SEARSPORT - After nearly two years of debate culminating in a string of sometimes-heated public hearings, the Planning Board is scheduled to begin deliberations next week on an application from Colorado-based DCP Midstream to build a liquefied petroleum gas (LPG, or propane) terminal at Mack Point.

The "tank," as the terminal is sometimes referred to after its largest feature a 22.7-million-gallon storage tank, has generated a mountain of testimony and technical data since it was first proposed in late 2010. It’s also been the subject of a half-dozen or more detailed studies by state and federal agencies, private consultants and a well-known counter-terrorism expert.

One of these studies, a 2012 Environmental Assessment by the Army Corps of Engineers, came under fire this week by two local groups that oppose the LPG terminal.

Islesboro Island Trust and Thanks But No Tank have filed a 60-day Notice of Intent to sue the Army Corps for violations of the National Environmental Policy Act and the Clean Water Act related to the agency’s May 2012 permit for the proposed propane terminal.

The groups want the Army Corps to withdraw the old permit and subject DCP Midstream’s proposal to a more extensive Environmental Impact Statement study. The major problem with the study behind the original permit, according to IIT and TBNT, is that it failed to consider the possibility that the Searsport terminal might be used for exports.

Concerns among residents of Searsport and neighboring towns about the development have included safety, adverse effects on property values and tourism, increased truck traffic on local roads and the implications of the specialized cargo ship traffic in Penobscot Bay.

One of the more puzzling questions surrounding the terminal proposal is where all that propane is going go.

DCP Midstream’s representatives have consistently said the facility would supply markets in New England and primarily Maine, but opponents are worried that the facility might reverse the flow and start exporting, a move they say would be consistent with today's markets.

“The reason that is being given just does not pass the straight face test,” said Steve Miller, executive director of IIT. “We've been in contact with people in the oil and gas industries who are scratching their heads. They say there’s nobody building import facilities, and in fact there’s a rush to convert existing import facilities for exporting.”

So why does it matter which way the propane flows?

The difference, according to Miller, is that the market for imported propane in the Northeast is naturally limited by geography, but if the flow were reversed for exports to markets in Europe or Asia, the volume could jump exponentially, meaning more trucks on the road and more ships in the bay.

“The major point is not whether they’re going to export, it’s that they could export,” he said. “The marketplace might compel them to consider exporting and to do that could be far more environmentally devastating than importing.”

Speaking on Friday, DCP Midstream spokeswoman Roz Elliott said company’s plans have not changed from the original application. She confirmed the basics: The facility is to be for import only, the propane would be distributed in Maine and New England, and there would be roughly 50 trucks per day in winter and fewer in the summer.

“We’re in this business for the long term,” she said. “We've seen shifts in the industry back and forth. We’re not looking at this in two year shifts … We’re confident in our business strategy and model. It’s intended to be an import [facility] and that’s what it is.”

Part of the idea of having a large terminal in Searsport, she said, is to have flexibility in the event of temporary constraints to supplies coming from Canada and the Midwest.

Elliott dismissed the research of opponents and called the latest action by IIT and TBNT “unfortunate” given the amount of work the Army Corps has already done — and in DCP’s view, done well.

“This feels like another desperate attempt by the opposition to stall things and that’s what they’ve been doing for two years,” she said.

The Planning Board is scheduled to begin deliberations on the DCP Midstream propane terminal application on March 27.

Ethan Andrews can be reached at news@penbaypilot.com