Predicting the fate of chlorinated aliphatics by hydrogeological modelling and DCIP data - Färgaren case study

We present a local flow model approach for the transport and the decay of a roughly 50 year old perchloroethylene contamination at a former dry cleaning facility at Kv. Färgaren in Kristianstad that sits above the largest aquifer in Sweden. The study demonstrates an efficient workflow integrating ERT for conceptualising and calibrating a three dimensional transient, multi aquifer groundwater transport problem with a sequential first-order decay contamination where only limited sample data is available for calibration - i.e. non-ideal, real world conditions. The 3D hydraulic model geometry is based on information from ERT data. It was possible to map resistivity signatures correlated with boreholes to geological features with a high degree of accuracy. On the Färgaren site itself, a 3D IP inversion model displayed some IP effects that correlated with historical perchloroethylene source terms. The simulations provide new information regarding the vulnerability of a critical groundwater resource, filling in knowledge gaps left by traditional sampling methods. It is concluded that there is potential for long term contamination of the regional sandstone aquifer, and that the plume front may already have reached its upper layers.