AYER -- Board of Health Chairman Heather Hasz thanked member Pam Papineau, "who came through and did a yeoman's job" collecting public comments on the Shepley's Hill Landfill cleanup plan by the Monday night deadline.
The comments are being forwarded to Base Realignment and Closure Commission civilian environmental coordinator Robert Simeone.
Papineau went over the details of the last Devens Restoration Advisory Board meeting. Those present at the meeting included Rachel Leary, of Sovereign Consulting, Inc., the firm the Army retained to plan and execute the project; representatives of Fish & Wildlife, MassDevelopment, the EPA, and DEP; members of People of Ayer Concerned about the Environment; and Simeone.
Papineau said discussion centered on the environmental cleanup activities being performed by the Army at the former Fort Devens Superfund sites known as Shepley's Hill Landfill and the former Railroad Roundhouse, both located along Plow Shop Pond.
Plow Shop Pond is the lowermost of the six ponds in the area and receives their inflow, as well as that from a watershed channeled through Grove Pond. The main inlet is on the eastern edge, adjacent to the railroad tracks. The water level is controlled by a dam located at the northwest corner of the pond, where it forms Nonacoicus Brook and its associated wetlands, which in turn flows directly into the Nashua River.
A tannery, located on the northwest corner of Grove Pond, operated intermittently from 1854 through June 1961.
Contaminants present in Plow Shop Pond include arsenic, polycyclic aromatic hydrocarbons (PAHs), chromium and mercury.
Area I of Plow Shop Pond, which is larger than the Railroad Roundhouse area, is the more difficult area of contamination to remediate, Papineau said.
Much of the discussion at the RAB meeting focused on a timeline showing the installation of pumps that would gradually lower the pond level from 30 to 21 acres.
Some expressed concern about the condition of the dam, owned, in part, by Calvin Moore. But "everyone there including the EPA thought it would not unduly stress what they are doing," Papineau said.
She said snow fencing and signs will be erected to keep people out, and there would be daily removal of "sludge" that will need to be dried and treated separately.
"The stuff taken away will be combined with a stabilizer to be used as a layering material in landfills -- not the top material, because it will have an acceptable level of contaminants for that purpose."
The process will take weeks, because there is going to be water continuing to come in from Grove; it is not going to be deoxygenated, she said. There still will be a flow of water from Grove into the pond and over the dam.
Although there will be some fish kill, an inventory will be kept of the organisms in the area.
"Their theory," said Papineau, "is that the fish will move into that deeper central area and the flow of oxygen in the water will keep them alive. PACE and the EPA did not seem terribly worried about the fish, but were more worried about invasive species in this drier area.
"They said they believe that the soil conditions, not so much in the Roundhouse area, but in the biggest area, is not where stuff like purple loosestrife likes to grow because of the steep embankment and shady pine area.
"But there will be monitoring of the area," she said, "and they have to return it to its original state. So I assume that if there is some purple loosestrife to begin with, we can have some afterward, just not an increase."
GPS will be used with a plus-or-minus 2-inch accuracy for the level of the pond, which will be marked with stakes.
The timeline for the remediation will depend upon the weather, and the pumping will last several weeks.
"The stuff they remove has to go to the staging area to dry out, and historically, August to September is a relatively drier period around here, which is why they had scheduled it this way," Papineau said.
Soil sampling will be done and sent on a daily basis to an analytical lab with a 24-hour turnaround, "so we won't start refilling anything until the data says it is OK," she said.
Monitoring will also be done for dissolved oxygen in the water to be sure that it is compatible with sustaining animal life. Once remediation is complete, a special grass blend will be put in to restore the wetlands.
Papineau concluded by adding that a site tour of the area will be offered in the second week of August.