By the end of next week, officials say, the massive Westside well known as Bellwood Quarry will be capable of holding billions of gallons of emergency drinking water.

How so? On Wednesday, City of Atlanta leaders announced that Driller Mike—a colossal, $11 million tunnel-boring machine fondly named after Atlanta rapper Killer Mike—had just finished chewing through five miles of earth to connect the reservoir with the Hemphill Water Treatment plant and the Chattahoochee River.

Next up, according to WABE, crews will coat the inside of the 400-foot-deep tunnel with concrete so water can flow through it.

After that, in comes 2.4 billion gallons of water, which will eventually serve not only as a 40-day water source in case of a drought or other catastrophe, but also as a glistening lake at the heart of what will one day be the city’s largest green space, the Westside Park at Bellwood Quarry.

Officials have said it will take between 30 and 90 days for the reservoir to fill with water redirected from the river.

Driller Mike’s dig through underground Atlanta—not to be confused with Underground Atlanta—was, at times, rocky, both figuratively and literally.

In August 2017, some residents living above or near the drill’s path complained that its adventure was a loud one.

It was so loud, in fact, that people living at a new Westside Heights apartment complex were breaking their leases to get away from the noise, which caused the building’s owner to sue the construction company working on the project.

But that $300 million part of the plan is now complete, and construction on the Westside Park is also underway.