Hydrogeological research as a basis for the preparation of the plan of monitoring groundwater contamination: A Case Study of the Stara Vas Landfill near Postojna (SW Slovenia)

 V Sloveniji je na krasu trenutno aktivnih devet odlagališč komunalnih odpadkov, med drugimi tudi Stara vas pri Postojni. Ker je za kraška območja značilna močna razpokanost kamninske osnove in zelo dobra prepustnosti, izcedne vode z odlagališč še posebej ogrožajo podzemno vodo. Sposobnost naravne filtracije je v krasu majhna,obseg možnega negativnega vpliva pa zelo velik. Sedaj veljavna zakonodaja predpisuje obratovalni monitoring, del katerega je tudi merjenje parametrov onesnaženosti podzemnih vod z nevarnimi snovmi, če so v vplivnem območju odlagališča. Temelj za izdelavo načrta monitoringa so ustrezne hidrogeološke raziskave. Za primer Stare vasi smo poleg osnovnih geoloških in hidrogeoloških podatkov uporabili še rezultate sledilnih poskusov, ožje območje odlagališča pa smo podrobno tektonsko-litološko kartirali v merilu 1:5000. Na osnovi ugotovljenih značilnosti pretakanja vode v podzemlju in v skladu s predpisi smo določili 3 točke monitoringa znotraj (izvira Malenščica in Vipava, jama Fužina) in eno izven vplivnega območja odlagališča (Matijeva jama) ter določili način spremljanja kakovosti vode in izdatnosti   For the present 9 land fills on karst are still active in Slovenia, among them also the Stara vas land fill near Postojna. As strong fissuration of the rock base and very good permeability istypical for karst areas, the waste waters from the landfills particularly endanger the groundwater.The capacity of natural filtration in karst is very low and the dimension of possible negative impact is very high. The actual legislation regulates the performance of operational monitoring, a part of which is also the measurement of parameters of contamination of groundwater by hazardous substances, if they are in the area of influence of the landfill. Preparation of the monitoring plan is based on adequate hydrogeological researches. Besides basic geological and hydrogeological data also the results of tracer tests were used in the case study of the Stara vas landfill.Additionally, the detailed tectonic-lithological mapping in the scale 1:5000 was performed in the narrow area of the landfill.Based on defined characteristics of underground water flow and in accordance with the regulations 3 monitoring points inside (Malenščica and Vipava springs, Fužina cave) and one point outside the area of influence of the landfill (Matijeva jama cave) were selected. The monitoring plan for the observation of water quality and capacity was suggested

Vulnerability Mapping in the Recharge Area of the Korentan Spring, Slovenia

Zaradi dobro razvitega sistema kraških kanalov in razpok, ki omogoča hiter tok podzemne vode in tudi hiter prenos škodljivih snovi, so kraški vodonosniki zelo ranljivi za onesnaženje. Osnovo za njihovo ustrezno varovanje predstavljajo karte ranljivosti. Za izdelavo teh kart so bile razvite različne metode, pri oceni ranljivosti zaledja izvira Korentan pri Postojni pa smo uporabili metodo EPIK, ki je bila že večkrat uspešno preizkušena na krasu in stopnjo ranljivosti določa v odvisnosti od štirih parametrov: razvitosti epikrasa, učinkovitosti varovalnega pokrova, pogojev infiltracije in razvitosti kraške mreže. Za oceno posameznih parametrov smo uporabili različne raziskovalne metode kot so podrobno strukturno-litološko in geomorfološko kartiranje ter vzporedna analiza hidravličnih in fizikalno-kemičnih odzivov izvira na padavinske dogodke. Izdelana karta ranljivosti opredeljuje območja zelo velike, velike in zmerne ranljivosti znotraj zaledja izvira Korentana in jo lahko uporabimo kot osnovo za omejitev varstvenih pasov.Karst aquifers are very vulnerable to pollution due to well developed system of karst channels and fissures which enable fast groundwater flow and also fast transport of pollutants. An expert bases for their protection are vulnerability maps. Different methods for the construction of these maps were developed, and to assess the vulnerability of the recharge area of the Korentan spring near Postojna the EPIK method was used. In this method, which was many times successfully tested on karst, the degree of vulnerabilty is defined on the basis of four parameters: developement of the epikarst, effectiveness of the protective cover, infiltration conditions, and development of the karst network. For the assessment of individual parameters different research methods were used, such as detailed structural-lithological and geomorphological mapping, and combined analysis of hydraulic and physico-chemical responses of the spring to recharge events. Final result is the vulnerability map, which defines the areas of very high, high and moderate vulnerability within the recharge area of the Korentan spring and can be used to set up the protection zones

Groundwaters of Serbian and Slovenian Dinaric Karst – Comparison of Current status, Use, Protection and Perspectives.

The Dinaric karst is the largest continuous karstland in Europe. With its outermost northwestern and eastern parts it extends to the territory of Slovenia and Serbia. Karst aquifers within it are very important sources of water supply in the two countries. We therefore decided to compare the characteristics of karst water resources and the approaches to the exploitation and protection of karst aquifers with the aim of searching for the most convenient methods for their research and management. Different characteristics of the two compared areas were established, as well as differences and similarities in the application of various research methods and the management approaches. The findings were summarized in the table which includes the most important parameters of karst water systems and research methods used for their study in the area of Dinaric karst in Serbia and Slovenia. As an example of good practice, two case studies are described in the article. For the Slovene part, vast experiences in the application of tracer tests with artificial tracers are reviewed and the guidelines for its efficient use in the research of karst aquifers are summarized. For the Serbian part, described case study of the detection of the pollution source in the recharge area of an important water source and the preparation of remedial measures are presented as an efficient approach to solve such problems on karst areas

Tracer tests as a tool for planning the monitoring of negative impacts of the Mozelj landfill (SE Slovenia) on karst waters

Tracer tests are one of the most useful researchmethods in karst hydrogeology and they have proved a valuable tool in various applied projects. In recent years we carried out a se­ries of tracer tests, and their results were used as the bases for planning the monitoring of water quality in the influence ar­eas of various pollution sources. In this paper, a case study of tracing at the landfill near Mozelj in southeastern Slovenia is described. The first goal was testing of the functioning of three monitoring boreholes, whichwere drilled at the margins of the landfill. As often happens in heterogeneous karst systems, they did not intersect the main flow paths from the landfill and are not suitable as monitoring points. On the other hand, the find­ings about the characteristics of tracer transport in the karst system and outflow throughthe karst springs were used for identifying the most suitable springs for monitoring and pre­paring an adequate sampling plan, whichshould be adapted to hydrological conditions

Water temperature as a natural tracer – a case study of the Malenščica karst spring (SW Slovenia)

For the adequate protection of karst springs it is important to understand the functioning of karst systems in their recharge areas. Besides tracer tests with artificial tracers, tracings with natural tracers, such as temperature, are a very useful research tool, especially in complex karst systems with various types and sources of recharge. Detailed monitoring of water levels and temperatures of the Malen&scaron;čica karst spring, as well as of the intermittent Cerknica Lake and Kotliči spring in its recharge area, indicated that temperature is a good tracer in winter and summer periods, especially when the Cerknica karst polje is flooded. High or low air temperatures influence the temperature of water, which sinks at the Cerknica polje and flows rapidly through karst channels toward the springs. Detailed analysis of selected events enabled calculation of the velocity of groundwater flow toward the Malen&scaron;čica spring under different hydrological conditions. The estimated values are in accordance with the velocities previously defined in this area, based on several tracer tests with artifi cial tracers. From the results, it is possible to assess the transport velocities of contaminants under different hydrological conditions. This is important information for the protection of the Malen&scaron;čica spring, which is captured for the public water supply.</span

Time series analysis, modelling and assessment of optimal exploitation of the Nemanja karst springs, Serbia

The time series analysis was applied in the case-study of a karst aquifer in Serbia in order to study its functioning, hydrody­namic behavior and hydraulic properties. Focusing on the defi­nition of groundwater budget, due to very complex function­ing of karst systems the correlation and spectral analyses were used to emphasize the importance of transforming the input data – precipitation to effective infiltration. The characteriza­tion of karst aquifer was further improved by separating the output component – discharge to base-flow and fast-flow com­ponents. Additionally, the importance of these transformations was proved in application of the regression model for the sim­ulation of discharges based on the effective infiltration func­tions. A recharge-discharge model was applied in accordance withthe active groundwater management, defining optimal “exploitable” regimes, whichincluded the analyses of storage changes in karst water reservoirs under natural conditions, and calculation of the potential exploitation conditions

Directions and dynamics of flow and transport of contaminants from the landfill near Sežana (SW Slovenia)

The characteristics of flow from the landfill near Sežana in the area of Kras were studied by the use of tracer test. In well permeable fissure on the karren surface near the landfill the fluorescent dye uranine was injected in order to study the directions and velocities of its flow through the karst aquifer. Monitoring of tracer concentrations in the period of one year and a half enabled us to make some conclusions about the dynamics of groundwater flow in the directions towards the Timava, Brojnica and Sardoč springs. Detailed observations were organised also at the Klariči pumping station, which is the main source of drinking water for the Kras region. Increased concentrations of tracer were measured only during extremely high waters. Different explanations are possible, but we can not exclude the possibility of a weak, not permanent underground water connection with the landfill. Calculation of the amount of recovered tracer confirmed the main flow direction towards the Timava springs (recovery rate 93%) and a secondary direction with lower flow velocity towards the Brojnica and Sardoč springs. Outflow through the Klariči pumping is estimated to only 0.003% of injected uranine.Key words: tracer test, landfill, Sežana, Kras, Slovenia

Tracer Test on the Mala Gora Landfill near Ribnica in South-Eastern Slovenia

The Mala gora landfill near Ribnica is one of the nine still active landfills on Slovene karst. According to our legislation the monitoring of its impact on groundwater have to be performed, but this can only be effective when the characteristics of the underground water flow in the area of the landfill are well known. Therefore a tracer test was carried out on the Mala gora landfill and the main underground water connections towards the Tominčev studenec, Javornikov izvir, Debeljakov izvir and Šica springs near the settlement Dvor in the Krka valley were proved. In lower concentrations the uranine was detected in the Podpeška jama and Kompoljska jama Caves, as well as in the Šica near Mala Račna spring and both springs of the Krka river. At high waters the flow from the landfill towards the Globočec spring was proved also, but this important source of water supply is primary recharged from other parts of the karst aquifer. The appearance of tracer is forwarded by favourable hydrological conditions and increased concentrations of uranine were measured at all springs after more intensive precipitation events even one year after the injection. Obtained results were considered in the preparation of the monitoring plan