ORRINGTON – Local people expressed frustration with the proposed cleanup of the former HoltraChem site Tuesday night, saying that the plan leaves too much mercury on-site.

“I’m a little disturbed that the report seems to be tending toward a ‘leave it all in place and pave it over’ option,” said Richard Judd, who lives less than a mile from the former chemical plant adjacent to the Penobscot River in Orrington.

Representatives from Camp, Dresser and McKee Inc., the firm hired by former plant owner Mallinckrodt Inc. to oversee the cleanup, explained their lengthy Corrective Measures Study Report to an audience of about 35 concerned residents and environmental and public health activists Tuesday night.

For just over 30 years, the site housed a chemical plant that left behind substantial mercury contamination in the soil, groundwater and river sediments, as well as less-extensive pollution from other chemicals.

Camp, Dresser and McKee have proposed spending at least five years to remediate the 235-acre site.

A clay barrier would be constructed underground to keep contaminated groundwater from reaching the river, then a water treatment facility would remove contaminants from the water before it was pumped into the river.

Once the barrier has been built, soil in more than 15 locations that is known to exceed the allowable mercury concentration would be excavated and consolidated.

The soil likely would be placed near where the cell building that contained elemental mercury – which is slated for demolition – is located. This site is expected to have the most-contaminated soils anywhere on the property.

However, tests have not been done, so CDM can’t be sure what will be found when the cell building is torn down.

Most of the mercury at the facility is not in its elemental form, which can easily be released into the air. Rather, it is bound to soil molecules, which makes it more stable.

If elemental mercury is found beneath the cell building, those soils will be treated and the elemental mercury moved off-site to a hazardous waste facility, said Michael Healy, a CDM engineer who wrote much of the plan.

The remaining mercury-contaminated soil that is consolidated on-site would be capped with the sort of materials used to top off a landfill, and left indefinitely, with the belief that the underground barrier and water treatment facility would prevent its contaminating either local groundwater or the Penobscot River, Healy explained.

“These systems are designed to last a lifetime,” he said.

But several area residents raised concerns that four of the facility’s existing landfills have been capped in a similar manner, and that the state Department of Environmental Protection has indicated that several of these landfills are, in fact, leaching contaminants.

“No water treatment system is perfect. It seems you ought to at least back that up with a liner,” said Nick Bennett, a staff scientist with the Natural Resources Council of Maine.

Healy replied that CDM believes that so long as the soil is piled above the water table and protected from rainfall, it would be just as safe as a fully sealed landfill.

Residents also questioned why CDM chose not to cap, excavate, or, in fact, take any action on an area containing chloropicrin, a toxic chemical remaining underground from a spill in the early 1980s.

Healy responded that chloropicrin eventually degrades in the environment, which mercury does not, making the chemical a lesser concern. He added that the contaminated area is within the region where groundwater will be contained and treated.

Healy’s answers did not satisfy the crowd, however.

Michael Belliveau of the Environmental Health Strategy Center in Bangor estimated, based on CDM data about contamination rates, that at least 12 tons of mercury, bound to soil, would remain on-site after the remediation, in addition to the 13 or more tons of mercury-contaminated sludge that is known to exist in the site’s five landfills.

Almost every speaker questioned CDM’s decision to leave the mercury on-site – a lower short-term risk of contaminating the air, but a much higher long-term risk for local residents.

Leaving the mercury on-site is also the cheapest option for the company, at somewhere around $20 million, as compared to $60 million or more for remediation methods with better potential in the long term, Belliveau said.

“The people here are the people who are going to have to live with this,” Bennett said. “They need a much more frank discussion of these risks … to understand what’s going to be affecting them and their families for a long time.”

The full plan is available at the Orrington town office and library, as well as on the DEP Web site. Written comments will be accepted until 5 p.m. Friday, Jan. 16. Send comments to Stacy Ladner, Project Manager, Maine Department of Environmental Protection, 17 State House Station, Augusta 04333, by fax to 287-7826, or by e-mail to Stacy.a.ladner@maine.gov