After years of being kicked off hiking trails and public parkland, local mountain bikers will soon have a place to do wheelies off rocks, bunny hop over logs and leap over large boulders.

The Backcountry Bicycle Trails Club (BBTC) is building Seattle's first mountain-bike park on a 1.5-acre site under Interstate 5, off the Lakeview Boulevard exit.

The stunt park, which will include obstacle courses and rock- and log-strewn trails, will be one of the nation's few municipal mountain-bike parks, according to the International Mountain Bicycling Association.

Despite the increasing popularity of mountain biking, places to ride are scarce, said Justin Vander Pol, executive director of the BBTC.

"We are facing the same challenge skateboarders went through 15 years ago before the city put in skateboard parks," Vander Pol said. "This project is a big victory for mountain bikers."

The stunt park will be part of a project called I-5 Open Space, which will encompass nearly eight acres. The bike park will cover about a quarter of the area and the rest will be used for a off-leash dog area, a 200-foot stairway, a pedestrian and bike path, public art and 14 parking spaces. The park is expected to be open by October.

In the mountain-biking community, the stunt park has generated buzz because many bikers have complained that authorities are cracking down on riding on trails and parkland.

In recent weeks, the U.S. Forest Service has stepped up security to keep mountain bikers from damaging the habitat around the lower Garcia Road at Snoqualmie Pass, a popular training ground even though it is off-limits for mountain bikers.

The Shoreline School District tore down jumps and a billboard-size wall that bikers had built at the southeast corner of Shorecrest High School.

"Kids have been building jumps in the woods. There is proof of that all over the city," said Jack Tomkinson, executive director of Urban Sparks, a community group that advocates for more public recreational spaces. "That is why we are trying to make it legal and safe."

The Fremont-based group lobbied for the I-5 bike park and is pushing to get other bike parks built in Beacon Hill, West Seattle and South King County.

The BBTC will pay for the design and maintenance of the stunt park, city officials said.

The rest of the park project will cost $1.8 million and is funded by the Pro Parks levy that Seattle voters approved in 2000. Construction started Wednesday.

The bike club has raised $115,000 and will start construction in late April.

The club wants to raise an additional $100,000 to add lighting and to complete 10 trails so riders, from beginners to pro-level, can practice turns, jumps and balance. The club will use volunteers to haul in thousands of boulders and rocks to simulate back-country terrain.

The stunt park originated with Simon Lawton, 36, a mountain-bike coach who, after moving to Eastlake in 1997, spotted the I-5 location and urged the biking community to lobby for a stunt park.

THOMAS JAMES HURST / THE SEATTLE TIMES The mountain-bike park will be constructed under Interstate 5, off the Lakeview Boulevard exit. "This project is a big victory for mountain bikers," says Justin Vander Pol, executive director of The Backcountry Bicycle Trails Club.

The project has picked up momentum in the past two years. The minutes from four public meetings indicate it has had overwhelming support from the Eastlake neighborhood.

A few residents, though, worried that bikers will make the park unsafe for other users. But park officials said the off-leash dog area will be fenced and bikers won't ride faster than 3 to 5 mph with all the boulders and logs on the trails. BMX motorcycles and other motorized vehicles will be banned from the stunt park.

The bike park "is entirely separated from the other [park area]. That was the key to getting the city's approval," said Andy Sheffer, the city's lead project manager for the I-5 park.

Tan Vinh: 206-515-5656 or tvinh@seattletimes.com