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Basic Scenarios

Basic scenarios

 The basic scenarios for the Tarnowskie Góry megasite were developed according to the defined risk reduction objectives. The following possibilities of technical measures were identified by the expert team to be included as possible solutions for the management of risk clusters:

  1. Source-oriented measures (see figure below):
    • primary sources (dumping sites) capping or removal,
    • contaminants immobilization in soils and Quaternary deposits (secondary source);




  1. Pathway oriented (see figure below):
    • construction of hydrological barrier:
      • internal (located within the chemical plant area to stabilize the plume within the source area), or
      • external (located outside the chemical plant, perpendicular to the groundwater flow and plume migration to contain the plume within the risk management zone (RMZ);




  1. Receptor oriented (see figure below):
    • monitoring,
    • water extraction regime at receptors (wells) development as a hydraulic barrier.




The effectiveness of the basic scenarios in fulfilling the management goals was analyzed based on modeling, and is discussed below.
  1. Containment of the boron plume (defined by the 1 mgB/dm3 concentration contours in groundwater) within the RMZ.
    This goal can be fulfilled with a narrow margin of certainty in every analyzed basic scenario and in any timeframe, even in the worst-case scenario of leaving the unsecured waste heaps within the megasite boundaries. The goal implies that the natural attenuation (NA) allows for plume dispersion in a time frame of 120 years.

  2. Stabilization of the contamination plume within the current boundaries.
    This goal cannot be fulfilled by separate but only by a combination of basic scenarios analyzed (i.e. source, pathway and receptor-oriented). The goal implies that the NA allows for plume dispersion in a timeframe of 80 years.

  3. Maximum possible reduction of the contamination plume within a moderate time frame.
    This goal cannot be fulfilled by separate but only by a combination of basic scenarios analyzed (i.e. source, pathway and receptor-oriented). The goal implies that the NA allows for plume dispersion in a timeframe of 60 years.
It can be concluded that the effects of basic scenarios applied separately are not effective enough to achieve risk reduction objectives (see figure below).





Therefore, basic scenarios were combined to build up the potential scenarios, by which the defined risk reduction objectives can be achieved. This was an iterative process taking into account: revized boundary conditions, defined risk reduction objectives and technical feasibility aspects.

Revision of the boundary conditions

As a result of the group of stakeholders (GOS) meeting, the boundary conditions of the Tarnowskie Góry megasite were revised to reflect the following aspects.
  1. Management within the risk clusters should be path- and receptor- oriented, and two key factors should be taken into account:
    • groundwater quality,
    • groundwater quantity,
  2. These factors should be addressed on different scales:
    • at the megasite,
    • at the RMZ and its risk clusters,
    • at the RMZ and the area around
  3. Hazardous waste removal and safe landfilling should be the basis for any potential scenario build-up as removing of the source eliminates contaminant flux to groundwater

    The officially established management plan for the Tarnowskie Góry megasite includes:
    • construction of a controlled landfill for hazardous waste of an area of 16 ha with the capacity of 1,6 million m3,
    • safe deposition of approximately 1.5 million m3 of hazardous waste in a way that complies with the legal Polish and EU requirements,
    • revitalization of the Stola river valley including the construction of new bed at the length of 800 m within the area of the chemical plant,
    • revitalization of the area of 50 hectares of previous dumping sites with the allocation of ca. 10 ha for the further use,
    • continuous long-term monitoring of all environmental compartments (soil, water and air).
    Note: The results of simulation studies show that land filling of waste has a moderate effect on improving groundwater quality in a short- (30 years) and medium-term (60-80) time frame. It guarantees that some of the risks, which occur on the surface level of the megasite, are moderated or eliminated. The remaining risk, due to the secondary sources of contamination (the Quaternary deposits) is attributed mainly to groundwater quality within the delineated RMZ. The total costs of this measure, including industrial constructions dismantling, construction of a safe landfill, waste removal and soil remediation, are estimated at the level of 12 million Euro.

  4. Site hydrogeology should be recognized as a key boundary condition of any management scenario.
    In the case of the Tarnowskie Góry megasite the dynamics of the hydrological system should be managed cohesively on a broader scale, even beyond the established RMZ (see figure below).

    The hydrological conditions are important for the receptors (operating wells) located in the south-western part of the RMZ. For example, changing of the water extraction regime beyond the RZM (lower extraction quantities in wells located in the western and higher in the south-western part) may result in the higher risk in the south-west of cluster IIb due to changes in groundwater flow directions. Moreover, increased water extraction of the Triassic layer II can result in groundwater deterioration.


  1. There is no direct short-term risk for the receptors due to low groundwater flow rates, therefore the megasite management can be more flexible both in time and space.

    2. Potential Scenarios

    Potential scenarios

     Potential scenarios

    In all potential scenarios to be applied for the Tarnowskie Góry megasite, a full realization of the liquidation program already approved with hazardous waste removal is assumed as a basic requirement. With regard to that, three potential scenarios were built up, by combining the source removal with other basic scenarios:

    S 1 - controlled natural attenuation (NA), i.e. source removal + monitoring and control of the hydrological regime (see figure below),



    S 2 - active groundwater remediation (AGWR), i.e. source removal + groundwater clean-up + monitoring,




    S 3- engineered natural attenuation (NA), i.e. source removal + increased abstraction of groundwater (specific and low-risk oriented) within the Risk Management Zone (RMZ) + monitoring




    These scenarios were further worked out by means of modeling, and key implementation issues were identified: infrastructure requirements, time frames and risk reduction effects. Detailed technical variants for the scenarios were developed and analyzed. (Reports can be found in About -> Deliverables: WP4

    Final Scenario

    Final scenario

     Preferred megasite scenarios

    According to the cost-efficiency and cost-benefit analysis (see deliverable 4.6) three preferred scenarios were taken into consideration. These scenarios can be fine-tuned with respect to technical, infrastructure and economical aspects. They depend heavily on the boundary conditions, which in the case of the Tarnowskie Góry megasite are very sensitive and may be a subject of changes in time. Having this in mind, the GOS decided to keep the management scheme open. However, most of the concepts (e.g. RMZ, risk clusters, plane of compliance, risk assessment, monitoring coupled with modeling) developed within the IMS should be integrated into the further actions of members of the GOS. The Scenario S1 and S3 are preferred because of their cost-efficiency and benefits. But the implementation of the scenario S2 was not excluded. The final decision will depend on the following:

    • Access to funds;
    • Elimination of knowledge and technological gaps,
    • Stabilization of environmental regulations

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