Cofferdam n. A water-tight inclosure, as of piles packed with clay, from which the water is pumped to expose the bottom (of a river, etc.) and permit the laying of foundations, building of piers, etc.
... long way from nowhere," Cappy replied thoughtfully. "It means sending a wrecking steamer down there with a lot of expert wreckers, divers, mechanics and carpenters; it means lumber for cofferdam and pontoons; it means donkey engines, cables, pumps, the stress of wind ... — Cappy Ricks Retires • Peter B. Kyne
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