As used in this chapter, unless the context requires a different meaning: “Authority” means an authority created under the provisions of § 15.2-5102 or Article 6 (§ 15.2-5152 et seq.) of this chapter or, if any such authority has been abolished, the entity succeeding to the principal functions thereof. “Bonds” and “revenue bonds” include notes, bonds, bond anticipation notes, and other obligations of an authority for the payment of money. “Cost,” as applied to a system, includes the purchase price of the system or the cost of acquiring all of the capital stock of the corporation owning such system and the amount to be paid to discharge all of its obligations in order to vest title to the system or any part thereof in the authority; the cost of improvements; the cost of all land, properties, rights, easements, franchises and permits acquired; the cost of all labor, machinery and equipment; financing and credit enhancement charges; interest prior to and during construction and for one year after completion of construction; any deposit to any bond interest and principal reserve account, start-up costs and reserves and expenditures for operating capital; cost of engineering and legal services, plans, specifications, surveys, estimates of costs and revenues; other expenses necessary or incident to the determining of the feasibility or practicability of any such acquisition, improvement, or construction; administrative expenses and such other expenses as may be necessary or incident to the financing authorized in this chapter and to the acquisition, improvement, or construction of any such system and the placing of the system in operation by the authority. Any obligation or expense incurred by an authority in connection with any of the foregoing items of cost and any obligation or expense incurred by the authority prior to the issuance of revenue bonds under the provisions of this chapter for engineering studies, for estimates of cost and revenues, and for other technical or professional services which may be utilized in the acquisition, improvement or construction of such system is a part of the cost of such system. “Cost of improvements” means the cost of constructing improvements and includes the cost of all labor and material; the cost of all land, property, rights, easements, franchises, and permits acquired which are deemed necessary for such construction; interest during any period of disuse during such construction; the cost of all machinery and equipment; financing charges; cost of engineering and legal expenses, plans, specifications; and such other expenses as may be necessary or incident to such construction. “Federal agency” means the United States of America or any department, agency, instrumentality, or bureau thereof. “Green roof” means a roof or partially covered roof consisting of plants, soil, or another lightweight growing medium that is installed on top of a waterproof membrane and designed in accordance with the Virginia Stormwater Management Program’s standards and specifications for green roofs, as set forth in the Virginia BMP Clearinghouse. “Improvements” means such repairs, replacements, additions, extensions and betterments of and to a system as an authority deems necessary to place or maintain the system in proper condition for the safe, efficient and economical operation thereof or to provide service in areas not currently receiving such service. “Owner” includes persons, federal agencies, and units of the Commonwealth having any title or interest in any system, or the services or facilities to be rendered thereby. “Political subdivision” means a locality or any institution or commission of the Commonwealth of Virginia. “Refuse” means solid waste, including sludge and other discarded material, such as solid, liquid, semi-solid or contained gaseous material resulting from industrial, commercial, mining, and agricultural operations or from community activities or residences. “Refuse” does not include (i) solid and dissolved materials in domestic sewage, (ii) solid or dissolved material in irrigation return flows or in industrial discharges which are sources subject to a permit from the Department of Environmental Quality, or (iii) source, special nuclear, or by-product material as defined by the Federal Atomic Energy Act of 1954 (42 U.S.C. § 2011, et seq.), as amended. “Refuse collection and disposal system” means a system, plant or facility designed to collect, manage, dispose of, or recover and use energy from refuse and the land, structures, vehicles and equipment for use in connection therewith. “Sewage” means the water-carried wastes created in and carried, or to be carried, away from residences, hotels, schools, hospitals, industrial establishments, commercial establishments or any other private or public buildings, together with such surface or ground water and household and industrial wastes as may be present. “Sewage disposal system” means any system, plant, disposal field, lagoon, pumping station, constructed drainage ditch or surface water intercepting ditch, incinerator, area devoted to sanitary landfills, or other works, installed for the purpose of treating, neutralizing, stabilizing or disposing of sewage, industrial waste or other wastes. “Sewer system” or “sewage system” means pipelines or conduits, pumping stations, and force mains, and all other constructions, devices, and appliances appurtenant thereto, used for conducting sewage, industrial wastes or other wastes to a plant of ultimate disposal. “Stormwater control system” means a structural system of any type that is designed to manage the runoff from land development projects or natural systems designated for such purposes, including, without limitation, retention basins, ponds, wetlands, sewers, conduits, pipelines, pumping and ventilating stations, and other plants, structures, and real and personal property used for support of the system. “System” means any sewage disposal system, sewer system, stormwater control system, water or waste system, and for authorities created under Article 6 (§ 15.2-5152 et seq.) of this chapter, such facilities as may be provided by the authority under § 15.2-5158. “Unit” means any department, institution or commission of the Commonwealth; any public corporate instrumentality thereof; any district; or any locality. “Water or waste system” means any water system, sewer system, sewage disposal system, or refuse collection and disposal system, or any combination of such systems. “Water system” means all plants, systems, facilities or properties used or useful or having the present capacity for future use in connection with the supply or distribution of water, or facilities incident thereto, and any integral part thereof, including water supply systems, water distribution systems, dams and facilities for the generation or transmission of hydroelectric power, reservoirs, wells, intakes, mains, laterals, pumping stations, standpipes, filtration plants, purification plants, hydrants, meters, valves and equipment, appurtenances, and all properties, rights, easements and franchises relating thereto and deemed necessary or convenient by the authority for the operation thereof but not including dams or facilities for the generation or transmission of hydroelectric power that are not incident to plants, systems, facilities or properties used or useful or having the present capacity for future use in connection with the supply or distribution of water.