ABOUT THE CATEGORY OF GAS-GEOCHEMICAL DANGER OF BACKFILL

Construction works on the backfill are connecting with the fire and explosion hazard due to their ability to generate biogas, consisting of combustible components. In addition, the biogas has a fairly high toxicity and represents a serious environmental hazard, especially near residential areas. Therefore, in areas within the planned construction engineering survey provides geochemical soil testing and determination the degree of hazard. This paper analyzes the existing criteria of soil geochemical hazards and offers their clarification. With regard to the fire and explosion hazard, the following considerations are given. In the design and construction of opened public constructions dangerous levels of the biogas are excluded. However, during the construction of enclosed volumes on such grounds the explosible concentrations of methane are possible. A dangerous concentration of methane should be considered a concentration of 1.056 % vol., which is 20 % of the lower flammability limits of methane (5.28 % vol.), adopted by the conditions of fire and explosion hazard. As a criterion of the environmental hazard of bulk gas-generating soils an excess of a concentration of at least one component of biogas compared to the corresponding MAC should be taken.