FORT PIERRE, S.D. (KELO) — The modeling that Navigator used for estimating the area that could be affected by a rupture to its proposed carbon-dioxide pipeline was the industry standard, according to an outside consultant for the South Dakota Public Utilities Commission staff.

The testimony by Matthew Frazell (FRUH-zel) on Wednesday contradicted statements made last week by a University of St. Thomas professor, John Abraham, who spoke on behalf of landowners opposed to the project.

Navigator initially used PHAST and ALOHA modeling to estimate the distance and intensity of the CO2 plume that would happen if a leak or a break occurred in the line. Abraham said Navigator should have used computational fluid dynamics (CFD) modeling instead.

But Frazell disagreed on that point Wednesday. He told James Moore, the lead attorney representing Navigator, that he had “no concern” about the modeling that the company used and said the PHAST and ALOHA approaches were “industry best practices.”

Brian Jorde, one of the attorneys representing the opposition landowners, tried to get Frazell to express a different conclusion. Frazell agreed that ALOHA has shortcomings such as not adjusting for terrain or complex meteorology. Regarding PHAST, Frazell said, “It is not the highest degree, but it’s pretty good at what it does.” PHAST also assumes flat ground and some meteorological functions, he said, “but it’s not the most complex.”

Frazell agreed with Jorde that CFD has the ability to model more complex inputs “but would not be the best modeling choice” for Navigator to have used along the entire route. Frazell said PHAST or CFD produces generally the same results for a large area, while CFD works better in small ones. He said the industry “has really arrived at PHAST as a good approach.”

Navigator now plans to use CFD modeling at some spots along a 1,350-mile network that would collect CO2 from ethanol producers and other agricultural facilities in South Dakota, Iowa, Minnesota, Nebraska, and Illinois, and then dispose it at a site in central Illinois. The proposed line would serve three ethanol plants in South Dakota at Aurora, Chancellor and Hudson.

The project hasn’t yet received a green light from regulators in any of the five states. The South Dakota commission wrapped up the seventh day of its hearing Wednesday. The proceeding is scheduled to continue through Friday.

Frazell said he has been employed since May 2012 by Environmental Resources Management, based in Dallas, Texas. Before that, he worked for a different company as an embedded consultant on a CO2 pipeline network in Colorado and another in Texas, Mississippi and Georgia.

Commissioner Chris Nelson asked whether the PUC needs to have CFD modeling performed before deciding whether to grant a permit to Navigator. “No sir, I don’t think CFD modeling is a necessity”, Frazell answered.

Frazell said CFD’s “greatest value” would be estimating dispersal plumes in high-consequence areas along the route. Nelson asked whether Frazell would want to see those results if he was one of the potentially affected people in those areas. “I’d want to see the outputs at least, maybe not the entirety of the model,” Frazell said. “Definitely the outputs would be very useful.”

The commission has designated, at Navigator’s request, that the plume modeling be kept confidential, meaning only the company’s officials, the various lawyers in the proceeding, and some of the witnesses are allowed to see it.

Nelson asked Frazell whether any of the CO2 lines where he worked had leaks while he was there. Frazell said there were three minor “pinhole” leaks a millimeter or two big. “From afar you’ll see some fog,” he said, that would be hovering chest high. Inside 100 yards, he said, the ground would be frozen because water in the air had crystallized.

The leaks, which often result from corrosion inside the pipe, are fixed by cutting out the piece of line and welding in a replacement, he said, and if a leak shows up in one stretch, it’s likely there could be another.

Greg Rislov, one of the commission’s senior advisers, asked Frazell to speak more about the various modeling methods. “No tool is going to be perfect. We can’t replicate the natural world,” Frazell said, noting that CFD modeling involves assumptions, too.

“There’s a lot of detail that goes into CFD modeling. It’s super interesting. In this case, PHAST is adequate,” Frazell said.