Jacksonville, FL · $100B (proposal)
JAX-10 · Jacksonville St. Johns River Surge Diverter
Four tunnel-boring machines carve a deep subterranean bypass beneath the St. Johns River, lined with concrete segments, feeding a massive underground retention vault — so that when storm surge pushes up the river, the excess water has somewhere to go besides downtown Jacksonville.
Pros
- The surface river stays untouched — no visual impact, no navigation interference during normal weather.
- TBM tunneling is a mature industry; the machines and methods exist today.
- Underground vaults avoid the land-acquisition fights of surface reservoirs.
Cons
- Four TBMs operating simultaneously under a major river is a recipe for water-table intrusion and collapse.
- Florida's limestone geology is Swiss cheese — tunneling through karst is notoriously unpredictable.
- A subterranean vault that fills with surge water must then be pumped dry — with what power, after a hurricane?
Feasibility: TBM technology is real — modern machines bore 15+ meter diameters routinely. But Florida karst geology has humbled every tunneling project attempted there; the "expandable waterproof epoxy" fix is hand-waving over a genuinely hard problem. Downgrade the ambition or pick a different geology.
Aerial mock-up: The river appears untouched; only heavily reinforced curvilinear intake vents far upstream, ringed by bio-filtration greenery, hint at the diverter below.
