Eh - pH diagram for system As - S - O - H
Eh - pH diagram for system As - S - O - H  Activity As(OH)4- = 0.0001 Activity SO4-2 = 0.0001
Eh - pH diagram for system As - S - O - H Activity As(OH)4- = 0.0001 Activity SO4-2 = 0.0001

 

Dissolved Arsenic Species
Eh pH diagram for system As - S - O - H Activity of As(OH)4- = 0.0001
Activity of SO4-2 =  0.0001 prepared using The Geochemist's Workbench
Eh pH diagram for system As - S - O - H Activity of As(OH)4- = 0.0001 Activity of SO4-2 = 0.0001 prepared using The Geochemist's Workbench

 

Eh pH Diagram for Cu - C - S - O - H
Eh pH Diagram for Cu - C - S - O - H  Activity Cu+ = 0.0001, HCO3- = 0.005, SO4-2 = 0.005
Eh pH Diagram for Cu - C - S - O - H Activity Cu+ = 0.0001, HCO3- = 0.005, SO4-2 = 0.005

Our Philosophy

Our philosophy is that projects that require expertise in environmental geochemistry follow a series of similar steps.  Such similarities exist because all environmental geochemistry projects require an understanding of the relationships between a source of chemicals and an environment.  These steps involve characterization of the source terms, understanding the geochemical condition of the receiving environment, as well as understanding the chemical reactions between the source and the environment.

Understanding and predicting the behavior of releases to the environment requires that the geochemical reactions between the source and geochemical setting be thoroughly understood.  In most situations, a series of competing reactions are taking place within the geochemical environment and it is critical to identify the dominant reactions early in the characterization process.  More importantly, the dominant reactions can change over time or as a function of distance as reactants are consumed and new chemical species are produced.  

To enhance our understanding of geochemical conditions models are often employed.  Because of the diversity of reactions that can occur in these situations, geochemical models can be used in many stages of a project.  The nature of a “model” can range from a simple qualitative description that may describe why the pH changes along a groundwater plume, to an Eh-pH diagram showing the importance of different chemical species, to complicated numerical models that may utilize various types of geologic, hydrologic and chemical data.   Although many models have been applied for long term predictions of water composition, geochemical models are often best used as a management tool to select the best options without having to resort to full scale testing or committing to a specific treatment method. 

This process of characterization, understanding geochemical conditions and modeling applies to projects that involve:

  • Permitting of new facilities that may require predictive models, such as a pit lake model,

  • Optimization of ongoing operations, such as improving in-situ recovery of metals, and

  • Remediation of previous releases, which may have occurred at legacy operations.

In our role as “a consultant to the consultant”, we have acquired the experience in developing the types of data that are needed for these diverse projects, as well as the ability to understand and quantify the detailed chemical reactions that are critical to a successful project outcome.  

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