As part of their management of environmental liability, a power transmission client wanted help evaluating the fate and transport of pentachlorophenol (PCP), creosote, and arsenate compounds from utility transmission line poles to the surrounding environment. Through modelling the current and anticipated behavior of contaminants along a transmission line, the goal of the project was to develop remediation criteria that were more reflective of the actual risk to receptors, and to provide a viable pathway to closure (i.e. obtaining a reclamation certificate) that would be acceptable to the regulator and industry stakeholders.
Matrix Solutions was retained to:
- Conceptualize and develop three discrete models for each of the contaminants considered,
- Evaluate the fate and transport of each contaminant under real-world scenarios, and
- Develop a risk assessment framework to determine the need for remediation at any pole location.
Our team performed multiple discrete fate and transport simulations using variations of input parameter values to reflect the range of soil and hydrogeological properties in Alberta, as well as variations in the chemical-specific properties of the contaminants. The modelling included scenarios wherein a pole had been installed within saturated soil or was in direct contact with a surficial aquifer. For creosote and PCP, additional modelling was completed for a scenario wherein the poles are installed within unsaturated conditions.
The modelling consisted of two parts:
- Determining how much contaminant could be released from a pole, at what rate, and over what period of time, and
- Modelling contaminant movement through soil and groundwater.
The modelling simulated expected downgradient concentrations of contaminants around poles over a 100-year period; as well as the contaminating distance from the pole since estimated time of installation.
This was a novel modelling project that had not previously been completed in Alberta. As such it required an extensive literature review and conceptual development to create an adaptable and informative model. Additionally, the modelling work was interdisciplinary and involved personnel from across Canada in multiple time zones. This presented unique challenges for project management and effective collaboration; however, they were readily identified and overcome by the project team.
Remediation of impacted soil at all pole locations is not feasible for various reasons, including depth of contamination, the remoteness of some lines, and the large number of locations involved. Therefore, Matrix Solutions utilized model results to create a risk assessment framework for determining the need for assessment/remediation at any particular pole location, and to subsequently develop site-specific remedial guidelines to reduce overall environmental liability while ensuring protection of all potential receptors.