Investigation of Waste Properties of Subway Construction as a Potential Component of Soil Layer

The construction of subway stations is inevitably accompanied by the formation of a large amount of waste that is extracted from the underground workings by rock. When the waste is transported, the air is polluted with the exhaust gases of the dump trucks, some of the waste can stay on the road surface, the use of dump trucks increases the load on the roadway, the disposal of waste at landfills harms the environment, and enterprises pay fees for the transportation as well as placement of the waste. The article deals with the waste from the construction of new stations in the Saint-Petersburg subway. In order to determine the possibility of using waste in the municipal economy, a comprehensive analysis of this waste was carried out, including determination of moisture content, acidity, total carbon content, as well as chemical and granulometric composition. On the basis of the study results, it was established that the waste in question belongs to the hazard class 5, which enables to use it as a component of the soil mixture. Afterwards, the hazard class 5 was confirmed by the method of bioassay based on the determination of water toxicity by changing the optical density of the Chlorella algae culture.