Atherton City Council
January 22, 2025

Atherton Channel Relining
City Council Study Session
January 22, 2025
Agenda
2 Channel Inspection and
Overview
Hydraulic model and flood
mapping
Conceptual design solutions
Considerations
Next Steps
Typical Channel Condition
3 Typical Channel Condition
4 Typical Channel Condition
5 Typical Channel Condition
6 Typical Channel Condition
7 Hydraulic Modeling
8 •USACE HEC-RAS Model
•Flowrates Based on 2001 Town
Wide Drainage Study
•Analyzed 100-yr, 25-yr and 10-yr
•1-ft Interval LiDAR Topographic
Mapping
•Included Bridges and Channel
Improvements
•Supplemental Field Topographic
Mapping to be Performed
Hydraulic Results
9 Conceptual Design
10 •Proposing In-Kind Repairs
▪ Concrete repairs of damaged shotcrete/secrete
•Alternative Repair Sections for Bank & Toe Scour
▪ Gabion Baskets, Rip Rap, & other Natural Measures
•Dependent on Environmental Permitting
Conceptual Design
11 Conceptual Design
12 Conceptual Design
13 Considerations
14 •Work Limits ▪ Existing Channel Easement ▪ Identify Construction Access/Easements
▪ Critical Repairs
•Potential Environmental
Constraints
•Permitting •Construction Cost
Next Steps
15 •Confirm Existing Channel Easement
•Perform Supplemental Field Topographic Mapping
•Finalize Limits of Proposed Repairs and Improvements
•Coordinate with Resource Agencies
•Continue with 30% Design, Cost Estimates & Coordination with Town Over Selected Repairs and Improvements
Questions?
City Council Study Session
January 22, 2025