The cause of a May 15 fire at the Suffolk landfill still hasn’t been determined, but members of the Southeastern Public Service Authority’s board had plenty of questions about it at Wednesday’s meeting.

“Naturally, an event like this raises a number of concerns,” said Pender & Coward attorney Dave Arnold, who represents Suffolk on the board.

The fire burned about five acres of grass and destroyed a well that pumps gas produced by the decaying trash out of the landfill. Nearly a dozen units from Suffolk Fire and Rescue, as well as vehicles operated by the Chuckatuck and Carrollton volunteer fire departments, responded to the fire, which was reported at 12:43 p.m.

The cause is undetermined, city spokeswoman Diana Klink said this week, adding that there was no sign the fire was intentionally set.

SPSA Executive Director Rowland Taylor said the fire happened on the back of Cells I and IV, which have been closed to trash dumping for some time. It was on the side of the mound of trash, about halfway up, Taylor said.

The windy day made for bad firefighting conditions, Taylor added.

“Suffolk Fire Department did an extremely good job, and they’re greatly appreciated,” Taylor said.

Taylor said the authority is concerned about the cause of the fire and is having its consultants monitor gas levels in the wells.

“We’re pretty confident at this point in stating there is no subsurface combustion,” said Scott Whitehurst, the landfill director. Subsurface combustion would indicate there is still fire within the mound of trash.

While the field monitoring hasn’t turned up any evidence that the trash is still burning, gas samples will be sent for laboratory analysis to get a better idea of the gas composition, Whitehurst said.

He said the well was so severely damaged that it was abandoned, meaning it was filled in with a special type of clay and topped with a temporary cap. Three other wellheads were damaged.

Whitehurst said it’s possible static on the pipes, made of HDPE, caused a spark and ignited the fire, although there’s no way to prove that. A fire several years ago near a well on the landfill is believed to have been caused by lightning, he said, and that’s the only previous similar fire at the landfill.

Arnold said he’s still concerned until the cause is identified.

“I realize that the situation was addressed aggressively, but until we know the cause, those concerns remain to some extent,” he said after the meeting. At the meeting, he raised the possibility of the fire having occurred at night and going undetected, but there is security on site that would have detected the fire.

A report on additional findings is expected at the June board meeting.

“Given that there are still unanswered questions, a supplemental report, as information becomes available, is warranted,” Arnold said.