37 Installation, maintenance and repair of machines which treat liquids and clean and purify environments, including solids control machines, production waste management machines, filtration and screening machines, and machines for completion services, all for the oil, gas and ecological industries; rental, installation and maintenance of cleaning machines, including high pressure washing and machines for cleaning sewers, containers and drill holes, slurry treating machines, all for the oil, gas and ecological industries; rental of solids control machines, production waste management machines, filtration and screening machines, and machines for completion services, all for the oil and gas industries; repair services for machines in the oil and gas industries, including solids control machines, production waste management machines, filtration and screening machines, and machines for completion services; construction supervision of subcontractors; technical supervision of building and construction projects; rental of treatment, cleaning and purification machines for use in the oil, gas and ecological industries