Inčukalna sērskābā gudrona dīķu piesārņotā pazemes ūdens kustības datormodelēšana

Abstract

At the Incukalns district, two abandoned gravel pits from 1955 to 1970 were used as dump sites for storing liquid sulphuric goudron (mixture of sulphuric acid and oil products). The dump sites were named the Northern and Southern pools. The Northern pool was filled with sand. Presently, the Southern pool contains goudron in the state of liquid, paste and stone. During sixty years, the pools are polluting groundwater that moves towards the Gauja river. Excavation of the goudron body of the Southern pool continues. The contaminated sand of the Northern pool will be taken away. In order to optimize the ongoing process of environmental recovery of the place, the researchers of Riga Technical University carried out computer based modelling of mass transport of contaminants (especially surface active substances (SAS)) by the groundwater flow. The research was done to the request from the company INTERGEO. It was found out that the SAS plumes of the Northern and Southern pools will reach the river, after 25 and 80 years (from 2015), accordingly. The SAS mass of the plumes was evaluated, respectively, 8000kg and 30000kg, for the Northern and Southern pool in 2015. The rate of the SAS inflow from the Northern pool plume into the Gauja river was estimated for 2039–2099 if no SAS destruction takes place: 660 kg – in 2039–2054; 2800 kg – in 2059-2079; 4000 kg – in 2079–2099. After 2119, the mass of zone SAS plume will be 540 kg. The unevenness of the SAS inflow rate is due to the smaller SAS concentration for the exterior part of the plume than for its central part. This fact was also confirmed by the hydrographs for the SAS concentration of the virtual monitoring wells. It was found that the SAS inflow into the Gauja river will have no real influence (even without SAS destruction) on the quality of river water, because its flow is much more stronger than that of the contaminated groundwater flow from the Northern pool.