The Framingham Board of Health voted unanimously Monday night to modify General Chemical Corp.'s site assignment to hold the local hazardous waste plant legally responsible for properly cleaning up their facility as they prepare to fully close.

The New Jersey-based General Chemical Corp. filed a notice of closure for their 2-acre facility on Leland Street in Framingham on March 1, after years of complaints from Framingham residents and officials about potential health hazards in the vicinity, including the nearby Woodrow Wilson Elementary School.

Although the plant is not accepting any new hazardous waste material as of 30 days after it filed for closure, the site is still technically open, as General Chemical has not yet surrendered their operating license, Framingham Board of Health director Ethan Mascoop said.

"Once you say you’re closing, you can’t just lock the door and walk away," Mascoop said. "There’s a process you have to follow."

General Chemical officials could not be reached for comment.

As the plant prepares to close, Framingham officials will now require notification from the company for any changes made to the property, any emergency plans the company carries out, and all reports and correspondence submitted to the state Department of Environmental Protection, which oversees the plant closing.

The plant is required to submit a closure plan to the Board of Health by July 30, a post-closure plan by Sept. 30, and an independent quality assurance statement by Dec. 31. If the plant cannot meet these deadlines, they must notify the board seven days in advance.

"We’ve put deadlines for information we need to get from General Chemical," Mascoop said.

The modified site assignment also requires the plant to stop all activity if any strange odors or other nuisances are detected, or if town police, fire or elected officials determine the plant to be threatening the public's health.

Framingham will also hold General Chemical financially responsible not just for the cleanup, but for any fees the town accrues while dealing with any violations on the company's part.

The new site assignment also allows local health officials to be admitted to the property with 24-hour advance notice, a rule set in place after Framingham officials were denied access to the property in late June during a pilot cleanup test, said Mascoop.

"The Board of Health felt, and still feels, that we had every right to enter the property under the old site assignment, and General Chemical denied us access," Mascoop said. "That was very disturbing, and also, in my opinion, outrageous."

Mascoop said Board of Health access to the site proved crucial in evaluating the plant's safety or danger to the public.

"When we inspect restaurants, we don’t just call up the facility and say, 'Hey, tell us how you're doing,'" Mascoop said. "They might be the most honorable people in the world, but we still have to go out there."

If General Chemical fails to follow the guidelines set forth by the town, Framingham holds the right to prosecute the company in state Superior Court, as defined by Massachusetts law, Mascoop said.

"We really carefully drafted this document - it went through a lot of review, and everything here is important," Mascoop said. "We’re trying to really look at how to make sure the neighborhood is safe."

In previous years, the Framingham Board of Health inspected the plant and found barrels of chemicals improperly stored, contaminated water pumped outside from the basement, and potential structural problems with a laboratory floor, resulting in DEP-issued fines for almost $30,000 in June 2010.

Local residents have also complained about the facility’s impact on their lifestyle, from family homes being bought by the company to concerns regarding the health risks posed to children attending school adjacent to the plant.

An initial pilot test conducted by General Chemical and overseen by MassDEP in late June showed the level of air pollution did not exceed any health limits, giving the green light for a full-fledged cleanup starting later this month, department officials said previously.

The full clean-up of the site was scheduled to start July 28 and last through Aug. 15, said department spokesperson Joe Ferson.

However, Framingham health officials recently criticized MassDEP for their oversight of the pilot test, citing a lack of notification to non-English speaking residents about the test, and the absence of the MassDEP division directly overseeing the plant closure during the pilot test.

"There are all sorts of reason it was unacceptable that DEP was not there to question and look," Mascoop said, citing the plant's unique location to densely populated areas, schools, aqueducts and railroad tracks. "To rely on General Chemical consultants alone is not reasonable."