Three-Dimension Flow and Solute Transport Modeling of the Eolian Aquifer in a Uniform Flow Field of a Chemical Plant

Abstract

A numerical model consisting of 24 columns, 20 rows and 2 layers was developed for the chemical plant to solve the’ three-dimension flow and solute transport and to delineate the chromium plume dispersion along the longitudinal, transverse and vertical z directions. The PROCESSING MODFLOW (PM) was used in conjunction with the U.S. Geological Survey’s “Modular Three-Dimension Finite- Difference Groundwater Flow Model”, MODFLOW, and the transport model MT3D. From 1972 to 1992, plant liquid effluents with a chromate concentration of 2 to 3 ppm were discharged into the unlined evaporation ponds. In 1992, evaporation ponds were lined to control the process of infiltration of chromate liquid waste into subsoil and to avoid mixing in groundwater through vertical and lateral movement. The model predicted the flow pattern and movement of resultant plume developed in the Eolian aquifer. Heads distribution deduced by the models for the steady state case is in close harmony with the observed heads. In transient case model realizations were obtained with 4 stress periods identifying the chromate liquid waste plume (1972 – 1992) during stress period 1, which disappeared from the major flow system in 120 years during the remaining stress periods. Finally, plume appears to be oriented along the Dohar Wah Canal and discharges into it. At specified nodes (1,11,6), (2,11,6), (1,7,6), (1,5,11) and (1,5,14) level of concentration monitored by the model for the simulation period of 80 to 140 years has assessed that chromium plume would arrive at village Kotla Mirza in year 2022.
Based on the most recent position of the contaminant plume, six monitoring well sites have been delineated at nodes (1,8,6), (1,8,8), (1,8,13), (1,11,6) (1,7,12) and (1,11,13) for future periodic water samplings.