Staff narrows waterfront flood mitigation to single pump‑station plan; Prince Street site is technically preferred but remains pre‑decisional

Alexandria staff on Jan. 28 recommended advancing a single‑pump‑station design and identified a Prince Street location as the "technically preferred" option for waterfront flood mitigation, but emphasized the recommendation remains pre‑decisional pending federal approvals and community feedback.

Division Chief Matt Landis, portfolio manager in the Capital Projects Division, outlined why the city must pair shoreline elevation improvements with a pump station: building a continuous shoreline protection (a bulkhead or raised promenade) without a pump would create a low‑lying "bathtub" that must be actively drained after storm events, he said (s:10897.735–s:10928.2295). "If we begin that operation and raise that shoreline elevation we create a bathtub that we have to find a way to drain," Landis said, explaining the technical need for pumping capacity and associated sewer upgrades.

Why it matters: Waterfront flooding in Alexandria happens from three sources—river overtopping, river backflow into sewer outfalls and intense stormwater events—and each requires different engineering responses. Staff said a single pump station tied to upgraded storm sewers will remove dependence on tide‑driven gravity outfalls and shorten post‑flood drainage time dramatically (staff estimated pumping could drain the protected area in under an hour once the water level falls below the bulkhead elevation) (s:11224.806–s:11274.315).

Alternatives considered and site selection: Staff studied five off‑park locations, private property acquisition options and a two‑pump approach. They found several off‑park options technically feasible but impracticable due to private property acquisition risks, higher construction impacts to South Union and Prince Street, utility conflicts and contaminated soils risks at Founders Park. A two‑pump plan would increase park impacts and operating complexity and was estimated to cost about $20 million more in capital expenses than a single‑pump approach. From the park locations, the Prince Street site was judged the least complex, least costly and the option that best preserved Strand Street views and healthy trees; Strand Street placement would be more concealed but interfere more with a pedestrianized Strand activation (s:11151.819–s:11224.025; s:11854.895–s:11941.814).

Scale, program and constraints: Staff said the concept station footprint has been reduced in recent design iterations and is now roughly 3,400–3,500 sq. ft. and about 24 feet tall (approx. 35 ft x 100 ft footprint in concept), down from an earlier ~5,000 sq. ft. concept; the reduction aims to minimize park impacts while meeting generator, fuel storage and mechanical/electrical space needs (s:13524.755–s:13564.681). Landis described flood‑sensitive versus floodable volumes in the building and noted the facility would include flood‑resilient utility rooms, generator space, and a submersible trash/debris collection area; staff also said restrooms and limited event power/storage could be folded into the program without materially increasing pump‑station size.

Permitting and process constraints: Landis stressed the plan is "pre‑decisional" while the city proceeds through NEPA and federal review because the site sits under a settlement deed involving the National Park Service that currently limits new structures on the parcel to 15 feet in height; staff said the NPS is collaborating and that a deed modification will be necessary. Army Corps permits and river‑bottom approvals are also required. Staff expects to begin construction in early 2027 with possible early work packages in late 2026, contingent on federal and local approvals (s:12366.57–s:12402.55; s:12486.109–s:12530.535).

Council reaction and requested follow‑up: Council members expressed concern about design aesthetics, visibility, tree preservation and construction impacts to adjacent businesses. Members asked staff to show energy‑efficiency and resilience tradeoffs for design options, to present cost ranges for park impacts and mitigation, and to expand community engagement that explains the NEPA/deed‑modification steps. Vice Mayor Bagley and other councilmembers emphasized the importance of visual design and the potential for integrated public amenities—restrooms, power for events and a stage—that could make the facility a civic asset rather than only an infrastructure element (s:12259.3–s:12295.329; s:14341.73–s:14382.824).

Next steps: Staff recommended continuing detailed design at the Prince Street preferred site while completing NEPA, coordinating the deed modification with NPS, proceeding to planning commission and BAR review, and preparing a detailed construction‑period mitigation and business‑outreach plan ahead of council decisions. Landis said staff will continue to refine footprints and architectural treatments and return to council with cost and sequencing information.