The Ilukste oil station pipelines diesel fuel from Belorus to the seaport town Ventspils in Latvia. In 1970-1996, the station also filled railway tanks. Due to oil leakages, groundwater under the railway terminal routes was contaminated. Mobile oil discharged from a steep bank of the nearby Ilukste river. To prevent oil inflow into the river, a special pond was dug for its intercepting. In 1996, remediation of the station area started and followed up until now. The work was supervised and financed by the station owner LatRosTrans Ltd. Since 2000, it was performed by the environmental company VentEko. In 1997, scientists of Riga Technical University (RTU) established the hydrogeological model of the contaminanted area. Due to use of the model and the code ARMOS, a disposition of the oil leakage source was found. The oil plume self-cleaning for about 25 years was predicted due to oil natural run off into the pond. In 2018, RTU assessed results of the sanitation. It was found out that the remediation process had reached its final stage, as productivity of the oil recovery was getting low. Comparison of the real sanitation results with the predicted course of the oil plume natural run off showed that the both processes differed mainly due to a repeated oil leakage in the area of the railway terminal. The case confirmed considerable value of the predictions that were obtained by modelling