A morning crash that caused a pickup to flip onto its side and spill caustic chemicals in the Hatch Road area created Highway 99 traffic backups as far south as Turlock yesterday.

The California Highway Patrol received its first call about an overturned vehicle, which was southbound of the freeway but ended up in the northbound lanes, at 7:31 a.m. Authorities quickly learned that pool chemicals that included muriatic acid and chlorine, were spilled.

Traffic backups were so lengthy that many motorists did U-turns through the center medians in the Keyes area.

According to the CHP, the crash occurred when Pedro Reyes, 23, of Modesto, was driving a 2006 Nissan pickup for Vintage Pool Service southbound in the center lane just north of Hatch Road when he merged into the 2009 Kenworth tractor-trailer rig in the slow lane. Reyes lost control and drifted into the center median guardrail, causing the pickup to flip into the northbound lanes and land on its roof. The crash broke open and spilled containers of both the acid and chlorine.

Reyes was rushed to Doctors Medical Center with minor injuries.

The driver of the big-rig, Daniel Rocha, 65, of Tracy, was not injured.

Traffic was disrupted for five hours as hazardous materials crews suited up to clean up the spill. Caltrans helped set up a detour through Ceres around the wreckage and spill site.

The CHP does not believe alcohol or drugs were a factor. Authorities do not know why Reyes drifted into the larger truck.