are prevalent along the corridor and are operated by Capital Metropolitan Transit Authority (Cap .... Table 3-1. Identif
/CAB7 CAPACITY 1.00 SURCHARGED
Table 9 summarizes the results of the existing conditions analysis. The systems modeled in hydraulic software HEC-RAS (Systems 1, 7, 8, 9, 10, and 11) appear to be in compliance with the City drainage code, except System 11. System 11 is out of compliance due to the overtopping depth exceeding six inches above the crown of the road. System 11 can be brought into compliance by raising the road elevation by 0.62 ft. The systems modeled and analyzed as a storm drain with Autodesk SSA (Systems 2, 3, 4, 5, 12, 13, 14, and 15) appear to be out of compliance. Documentation of System 6 shows that the culvert meets compliance.
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Table 9. Summary of Existing Systems
Drainage System 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Do the major Is the water surface elevation at the bridge or drainage structure(s) Is the 25-year hydraulic grade culvert upstream face within the allowable 100line six inches or less below have capacity to year event overtopping depth of six inches the theoretical gutter flow line above the crown or any top of upstream curb convey the 25-yr elevation, whichever is lower? of the storm drain inlets? event? yes ---yes yes no ---yes no ---no no ---yes no ---yes ---yes yes ---yes yes ---yes yes ---yes yes ---yes yes ---no no no ---no no ---no no ----
Is the COA criteria met? yes no no no no yes yes yes yes yes no no no no
A copy of the existing conditions Autodesk SSA analysis output is found in Appendix D. Proposed Improvements The transportation configuration proposed for the East Riverside Corridor will require modification of existing major storm drain systems due to the roadway widening and the need to drain the train trackway. Existing inlets and lateral lines will likely be replaced. Assuming the proposed roadway drains outward toward the right of way line, the storm drain design includes the following: •
•
• • •
For segments with medians dividing the roadway and bicycle track, drainage inlets will be placed along those medians to simultaneously drain both. For roadway segments where the vehicle lanes and bicycle lanes are not separated, inlets will be placed at the curb. The roadway is super-elevated from approximately 1,000 ft east of the Willow Creek Dr. to 350 ft west of Wickersham Dr. This section of the road way is divided, requiring inlets along the north curbs of the both roadways. The proposed train trackway will require some type of drainage. Inlets will be placed between tracks for the purpose of this study. The inlets will drain toward the trunk line, which will run parallel with E. Riverside Dr. And, the trunk line will increase in pipe size as it reaches the system's major structure and outfalls along the north side of E. Riverside Dr.
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For systems whose major structures do not meet capacity and/or whose existing configuration would not be easy to tie into with the proposed lateral network, analysis to size the major structure included: • • • • • •
Calculating discharges using the rational method. Using the existing system's tailwater conditions for the 25-yr event. Maintaining the existing system's downstream invert elevation. Calculating an upstream invert elevation that provides three feet of cover. Contour data provided the existing ground elevation. Determining the pipe length based on the proposed roadway configuration. And, assuming the proposed structure was in the approximate location as the existing structure.
For systems whose major structures meet capacity and whose existing configuration would be easy to tie into with the proposed lateral configuration, the major structure was extended to the proposed roadway width. Summary of proposed modifications and replacement follow in the table below. Table 10. Summary of Existing Major Drainage Structures and Proposed Improvements Existing Conditions
Drainage System
Existing Major Structure
1
2-7’x 6’ culvert
Proposed Conditions
Evaluation Summary
Proposed Improvement
Meets code
---
30" rcp
Design capacity>peak flow tailwater controlled
Replace with 36" rcp, 138 ft long
3
42" rcp and 60" rcp
Design capacity>peak flow hgl exceeded for 42" rcp
Replace with 48" rcp, 178 ft long
4
54" rcp
Design capacitypeak flow hgl exceed for the 18" rcp
Replace with 42" rcp, 200 ft long
6
2-9'x5' culvert
2
Meets code
Extend 21 ft on the upstream side
7
2 bridge decks, 43 ft wide
Meets code
Widen south deck to 44 ft Widen north deck to 44.5 ft
8
2-8'x5' culvert
Meets code
Extend 60 ft
9
7'x5' culvert
Meets code
Extend 21 ft
10
4-5'x4' culvert
Meets code
Extend 24 ft
11
2-6'x6'
Culvert's curb/crown upstream is overtopped by 6" or more
Extend 36 ft
12
6'x3' culvert
Design capacity>peak flow
Replace with 6'x4' culvert, 287 ft long
13
2-8'x5' culvert
Design capacity
