Deep excavation below the water table during the construction of a rolling mill for Italsider's Genoa iron and steel works necessitated a number of special procedures to permit the construction work to go on without affecting the regular operation of plants. Three different stages of construction work were required due to singular working conditions and soil nature: (1) construction work to contain the soil pressure; (2) waterproofing of the excavated bottom by grouting; and (3) waterproofing of the excavated walls by a ″freezing system″ . This paper presents a summary of the first two stages of work, and provides details about ground freezing.