Potential encroachment of a road on a Superfund site in the Rockland section of the former South Weymouth Naval Air Station is the focus of a public meeting Thursday from 7 to 8:45 p.m. at the Tufts Library, 46 Broad St., Weymouth. The Advocates of Rockland, Abington, Weymouth and Hingham, an environmental group that has been keeping tabs on the cleanup and development at the former base, believes that a guardrail will cross into the Old Swamp River cleanup site, said group member Mary Parsons of Rockland. For more information, visit arawh.org or e-mail inforequest@arawh.org. - Steve Hatch