After decades of halting progress removing toxic lead in the Mill River left by the former Exide battery plant, Conservation Director Thomas Steinke wants state action slowed on the cleanup plan so efforts to remove chromium from the waterway can be advanced to the same timeframe.

Exide Group Inc., under orders from the state Department of Energy and Environmental Protection to remove the lead that was leaked from its Post Road factory for 30 years, has been conducting informational meetings with residents and town officials in preparation for a formal hearing before the DEEP in either February or March for permits for its plan.

Superior Plating, which still operates on Lacey Place across the river from the 6.2-acre Exide site, is under a similar order to clear chromium in the river, but has yet to provide an assessment of the extent of the contamination that state officials feel is acceptable.

Rather than have the river undergo dredging at different times for the two remediation projects, Steinke thinks it would make more sense to have work for both cleanups done at the same time.

"We've spent 30 years getting to this point," Steinke said after a meeting of the Conservation Commission last week. "A few more years may result in getting Superior Plating on board and all the dredging could be done at once. That would be an ideal outcome."

Remediation on the Exide property and abutting Mill River began in 1983, when about 4,000 yards of contaminated sediment was removed from the river, while ground contaminants were removed between 1987 and 1990.

The lead contamination probably was caused by spills during the manufacture of batteries that Exide produced before the factory shut down in 1981.

The factory building itself was demolished in 2005, followed by removal of 13,000 tons of demolition debris, 10,000 tons of contaminated soil and about 4,000 feet of contaminated piping.

Also razed was Exide's administrative building that was designed by award-winning architect Cameron Clark, although a doorway facade was preserved.

Attempts were made to save as much of that building as possible, but it proved to be located too close to contaminated soil to be salvaged.

The latest DEEP cleanup order was issued in 2008 when lead-pollution levels failed to subside after those first efforts in 1983.

Representative Town Meeting member Kathryn Braun, R-8, agrees that the lead and chromium cleanups should take place at the same time.

"Our town leaders and Conservation Commission must pressure the DEEP to require a one-time, consolidated cleanup," Braun said, adding the commission should require that a local wetlands permit application.

Braun said after many years, "It now seems both hasty and premature to push the Exide lead cleanup this spring without a plan for the Superior Planing chromium cleanup."

A piecemeal approach, she said, would cause a second disruption to the river, its ecology, and neighbors.

"Let's do it right the first time and protect the best interests of our town," Braun said.

Peter Hill, a supervising environmental engineer with the DEEP, said the state plans to try to coordinate the Superior Plating cleanup with the Exide dredging, "though we can't guarantee it will happen at the same time."

"The Exide work will address much of the chromium problem," Hill said, "but there will be some that remains. We're working with Exide and Superior right now to determine how much."

Steinke said any chromium that is "co-located" with lead will be removed under the Exide plan, which calls for 21,000 cubic yards of material to be dredged over a two-year period.

He said contaminated areas of the river would be cordoned off with silt curtains and a hydraulic dredge used to suck up the contaminated sediment that would be brought through a pipeline to Exide's Post Road facility. There, the sediment would be dewatered and placed in large textile tubes and the tubes shipped off site for disposal.

Areas south of Interstate 95 would be cleaned to a level of 220 milligrams of lead per kilogram, while areas above the highway would be cleaned to 400 milligrams per kilogram.

Steinke said there are still questions about the Exide proposal that he expects will be answered when the formal DEEP application is heard.

"What kind of hydraulic dredge will they use; how will they get into the five dredge areas; if they are using a temporary ramp, what kind of permits will they need?" Steinke said are among the unresolved issues.