“Applicant” means any bona fide governmental agency or incorporated nonprofit organization or association responsible for construction of sewerage facilities. “Construction” means pertinent design and engineering services and the physical installation of any new, or extension of, an existing public sewer system or of any temporary sewage treatment facility. “Extension” means adding sewage collecting facilities and equipment to an existing system. “Improvement” means the installation of adequate means for collecting and treating sewage to abate or prevent public health hazards. “Individual sewerage system” means a single system of sewers and piping, treatment tanks or other facilities serving only a single lot and disposing of sewage or individual wastes of a liquid nature, in whole or in part, on or in the soil of the property into any waters of this State, or by other methods. “Public sanitary sewer system” means any system serving two or more individual lots for the collection and disposal of sewage, including various devices for the treatment of the sewage. “Temporary sewage treatment plant” means any facility constructed to treat sewage before discharge into a stream or onto the ground surface or into the soil, which is to be abandoned when a permanent system is declared available by the Department of the Environment.