Quintessa's hydrogeological modelling consultants specialise in flow and transport problems that are typically encountered in relation to radioactively contaminated sites, near-surface and deep geological storage / disposal, and construction and operation of engineered facilities.

Quintessa's hydrogeological modelling capabilities and experience includes:

  • saturated groundwater flow and contaminant transport conceptual and mathematical modelling of impermeable environments where the permeability is governed by discontinuities and is therefore highly heterogeneous;
  • specification and interpretation of hydrogeological investigations including hydraulic tests and water balance studies, particularly for complex heterogeneous Quaternary deposits and low permeability systems;
  • near-surface hydrology modelling and its coupling to groundwater flow at depth;
  • radionuclide geochemical and transport behaviour;
  • leak detection and leak scenario modelling;
  • seepage into excavations, shafts and tunnels during dewatering;
  • impacts of groundwater abstraction on the water table, flow and contaminant transport;
  • multi-phase flow behaviour in relation to deep geological disposal (including coupled gas generation), CO2 and natural gas storage systems, non-aqueous phase liquids (NAPLs) and hydrates;
  • coupled hydro-mechanical behaviour in relation to rocks that exhibit creep and swelling clays such as bentonite; and
  • coupled hydro-mechanical-chemical behaviour in relation to erosion of bentonite.  

For projects beyond standalone calculations, our preferred approach is to ensure that hydrogeological models are developed within the wider framework of systematically developing system understanding, identifying the important Features Events and Processes (FEPs) and process couplings (phenomenology), and managing uncertainty. This leads to the approach of starting with simple models and only adding complexity as necessary thereby ensuring that resources are focussed on the key FEPs, couplings and uncertainties. The FEPs and couplings included in, and excluded from, the final model can then be justified. We have a strong focus on sense checking model results using logical analysis, simple analytical solutions and simple supporting models.  

We can work within a customer’s approach to developing system understanding, or we can also guide the approach, for example using techniques such as Evidence Support Logic (ESL) to identify the scenarios to be modelled, key FEPs, couplings and uncertainties.

Quintessa uses start-of-the-art commercial and in-house software, selecting the most appropriate code for the nature of the problem including the key FEPs. Our in-house QPAC software enables us to tackle complex coupled THMC problems; specifying all processes and process couplings that are of interest. Thus when using QPAC, our conceptual model is not based on the functionality of a specific code. Instead, we specify the conceptual model based on understanding of the key processes and then use the numerical model to test the conceptual model.