Question of the Day - 11 August 2023

We answered this question last year in June, though at that time, we found little to no information that addressed the issue and had to extrapolate.

We were relegated to speculation based on Boring's proposal to construct "Las Olas Loop," a transportation tunnel between downtown Ft. Lauderdale and the beach. That proposal was quickly accepted by a city whose water table at its deepest is around eight feet and can come as close to the surface as three feet. Plus, the highest land elevation is around six feet and the area floods frequently with or without storms (high tides, for example). In addition, a lot of the real estate is built on reclaimed wetlands, consisting of sand and karst (eroded limestone), which is porous and unstable (where sinkholes come from). 

We noted that Boring could and/or would construct a tunnel loop in the face of such environmental challenges by throwing a lot of money at it. That led us to assume that any company that believes it can build a flood-proof tunnel in southeastern Florida must have enough experience and success in waterproofing its tunnels in Las Vegas to pull it off successfully.  

Since then, however, more a few more details have emerged about Boring's flood-mitigation efforts for the Las Vegas Loop. 

Last year's monsoon was fairly ferocious, the wettest in more than a decade, with flooding all around the valley. That led the Review-Journal's transportation reporter, Mick Akers, to ask Steve Hill, CEO of the Las Vegas Convention and Visitors Authority, this same question.  

Hill told Akers that, first, the tunnels are being dug below the water table, which precludes, for the most part, seepage into them through the walls. Any that does infiltrate can be pumped out by the pumping system required by the county via the permitting process. 

Second, flooding from above, with flood waters entering the tunnels via the entrances and exits, has also been accounted for, simply by building them above the drainage level. Hill said, "There’s really no way for water to drain into the tunnels. That’s designed into the process,” another part of the permitting.

Of course, anything can happen, but also based on the tunnels remaining dry through a very wet monsoon in 2022, we conclude, again, that the tunnels are as flood-proof as Boring designers, engineers, and construction workers and county building inspectors can make them.