A cluster of recent hazardous material spills closing Chattanooga highways has left officials wondering about their causes.
The city saw two spills within two days in early August and two more Wednesday — though the second spill last week was caused by a crash and cleared quickly by firefighters after they saw the leaking substance was a household floor degreaser.
Hazardous spills are usually rare events in Chattanooga, Assistant Chief Terry Knowles, over special operations at the Chattanooga Fire Department, said. The city typically records a couple of large spills a year, if that, Knowles said, though the department did not have data on local spills readily available Friday.
"Nothing of this quantity, and this size, and this frequent in this amount of time," Knowles said by phone, adding that he believes the incidents to be isolated.
The department can't be sure why Chattanooga has seen such an uptick in hazardous spills, Knowles said. Responders have talked with investigators from the Tennessee Highway Patrol and U.S. Department of Transportation, Knowles said. Representatives for both agencies did not return requests for comment Friday.
There could be several explanations for the spills, Thomas Wasson, trucking expert with the Chattanooga-based logistics company FreightWaves, said.
One could be sheer volume, Wasson said.
The city sits along Freight Alley where more than 7,000 trucks travel each day, Shannon Millsaps, transportation and infrastructure director at Thrive Regional Partnership, said by phone. More than 80% of those trucks are passing through the Chattanooga area, not starting or ending here, according to data analyzed by the partnership.
But the trucks involved in recent spills look more like short-haul vehicles, without sleeper bays used on longer trips, Wasson said. That means they are likely traveling to or from local suppliers, or at least staying in the region, Wasson said.
Recent hazardous material spills in Chattanooga
— Aug. 2: FedEx truck carrying organic peroxide on Highway 153. Driver smelled fumes and saw smoke.
— Aug. 3: Averitt Express truck carrying organic peroxide and sodium hydroxide on McBrien Road near Interstate 24. Chemicals caught fire and forced evacuations.
— Wednesday, around 4 p.m.: FedEx truck carrying organic peroxide on I-24 eastbound near Germantown Road exit.
— Wednesday, around 8 p.m.: Napora truck carrying floor degreaser on I-24 westbound near Fourth Avenue exit. Van crashed into truck after coming up wrong way on exit ramp, causing spill.
Wasson also said he's heard anecdotally that some carriers are transitioning hazardous materials away from trains and onto trucks, particularly after a train carrying hazardous materials derailed in East Palestine, Ohio, earlier this year and caused a multiday chemical fire. Demand for shipped goods also rose in the past few years, Wasson said, generally putting more trucks on the road.
"Certainly the projections that we see based on that data, all the way out to 2040 and 2045, absolutely indicates an increase in truckborne freight," Millsaps said.
On a technical level, spills can be caused by driver error, the person loading the truck or other factors, Wasson said. Chattanooga's hilly landscape can also make things shift during transit, Wasson said.
The spills
On Aug. 2 and 3, separate truck spills temporarily shut down Highway 153 and Interstate 24, respectively.
The second of those caught fire in a parking lot off McBrien Road and I-24, prompting evacuations in the area and closing the lot for days as the spill was contained and cleaned. The Averitt Express truck had been driving from Averitt's Chattanooga service center to its center in Birmingham, Alabama, a company spokesperson said.
(READ MORE: Officials say chemical spill that caused fire near East Ridge will take days to clean)
The August incidents involved organic peroxide, and another spill involving the same chemical shut down eastbound I-24 for about four hours Wednesday.
All three organic peroxide spills were caused by holes in the totes carrying the chemical, according to the Fire Department.
The chemical heats up when exposed to air and can catch fire.
Two of the spills involved FedEx trucks. A spokesperson for the company declined to say where those trucks were going or coming from at the time of the spills.
"Safety is the utmost priority at FedEx, and the company is approved to carry shipments containing hazardous materials," spokesperson David Westrick said in an email. "We are cooperating with authorities and cannot further comment on matters involving our customers or their freight."
A fourth hazmat response farther west on I-24 extended the highway's shutdown Wednesday. Unlike the others, that incident was caused by a crash when a van came onto the highway the wrong way up the Fourth Avenue exit ramp.
"I think it's been an eye-opener for the public," Lindsey Rogers, spokesperson for the Chattanooga Fire Department, said by phone. "I don't think that the general public, number one, realizes that regular old FedEx truck rolling down the road could have so many different kinds of hazardous materials on board."
Contact Ellen Gerst at egerst@timesfreepress.com or 423-757-6319.