Analysis and specifications of filtration of surface runoff from railway track ballast section

Summary

Rail transport facilities are fixed structures that produce continuous impact on the environment. The main facilities – pollution sources among rail transport facilities are railway stations. In most cases polluted runoff from railway station tracks generated mainly as a result of atmospheric precipitations leaks through the surface relief, infiltrates into the subsurface, penetrates deeply and drains with underground water into the nearest water bodies. The processes of surface runoff filtration through multilayer porous media that are taking place in the ballast section of the railway track have been analyzed and specified. Possible hypotheses of liquid behavior and properties in multilayer porous media, in particular of the liquid on the surface of ballast section of the railway track accumulated as a result of atmospheric precipitations; steady and unsteady liquid seepage into the railway ballast depth; dissipation of oil product spills on railway tracks are presented.

Key words

filtration , oil products , surface runoff , train track , ballast section

On designing surface runoff control schemes (to be discussed)

Summary

The necessity of the rainfall flow rate and volume control before the treatment facilities is stipulated in Code of Practice 32.13330.2012. The recommendations given by NII VODGEO suggest three control schemes designed on the basis of the theoretic runoff hydrograph described by two curves (flow rate increase and decrease) expressed through the maximum flow rate. The given functions have been obtained with the use of the runoff flow rate equation following the method of limit intensities with a constant runoff coefficient which is a special case. Presented in the article is a proximate description of the theoretic runoff hydrograph with account of using a variable runoff coefficient which is a more general case. The analysis of the method of calculating the rainfall flow and volume control schemes is presented. A calculation example is considered, a comparative assessment of the results obtained is given. It is shown that when using the existing method of calculating surface runoff control systems and determining the capacity of pumping station tanks the calculations of the maximum flow rate of the design rainfall shall be carried out with the use of the variable surface runoff coefficient that provides for the maximum approximation to the theoretic runoff hydrograph.

Key words

design runoff hydrograph , rainfall flow rate and volume control scheme , runoff coefficient , pumping station tank capacity