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South 180th Street Grade Separation
Draft Technical Information Report
Submitted to
City of Tukwila
Public Works Department
Tukwila, Washington
Submitted by
BERGER/ABAM
' E N G I N E E R S I N C.
Job No. A99002 April 1999
DRAFT TECHNICAL INFORMATION REPORT
South 180th Street Grade Separation
Submitted to
I� City of Tukwila
Public Works Department
1 Tukwila, Washington
April 1999
Submitted by
BERGER/ABAM Engineers Inc.
33301 Ninth Avenue South, Suite 300
Federal Way,Washington 98003-2600
' Job No.A99002
DRAFT TECHNICAL INFORMATION REPORT
SOUTH 180TH STREET GRADE SEPARATION
TABLE OF CONTENTS
SECTION PAGE
1.0 Project Overview ............................................................................................................ 1
2.0 Preliminary Conditions Summary and Off-Site Analysis ..................................... 6
3.0 Flow Control and Water Quality Facility Analysis and Design .......................... 10
4.0 Conveyance Systems Analysis and Design ............................................................... 14
5.0 Special Reports and Studies ........................................................................................ 19
6.0 Basin and Community Plan Areas .............................................................................. 20
7.0 Other Permits .................................................................................................................. 21
8.0 Erosion/Sedimentation Control Design .................................................................... 22
9.0 Bond Quantities Worksheet, Retention/Detention Facility Summary Sheet
and Sketch, and Declaration of Covenant ................................................................ 23
10. Maintenance and Operations Manual ....................................................................... 24
i
1
Draft Technical Information Report
' South 180th Street Grade Separation ii April 1999
1� 1.0 PROJECT OVERVIEW
South 180th Street, an east-west principal arterial located in the Tukwila, Renton, and Kent areas of
the Green River Valley,will be reconstructed to provide a grade separation between vehicular traffic
and railroad tracks. The proposed roadway with five lanes,Class III bicycle route,curb and gutter,
and sidewalks will pass under the existing railroad tracks and Interurban Trail. The project location
and project limits are shown on the vicinity map in Figure 1.
A system of catch basins and closed lines is proposed to collect and convey runoff. The runoff
collected from the depressed roadway will be pumped to a new stormwater facility.
The project will add approximately 0.502 acre(21,867 square feet)of new impervious surface to the
site. Following is the summary of the surface areas of the project.
Existing Proposed Net (increase)
Impervious area(sidewalk) 0.368 acre 0.439 acre 0.071 acre
Impervious area(roadway) 2.017 acre 2.448 acre 0.431 acre
Total impervious area 2.385 acre 2.877 acre 0.502 acre
Pervious area 0.502 acre 0.0 acre
Total project area 2.887 acres 2.887 acres
Water quality and water quantity controls are required for this project.
Draft Technical Information Report
South 180th Street Grade Separation 1 April 1999
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Source:
Vicinity Map
BERGER/ABAM Engineers, Inc. 1999 South 180th Street Grade Separation Figure 1
King County Department artment of Development and Environmental Services
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Project Owner Project Name
City of Tukwiila Deot. of Public Works South 180"' Street Grade Seoaration
Address Location
6300 Southcenter Blvd, Suite 100 Township 23N
Tukwilla, WA 98118 Ranae 4E
Phone (206) 433-0179 Section 36
Project Engineer
Chris Walcott
Company
BERGER/ABAM Enaineers Inc.
Address/Phone 206 431-2300
Part 3 >TYPE°'OIF PERI�+IiT �,� .�.
< 5�
PPLiCATI£ 1+ ::NOW RM's" . <
Subdivison V DFW HPA Shoreline Management
Short Subdivision ,/COE 404 Rockery
vl Grading DOE Dam Safety Structural Vaults
Commercial FEMA Floodplain Other
Other JARPA COE Wetlands
Fart 5 SiTEC ( IA F I i JY:AN0,DRAI�l AQE WtN
x, € P. ,
Community
N/A
Drainage Basin
Sorinabrook Creek
9� 9,10
Yz
River Floodplain FEMA (see Fia. 2)
Stream Sr)rinabrook Creek. and Mill Creek Wetlands See Wetlands Study
Critical Stream Reach Seeps/Springs
Depress ions/Swales High Groundwater Table
Lake Groundwater Recharge
Steep Slopes Other
Draft Technical Information Report
South 180th Street Grade Separation 3 April 1999
Soil Type Slopes Erosion Potential Erosive Velcoties
Woodinville Silt Loan 0—3% moderate
Puyallup Fine Sandy Loam 0—3% moderate
Urban Land 0—3% moderate
Additional Sheets Attached
0 ,. .,
REFERENCE LIMITATION/SITE CONSTRAINT
Ch. 4— Downstream Analysis
jAdditional Sheets Attached
.
MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION AFTER CONSTRUCTION
✓ Sedimentation Facilities Stabilize Exposed Surface
✓Stabilized Construction Entrance ✓ Remove and Restore Temporary ESC Facilities
v/ Perimeter Runoff Control ✓ Clean and Remove All Silt and Debris
Clearing and Grading Restrictions ✓ Ensure Operation of Permanent Facilities
Cover Practices Flag Limits of SAO and open space
Construction Sequence
preservation areas
Other . Other
Draft Technical Information Report
South 180th Street Grade Separation 4 April 1999
PURFGEiv
A' R SYTII
Grass Lined Tank Infiltration
Method of Analysis
Channel Vault Depression SBUH, RATIONAL
Pipe System Energy Dissapator Flow Dispersal Compensation/
Mitigation of
Open Channel Wetland Waiver Eliminated Site
Dry Pond
Stream Regional Storage
Wet Pond Detention
Brief Description of System Operation Catch basins and closed lines collect and convey runoff
to pump station. Runoff is lifted to oond for WQ and flow control
Facility Related Site Limitations
Reference Facility Limitation
Pam# # STRUCTURAL ANALYSIS Part t2 EASI~futl N'FSfTRAfT
tCast in Place Vault Drainage Easement
Retaining Wall Access Easement
Rockery>4' High Native Growth Protection Easement
Structural on Steep Slope Tract
Other Other
Part 13 SIGNATURE OF PROFESSIONAL ENGINEER
I or a civil engineer under my supervision have visited the site. Actual site conditions as observed
1 were incorporated into this worksheet and the attachments. To the best of my knowledge the
information provided here is accurate.
Signed/Date
Draft Technical Information Report
South 180th Street Grade Separation 5 April 1999
2.0 PRELI IINARY CONDITIONS SUMMARY AND OFF-SITE ANALYSIS
The existing drainage system consists of two separate closed pipe systems,one on either side of the
tracks. On the west side,the runoff collected along South 180th Street is conveyed to the system on
72nd Avenue South. East of the tracks, all runoff is collected and eventually discharged to
Springbrook Creek via a 36-inch outlet. There are no water quality or water quantity controls for
the roadway runoff.
The portion of the project adjacent to Springbrook Creek is in a FEMA floodplain. See Figure 2,
FEMA Floodplain.
The entire project lies within a watershed defined by the City of Kent as Springbrook, Mill, and
Garrison Creek Watershed. See Figure 3 for the watershed boundary. Springbrook Creek crosses
South 108th Street via a 12-foot by 19-foot elliptical metal culvert located about 500 feet east of the
tracks. The subbasins and drainage systems are described in more details in the following sections.
Schematics of existing and proposed subbasins boundary are shown on Figure 4.
Subbasin West
72nd Avenue South. (Station 51+00) to Railroad Tracks (Station 56+10)
Runoff from the roadway and few adjacent properties is collected along South 180th Street and
conveyed to a 12-inch trunk line on 72nd Avenue South. This system flows south to South 182nd
Street,then east under the railroad, and finally discharges to Mill Creek, a tributary to Springbrook
Creek.
Subbasin East
Railroad Tracks (Station 56+10) to End of Project(Station 66+70)
( Roadway runoff from this section is collected by a system of catch basins and conveyed to a deep
system of 36-inch RCP located on the north side of the road. The 36-inch RCP system also drains the
off-site areas adjacent to South 180th Street. Flow from the 36-inch RCP system discharges to
Springbrook Creek at a location about 30 feet north of South 180th Street.
Draft Technical Information Report
South 180th Street Grade Separation 6 April 1999
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Source: Springbrook Creek Watershed Boundary
Harza Northwest Inc. 1994 South 180th Street Grade Separation Figure 3
Existing Subbas i ns caa* c�
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= N
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® Contributing area
.—m.— Flow line
Source:
Subbasins
BERGERBAM Engineers,Inc.1999 Figure 4
South 18Oth Street Grade Separation
3.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN
Flow Control
The detention facility was designed to meet Level 1 Flow Control Standards as specified in the King
County Surface Water Design Manual(KCSWDM). The detention pond was sized to detain the
proposed peak discharge rates to the limit of the existing discharge rates for the two-year and ten-
year storms.
Hydrologic models for detention facility design were developed using the SBUH method with 24-hour
storm events, and Type la Hyetograph as implemented by the WaterWorks computer program.
Table 1 shows the peak flow rates for the existing and proposed condition of roadway in Subbasin
East and the required detention volume.
Table 1. Subbasin East Peak Flows
Existing Proposed Pond
Limits of drain area Station 56+10 to 62+70 Station 52+08 to 62+70
Pervious area 0.502 acre 0.000 acre
Impervious area 0.909 acre 1.877 acres
Two-year flow 0.44 cfs 0.83 cfs 0.43 cfs
Ten-year flow 0.71 cfs 1.23 cfs 0.70 cfs
Detention volume 3394 cf
Right-of-way required 0.5 acre
WaterWorks outputs are attached at the end of the section.
Water Quality
Roadway improvements will add 0.431 acre of roadway surface to the site. Water quality volume
was determined for an area equal to 0.431 acre in Subbasin East using the method listed in the
KCSWDM for basic wetpond. Computations for the required volume are attached at the end of this
section.
Combined Detention and Wetpond
The new pond was designed using the guidelines listed in the KCSWDM for combined detention and
wetpond with 3H:1V interior slopes, 2H:1V exterior slope, and 1 foot of freeboard. A permanent pool
of water at the bottom of the pond will provide water quality treatment while a live storage at the
upper level provides detention capacity. An emergency overflow was provided to discharge 100-year
flow for developed condition. An access ramp of 12 feet wide was provided to the wetpool cell at a
maximum grade of 15 percent.
Draft Technical Information Report
' South 180th Street Grade Separation 10 April 1999
t
SOUTH 180TH STREET GRADE SEPARATION
DETENTION VOLUME
(WaterWorks Outputs)
Drainage Area: Existing
Hyd Method: SBUH Hyd Loss Method: SCS CN Number
Peak Factor: 484.00 SCS Abs: 0.20
Storm Dur 24.00 hrs
Area CN TC
Pervious 0.5020 ac 79.00 0.11 hrs
Impervious 0.9090 ac 98.00 0.06 hrs
Total 1.4110 ac
Supporting Data:
Pervious CN Data:
79.00 0.5020 ac
Impervious CN Data:
98.00 0.9090 ac
Pervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Sheet 20.00 ft 2.00% 0.1500 3.42 min
Shallow 370.00 ft 2.00% 27.0000 1.61 min
Channel 200.00 ft 0.50% 42.0000 1.12 min
Channel 100.00 ft 2.00% 42.0000 0.28 min
Impervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Sheet 32.00 ft 2.00% 0.0110 0.62 min
Shallow 370.00 ft 2.00% 27.0000 1.61 min
Channel 200.00 ft 0.50% 42.0000 1.12 min
Channel 100.00 ft 2.00% 42.0000 0.28 min
TC of 3.63 min<5 min, program will use a tc of 5 min in computations.
Precipitation Flow Time Volume
2 yr 2.0 in 0.4392 cfs 7.83 hrs 6807.43 cf-0.1563 acft
' 10 yr 2.9 in 0.7075 cfs 7.83 hrs 10840.58 cf-0.2489 acft
Drainage Area: Proposed
Hyd Method: SBUH Hyd Loss Method: SCS CN Number
Peak Factor: 484.00 SCS Abs: 0.20
Storm Dur 24.00 hrs
Area CN TC
Pervious 0.0000 ac 0.00 0.00 hrs
Impervious 1.11770 ac 98.00 0.08 hrs
Total 1.8770 ac
Supporting Data:
Impervious CN Data:
' PAVED 98.00 1.8770 ac
Impervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Sheet 32.00 ft 2.00% 0.0110 0.62 min
Shallow 260.00 ft 5.00% 27.0000 0.72 min
Channel 180.00 ft 2.70% 42.0000 0.43 min
Channel 150.00 ft 0.50% 42.0000 0.84 min
TC of 2.61 min<5 min, program will use a tc of 5 min in computations.
Draft Technical Information Report
South 180th Street Grade Separation 11 April 1999
Precipitation Flow Time Volume
2 yr 2.0 in 0.8290 cfs 8.00 hrs 12088.10 cf-0.2775 acft
' 10-yr 2.9 in 1.2303 cfs 8.00 hrs 18182.18 cf-0.4174 acft
100 yr 4.0 in 1.7162 cfs 8.00 hrs 25651.81 cf-0.5889 acft
RLPCOMPUTE [POND-3] SUMMARY
2 yr Match Q: 0.44 cfs Peak Out Q: 0.43 cfs Peak Stg: 1.31 ft Active Vol: 2616.30 cf
10 yr Match Q: 0.71 cfs Peak Out Q: 0.70 cfs Peak Stg: 1.51 ft Active Vol: 3394.02 cf
DISCHARGE [D-003]
Lowest Orif Elev 0.5 ft Orifice dia. 5 in.
Distance to 2"d orif. 0.45 ft Orifice dia. 3.5 in
Overflow opening: 0.5 ft x 1.5 ft
ITS 1 y, N►�-s R14�VN�G(,<, rU IrU Vw
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Draft Technical Information Report
South 180th Street Grade Separation 12 April 1999
Project-S, I g n n-i CT. Sheet of
Job Number A qq on 2
BERGER/ABAM S„bjw u l A T�.eez)u A Lj T Y Designer
E N G I N E E R S I N c. iJ
DBte�f�q�1 _
RED' KCS WDM G,.4.1. 1
BASIC WET POND
kJETf00L VOLUME V6
V& = (MIA, -t 0.2S A+ t 0. 1 A t -t- 0.01 A, ) R
O. 4 3 I 4c,
1
= 19, 774 Sic
A = A = A = _
R _ p 47 //
Vj� = O,q 19, 774) x 0,47 = 6 6 2 CF
..
V6 _ VA
4COOI-L
V = 3x 6G .2- = F1, C19G GF
Draft Technical Information Report
South 180th Street Grade Separation 13 April 1999
4.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN
General
The proposed conveyance system was analyzed and designed in accordance with the current
guidelines listed in the KCSWDM. The Rational Method was used to compute peak discharges for
all pipelines and to determine pump capacity. Table 2 shows the precipitation coefficients and
calculated peak flows. Gutter flows and inlet spacing were determined by using the method listed in
the Washington State Department of Transportation(WSDOT)Hydraulics Manual. The Backwater
Analysis method was used to analyze the new system to verify adequate capacity. Computations are
attached at the end of this section.
Table 2. Precipitation Intensity Coefficients for Rational Method
Precipitation a b Flow
3.4 inches 2.66 0.65 4.626 cfs
4.0 inches 2.61 0.63 5.543 cfs
Source: King County Surface Water Design Manual
Runoff from South 180th Street will be collected by catch basins along the gutter on both sides of the
roadway. No modifications are proposed for the off-site lines.
Subbasin West
72nd Avenue South (Station 51+00) to Station 52+08
No modifications are proposed to the existing system west of 72nd Avenue South. The existing
roadway storm sewer system east of the intersection must be removed. New catch basins and 12-
inch pipe will collect and convey runoff from Station 52+08 to the west. This system will be tied to
the existing system on 72nd Avenue South.
Subbasin East
Station 52+08 to Springbrook Creek Culvert(Station 62+70)
Runoff will be collected by catch basins along the gutter on both sides of the roadway. The mainline
of 12-inch pipe will convey the flow to the underground pump station located approximately at
Station 58+15, under the sidewalk on the north side of the road. The station will have two pumps
that alternate pumping the runoff. This allows for even wear on both pumps and provides for a
backup pump during the maintenance or replacement of one pump. The runoff then will be pumped
to the new stormwater facility located 50 feet north of South 180th Street and east of the tracks for
water quality and water quantity control. Discharges from the new facility will be conveyed via 12-
inch pipe under the existing driveway to Springbrook Creek.
The existing system west of the culvert will be removed.
Springbrook Creek Culvert(Station 62+70) to End of Project(Station 66+70)
No major modifications are proposed to the existing system. New catch basins will be connected to
the existing system on both sides of South 180th Street.
Draft Technical Information Report
South 180th Street Grade Separation 14 April 1999
Prgect S 1 SC D T H �T sMW---L- of
.lob N=bw /4 R w O .2
BERGER/ABAM « PEAK El n 1^1 t ;g„�- M ,
Date
REFF—R,ENCi= KC,SWDM
RATIONJAL METHOD
i
T = L (60 kR L = 607
ka- 20
S = O, O,2,7
I = P L A = 1. 09 Q Z 5
Q = G r A L = O,c/o
T = 607 (6o x -ZO x O,o27) 3 .Og rnin .
LET- T = 6 , 3 ►��-�,.
FOR 25_yR
r o.65 _
t, .2,661(r-. 3� D, g0¢
I = 3, 4 X 0, ?04 = 2, 734
Q = o,q X z,734 X 1. 8g = 4. 6a6 CFS
FOR 100-YR
• O.6 3
I = 4 - 0 X OAII = 3 ,.276
Q = O,9 x 3,2 7C X I,8 8 = 5, 543 LFS
Draft Technical Information Report
South 180th Street Grade Separation 15 April 1999
Project Sheet d
Job Number
BERGER/ Subject�
ABAM RA►1LAAF Designer Nt D
E N G I N E E R
rrUrTP—P FLOI,-1 Date__ 2�I11 yq
R.EFf u •R� c.� � ws1>07 +fyD. M,4NUAC. S, 4, ) 5, 57
rnaac = 4 t O,5 CI1 � � = 9, 5
GI ae E T L, = O, 12'
v
p II TRAVE I.ED LA JE
}
d da /O
e ,
d xs. s 0.19 x s.s •
da c C. I.2 OK_
Draft Technical Information Report
South 180th Street Grade Separation 16 April 1999
180inlet.xl5
HIGHWAY DRAINAGE (English Units)
T= 5 Project Name: S. 180th St. Grade Separation
m= 6.89 Project Number: A99002
n= 0.539 S.R.: NA
C= 0.9 Designed By: MD
I = 2.89384 (25-yr 24-hour storm) Date: 2/11/99
GW= 1.67
Width= 38.5 (1/2 of roadway width+sidewalk) dmax= 0.19' (depth of flow at face of curb)
Zmax= 9.50' (from curb to 1/2 of lane)
Sta. Width Distance I Delta QlSum Q1 Sloe I SuperIG.W.1 d I Zd I V 1 Q bp 1
52+00.00 ---- ------- ---- ---- ---- ---- --- --- --- --- ---- ------------
54+60.00 38.5 260.00 0.598 0.598 0.0420 0.02 1.67 0.09 4.45 3.54 0.171 standard grate
56+40.00 38.5 180.00 0.414 0.585 0.0180 0.02 1.67 0.10 5.17 2.61 0.207 standard grate
57+07.00 38.5 67.00 0.154 0.361 0.0020 0.02 1.67 0.13 6.51 1.04 0.164 standard grate
57+27.57 38.5 20.57 0.047 0.211 0.0005 0.02 1.67 0.14 6.91 0.54 0.101 standard grate
62+70.00 ---- ------- ---- ---- ---- ---- --- --- ---
--- ---- ------------
59+80.00 38.5 290.00 0.668 0.668 0.0430 0.02 1.67 0.09 4.62 3.69 0.202 standard grate
58+15.00 38.5 165.00 0.380 0.581 0.0180 0.02 1.67 0.10 5.16 2.61 0.205 standard grate
57+48.00 38.5 67.00 0.154 0.359 0.0020 0.02 1.67 0.13 6.50 1.04 0.163 standard grate
57+27.57 38.5 20.43 0.047 0.210 0.0005 0.02 1.67 0.14 6.89 0.54 0.100 standard grate
Reference: WSDOT Hydraulics Manual 5.4, 5.5
Draft Technical Information Report
' South 180th Street Grade Separation 17 April 1999
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x Backwater Calculation 25-yr 244vs Stan„ -
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p _12 10 1.987 1.987 0.000 12.00 20.00 0.005 O.OE2 0.5 0.01 0-00 8.30 _8.40 0.79 2.50 0.10 0.59 0.79 7.095 0.051 7.15 0.05 0.10 7.29 7.27 0.092 0.00 0.00b,20 &92 1.72
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5.0 SPECIAL REPORTS AND STUDIES
Because there are no new roadway developments proposed within the floodplain, a flood hazard
study is not needed for this project. However,the project will impact the wetlands located within the
project site thus impacting their flood storage capacity. The impacts to these wetlands will be
analyzed in the following sections. See South 180th Street Grade Separation Wetlands Study,
(BERGER/ABAM Engineers Inc., 1999)for detailed descriptions of the wetlands.
The project proposes to fill part of the wetlands located between the existing tracks to construct the
shooflies for the railroad tracks. Approximately 1.09 acres of Wetland B,which is located north of
South 180th Street,will be filled. Assuming that the displaced volume of 170,000 cubic feet of water
in this impacted area is added to the remaining of 24.5 acres of Wetland B and the connecting
wetlands,the water level would be raised by 1.9 inches. This small change in water elevation will
not create or aggravate any existing drainage problem in the Springbrook Creek floodplain.
Wetland C,which is located between the existing tracks and south of South 180th Street will be
completely filled. Because Wetland C is less than 0.1 acre in size,and its flood storage capacity is
low,impacts to downstream flooding is minimal.
A wetland mitigation plan was developed for the project to compensate for impacts on Wetland B and
Wetland C at a ratio of 1.5 to 1 (area created to area impacted). The impacted flood storage capacity
is thus compensated.
Other Studies
A geotechnical engineering report, studies of wetlands, streams, and wildlife were completed for this
project.
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Draft Technical Information Report
South 180th Street Grade Separation 19 April 1999
6.0 BASIN AND COMMUNITY PLAN AREAS
Not applicable for this project.
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Draft Technical Information Report
South 180th Street Grade Separation 20 April 1999
r7.0 OTHER PERNUTS
The required permits needed for this project are listed below.
Grading
DFW HPA
COE 404
JARPA
Draft Technical Information Report
South 180th Street Grade Separation 21 April 1999
8.0 EROSION/SEDIMENTATION CONTROL DESIGN
A Temporary Erosion and Sediment Control Plan will be submitted with the final construction plans
to the City of Tukwila for approval with the construction permit application. At a minimum,filter
fabric fences will be installed downslope of all construction areas and sediment traps will be used to
protect new and existing catch basins. Further measures will be considered when construction
methods and schedules are set.
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Draft Technical Information Report
South 180th Street Grade Separation 22 April 1999
f9.0 BOND QUANTITIES WORKSHEET,RETENTION/DETENTION FACILITY SUMMARY
SHEET AND DECLARATION OF COVENANT
Bond Quantities Worksheet
The stormwater facilities will be bonded per the requirements of the City of Tukwila.
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Draft Technical Information Report
South 180th Street Grade Separation 23 April 1999
10.0 MAINTENANCE AND OPERATIONS MANUAL
A Maintenance and Operations Manual will be prepared for the stormwater facilities as outlined the
KCSWDM.
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Draft Technical Information Report
' South 180th Street Grade Separation 24 April 1999
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