The Maine Department of Environmental Protection is once again proposing a major rewrite of the state’s metallic mining regulations, reviving a controversial issue that failed twice in the Legislature during the past two years.

DEP officials said the proposed rules are needed to address inconsistencies between existing rules and statutes that could hamper the department’s ability to thoroughly review a mining permit application. The proposal will be presented Thursday to the Maine Board of Environmental Protection as a first step in what is likely to be a lengthy and potentially contentious debate over mining in Maine.

“If we get an application, we need to have something that is workable. And what we have now is not workable,” said Melanie Loyzim, deputy commissioner at the DEP.

Some critics of the department’s earlier mining rule-change proposals are already expressing concerns, however.

“I think it still has very big problems,” said Nick Bennett, staff scientist at the Natural Resources Council of Maine. “For example, it allows mines in floodplains and flood hazard areas. Why would anybody do that?”

This is merely the latest chapter in a four-year-long battle prompted by J.D. Irving Ltd.’s interest in mining under Bald Mountain in Aroostook County. Located about 35 miles west of Presque Isle, Bald Mountain is believed to contain significant deposits of gold, silver and other minerals. But the state’s restrictive environmental regulations have made commercial mining for minerals unfeasible in Maine, according to industry representatives and local supporters of the Aroostook County project.

In 2013-14, the Board of Environmental Protection spent months working on new rules proposed by the DEP and eventually sent an amended version to the Legislature for approval, as required. But lawmakers tossed out the board’s rules in 2014 and directed the DEP to return with a new proposal. Gov. Paul LePage then successfully vetoed that bill and in 2015 a detailed proposal crafted by members of the Legislature’s Environment and Natural Resources Committee failed to pass both chambers.

LePage has since seized on the defeat of the mining rules to accuse Maine’s environmental community – and particularly the Natural Resources Council of Maine – of killing economic development in struggling parts of the state. LePage repeatedly made comments at town hall-style forums against NRCM and in support of mining jobs in recent months before Bennett or several others involved in the mining debates over the past four years knew the DEP was preparing another version.

As with previous versions, the DEP’s latest proposal would create a multi-tiered permitting system depending on whether a company is merely exploring a site or actually mining for minerals. Applicants for “advanced exploration” or mining permits would need to submit plans for managing and processing wastes as well as fully fund a “financial assurance” account prior to a permit being issued to cover clean-up costs.

Additionally, the proposed rules would prohibit treatment of mine waste sites for more than 10 years after a mine is closed – language intended to prevent companies from “perpetual care” of sites.

“The proposed rule is based on the 2014 provisionally adopted rule but incorporates revisions to address a number of environmental, technical and legal concerns raised by legislators, board members and a large number of stakeholders during the prior rulemaking proceedings and the numerous legislative hearings and work sessions,” reads a staff memo filed with the Board of Environmental Protection.

Bennett and others say the changes do not go far enough, however.

For instance, he said the amount of “financial assurance” required would not cover a disaster. He also strongly criticized provisions allowing mine operators to cover mine waste with water in order to prevent a chemical reaction, known as acid mine drainage, that happens when minerals in the waste rock react with the air.

Bennett said mining companies should be required to use “dry management” of mine waste as it is being removed, especially considering that other provisions of the rules preventing treatment for longer than 10 years after a mine is closed.

“Once you put that stuff underwater, you’re not going to want to take it out because that’s why you put it underwater in the first place,” Bennett said.

Bennett and Lew Kingsbury, a Pittston resident who has been heavily involved in the mining debate, also interpret the propose rule’s language as potentially allowing mining on public reserved lands and other state-owned lands.

Kingsbury said it was “unconscionable” that the DEP could be leaving a door open to mining in public lands through a rule change. Kingsbury and others have argued that the Maine Constitution requires a two-thirds vote in the Legislature to allow mining or other “substantially altered” uses of public lands.

Loyzim said she hopes critics of the previous versions will work with the board, the DEP and the Legislature to improve the current rules as a way to better protect the environment.

“I understand that people oppose mining in general,” Loyzim said. “Meanwhile, there is a rule that allows for it . . . so if you can, help us to make it better.”