Cornell has completed field investigations and evaluated options for cleaning up its former low-level radiation disposal site (RDS) in the town of Lansing, north of Tompkins County Airport. The proposed cleanup plan for the site, plus alternatives that were considered, will be described at a public meeting Thursday, April 26, at 7 p.m. in DeWitt Middle School, Warren Road, Ithaca. The public will have the opportunity to comment through June 13.

The meeting will be conducted by the New York State Department of Environmental Conservation (DEC), which is responsible for selecting a final remedy for the disposal site.

In addition, representatives from the New York State Department of Health, the DEC and from Cornell will be available to answer questions at DeWitt Middle School, May 15 from 4 to 6 p.m. and from 7 to 9 p.m.

Between 1956 and 1978, Cornell's two-acre RDS was used to bury research materials containing low-level radioactivity, in accordance with state and federal regulations in effect at that time. Studies of the site and monitoring have been under way since 1984. In 1996, a new impermeable cap was installed over the site to reduce penetration by surface water.

Field investigations and risk assessments for the RDS were discussed at a public meeting in March 1998, as well as in a series of newsletters issued by Cornell and in news articles by local media. According to Donna Connery, project manager for Cornell's Environmental Compliance Office, the cleanup plan for the RDS addresses the disposal area itself and groundwater contamination extending about 400 feet southwest of the site to Snyder Road. Although the risk assessment performed showed that the site does not pose unacceptable health risks, "Cornell has proposed a plan that includes constructing an underground clay wall around the waste area and injecting cement grout into fractured rock to isolate the most highly contaminated groundwater," Connery says. "This should contain the disposal area and prevent future releases from the site."

As for the groundwater plume that already has left the site, water will be removed from a series of groundwater recovery wells constructed specifically for this purpose along Snyder Road and treated in an upgraded facility near the site, according to Connery.

"Groundwater from the recovery wells will be treated to remove paradioxane, the main contaminant at the site. Paradioxane is a solvent that was used in radiation experiments going back four decades," she says. "Although the site contains irradiated research materials, the paradioxane is of current concern because it has migrated from the site." An ultraviolet oxidation system will be used to treat the water and remove the paradioxane.

This new treatment system will be installed at the existing groundwater treatment plant designed for Cornell's former chemical disposal site (CDS), which is 800 feet east of the RDS. The CDS was used to bury laboratory waste chemicals from 1962 to 1978 in accordance with state and federal regulations in effect at that time. Remedial measures to control migration of contaminated groundwater from the CDS have been in effect since 1992. Treated water from the plant must meet DEC requirements before being discharged to a holding pond and then to a nearby stream.

The plan being proposed for the RDS is estimated to cost about $10 million dollars. Construction of the groundwater recovery system is in process, with construction of the barrier walls around the disposal area to follow after regulatory approval of the final plan. Operation of the RDS groundwater recovery and treatment system is expected to continue for 20 years, with ongoing monitoring.

"The cleanup plan for the RDS, a combination of isolating the waste-disposal area and the groundwater recovery and treatment system, should effectively isolate the waste from the environment and prevent further movement of contaminants in the groundwater," Connery says.

The cleanup plan for the RDS is described in a feasibility study that compares alternative approaches. Copies of the study and DEC's proposed remedial action plan for the RDS, which discusses the agency's rationale for the plan, are available for public review at the following locations: Tompkins County Public Library, 101 E. Green Street, Ithaca; Lansing Village Hall, 2405 N. Triphammer Road; and Cornell's Environmental Compliance Office at East Hill Plaza on Pine Tree Road, Ithaca.