AYER -- Capped for 20 years now, the Army is continuing its work to remove arsenic in and around the area of the former Fort Devens Shepley's Hill Landfill. The 84-acre landfill dates back to the 1920s and was open for several decades but was finally capped in 1993.

The landfill is in the northeast corner of the former Fort Devens "Superfund" site, which directly abuts private land located off West Main and Shirley Streets and both the Plow Shop and Grove Ponds. High levels of arsenic -- in places found to be 400 times the acceptable level for drinking water -- were detected after the base closure, and testing has confirmed the existence of high levels of arsenic in the groundwater north of the landfill in an area where 65 to 70 Ayer homes are located.

The Ayer Board of Health held a public hearing to gather public comment and feedback on the Army's next steps for filing with the Environmental Protection Agency, which has jurisdiction over the cleanup.

The Army's October 2012 draft report, called an "Explanation of Significant Differences" is available on the town's website (www.ayer.ma.us). The draft report is also available in hard copy for review at Ayer library and DPW offices, as well as the town hall offices of the town clerk, selectmen and Board of Health.

Terrie Boguski, the town's EPA grant-funded technical assistant, explained that there's no perceived threat to public health and stressed that the town supplied drinking water is safe. However, Boguski said the town is "looking towards the future" to ensure that no one uses private wells for drinking water or to irrigate crops.

The semi-metal element is odorless and tasteless. Arsenic is naturally occurring but also used in industrially to make metal and glass products, electronics and to preserve wood.

Arsenic doesn't degrade into another substance, said Boguski. "There's no treatment that's going to turn it into something else. It will always be arsenic."

Arsenic is not on the land's surface but has been confirmed in high concentrations in groundwater around the landfill and in nearby Plow Shop Pond. Long-term concerns are also that Plow Shop Pond is linked to Grove Pond, one of Ayer's two drinking water aquifer protections zones (the other being on Spectacle Pond on the Ayer-Littleton line).

Exposure to arsenic can trigger a litany of illnesses, including gastrointestinal injury, paralysis, blindness and cancers of the bladder, lungs, skin, kidney, nasal passages, liver and prostate.

The affected Ayer homes are all believed to be serviced by municipal water service and not by private wells drawing water from the contaminated area. Part of the Army's plan includes a fresh outreach effort to identify any private wells -- abandoned or active -- in the area of concern to ensure the wells are capped and closed.

Board of Health member Pamela Papineau asked if the Army will bear that cost. Robert Simeone, the Army Base Realignment and Closure Environmental Coordinator for Ft. Devens, said "in the unlikely scenario a well is found, yes, the Army -- and assuming the landowner allows permission -- the Army will decommission those wells accordingly at our expense."

The Army also is also asking that the Ayer Board of Health put additional well water controls in place, including a moratorium on future private wells in the area. That language is in development and remains under board review.

Donald Christy of 175 West Main St. said he'd moved there 18 years ago, but his wife, Catherine Van Zandt, has lived in Ayer all her life. "She's had cancer four times," said Christy.

Christy wondered if residents were drinking "poison water" and suggested residents might consider a class action lawsuit against the Army, as was filed in 1993 against Pacific Gas and Electric Company of California.

The case alleged that PG&E caused illness and cancer by discharging water containing hexavalent chromium into unlined retaining ponds in Hinkley, Calif. The matter settled in 1996 for $333 million. "Perhaps we're selling ourselves short in not getting an attorney," said Christy. 

Christy, whose house is located outside the mapped Ayer "affected area," confirmed that his house is connected to town water and does not draw water from a private well. Simeone said the Army "did not get a 100 percent response" during previous homeowner surveys sent to residents in the affected areas, but that the Army's ongoing response plan includes a new survey launch.

The source of the arsenic has long been debated. The Army has maintained that arsenic is naturally occurring in the area due to granite. But the grassroots group People of Ayer Concerned for the Environment have advocated for an Army-financed cleanup, noting the former Army landfill was in use for decades, pre-dated modern landfill liner technology, and that arsenic concentrations are highest under and closest to the landfill and in the adjacent Plow Shop Pond.

Selectman Frank Maxant wanted assurances that the town wouldn't "shoulder" any of the cost of the Army cleanup. "If so, I'd be completely against it."

Simeone answered that "there's no burden on the town." In addition to providing updates to the Board of Health, the Army will continue to implement controls in the years to come. "The only thing we cannot do is enforce the Board of Health regulations regarding the moratorium on installing new wells."

The expense of capping wells will be borne by the Army, but property owners will not be compensated on any lost value to their properties. "The Army has no authority to evaluate any loss of property value under the cleanup."

Calvin Moore asked about other heavy metals found in and around Plow Shop Pond, of which he's a half owner. Ginny Lombardo of the EPA New England Division said that wasn't the purpose of the meeting and that work is still afoot to locate those responsible for that matter, including the current day owner of lands that once served as a tannery aside Grove Pond.

Ellen Neelands said it was her understanding that people were not to eat fish caught in either Plow Shop or Grove Ponds. Lombardo said that's true but the situation is over air pollutant mercury contamination, which she said is "very common in Massachusetts, and that's not because of the Army."

Lombardo said perhaps the Army and EPA could join to post signs warning against eating the fish. "That is a valid concern," said Lombardo.

PACE co-founder Laurie Nehring said she's been involved in monitoring the landfill area arsenic situation since her daughter was a baby. Her daughter turned 16 on March 19.

Nehring was enthused that the Army is planning to dredge Plow Shop Pond over the summer to remove settled arsenic from the pond floor.

Lombardo emphasized that the Army is going to be responsible for routine reporting on the situation "in perpetuity" since the area is a Superfund site where "waste is left in place" in the form of the landfill materials.

When asked about the effectiveness of the groundwater treatment and pumping aside the landfill, Simeone said such efforts will take some 100 years to clean groundwater of arsenic down gradient from the landfill. The Army had sought to stop the treatment plant operations, citing costs of $1 million a year. That request was denied by the DEP and EPA.

Simeone confirmed the pump was "offline" for a week earlier this month "due to a funding limitation" when the contract for the work ran out. It's back in operation now, he said, with no plans to stop treating the groundwater.

Follow Mary Arata at twitter.com/maryearata.