Don’t leave your backpacks open and don’t pick up tools without gloves. Leaving a bag open allows creatures to crawl inside while handling tools without gloves is an invitation to a poison oak rash.

These were among the tips a group of volunteers received Saturday as they prepared themselves to repair segments of Oat Hill Mine Trail in May. The training session took place at Skyline Park in Napa.

The event, scheduled for May 16, 17 and 18, could draw up to 200 volunteers to Calistoga for a weekend of work and fun under the auspices of the Napa County Park and Open Space District and Volunteers for Outdoor America. The Redwood City-based Volunteers for Outdoor America — or V.O.CAL, whose staff of three organize work parties throughout northern California, providing expertise on how to work with volunteers, logistics and tools.

The May work party along the 8.5-mile long historic trail in Calistoga will be the Open Space District’s biggest event since the agency was formed a year ago.

Napa County Open Space District General Manager John Woodbury said the district wants to install signage to make the trail safe to the public. Other tasks will include removing brush that encroaches the trail and erosion repair.

The work will not be done for aesthetics reasons, Woodbury said.

Chino Yip, the district’s stewardship coordinator stressed the trail will not be altered.

“We will not widen or smooth it out,” Yip said recently. “It’s not going to be easier to hike. It’ll just be safer,” he added.

Barry Christian, a volunteer from American Canyon who trained as a crew leader at Skyline Park Saturday, is helping Yip organize the May event’s logistics.

That includes hiking and riding the 8.5-mile long trail with Yip and V.O.CAL members to survey what needs to be done and how.

V.O.CAL staff members are training volunteers for future projects, he also said.

“I’m learning as I go,” Christian said. “I like the (V.O.CAL) model,” added Christian, who has organized work party days at the Jack and Bernice Newell Open Space Preserve, a 640-acre preserve east of American Canyon.

Another volunteer crew leader, Robin Peters of St. Helena, said she wants to give back to the community.

“I hike it at least 30 times a year and I love it,” she said, referring to the Oat Hill Mine Trail. “It’s something that means a lot to me.”

The trail project was first scheduled for last fall, organizers said. However, the event was delayed after a property owner filed suit against Napa County over the public use of the trail on his land. The dispute between Lantz Properties III LLC and Napa County remains in litigation in Napa County Superior Court, according to court papers.

The first half-mile segment of the trail that crosses the Lantz property will not be worked on, the organizers said.

Yip estimates about 80 people have signed up for the event so far. The volunteers, who will camp at Calistoga Mineral Water in Calistoga and walk to the trail, will be fed free of charge. Entertainment is also planned.

V.O.CAL founder Cathy Moyer, said her organization hopes to raise $50,000 with this project from in-kind and cash donations. The money will be used for future work projects, she said.

The event is free of charge but pre-registration is required. Youths under 16 years of age must attend with an adult.

What: Oat Hill Mine Trail work party

When: May 16, 17 and 18

Where: Oat Hill Mine in Calistoga

To sign up: 650-298-9774 or visit www.v-o-cal.org