The Army Corps of Engineers will hold a public hearing Thursday at 7 p.m. in Town Hall on a project to clean up a property at Arsenal Street and Greenough Boulevard that is contaminated with polychlorinated biphenyls, and turn it into wetlands suitable for recreational use. The property was used by the Army until the mid-1960s for storing equipment, vehicles, and various scrap material. The Army Corps is working with the town to decontaminate the site by removing the polluted soil and cap the property to create a wetland, which would be transferred from the federal government to the state Department of Conservation and Recreation. Corps officials said they hope to start construction in the spring and finish the project by the end of this year. The meeting will include a presentation on the project, and an opportunity for residents to provide feedback on the proposal.