HomeMy WebLinkAbout20240425 Memo (Grady Way Stm) 2200335.10 Page 1 of 1
TO: Huy Huynh
City of Renton Department of Engineering
Division
DATE: April 25, 2024
FROM: Yi Yang, PE
Seattle - (206) 267-2425
PROJECT NO.: AHBL #2200335.10
PROJECT NAME: Watershed Affordable Housing
Apartments
SUBJECT: South Grady Way Existing Storm Line Upgrade
In accordance with the directive from the City of Renton, the project proposes to upgrade the exiting storm pipes
on the southeast side of South Grady Way, from CB 135355 to CB 136908 (City of Renton GIS Facility ID
Number). The existing storm lines are 8” concrete pipes that connect to an 18” concrete pipe. The project will
replace the existing pipes with 12” ductile iron pipes. The new pipe will match the crown of existing pipe. Curb and
gutter will be reinstalled, and pavement will be restored for the utility trench.
The Project Engineer has conducted a conveyance analysis for the existing and proposed storm pipes. The
existing pipe has a capacity of discharging 1.19 cubic feet per second when it’s 90% full. The new pipe will be
able to discharge 3.79 cubic feet per second when it’s 90% full. See attached documents for a FlowMaster
Report.
It is determined the new pipes have adequate capacity and will not create any new problems to the downstream
drainage system.
YY
c: Taylor Galbraith, Sierra Construction Company, Inc.
Attachment
C:\Users\yyang\Desktop\20240425 Memo (Grady Way Stm) 2200335.10.docx
Ex. 8" Conc.
Project Description
Manning FormulaFriction Method
DischargeSolve For
Input Data
0.013Roughness Coefficient
ft/ft0.009Channel Slope
in7.2Normal Depth
in8.0Diameter
Results
cfs1.19Discharge
ft²0.3Flow Area
ft1.7Wetted Perimeter
in2.4Hydraulic Radius
ft0.40Top Width
in6.2Critical Depth
%90.0Percent Full
ft/ft0.011Critical Slope
ft/s3.59Velocity
ft0.20Velocity Head
ft0.80Specific Energy
0.696Froude Number
cfs1.20Maximum Discharge
cfs1.11Discharge Full
ft/ft0.010Slope Full
SubcriticalFlow Type
GVF Input Data
in0.0Downstream Depth
ft0.0Length
0Number Of Steps
GVF Output Data
in0.0Upstream Depth
N/AProfile Description
ft0.00Profile Headloss
%0.0Average End Depth Over Rise
%41.6Normal Depth Over Rise
ft/sInfinityDownstream Velocity
ft/sInfinityUpstream Velocity
in7.2Normal Depth
in6.2Critical Depth
ft/ft0.009Channel Slope
ft/ft0.011Critical Slope
Page 1 of 227 Siemon Company Drive Suite 200 W
Watertown, CT 06795 USA +1-203-755-1666
4/24/2024
FlowMaster
[10.03.00.03]
Bentley Systems, Inc. Haestad Methods Solution
CenterROW Conveyance.fm8
New 12" DI
Project Description
Manning FormulaFriction Method
DischargeSolve For
Input Data
0.012Roughness Coefficient
ft/ft0.009Channel Slope
in10.8Normal Depth
in12.0Diameter
Results
cfs3.79Discharge
ft²0.7Flow Area
ft2.5Wetted Perimeter
in3.6Hydraulic Radius
ft0.60Top Width
in9.9Critical Depth
%90.0Percent Full
ft/ft0.009Critical Slope
ft/s5.09Velocity
ft0.40Velocity Head
ft1.30Specific Energy
0.806Froude Number
cfs3.83Maximum Discharge
cfs3.56Discharge Full
ft/ft0.010Slope Full
SubcriticalFlow Type
GVF Input Data
in0.0Downstream Depth
ft0.0Length
0Number Of Steps
GVF Output Data
in0.0Upstream Depth
N/AProfile Description
ft0.00Profile Headloss
%0.0Average End Depth Over Rise
%60.0Normal Depth Over Rise
ft/sInfinityDownstream Velocity
ft/sInfinityUpstream Velocity
in10.8Normal Depth
in9.9Critical Depth
ft/ft0.009Channel Slope
ft/ft0.009Critical Slope
Page 2 of 227 Siemon Company Drive Suite 200 W
Watertown, CT 06795 USA +1-203-755-1666
4/24/2024
FlowMaster
[10.03.00.03]
Bentley Systems, Inc. Haestad Methods Solution
CenterROW Conveyance.fm8