These guidelines were commissioned by the Ministry of Environment of British Columbia (BC MoE) under contract GS12ESD-116 and are referred to as "groundwater modelling guidelines" or simply "guidelines" throughout this document.
These guidelines were written by Dr. Christoph Wels (Robertson GeoConsultants Inc.), Dan Mackie and Jacek Scibek (both of SRK Consulting (Canada) Inc.). The authors have over 40 years of combined experience in groundwater modelling for the mining and groundwater resource industry.
The development of natural resources in British Columbia includes hard-rock mining, aggregate mining, and groundwater extraction projects. Development, operation, and closure of such projects involve an assessment of environmental impacts before a project can be approved by the regulatory agencies. Note that oil and gas developments may also use significant amounts of groundwater resources. Although this industry sector is not covered explicitly included in these guidelines, the general principles discussed in these guidelines may also apply to that sector.
The scale and nature of mining projects and large groundwater extraction projects may impact the receiving environment (including groundwater and/or surface water). The impact needs to be quantified prior to undertaking the project.
Recent advances in computing power and user-friendly modelling software have made the use of numerical groundwater models for impact assessments common. Table 1-1 lists mining and groundwater extraction projects that submitted full Environmental Assessment (EA) applications and were accepted for review by the B.C. Environmental Assessment Office (EAO) in the last decade. A review of the groundwater modeling studies completed for these projects indicates that most proponents used numerical groundwater models to support their (EA) application.
The use of numerical groundwater models enables decision makers to study and evaluate large and complex resource development projects. Sophisticated models and modelling platforms are, however, no guarantee of good modelling practice. The complexities of groundwater models used for impact assessment may even lead to misuse and/or misinterpretation.
To address the complexity and avoid potential misuse of groundwater models, there is a need to provide guidance to industry and government agencies on how to develop, use, and review groundwater models used to assess environmental impacts due to mining and large groundwater extraction projects.
These guidelines address the broader concepts of groundwater modelling related to the EA process in British Columbia. Yet, these guidelines reflect generally accepted best practices in groundwater modelling and as such should be applicable to a wider range of groundwater modelling applications.
To the best of our knowledge no groundwater modelling guidelines are presently available for any Canadian jurisdiction and none of the international guidelines reviewed (see Appendix A) has a specific focus on resource industries such as mining and/or groundwater extraction.
The objective of this document is accordingly to provide guidelines for groundwater modelling undertaken to identify and assess the impacts of natural resource projects in British Columbia, with specific emphasis on:
- Hardrock mining (metal, coal)
- Aggregate Mining (gravel)
- Large groundwater extraction projects (>75 L/s)
These guidelines provide general guidance based on accepted "best practices" for:
- Development and use of groundwater models by resource industry groundwater professionals.
- Review of groundwater models by regulators.
This document was written for use by the industry ("proponent") and regulatory staff or agency ("regulator") involved in the assessment of environmental impacts for natural resource projects in British Columbia using groundwater modelling. These guidelines assume that the reader has an understanding of hydrogeology and a basic understanding of groundwater modelling. Practical experience in groundwater modelling is not, however, required to use these guidelines.
These guidelines discuss basic concepts of groundwater modelling. The reader is strongly encouraged to study standard textbooks on hydrogeology and groundwater modelling if he/she has no formal training in these subject areas (see Appendix B for a list of recommended readings).
A supplementary online course (based on these guidelines) serves as a self-directed training tool for regulators involved in developing or reviewing groundwater modelling projects. This on-line training course can be accessed free of charge by the regulators and the wider public at the following URL: http://www.rgc.ca/moe/guidelines/.
1Industry means a person, company or entity who is in the business to develop a natural resource (e.g. mining or large extraction well project) and includes environmental and groundwater consultants in the business of doing the groundwater modelling and impact assessment work for the industry
The guidelines include the following sections:
- Section 2 - Proponent-Regulator Interaction in the B.C. System, provides background information to groundwater modelling in the context of the British Columbian regulatory process. Specifically, this section describes the regulatory process as it affects preparation by the proponent (project developer) of groundwater models to support project review by the regulators who are charged with assessing the potential adverse effects of a proposed Project and making recommendations to the responsible Ministers for an Environmental Assessment Certificate, allowing a proposed Project to proceed to the permitting stage.
- Section 3 - Groundwater Modelling for Impact Assessment of Natural Resource Projects, describes the application of groundwater models for assessing the impact of resource development projects on the groundwater. Specifically, this section addresses what issues may be evaluated with groundwater models to establish potential impacts and identify mitigative measures for hard rock mining, aggregate mining, and groundwater extraction projects.
- Section 4 - Conceptual Model Development, describes the process of developing a conceptual model of the groundwater system at a specific site. The section establishes how information about the site geology, hydrology, potential contaminants, and project-specific features may be assembled into a conceptual model that forms the basis of the mathematical groundwater model.
- Section 5 - Mathematical Model Selection, describes the types of mathematical models that may be used to quantify groundwater flow and solute transport at a site both before and after initiation of the project. The section provides guidance on the selection of specific mathematical models.
- Section 6 - Numerical Model Setup, describes how to set up a mathematical groundwater model. The section deals with the technical approach to the definition of the model domain, numerical grid, boundary conditions, layers (that represent different geological strata), and how to mathematically represent sinks and sources, including those project facilities that may be the origin of contaminants to the groundwater.
- Section 7 - Model Calibration & Verification, deals with the calibration and verification of groundwater models. Calibration is a process of refining model parameters based on comparison of field data to model-predicted values. Verification is the use of alternative analytical techniques to establish the extent to which the select model is robust in its prediction of the groundwater flow system.
- Section 8 - Model Prediction & Uncertainty, describes how a groundwater model is used to predict in what way groundwater responds to the construction and operation of project facilities, including, for example, excavation of an open pit, placement of a tailings impoundment, or extraction of groundwater for project use. This section also discusses how to assess the uncertainty in model predictions.
- Section 9 - Transport Modelling, provides an overview of the methods used to model and evaluate the migration of contaminants of concern (CoCs) in groundwater that may impact the environment.
- Section 10 - Model Documentation, provides guidance for documenting groundwater modelling in order to facilitate review and approval by regulators.
- Section 11 - Model Review, provides guidance on for reviewing groundwater studies submitted by a proponent for review and project approval.
In order to illustrate the applicability of these guidelines, three representative case studies were also included in these guidelines (see Appendix C). These case studies include:
- A proposed open pit mine (hardrock)
- A proposed underground mine (hardrock);
- A proposed large (>75 L/s) groundwater extraction project (surficial)
Every resource project has a unique combination of site conditions, project activities, and modelling requirements. Professional judgment by the modeller, based on experience, and specific conditions and requirements of a project or a site, is required to select the best approach to modelling a particular site and project. These guidelines therefore provide generally applicable guidance and a framework for groundwater modelling. The guidelines do not set prescriptive standards.
Professional judgment introduces subjectivity into the modelling process and may result in questions and debates within the regulatory process. These guidelines therefore recommend that the industry proponent consults the regulatory agencies on key aspects of the modelling project so any questions and debates can be addressed in a timely manner.