The Use of Tunnels in Minimizing Flood Water Damage

Here’s an idea for processing storm water runoff, i.e., precipitation from rain and snowmelt that flows over land without percolating into the ground.

There is no doubt that climate change is exacerbating the problems that our civilization faces with storm water.  Not only are flooding events from violent storms more frequent, but sea-level rise is pushing water that was formerly contained in our oceans and aquifers up onto land; this latter effect is called “sunny-day flooding.”

Through the millennia, civil engineers have found ways to collect this runoff and send it downstream into large waterways like rivers, lakes, and oceans.

This particular concept calls for boring enormous tunnels, 12 feet in diameter, far beneath the Earth’s surface, below all current infrastructure.  Current technologies enable tunnels to be built at a rate of one mile per month.  Given that the United States has 317 cites whose population is greater than 100K, does that seem like a workable approach?

Note the one-size-fits-all approach.  It doesn’t come in 2-foot, 4-foot, or 6-foot diameters, only 12 feet.  Does that make sense, given the incredible range of needs associated with different urban layouts and storm volumes?

Also, the concept isn’t designed to move the storm water towards larger waterways, but to store it in the tunnels, letting it slowly infiltrate into the underground surroundings.

From what I can see in the website linked above, I can’t estimate the cost per mile, but it must be astronomical.

Climate change is already necessitating that we adapt to flood waters, but it seems extremely unlikely that the concept here will play a meaningful role in these adaptation strategies.