Gusting winds caused a pair of mishaps Tuesday in the Black Hills.

A large gust knocked over a partially constructed roof at what will eventually be a Rapid Valley car wash mid-afternoon, and a stiff breeze Tuesday morning knocked over a semitrailer transporting chemicals.

National Weather Service meteorologist Megan Holm said gusts of up to 51 miles per hour occurred in Rapid City and that a wind advisory was issued for Pennington and surrounding counties from noon Tuesday until 3 a.m. Wednesday.

Capt. Dan Goodart of the Rapid City fire department said the semi accident occurred in an area that is typically very windy.

The southbound semitrailer tipped over onto the S.D. Highway 79 median because of winds gusting through the canyon west of Buffalo Gap.

Goodart said the area has seen its share of accidents.

"The wind caught the trailer and dumped him on his side," he said.

The driver was not hurt, and the truck stayed more or less intact, according to Goodart.

The accident occurred about 10 a.m., and the Rapid City fire department's Hazardous Materials team was working at the scene for much of the day, Goodart said. The Custer County Sheriff's Department, Custer County emergency manager and South Dakota Highway Patrol were also on the scene.

Goodart said between five and 10 gallons of the anti-corrosion chemical sodium tolyltriazole spilled onto the ground before the truck and trailer were set upright in the afternoon.

Northbound and southbound traffic on the four-lane divided highway was stopped for a period of time, and some traffic was re-routed through Buffalo Gap because of the accident.

The South Dakota Department of Environment and Natural Resources will likely send someone to check up on the spilled chemical, Goodart said, although he said the product didn't seem to be highly toxic.

The hazmat team sprinkled some neutralizer on the product to bring down the pH level, Goodart said. Workers were done on scene at about 5 p.m., he said.

Nalco Company out of Pennsylvania was transporting the chemical.

The incident at the construction site of the Zaug Wash in Rapid Valley, which is being opened by Doug Zaug, occurred while crew members of Whalen Construction were on lunch break.

Whalen Construction owner Greg Whalen said the crew had partially braced the roof trusses and then went on lunch break, planning to finish up the work when they came back.

The crew was surprised upon returning to the scene to find that a gust of wind had collapsed the roof trusses like a deck of cards - especially because the wind hadn't been high when they left.

"There was nothing more than a breeze when we left," Whalen said.

Whalen said the crew will be able to make up the work in about half a day Friday, when the wind is expected to settle down.

Zaug called the incident a minor setback and said he still hopes to be done with the construction by the end of February.

"So far, we're kind of ahead of schedule. It's a little bit of a setback, obviously, but Whalen Construction has been doing a really good job as far as being on time and on schedule," he said.

Holm said high wind gusts occurred in several area towns, including gusts of 45 mph in Faith, 49 mph in Buffalo and 43 in Philip. She said high winds will persist in the Pennington County area until Friday.

Contact Ryan Woodard at 394-8412 or ryan.woodard@rapidcityjournal.com