Waterfront Flooding in Alexandria
The City of Alexandria’s historic district is located along the Potomac River just south of the Washington, DC metropolitan area’s Reagan National Airport. The state of Alexandria’s current waterfront infrastructure can be traced back to the location’s use as an early seaport. As the City developed into a major port for regional and international trade in the late 18th century, inhabitants expanded the shoreline to add valuable waterfront real estate by building on sunken ship hulls and other forms of fill. Over the years, this amended shoreline was further developed and is now home to parks and trails, arts facilities, restaurants, shops, and historic homes.
The origin of Alexandria’s contemporary shoreline and situation at sea level leaves valuable assets and public infrastructure highly prone to flooding from three different sources:
- Potomac River backflow or tidewater backing up into the sewer system
- River water overtopping the existing bulkhead
- Rainwater runoff inundating streets and sewers
About the Project
The City's first Waterfront flood mitigation concept – the "Waterfront Plan" (hereafter referred to as the "Schematic Landscape" design) – was developed in 2014. This high-level model reflected development principles established during the extensive Waterfront Small Area planning process. As the Schematic Landscape design progressed, engineering and cost analysis exercises yielded new insights that questioned the Schematic Landscape’s feasibility. These concerns, plus new funding constraints and regulatory changes, mandated a re-engineered approach to Waterfront flood mitigation design.
In 2020, the City announced the Schematic Landscape design was no longer feasible due to cost escalation; however, the principles identified through that project would serve as a starting point for developing an updated, resiliency- and cost-based design process. The City embarked on an intensive series of engineering exercises to develop an array of new concept models suggesting what the City could do to address waterfront flooding, given regulatory requirements and available funding. Finally, after incorporating ongoing input from the City's Waterfront Commission and a special Flood Mitigation Subcommittee, a new preferred design concept was selected. Read more about the Waterfront Flood Mitigation Project's history.
Current Design
Today, the Waterfront Flood Mitigation Project aims to:
- Reduce the frequency and severity of the three types of flooding
- Replace aging and failing shoreline infrastructure
- Improve public accessibility and public amenities
- Actualize the goals of the Waterfront Small Area Plan
To meet these goals, the City is developing new flood management infrastructure, park, and streetscape improvements for six locations along Alexandria’s Waterfront. While the design concepts draw heavily from the Schematic Landscape and Waterfront Small Area Plan, they have been updated to reflect several new important factors, including:
- New engineering options
- Cost inflation and budget constraints
- Flood mitigation and resiliency best practices
- Site condition assessments
- Regulatory requirements
Currently, two or more designs are being developed for each of the project areas, to include both a cost-based concept (scoping to budget) and a technically preferred concept (should additional funding be obtained). The cost-based concept meets the essential project requirements for flood mitigation and may be constructed within the current budget (according to current estimates). Technically preferred concepts feature infrastructure and landscape options that provide valuable additional benefits or efficiencies, but that cannot be constructed within the current budget. Nevertheless, the potential benefits offered by these concepts are great enough that the City is continuing to develop the designs in case additional funding becomes available through grants or future CIP funding cycles.
All project design elements will continue to evolve as other factors emerge during the project’s transition from conceptual design to constructed infrastructure. The current design for each project area can be found below:
Map Legend:
1. Point Lumley Park and Bulkhead
Current Design Concepts*
Park and Bulkhead Improvements
| Cost-based Concept | Technically Preferred Concept |
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Status:
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Features:
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* All designs are drafts, deliberative, and pre-decisional. A determination of budget feasibility is based on cost estimates. Affordability will be evaluated based on ongoing design development/engineering, cost estimation, and risk assessments.
2. Pump Station and Stormwater Conveyance
Current Design Concepts*
Stormwater Conveyance System
A network of new large stormwater pipes will be installed under portions of Union Street, Strand Street, Duke Street, Prince Street, King Street, Cameron Street, and Thompsons Alley, and will replace the existing undersized and aging sewer pipes. The new system will convey water from flood-prone areas along Alexandria's Waterfront to the new pump station, and then out into the Potomac River.
Waterfront Park-Strand Street Pump Station
Pump Station Features:
- Performance of two pump stations in one location
- Public restrooms
- Electric power for park programs
- Opportunity to provide other City event facilities
Pump Station Structure
The City determined that a single pump station will perform and provide the level of service necessary to satisfy the project objectives. The structure must comply with building codes, meet certain floodproofing, structural integrity, and maintenance access requirements to operate correctly, as well as reflect industry best practices for resiliency and redundancy for critical infrastructure.
The structural layout shown in the illustration above is not the final design. The pump station design is still highly conceptual. The final design will reflect input from Alexandria Board of Architectural Review. The project team will also continue to evolve the design to minimize park and visual impacts while integrating the facility and important program support services into the public space.
* All designs are drafts, deliberative, and pre-decisional.
3. King Street Park/Waterfront Park and Bulkhead
Current Design Concepts*
Park and Bulkhead Improvements
| Cost-based Concept | Technically Preferred Concept |
|---|---|
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Status:
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Features:
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* All designs are drafts, deliberative, and pre-decisional. The determination of budget feasibility is based on cost estimates. Affordability will be evaluated based on ongoing design development/engineering, cost estimation, and risk assessments.
4. King Street and Strand Street Pedestrian Area
Design Concept
Following the installation of the stormwater conveyance infrastructure, the City is updating the pedestrian zone on the recently pedestrianized 100 and unit blocks of King Street and Strand Street.
While the King Street and Strand Street pedestrian zone is being designed and constructed in conjunction with Waterfront flood mitigation infrastructure, separate funds were obtained to complete this work. For more information, visit the Lower King Street Pedestrianization Project webpage.
5. Chart House and Thompsons Alley Bulkhead
Current Chart House/Thompsons Alley Bulkhead Design Concepts
| Cost-based Concept | Technically Preferred Concept | Partial Promenade Concept |
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Status:
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Features:
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* All designs are drafts, deliberative, and pre-decisional. The determination of budget feasibility is based on cost estimates. Affordability will be evaluated based on ongoing design development/engineering, cost estimation, and risk assessments.
6. Founders Park Staging Area
Infrastructure is no longer planned for Founders Park; however, Founders Park will likely be used for project staging during construction. A tree protection area will be placed around the cluster of mature trees within the park known as the “grove.” The grounds will then be restored to pre-construction conditions once improvements and construction staging are complete.
Project Schedule
2019 – 2024 Timeline-To-Date
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| 2020 |
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| 2021 |
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| 2024 |
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2024 – 2027 Anticipated Timeline
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| 2026 |
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| 2028 |
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* Design completion date could be impacted by regulatory and grantor reviews.* Construction is anticipated to occur after City’s 275th Anniversary celebration. |
Capital Budget and Funding
The Waterfront Implementation Project budget is currently funded by the City’s Capital Infrastructure Program (CIP) funds. The City has applied for several state and federal grants, and will continue to evaluate additional alternative and external funding opportunities for the project which may help deliver more of the desired project elements:
Capital Infrastructure Program Funds (CIP Funds)
- Source: City of Alexandria
- Amount: $102 million (No additional funding is anticipated within 10-year CIP)
- Date Approved: May 2022
- Purpose: Design and construction
Virginia Community Flood Preparedness Fund Grant (DCR GRANt)
- Source: Virginia Department of Conservation and Recreation (DCR)
- Amount: $3.24 million
- Date Awarded: December 27, 2021
- Purpose: Flood mitigation and stormwater management design phase services up to 30% design. Not intended to cover costs of construction