Wichita ? An engineer for utility company ONEOK testified he “arbitrarily” disregarded the weight of natural gas in the hole when he calculated the maximum operating pressure for an underground natural gas storage cavern near Hutchinson.

The testimony by chief gas transportation engineer Gary Macha came Tuesday in a lawsuit filed against ONEOK by two Hutchinson businesses whose buildings were destroyed during the 2001 gas explosions in that city.

Natural gas believed to come from the leaking storage cavern settled under the city, spawning geysers that spewed gas for months through long-abandoned salt mining wells.

The explosion and fire on Jan. 17, 2001, was one of a series of natural gas eruptions in Hutchinson, about seven miles from the storage field, that destroyed downtown businesses. Another explosion at a mobile home park the next day killed a couple whose survivors reached an out-of-court settlement with ONEOK.

Macha’s decision in May 1997 cleared the way for gas controllers in Tulsa, Okla., to operate the cavern at 680 pounds per square inch of gas pressure, Macha said.

That figure was 10 pounds of pressure more than what geologic engineer Joe Ratigan testified last week was the absolute maximum for the cavern.

Macha’s figure is also 15 pounds less than pressures recorded on Jan. 14, 2001, when Ratigan believes the leak developed in the cavern — sending as much as 163 million cubic feet of natural gas under Hutchinson.

“Our experience, my experience, had never included the weight of the gas, Macha said.

Macha testified he decided to not to include the weight of the gas in his calculations.

“Was that the thing for me to arbitrarily do? In hindsight, I wouldn’t do that again,” he said.

Macha’s testimony also came on a day when he talked about the company’s 1993 decision to forgo double-lined well casings in an effort to store more gas in caverns.

Mark Biberstein, an attorney for the plaintiffs, introduced a memo from consultant Dik Armer of Pratt that forecast future casing integrity problems.

The memo told state regulators that the double liners would be eliminated to use the caverns to their fullest capacity.

“Sometime in the future we will have an integrity problem in the original production casings,” Armer wrote, adding that would be the time to put the second liners in the wells.

Macha flatly denied allegations from Biberstein that ONEOK misled officials with the Kansas Department of Health and Environment about the source of small amounts of gas leaking in 1995 into groundwater around the storage field.

Testimony is expected to continue through next week.