Justification of the optimal base choice for the anti-filtration circuit during the reclamation of toxic waste storage facilities

Introduction. Storage facilities, designated for the toxic production waste and located on the premises of the former Sredne-Volzhsky chemical plant in Chapayevsk, Samara Region, are sources of negative environmental impacts. The situation is aggravated by the lack of a reliable seepage prevention circuit at toxic waste storage facilities, enclosed by natural impermeable layers. The purpose of the study is to substantiate the choice of the optimal base for seepage prevention curtains along the perimeter of toxic waste storage facilities by clarifying the filtration characteristics of impervious soils using the interpretation of special experimental filtration works, followed by the testing of the effectiveness of engineering solutions using the developed geological filtration model. Materials and methods. Processing Modflow is the software designed for the 3D filtration and pollutant transport modeling. The input data for a geological filtration model included technical reports on engineering surveys conducted in 2013 on the premises of the former Sredne-Volzhsky chemical plant, as well as the results of special experimental and filtration works and plant site level observations interpreted using the ANSDIMAT software. Results. The filtration characteristics of the clay rocks of Upper Quaternary deposits were clarified as a result of the interpretation of special experimental and filtration works by the ANSDIMAT software through graphic analytical methods, and the application of a numerical model by the Processing Modflow software to imitate these works. The resulting characteristics confirmed the usability of this engineering geological element as the base for the designed anti-seepage curtains. The Processing Modflow software was applied to confirm the high efficiency of the filtration prevention circuit, which allowed to significantly reduce inflows in toxic waste storage facilities in the course of their reclamation. Conclusions. In the process of reclamation of the area, occupied by the former Sredne-Volzhsky chemical plant, the option, recommended for implementation, is the installation of anti-seepage curtains around the perimeter of the toxic waste storage facilities for the circuit to be enclosed by the clay rock of the Upper Quaternary deposits. The proposed engineering solution will allow the highly toxic filtrate to be concentrated inside the toxic waste storage facilities to prevent its penetration into the environment.