Numerical model assessment of chlorinated solvents behavior in limestone fractured and karstic aquifer

The understanding of the transport and degradation phenomena of chlorinated solvents in fractured aquifers as well as the assessment of the clean up times is a challenge. In the present study a model for reactive transport and reductive dechlorination of chlorinated solvents in fractured aquifers is developed. Rough walled parallel plate model including non-linear flow behavior is coupled with random walk particle tracking incorporating particle exchange between fracture and matrix, adsorption processes and dechlorination reaction network. The developed model is applied to a case study of the groundwater contamination in the industrial area of Modugno – Bari (Italy), where the limestone aquifer presents a fractured and karstic nature. The steady state distribution of the contamination by chlorinated solvents with the source at the hot spot is obtained and compared with the contaminated observed scenario in order to detect the plausible transport and degradation processes. A sensitivity analysis is performed on the flow, transport and degradation parameters. Finally, the influence of non – Darcian flow regime on the contaminated transport is put in evidence simulating the effect of multiple pumping and reinjection of the treated groundwater.