
Commonwealth, Ashby, Glebe Flood Mitigation Project


Overview

The Commonwealth, Ashby, Glebe Flood Mitigation Project combined the top two large capacity projects will provide flood relief for the neighborhood near the intersections of Commonwealth Avenue and East Glebe Road, and Ashby Street and East Glebe Road. The proposed design includes new parallel relief sewers along Commonwealth Avenue and East Glebe Road, which will increase the capacity of the storm sewer system. Additionally, a new outfall will be installed to discharge flows to Four Mile Run. Finally, green infrastructure practices will be implemented to provide a water quality benefit to the watershed.
• Status: In design
• Total Estimated Cost: $50,000,000
• Funding Source: Stormwater Utility, Community Flood Preparedness Fund (CFPF) grant
Background
The City of Alexandria has experienced repeated and increasingly frequent flooding caused by climate change-induced storms near the intersections of Commonwealth Avenue near East Glebe Road, and East Glebe Road near Ashby Street. These increased flooding occurrences corroborate findings from the City of Alexandria’s Storm Sewer Capacity Analysis (CASSCA, 2016), which shows storm sewer networks along Commonwealth Avenue and East Glebe Road within the project area do not have adequate capacity to convey runoff from the intense storm events experienced in recent years. This increased flooding is attributed to old infrastructure, design criteria at the time of construction and climate change.
Project stages
Planning
A project planning task was developed and awarded to the consulting firm Jacobs in early 2022. Planning tasks are the basis for the design stage of work and is conducted concurrently with the procurement of the design phase contractor.
Planning tasks:
• Data collection
• Modeling of existing conditions in the sewershed
• Development of high-performing alternatives to alleviate flooding
The City and the consultant identified a preferred alternative, which acts as the basis for the design stage of work. This work was performed concurrently with the procurement of the design phase contractor.
Design
The design phase contract was advertised in early 2022 and awarded to Jacobs as the prime contractor in late 2022. Jacobs will lead a multi-discipline team for the duration of the design phase. The project will be developed in close collaboration with City staff and the community. After completion of the design, the project will be advertised for construction.
Design tasks:
• Detailed site survey
• Storm sewer modeling
• Development of construction drawings
Construction
Construction is expected to start in 2026 and end by 2027.
On-Site: Photos from the project site
A visual look at progress on the Commonwealth, Ashby, Glebe Flood Mitigation Project.












News and Public Announcements
Project notices
• Surveyors from RDA will be implementing traffic control, including mobile lane closures, along Glebe Road from Commonwealth Avenue to past Montrose Avenue on Feb. 1. Drivers should heed flaggers and stop as directed. The process is expected to take eight hours.
• Nov. 15: Staff from the City and Jacobs conduct a site walk along Commonwealth Avenue, Ashby Street and Glebe Road.
Community meetings
- Public kick-off meeting, Feb. 21, 2023
Contacts
For the community:
Jonathan Whiteleather, P.E.
Technical Project Manager
703.399.9392
jonathan.whiteleather@alexandriava.gov
For the media:
Camila Olivares
Senior Communications Officer, Department of Transportation & Environmental Services
703.541.9594
camila.olivares@alexandriava.gov