LOUISVILLE. Ky.  - The largest construction project currently going on in Louisville is well under way and most residents likely haven’t even heard of it. It’s a tunnel, snaking four miles west from downtown and, when completed, it’s meant to keep crucial waterways clean.

Over a 24-hour period around 60 workers climb into a cage and are lowered by crane 200 feet down a dark shaft, finally reaching the horizontal tunnel. The travel is not done yet. Tracks for a locomotive have been laid to carry the hard-hat-clad men and women the ever-growing length of the cavern until they reach the end. This round-the-clock effort is expected to bring the project to completion by December 2020.

"Once you go below ground and you get over that, I guess, fear, if you will, of getting in a cage and being lowered 200 feet below ground; once you’re down there you really don’t notice much of a difference," said project manager Jacob Mathis. The tunnel, 20 feet in diameter, will be able to hold 55 million gallons of storm water and sewage safely below ground until the storm passes, keeping any from spilling over into the Ohio River or nearby Beargrass Creek.

"It will help improve the quality of water that we use on a daily basis for recreation," aded Mathis. "The Ohio River is a big asset to us; a lot of recreation with boating and other activities that take place, so we want to make sure that’s as clean as possible for the people who live here."

Aside from the cranes it’s out of sight and out of mind for the everyday Louisvillian, and that’s just how the sewer district wants it; with citizens calm and water collected.