One consequence of increasingurbanization is that a man-made ecosystem arises in a city, which includes a very unusual geoecosystem, which arises from changes in the geological environment from man-made factors. The geological environment of a city at present Consists in the main of polluted areas: spaces under housing, roads, and areas in industrial zones, suchas oil, gas, and product pipelines; municipal support systems, stores, and so on. Particular note should be taken of areas occupied by wastes from industry and domestic sources, since the ecological consequences of storing rubbish take years or even decades to appear: air pollution, the pollution of ground and surface waters, polluted soils, and changes in phytocenoses.The volume of solid domestic wastes is increasing continuously not only in total but also per head. Various sources indicate that this rubbish in Russia amounts to 56 million tonnes a year, of which about 96% is shipped to tips. In addition to these tips for the planned dumping of wastes, cities and other inhabited areas also contain unauthorized dumps, which cover large areas. Under such dumps, artificial geological formations arise because of irresponsible human activities, which may be represented by areas of not less than 0.5 hectare with deposit thicknesses of more than 1 m, in which chemical and biological processes transform the wastes, which is accompanied by the destruction of organic material and the formation of infiltrating solutions and biogas (tip gas: an ecologically hazardous mixture of methane, carbon dioxide, hydrogen sulfide, oxides of nitrogen, hydrogen, methylmercaptan, and other gases).Unauthorized dumps usually arise in areas that have not been evaluated for their suitability for such dumps, and very often in former quarries. Many of these quarries lie in river flood plains having very unfavorable hydrogeological conditions: highly permeable rocks, high water table, and emergence of groundwater in springs. There is a danger of adverse effects on the environment in such cases, which is steadily increasing, and in some places, groundwater has been polluted along with the environment throughout the existence of the dumps.It is necessary to reuse polluted areas, and these should be cleaned up and included in the infrastructure of the region, city, or village. Effective construction on polluted areas requires one to determine the purpose of the cleanup or rehabilitation of the particular area together with the factors that hinder the reuse of such areas. Such factors include poor and inhomogeneous low-grade soils for foundations of man-made origin; the possibility that the basements in buildings will be infiltrated by gas present in the soil; toxic pollutants may infiltrate groundwater; and the incompleteness of information on the ecological setting in the area.Rehabilitating or cleaning up polluted areas is a complicated process, which must be examined on the basis of regional planning, and the forward planning for the city or region; allowance must also be made for the re...