SUBSURFACE CHARACTERISATION, MODELLING, MONITORING, AND REMEDIATION OF FRACTURED ROCKS - OVERVIEW OF THE NRC REPORT

A committee of the National Research Council has conducted a study to address issues relevant to subsurface flow and contaminant transport in fractured media, including low permeability and low porosity media, as well as in deep (3 to 5 kilometres) fracture systems. Subsurface characterisation, modelling, monitoring, and remediation (SCMMR) issues applicable throughout the lifecycle of engineered facilities that have the potential to release contaminants and pose risk to groundwater quality have been considered.

As part of its information gathering, the committee convened a workshop to examine the state-of-art and state-of-practice in:

• Subsurface fracture and matrix characterisation, especially relevant geotechnical, hydrological, and geochemical properties, and the development of conceptual models;

• Detection of fluid and contaminant pathways and travel times;

• Detection and modelling of factors that affect changes in geotechnical and hydrological properties over time (e.g., decades to millennium), including thermal, hydrological, chemical, and mechanical (THCM) processes;

• Groundwater and contaminant transport modelling, monitoring, and remediation, and how these can aid decision making during facility design, operation, remediation, and decommissioning;

The committee is issuing a final report in October that will include findings and conclusions with respect to (i) where research and development could improve the current state-of-art in SCMMR, and (ii) where incorporation of scientific and technical advances could enhance the state-of-practice in SCMMR and (iii) where enhanced science-based understanding could inform federal regulations, policies, and implementing guidance.

This talk will present the overview of the finding of the committee, delivered by one of the ten committee members. The focus will be on how the state of the art has advanced over the past 20 years, present the committee’s recommendations on a holistic and heuristic approach to site investigation in fractured rock, and discuss where additional research is needed to allow for effective characterisation, investigation, monitoring, and remediation at fractured rock sites.