The 9:45 a.m. accident didn't hurt anyone but it dumped part of the truck's load, spilling 160 gallons of fluid used in hydraulic fracturing, a Casper fire department spokesman said. The tipped semi and spill snarled traffic at the intersection of Poplar and First streets for nearly five hours as emergency crews cleaned up the spill and righted the truck and its load.

Casper Fire/EMS Public Information Officer Patrick McJunkin said the semitrailer was hauling nearly 4,000 gallons of a fluid known as CL-23 Crosslinker, a clear, colorless liquid produced by oilfield services company Halliburton and used in hydraulic fracturing to ease the flow of fracturing fluid underground. Dedicated Transport of Mills owns the vehicle, authorities said.

Two of the trailer's 12 tanks were punctured and one tank's lid busted off during the semitrailer's fall, McJunkin said. At least half of one tank had drained as a result, the liquid pooling within a makeshift dike local officials built with dirt in the middle of the road.

The acidic chemical posed a "light to mild" inhalation hazard but did not appear to be flammable, McJunkin said.

The driver was unhurt and already outside the overturned vehicle when first responders arrived shortly after 9:45 a.m., said McJunkin. The driver was attempting a left turn from First Street onto northbound Poplar Street when the vehicle tipped onto its right side.

Casper law enforcement directed traffic away from the intersection until mid-afternoon, when two tow trucks righted the vehicle and hauled it away about 2:15 p.m.

Local hazardous material officials used forklifts to move the trailer's contents onto a separate semitrailer for transport back to Dedicated Transport in Mills. Crews finished cleaning up the spill by about 4 p.m. and soon reopened the intersection.

City of Casper traffic sergeant Pete Abrams said on the scene that while the exact cause of the crash was still under investigation, speed and a shifting load were contributing factors. And while the accident likely would have happened without the wind blowing, Abrams said, the breeze certainly helped to tip over the trailer.

A steady 21 mph wind from the west with gusts to 31 mph was buffeting the Casper/Natrona County International Airport at about the time of the accident, according to the National Weather Service.

A man standing near the driver's side of the semitrailer who identified himself as the driver but refused to give his name said Thursday morning he had driven the Poplar Street route hundreds of times. He said he was taking the turn while traveling about 22 mph, and tipped over.

McJunkin said the driver likely climbed out of the driver's side door or window before emergency services arrived. Local officials looking for the semitrailer's paperwork broke the passenger side windshield.

No telephone number was listed for the company, and calls to what appeared to be an Ohio-based parent company with the same name weren't returned.