A public property site, situated on an alluvial terrace of the Idice Stream (Emilia Romagna Region-Italy) was contaminated by a layer of waste, constituted by vitrified fly ashes and ceramic materials produced by an incinerator of municipal solid waste. The waste had high contents of heavy metals which exceeded the Italian legal concentration limits for Cd, Cu, Pb and Zn (D. Lgs. 152/06, all. 5, tab.1). The in-situ remediation of the area was possible. In this study, alternative materials than the Portland cement were tested for the environmental restoration and the further naturalization of the area. Leaching tests were carried out treating the ashes with different concentrations of hydrated lime (CaOH2) and also with lime at 20% concentration and smectic marlstone. At the end of the leaching test, most of the heavy metals in the waste were immobilized in the waste by the lime/marlstone treatment.