The construction, maintenance or repair of shipyards, wharves, docks and related terminals, piers, waterfront pile driving and related equipment, dolphins, breakwaters, revetments, bulkheads, seawalls, retaining walls, cofferdams, caissons, underwater welding, marine diving and salvaging, underwater construction, and related dredging and draglines for harbors and other construction in navigable waterways. Wharves, docks, harbor improvements and terminals is a subclassification of Heavy Construction.