GONZALES, La. (AP) — Officials at a Houston-based brine company said Friday it will be at least 40 days before they get definitive answers about an enormous sinkhole that opened up in Assumption Parish.

Mark Cartwright, president of United Brine Services, a subsidiary of Texas Brine Co., said the company spent the last week "intensely focused" on an emergency response as they try to figure out the cause behind a sinkhole near Bayou Corne.

Cartwright said they'll be drilling a relief well to investigate a brine cavern they own, which is housed within the Napoleonville salt dome. It will take at least 40 days to drill the well, and scientists have speculated that the 372-foot-wide and 422-foot-deep sinkhole might be related to structural problems within the cavern, he said.

"Our efforts are going to be more focused on diagnostics, and looking into what caused this event," Cartwright said at a press conference in Gonzales.

Commissioner of Conservation Jim Welsh ordered the company Thursday to drill a well and investigate the salt cavern and "further evaluate potential causes of the subsidence near its well site," as well as obtain samples of cavern content.

Cartwright said the company was just as shocked as anyone else when the sinkhole erupted last Friday, swallowing up an acre of bald cypress trees and leaving diesel fumes and slurry water in its wake.

The sinkhole sits on top of an underground mountain of salt and residents of Bayou Corne have been reporting tremors and gas bubbles for weeks. Despite a battery of diagnostic tests from federal, state and local officials, no one has been able to pinpoint the source of either occurrence.

When the sinkhole expanded Sunday, the owners of three natural gas pipelines at the edge of the liquefied area were asked to flare off and depressurize their pipelines as a precaution. Louisiana Highway 70 was temporarily closed and Gov. Bobby Jindal declared a state of emergency in Assumption Parish. At least 150 homes and several businesses were ordered to evacuate.

Cartwright said they never thought their salt cavern, which was plugged and abandoned in 2011 and isn't used to store natural gas, would be behind the gas bubbles and tremors. But seismic readings from the U.S. Geological Survey were able to narrow down the concentration of the earthquakes to the western edge of the dome, which is where the Texas Brine salt cavern lies.

Cartwright said the well was abandoned after the company unsuccessfully tried to work over the cavern for additional resources in 2010. That was when they noticed there might be a possible breach in the dome because the well failed a pressure test. The well was then taken out of service.

Vice President of Operations Bruce Martin said they disclosed all the issues they knew about the well to the state Department of Natural Resources.

"I don't think anyone was able to see this coming. In fact, our own experts predicted that if a cavern at this depth were to fail catastrophically, it would be extremely unlikely or improbable that it would manifest itself at the surface. So you can imagine our surprise when the sinkhole developed," Cartwright said.

It's still unclear if the salt dome has been breached. Cartwright says they believe the sinkhole won't have any more sudden changes, though it could still grow. He said once they discover the cause behind it, it will be turned into a lake.

However, Cartwright said there is still no conclusive evidence that the sinkhole was caused by their brine cavern. Residents who have been forced to evacuate have asked for compensation and assistance.

"We're discussing presently what we can do to support that community," Martin said, adding that he's discussing possibilities with his insurance provider.

Residents say they're not buying it.

Four people in Assumption Parish have filed a federal lawsuit against Texas Brine, saying the sinkhole and resulting contamination caused damage to plaintiffs who are in need of medical monitoring. The lawsuit also says the public was never warned of any dangers that might be a result of drilling in the salt dome.

All four plaintiffs were forced to evacuate their homes as a result of the sinkhole. The lawsuit says the sinkhole and resulting contamination violated the Clean Water Act and the sinkhole was caused by "willful misconduct and/or willful negligence."

Nick Romero, another resident of Bayou Corne, said he's sick of the misinformation he's being fed from the company and his state officials.

"It's time for the incompetence to go away and people to act responsibly. They're saying they are and it looks that way, but to me it's slow, it's really slow," Romero said.