About a mile from Midtown, there’s a 400 foot hole in the ground. Bellwood Quarry was mined for a century. Now the city’s transforming it into a reservoir, and the hundreds of acres around it will eventually be Atlanta’s biggest park.

It looks like some place in the Rocky Mountains. Bellwood Quarry has steep granite walls and crystal clear water. A road snakes down the side to the bottom.

Atlanta City Councilman Michael Julian Bond says he grew up near here. He remembers as a kid, the community was not happy with the quarry.

“You could hear them blasting. You could hear the trains,” he said. “The sound would just kind of travel.”

The granite from the quarry was used in Atlanta’s buildings and roads. The company that mined there stopped in 2007.

“The rock here is beautiful,” Bond said. “And the lake at the bottom, with its blue-green turquoise color, you couldn’t have painted a prettier picture, even on a day like today when it’s overcast and it’s raining.”

It is a great view, but it’s not one most people will ever see. Eventually the ledge where we’re standing will be underwater, explained Margaret Tanner, deputy commissioner of Atlanta’s Department of Watershed Management.

“It is just perfectly made for our uses and our needs for raw water,” she said. When it’s full, in seven or eight years, Bellwood Quarry will hold more than a billion gallons from the Chattahoochee River. It’ll serve as a backup supply for the city. “This will provide us more than 30 days of storage.”

Then there’s all the land around the reservoir, about 300 acres. Some of that will go to Watershed Management’s operations. The rest will be a park connected to the BeltLine; with hiking and biking trails, baseball fields, open meadows and an amphitheater.

“This park is so big by comparison to any of our other components, that it will be built in phases over the next 15 years,” BeltLine CEO Paul Morris said.

The park will be bigger than Piedmont and will cost nearly $38 million to develop.

Urban planner Alex Garvin was one of the early visionaries of the BeltLine and its parks. He first caught a glimpse of the quarry and the land around it from a helicopter.

“I looked at it, and it was in sneezing distance of Peachtree Street,” Garvin said.

Fixing up the quarry will have a big impact on the neighborhoods around it, he said.

“I think that when the Bellwood Quarry finally opens as a real park, there’s going to be an awful lot of housing construction around there,” Garvin said. “People will want to live around that park.”

That happened around the BeltLine on the east side of town, where Old Fourth Ward property values are shooting up.

Bellwood Quarry is near Hollowell Parkway, what used to be called Bankhead Highway. It’s lined with boarded up buildings and abandoned houses. City Councilwoman Felicia Moore, who represents the district, is excited about the potential.

“It seems to me that that project, particularly being so close to the transit, really has opportunity to be a catalyst for not only that part of Hollowell Parkway, but may spur some development up and down the corridor,” she said.

Gentrification is always a concern, Moore said, but there are ways to manage it by helping seniors keep up their homes, for instance. Moore emphasized that her priority is involving the community in park planning. “Particularly those that have lived there a long time that have suffered through all the blasting, all the gravel on the roads.”

But not everyone’s convinced that a nice park could really happen here.

“You have to make a believer out of me,” Rhonda Bettan said. She was waiting for a bus at the Bankhead MARTA station. She said she’d like to have bike and walking trails, but she doesn’t trust the city to maintain them on her side of town.

“You go to Marietta, you go to Conyers and different places,” Bettan said. “They have really nice parks that you enjoy.”

The plan for the park is that it would rival the parks Bettan likes to visit. But it’s still a ways off.

Michael Julian Bond has formed a City Council committee to discuss more planning for the park. It’s supposed to start meeting early this year.