Back-to-back weeklong trade conventions will descend upon the Ann Arbor area starting Aug. 1, bringing a combined 4,000 visitors to the community and generating an economic impact of $10 million.

“This is probably the most significant business we’ll bring in over the year,” said Mary Kerr of the Ann Arbor Convention & Visitors Bureau.

The visitors will fill about half of Washtenaw County’s 4,000 hotel rooms for two straight weeks, giving associated businesses - such as restaurants, caterers and car rental agencies- the chance to significantly boost their August revenue.

The first group is the National Training Institute for the National Joint Apprenticeship & Training Committee, which comes to the University of Michigan for the first time Aug. 1-7.

Next up is the 20th annual visit from the instructor training program of the national plumbing and pipefitting union, which will be conducting classes at Washtenaw Community College Aug. 8-14.

“Each group will have a tremendous economic impact on local businesses,” Kerr said.

Among them: Haab’s Restaurant in Ypsilanti, where co-owner Mike Kabat cultivated a relationship in the early years with the “UA” - United Association of Journeymen and Apprentices of the Plumbing and Pipefitting Industry.

Twenty years after they first came to town, Kabat said, some members of the UA have booked reservations at Haab’s for the second week of August all the way through 2015.

The business uptick is meaningful, Kabat said.

“It you take New Year’s Eve and the Ohio State/University of Michigan football game and Mother’s Day - and put them all together - that’s the plumbers (convention) and we do that seven days in a row,” he said.

But it’s the ongoing relationship that’s important for Kabat and his staff, he added.

“We’ve got guys coming in for 20 years now,” he said. “… It really is like family now with the UA.”

One reason they’ll stop at Haab’s is the annual swizzle stick giveaway. Kabat commissions a unique design annually from Woodbury Pewter in Connecticut, and he keeps it secret until just before the convention. Sticks from previous years are available for sale, either in-person or online. “They buy them as Christmas gifts,” Kabat said.

The NTI group, estimated at about 2,000, is expected to forge similar relationships in town, Kerr said. It’s a 20-year-old program of the National Joint Apprenticeship & Training Committee that is moving from the University of Tennessee to this area because of the facilities at U-M.

To prepare the local hospitality community for the conventions, CVB staff met with groups to discuss the weeks’ events, set up welcome banners and distribute welcome buttons. They booked blocks of hotel rooms and - working with the Mainstreet Area Association - set up free block parties downtown on Aug. 5 and 10 to provide evening activities.

Staff at the Holiday Inn on Plymouth Road will wear special NJATC T-shirts and welcome buttons, decorate the lobby with welcoming banners and offer specials at Guy Hollerin’s restaurant, which will open at 6 a.m. next week to be a breakfast option for the convention guests.

August is always busy, said manager Joe Sefcovic, thanks to the UA convention. But during a year when hotel occupancy is down 15 percent, attracting the second group “is an added shot in the arm to the hotels, restaurants and attractions in Ann Arbor.”

The NJATC will launch its program with a two-day electrical industry trade show. Even that was an opportunity for local businesses, said Tom Murray of Conor O’Neills in downtown Ann Arbor.

“We’re going to participate … we’ll put a table up there and put some samplings of food out and let them know what we’ve got going on,” he said.

The UA convention week typically represents a 20-percent increase in business, Murray estimated.

He’s hoping that his staff builds a similar rapport with the electrical training group.

And he’s expecting events like the downtown block parties to show the participants why Ann Arbor is a worthy convention destination.

“It’ll give them a feel for what Ann Arbor is like in the summer time,” Murray said.

Photo taken by Mark Bialek: Mike Kabat, owner of Haab's restaurant in Ypsilanti, shows off his collection of swizzle sticks. He is celebrating the 20th anniversary of the United Association of Journeymen and Apprentices of the Plumbing and Pipefitting Industry coming to town.