Underwater building and construction; Underwater construction; Underwater repair; Cleaning of silt, marine growth and debris from underwater structures; Concrete repair services; Consultation services in the field of cleaning of underwater structures; Installation and maintenance of water screens, sluice gates, gate valves, flocculators and scrappers, and mechanical bar rakes; Installation, maintenance and repair of underwater structures, namely, water screens, sluice gates, gate valves, flocculators and scrappers, and mechanical bar rakes; Maintenance and/or repair of underwater structures, namely, water screens, sluice gates, gate valves, flocculators and scrappers, and mechanical bar rakes; Maintenance of water pollution control equipment; Maintenance of water purifying apparatus; Provision of information relating to the repair or maintenance of water pollution control equipment; Repair of underwater structures, namely water screens, sluice gates, gate valves, flocculators and scrappers, and mechanical bar rakes; Repair or maintenance of water pollution control equipment; Repair or maintenance of water purifying apparatus for industrial purposes; Underwater dredging