may be modified under the provisions for zero-lot-line and townhouse
deveiopments.
(King County 3-2001)
21 A-105
SITE STATISTICS - H.B. III
Total Area 192,662sf (4.�2�ac j
Total Developed Area 188,954sf (4.�38ac)
No of Future Lots 23
L�DISTURBED
Tract A - VGetland 3,708
Subtotal 3,708
I1��IPERVIOtiS
Nlain Roadwa��s: '
Il�vaco Place N� 9,323
NE Sth Place 17,832
Ilwaco Avenue NE 13,024
Jericho Avenue NE 9,990
NE Sth Street 1,491
51,660
Lots (4,OOOsf/lot*23 lots Max Imp) 92,000
Subtotal 143,660
PERVIOUS
1lain Road���avs:
NE Sth Place 642
Ilwaco Avenue NE 176
Jericho Avenue NE 483
I�'E �th Street 2b6
NE 6th Street ROW 3,150
4,717
Lots (132,577sf-92,OOOs�: 40,�77
Subtotal 45,294
Total 192,662
SITE ST�TISTICS - H.B. V
Total Area 37,3�44 (0.857ac)
No of Lots 6
I�-IPERVIOUS
Lots (4,OOOsfilot* 61ots Max Imp) 24,000
Subtotal 24,000
PERVIOUS
Lots (37,344sf-24,OOOs fl: 13,344
Subtotal 13,344
Total 37,344
Curc I)csi�n. Ini. H�.inu� Rr�iul:r- Ph:nc\ I'�. I ��I�,
LOT BREAKDOWN
HONEY BROOKE - PHASE III
Area Area (s� Area (st)
Lot No. (SF} Lot No. ! (SF) Lot No. (SF)
lA&1B 10,624 9 ; 5,329 � 17 6,002
2 5,456 10 I 5,329 � 18 5,876
3 4,652 11 6,252 , 19 6,182
4 j 4,652 12 8,007 ' 20 , 6,182
5 4,640 13 5,323 21 ' 6,168
6 6,169 14 5,324 22 6,109 ,
7 7,370 15 5,326
8 5,338 16 6,267 �
�
�
� TOTAL 132,57
Note: �
132,577sf�`0.75imp/231ots=4,323 sf imp/lot Use 4,OOOsf imp/lo
HONEY BROOKE - PHASE V
Area ; '� Area (s� ' Area (sf)
Lot No. (SF) Lot No. (SF) Lot No. (SF)
1 7,820 3 5,980 5 7,444
2 5,455 4 ,; 5,303 6 5,342 ,
; TOTAL; 37,344
Note: , i ,
37,344sfl`0.75im /61ots=4,b68 sf imp/lot Use 4,OOOsf im /lot '
Core Design.[nc. Hone}�Broukc-Phase�� Pg.2 of 2
Flow :requency =�na1_.sis
Time Series File:predev.ts�
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----�lc�fr Frequency analysis---- --
Flow Rate Rank Time of Peak - - Peaks - - Rank Return F��b
(CFS} (CFS) Perioc
0.433 4 2/09/O1 15:00 0.887 1 100 .00 � . 990
0.255 7 1/05/02 16:00 0.480 2 25 .00 0. 96C
0.480 2 2/27/03 7:00 0.445 3 10 . 00 0.90C
0 .170 8 8/26/04 2 :00 0.433 4 5 .00 0.80C
0 .263 6 1/05/05 8:00 0.419 5 3 .00 0.66''
0 .445 3 1/18/06 16:00 0.263 6 2 .00 0.50C
0.419 5 11/24/06 3 :00 0.255 7 1.30 0.231
0. 887 1 1/09/08 6:00 0.170 8 1. 10 0.091
Computed Peaks 0 . %51 50 . 00 0 . 980
Flow Frequency Analysis
Time Series File:dev.tsf
Project Locaticn:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis- -
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
1.05 6 2/09/Ol 2 :00 2. 10 1 100 . 00 0 .990
0. 884 8 1/05/02 16:00 1.43 2 25 .00 0. 960
1.26 3 2/27/03 7 :00 1.26 3 10 .00 0. 900
0 . 984 7 8/26/04 2 :00 1. 18 4 5.00 0. 800
1.18 4 10/28/04 16:00 1. 12 5 3 .00 0. 667
1 .12 5 1/18/06 16:00 1. 05 6 2 . 00 0.500
1 .43 2 10/26/06 0:00 0 .984 7 1.30 0.231
� . 10 1 1/09/08 6:00 0 .884 8 1. 10 0 .091
Compu�ed Peaks 1. 88 50 . 00 0. °80
B. DETENTION ROUTING CALCULATION II
The detention routing calculation, a continuation of the hydrologic analysis, uses KCRTS '��
to size a stormwater control vault that mitigates the effects of the proposed development
(Honey Brooke III and Honey Brooke V). The combined detention/wet vault will be
desi�ned according to Level 2 Performance Criteria (KCSWDM pg. 1-33) per the King
County Flow Control Applications Map (attached). The follo�ving KCRTS printout
shows a vault 52' wide by 184' lon� and 5' deep (47,840c fl in conjunction with the
documented control structure will provide enough live storage (detention) to meet the
aforementioned requirements.
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Retention/Detention Facility
Tyne of Facility: Detention Vault
Facility Length: 184.00 ft
Facility Width: 52.00 ft
Facility Area: 9568 . sq. ft
Effective Storage Depth: 5 .00 ft
Stage 0 Elevation: 4a2 .80 ft
Storage Volume: 47840. cu. ft
Riser Head: 5.00 f�
Riser Diameter: 12 .00 inches
Number of orif�ces: 2
Full Head Pipe
Orifice � Height Diameter Discharge Diameter
(ft) iin) (CFS1 {in)
1 0.00 1.79 0. 194
2 2 .50 1.88 0. 151 4 .0
Top Notch Weir: None
Cutflow Rating Curve: None
Stage Elevation Storage Discharge Percolation
(ft) (ft) (cu. ft) ,ac-=t) (cfs} (cfs)
0.00 442 . 80 �. 0. 000 0.000 0.00
0.02 442 . 82 191. 0.004 0.012 0.00
0.04 442 .84 383 . 0.009 0.017 0.00
0. 06 442 .86 574. 0.013 0 .021 0.00
0.07 442 .87 670. 0.015 0 .024 0.00
0.09 442 .89 861. 0.020 0.027 0.00
0 .11 442 .91 1053. 0.024 0.029 0.00
0 .13 442 .93 1244. 0.029_. 0.031 0.00
0.15 442 .95 1435. 0.033` 0.034 0.00
0.25 443 .05 2392 . 0. 055 0.043 0.00
0 .35 443 .15 3349. 0 . 077 0.051 0.00
0 .45 443 .25 4306. 0 .099 0. 058 0.00
0 .55 443 .35 5262 . 0 . 121 0. 064 0.00
0.65 443 .45 6219. 0 . 143 0. 070 0.00
0.75 443 .55 7176. 0 . 165 0. 075 0.00
0.85 443 .65 8133 . 0 .187 0. 080 0 .00
0.95 443 .75 9090. 0.209 0. 085 0.00
1.05 443 . 85 10046. 0.231 0. 089 0 .00
1.15 443 .95 11003 . 0 .253 0. 093 0 .00
1.25 444 .05 11960. 0 .275 0 .097 0_00
1.35 444 .15 12917. 0 .297 0 .101 0.00
1.45 444 .25 13874. 0 .318 0 .105 0.00
1.55 444 .35 14830. 0 .340 D.108 0.00
1.65 444 .45 15787. 0 .362 0. 112 0.00
1.75 444 .55 16744. 0 .384 0.115 0 . 00
1. 85 444 .65 17701. 0.406 0. 118 0.00
' 1. 95 444 .75 18658. 0.428 0. 121 0. 00
2. �5 444 .85 19614. 0.450 0.124 O. Ou
2 .15 444 . 95 20571. 0.472 0.127 0 . 00
2 .25 445 .05 21528. 0 .�94 0. 130 0. 00
2 .35 445 . 15 22485_ 0 . 5'_0' 0 . 133 C . GO
�. .45 �4� . =5 234?� . 0 . 533 0 . =36 C . GO
2 .50 445 .30 23920. 0 .549 0 . 137 0 .00
2 .52 445 .32 24111. 0 .554 0 . 139 0.00
2 .54 445 .34 24303 . 0 .558 0 . 141 0.00
2 .56 445 .36 24494. 0 .562 0. 145 0.00
2 .58 445 .38 24685. 0 .567 0. 151 0.00
2 . 60 445 .40 24877 . 0 .571 0. 158 0 .00
2 . 62 445 .42 25068. 0 .575 0. 166 0 .00
2 .64 445 .44 25260. 0 .580 0 .175 0 .00
2 .66 445 .46 25451. 0.584 0 .179 0.00
2 .76 445.56 26408 . 0.606 0 .193 0.00
2 .86 445.66 27364 . 0.628 0.204 0.00
2 .96 445.76 28321. 0.650 0.214 0.00
3 .06 445.86 29278. 0. 672 0.223 0.00
3 .16 445 .96 30235 . 0.694 0.232 0.00
3 .26 446 .06 31192. 0.716 0.240 0.00
3 .36 446 .16 32148. 0.738 0.247 0.00
3 .46 446 .26 33105. 0.760 0.255 0.00
3 .56 446.36 34062 . 0 .782 0.262 0.00
3 .66 446.46 35019. 0 .804 0.269 0 .00
3 .76 446.56 35976. 0 .826 0.275 0 . 00
3 _86 446. 66 36932 . O .Sa8 0 .282 0 . 00
3 . 96 446. 76 37889. 0.870 0 .288 0. 00
4.06 446. 86 38846. 0.892 0 .294 0. 00
4. 16 446. 96 39803 . 0.914 0.300 0.00
4 .26 447. 06 40760. 0.936 0.306 0.00
4 .36 447 .16 41716. 0.958 0.311 0.00 j
4 .46 447 .26 42673 . 0. 980 0.317 0.00
4 .56 447 .36 43630. 1.002 0.322 0.00
4.66 447 .46 44587. 1.024 0.328 0.00
4.76 447 .56 45544 . 1.046 0.333 0 .00 I
4.86 447 .66 46500. 1.068 0.338 0.00 '
4 .96 447 .76 47457. 1.089 0 .343 0 .00
5. 00 447 .80 47840. 1.098 0 .345 0. 00
5.10 447 .90 48797. 1.120 0 .658 0. 00 '
5.20 448.00 49754. 1.142 1.230 0. 00 ��
5.30 448. 10 50710. 1.164 1.960 0.00
5 .40 448.20 51667. 1.186 2 .760 0.00
5.50 448 .30 52624. 1.208 3 .040 0.00
5.60 448 .40 53581. 1.230 3 .300 0.00
� 5.70 448 .50 54538. 1.252 3 .540 0. 00
5 .80 448 .60 55494. 1.274 3 .770 0.00
5 .90 446 .70 56451. 1.296 3 . 970 0 .00
6.00 448 .80 57408. 1.318 4 .170 0 .00
6.10 448 .90 58365. 1.340 4 .360 0 .00
6.20 449.00 59322 . 1.362 4 .540 0. 00
6.30 449.10 60278. 1.384 4 .720 0.00
6.40 449.20 61235. 1.406 4.880 0.00
6.50 449.30 62192 . 1.428 5. 040 0.00
6.60 449.40 63149. 1.450 5.200 0.00
6.70 449.50 64106. 1.472 5 .350 0 .00
6.80 449.60 65062. 1.494 5 .500 0 .00
6. 90 449 .70 66019. 1.516 5 .640 0 .00
7. 00 449 .80 66976. 1.538 5 .780 0.00
• ' ' �i
3�.;d �nrloo: Cutfl��,r Fea� ��orage I
Target Calc Stage E_ev ;:Cu-Ftj i�c-rti '
1 2 .10 0 . 89 1.39 5.22 448 . 02 49958 . 1. 147
2 1.05 ******* 0 .�6 5 .04 447 . 84 a8205 . 1. 10?
3 1.06 ******* 0.32 4.48 447 .28 42896. 0 . 9fi5
4 1.12 ******* 0 .29 4.06 446 . 86 38856. 0 . 892 '
5 1.26 ******* 0 .27 3 .64 446 .44 34813 . 0 .799
6 0.67 ******* 0 .21 2 .90 445 . 70 27760. 0 .637
7 0.88 ******* 0 .13 2 . 15 444 . 95 20587. 0 .473
8 0.98 ******* 0.12 1. 86 444 . 66 17787. 0 .408
----------------------------
Route Time Series through Facility
Inflow Time Series File:dev.tsf
Outflow Time Series File:rdouc
Inflow/Ou�flow Analys�s
Peak Inflow Discharge: 2 .10 CFS at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge: 1.39 CFS at 10 :00 on Jan 9 in Year 8
Peak Rese?-voir Stage: 5.22 Ft
Peak Reservoir Elev: 448.02 Ft
Peak Reservoir Storage: 49958. Cu-Ft
. 1. 147 AC-Ft
Flow Duration from Time Series File:rdout.tsf
Cutoff Count Frequency CDF Exceedence_Probability
CFS °s % %
0. 007 41506 67.691 67.691 32 .309 0 .323E+00
0.020 3807 6.208 73 . 699 26.101 0 .261E+00
0. 033 3820 6.230 80.129 19.871 0.199E+00
0. 046 3592 5.858 85.987 14 .013 0.140E+00
0. 059 2794 4 .556 90.543 9.457 0.946E-01
�. 072 1958 3 .193 93 .736 6.264 0.626E-01
0.085 1362 2 .221 95 .957 4.043 0 .404E-01
0.098 909 1.482 97 .440 2 .560 0 .256E-01
0.111 602 0 .982 98.421 1.579 0 .158E-01
0. 124 434 0 .708 99.129 0.871 0 .871E-02
0. 137 239 0.390 99.519 0.481 0.481E-02
0. 150 21 0.034 99.553 0.447 0.447E-02
0 . 163 12 0.020 99.573 0.427 0 .427E-02
0 . 176 11 0.018 99.591 0 .409 0 .409E-02
0 . 189 32 0.052 99.643 0.357 0 .357E-02
0 .202 45 0 .073 99.716 0.284 0 .284E-02
0 .215 32 0 .052 99.768 0.232 0 .232E-02
0.228 17 0 .028 99.796 0 .204 0 .204E-02
0.241 21 0.034 99.830 0. 170 0 . 170E-02
0.254 20 0.033 99.863 0.137 0 . 137E-02
0 .268 19 0.031 99.894 0.106 0 . 106E-02
0 .281 20 0.033 99.927 0.073 0.734E-03
0 .294 13 0.021 99.948 0.052 0.522E-03
0 .307 9 0.015 99.962 0. 038 0.375E-03
0.320 10 0.016 99.979 0. 021 0 .212E-03
0.333 5 0.008 99.987 0.013 0 . 130E-03
0.346 6 0.010 95.997 0.003 0.326E-04
a.359 0 0.000 99.997 0.003 0 .326E-04
0.372 0 0.000 99.997 0.003 0.326E-04
0 .385 0 0.000 99.997 0.003 0.326E-04
0.398 0 0.000 99.997 0.003 0.326E-04
0.411 0 0:000 99.997 0.003 0.326E-04
0.424 0 0.000 99.997 0.003 0.326E-04
0.437 0 0.000 99.997 0.003 0.326E-04
0 .450 0 0.000 99.997 0.003 0.326E-04
0 .463 1 0. 002 99. 998 0 . 002 0 . 163E-0�
Duration Comparison Anaylsis
Base File: predev.tsf
New File: rdout.tsf
Cutoff Units: Discharge in CFS
-----Fraction of Time---- ---------Check of Tolerarce------
Cutoff Base New %Change Probability Base New %Change
0 . 132 ' 0.68E-02 0.58E-02 -13 .5 I 0.68E-02 0 .132 0. 129 -2 .4
0 . 159 ' 0.48E-02 0.43E-02 -9.5 I 0.48E-02 0 .159 0. 138 -13 .2
0 . 186 'i 0.33E-02 0.37E-02 10 .7 � 0.33E-02 0 .186 0.193 3 .7
0 .212 � 0.23E-02 0.24E-02 7 .2 I 0.23E-02 0.212 0.217 2 .1
0 .239 � 0. 15E-02 0.18E-02 22.2 I 0.15E-02 0.239 0.250 4 .4
0 .266 � 0. 11E-02 0. 11E-02 0 .0 I 0 .11E-02 0.266 0.266 0.0
0.293 � 0.80E-03 0 .54E-03 -32.7 � O.SOE-03 0 .293 0.279 -4 . 9
0.320 I 0.62E-03 0.21E-03 -65.8 I 0 .62E-03 0.320 0.289 -9. 7
0.347 I 0.39E-03 0.33E-04 -91.7 ; 0.39E-03 0.347 0.306 -11. 9
0.374 I 0.28E-03 0.33E-04 -88.2 ; 0.28E-03 0.374 0 .314 -16.0
0 .401 � 0.15E-03 0.33E-04 -77.8 ; 0.15E-03 0.401 0 .332 -17.2
0 .427 I 0.82E-04 0_33E-04 -60.0 � 0.82E-04 0.427 0 .341 -20.2
0 .454 I 0.33E-a4 0.16E-04 -50.0 � 0.33E-04 0.454 0.453 -0.2
Maximum positive excursion = 0.016 cfs ( 7.3%)
occuring at 0 .217 cfs on the Base Data:predev.tsf
and at 0.233 cfs on the New Data:rdout.tsf
Maximum negative excursion = 0.100 cfs (-22 .�°1
occuring at 0.444 cfs on the Base Data:predev.ts�
and at 0.344 cfs on the New Data:rdout.tsf
, . .
PROBABILITY EXCEEDENCE CURVE
CORE JOB NO. 03 044
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Probability Exceedence
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Conputin9 <iou llurations J ��
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SECT'ION�.� DEIE�ITION FACTLITIES
Riser Overfiow
The nomo�raph in Fi�ure�.3.4.H can be used to determine the head (in feet) above a riser of given
diameter and for a�ven flow(usuatly the 100-year peak flow for developed conditions).
FIG�JRE 5.3.4.H RISER INFLOW CURVFS
100 � � � I 72 54 48
�
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� 27 � �
; ; �
; � � I _ � ±
I � 24 �
� �z I �
21 �� � I
� I
� � I , I �
W I
� � � � $ � � I i
� I � i ; Z
a � � � i
� �� � i 15 W j }
.. �
i
p � i
7 �
Q 12 � �
10
I (
I
� �
I I I
Q�,, =2.k �
�y� ! ' ! I
i ' �
� s
I ' , i
� �
�
1 � � '' , � I i
0.1 �•S ��` 1 10
H EAD IN FEET (m easured from crest of riser)
QWQ1f=9.739 DHs�z
s �iz
Q,�;s1Ce=3.782 D H
Q in cfs, D and H in feet
Slope change occurs at weir-orifice transition
9/1/98 1998 Surface WaterDesi�n Manual
5-50
� � � .
C. WATER QUALITY VOLU:�TE CALCULATION
The water quality volumes for Honey Brooke—Phase III & Phase V were calculated '
using the King County Surface Water Design �ianual (KCSWDvi), 1998 Edition, pages
6-68 to 6-71.
Ub= ���.9Ai + �.ZSL�ig-� �.l�f��f- �.I�E�����1��
Where, Vb =wetpool volume (c fl
f= volume factor
A; = area of impervious surface (sf}
Atg= area of till soil covered with grass (s fl
An-= area of till soil covered with forest (s fl
Ao = area of outwash soil co�-ered with grass or forest
R=rainfall from mean annual storm (inches)
(refer to the attached precipitation�aph) ',
Thus,
Vb = 3[(0.9(167,663) + 0.25(58,632))(0.47I12)]
V"b= 19,453cf
Taking into account the detention/wet vault footprint as derived in Section N-B of this
report (52'x184'), the depth of storaQe needed to satisfy the requirements is shown below:
Depth of �!
Dead Storage= 19,453/(184*5�) =2.04ft ,
2.44ft (or?3,246c� of water quality storage was provided.
Core llesi�n. Inc Hone�� 13rool:c — Phase A� Y:���e S
♦ , , t 6.4.1 WE'IPONDS—BASIC r1ND LARGE—METNODS OF ANALYSIS ,
FIGti�6.4.i.A P4REC�ITATION FOR iVIEAN�'VNUA�.STORM IN IIVCHES (FEET)
sT i.a� r� i.a
ST 1 1 -._._._<,. ST 1 0 I,� 3.8 LA. 0.9 L"�,,.1�:��. ����,:.
�
- , �,� �,� .- q ..n.: ....r
� S } 1� ^ �J^ —
; r
. � . .
. , 5 m-,�.
, � _� ,�� ' —.1 }�*. .'
1 ' 1�
���+-���; 11 '� •�B ���
- � I� f. � � �~ �,:
��. ,.� _ .� , y ,, $
:J
' f �� � i ` � ' r—l
tE+ ;
� ..'�'--` � '', , \ �_�ti.. `,�
:`i i � .�:�.: ) � ^� A
2. 1 tY .� � `��' r'� D
F '� ,F-�"{— i �s � .�,,v`--�_-'
� .�� �y � ���!'"� �� �� r C
.�`
u:� 3 ::r �. _' : et -
K � , ' � ^ �
'�°"� �,� �� � f �— � ' �,
_ �� ; _�{ ; � ,�� �.��.-''�
T��, �;� f� �.; . � �
`", ' ,:� 1 � =r �„^�' �^ �i, ��
' �1 ,.�, � , .�,T. -� -, ',
i _ f '
Ia-�i � � I. .;:z _' ` _k�- _ / �:^ .t. '�
� s.� ��. n....� - � '� �i' ��... , �.` --� . \�
.� _.�� � � tV �� �s ` \\ � / �.. :
( _ � t^, �-.;: . E� __:.:.J' `� '
I�_ ^ � 9 q=.._. � \�' -
� a-",r-�-� ��F �d, � p ' .�. w ,�� ;' \
/ i
( - —_1;� � i �: r � �� �
� -11x ��_ F ''..��'�''— /, /r
;�4 .' � � Q \
.�. '� r ('� _ "� i n
� �� ���� `�.�� � L"
- , �}� �f'�.
� '-E-� .: ..i_ : Q . Q
': � � 1.J.°, , _
_ :, i. �..�_ �,
:� � r_ 9 \—
�=soo.a - ���_,
�" 'Q " P
- ��. � �� .+ ".^ \^ � �
,...__-" •—.r� .� ,� %���'��` /' ,_
0.54 r z' ��' .,o , 0.�_ _
n ;� 9' ��`�� ��; a
(0.045' ) ,,T� -
,.x._. .o�.,t ��,
0_4 7" o`•,
(0.039' } � . " ' -
� ��_-'_..�
_� ----i
-� Incorporated Area - ---� '�
I._c:� River/Lake 0.47" '' �� �-.
— MajorRoad (0.039') 0.52" '�� �" `"`��
�� 0.65" `
PIOTE:Areas east of the eastemmost isopluviai should use 0.65 ��•043'b.5 0'"
(0.054' )
inches unless rainraU data is availabte tor the location of interest (0.047' }
�The mean annual stocm is a concepwai stortn famd
by dividing the arvwal preapAation 6y the total rxxnber
ofstartneveMsperyear _ _.._ . _. _
result,generates large amounu of runoff. For this application,till soil types include Buckley and
bedrock soils,and alluvial and outwash soils that have a seasonally high water table or are underlain at
� a shatlow depth(less than 5 feet)by glacial till. U.S. Soil Conservation Service (SCS)hydrologic soil
groups that are classified as till soils include a few B,most C, and all D soils. See Chapter 3 for
classification of specific SCS soil rypes.
1998 Sur�ace VVater Design tifanual 9!1/98
6-69