Since the 1980s, island equestrians have transformed Paradise Ridge from a Cold War-era missile site into a haven for horse riders, and they are poised to make further changes this year.

Paradise Ridge has belonged to the Vashon Park District since the district’s earliest days. Since that time, island horse enthusiasts have created riding trails and other amenities there, including — most notably — the large covered arena built in 2010, for which equestrians raised the bulk of the funds for the nearly $500,000 project.

Last year the park saw the biggest change in recent years, when the district terminated the longtime caretaker position there, and the home that had belonged to Scott Provost and his family was removed, potentially opening up a large area of the park to the public. Now, equestrians are studying the park and trying to determine how best to remove a considerable amount of asphalt and concrete, left over from the park’s military days, and create an open, usable green space.

Last week, on a walk-through of the area, Donna Baxter and Hannah Knaebel, members of Vashon’s large horse community, discussed riders’ ideas and the thoughts behind the potential project, which they say has considerable support.

“The best choice for most people is green space,” Knaebel said. “Our goal is to benefit as many people as many days as possible.”

In December of last year, equestrians asked the park district to earmark $10,000 for work that might need to be done at Paradise Ridge because of the house removal. In January, Knaebel and Baxter said, park users broadened their outlook beyond the former caretaker site and began considering how they might best use the areas beyond it as well. Now, many in the horse community have agreed that getting rid of the large number of impervious surfaces would best serve the park and its users.

In that area of the park, the open spaces are broken up by areas of asphalt and concrete — former driveways, stairways and sidewalks — making them unusable for riders, as it is not safe for horses to cross the hard surfaces. Without those areas as impediments, a large, continuous green space would be opened for equestrians and others who want to use the park. Doing so would provide opportunities for equestrians who cannot use the park now, including several who drive carts, Knaebel said. Jumping areas would also be greatly increased.

The park is 43 acres, but more space would be welcomed, she added.

“It sounds huge,” she said, “but the usable area is steep and limited by trees and rocky terrain and is heavily wooded.”

The Vashon Maury Island Horse Association met last month about the issue and drew nearly 60 people, Knaebel said, a large number compared to what is typical. The group is slated to meet again tonight to help finalize the plans.

Both Knaebel and Baxter concede the difficulty of the project, as the surfaces are extremely thick and some were built to withstand tanks driving on them. Indeed, in one concrete area that measures 220 feet long and 30 feet wide, the concrete is 8 inches thick and is estimated to weigh 282 tons. In another place in the woods, a staircase that no longer leads anywhere has 18 concrete steps and each measures 4 feet by 5 feet. In another location — the former parking lot of the officers’ quarters — the concrete, reinforced with rebar, also weighs more than 200 tons.

Now the group is refining the project and its proposal, creating committees, nailing down costs to remove and dispose of the materials and looking ahead to fundraising. Currently, Knaebel said, she believes that the whole project will cost at most $30,000, and fundraising is expected to be necessary.

The group is also slated to present its proposal to the park district, hoping that commissioners will agree and allocate the $10,000, if not more, to the project. Knaebel will likely present the information, Baxter said, either later this month or early next.

“We hope the Vashon Park District will be committed to it,” she said, “but we’re determined to make it happen.”