Investigation on the factors for site selection of solid waste transfer statios for 22nd district of Tehran municipally considering environmental issue, air and waste leachate

The development of urban communities, growth of urbanism, emergence of metropolises, and subsequent increase in the volume of residues and municipal wastes, besides adding to numerous urban problems, pose serious threats to the environment and people's health which, together with the need for transfer stations for temporary accumulation of wastes, has drawn world attention to this issue. The usage of waste transfer stations is recommended in order to improve and enhance solid wastes transportation system. Most cities posses waste transfer stations, however, it should be mentioned that potential effects of wastes on individual's health and safety are still unclear.Proper site selection, design, and operation of equipments lead into the appropriate management of waste transfer stations so that health, safety, and welfare of society as well as the absence of adverse environmental impacts could be ensured. The purpose of this study is to investigate environmental aspects and sanitary conditions of waste transfer stations in terms of the volume of generated leachate around the stations and emission of unfavorable odors and polluted gases during the operation of stations located at residential areas. To accomplish these goals, sampling and some measurements were carried out at each station in the first step. Investigations showed the lack of health facilities, appropriate accommodation for workers, personal protective equipments, and proper physical conditions in 90% of stations. The obtained results indicate that the level of leachate-induced pollution at the bottom of stations, which ultimately escapes to soil and water resources, is significantly higher than standards recommended by Department of Environment (DOE). Septic tank leachate sampling showed that BOD and COD level of the studied station was 49700 and 31800 mg/l, respectively which, in all cases, are higher than sewage effluent standards. In addition, the amount of particles measured at the eastern side of the station was 153 and 753 microgram/m3 which are higher than air pollutant's standards. The level of pollutant gases of NH3 and H2S9NH3 is zero or insignificant. Investigations revealed that the station has septic leachate collection system and its effluent enters absorbing wells. Furthermore, rinsing of waste transporting vehicles leads into flow of polluted water at the station and then, entering absorbing wells.