Data Analysis and Simulation of TCE and PCB Waste Dumping at the Smithville Phase 4 Bedrock Remediation Site

During the late 1970s and early 1980s wastes and solvents, including TCE and PCBs, were stored at the Chemical Waste Management Ltd. (CWML) site in Smithville Ontario. Poor management practices resulted in contaminant spills and the development of a groundwater plume that impacted the municipal water supply. The Ontario Ministry of the Environment (MOE) assumed management of the site and undertook a four-phase program to remediate both the site and underlying soil, bedrock and groundwater systems. Earthfx was retained to design and populate the site database, perform geostatistical analysis of plume extents, and undertake numerical simulation of the groundwater system.

To begin, a comprehensive database of all long term monitoring records was created. Earthfx scanned and digitized over 100,000 records of historical data and developed an automated 27 step QA process to ensure data collection integrity. An interactive graphing system was developed to present and review TCE and related historical contamination data (Figure 1). Over 1 gigabyte of data was compiled, including maps, air photos, borehole geophysics, water level and water quality data, geological descriptions, surface water information, atmospheric conditions and private water well records.

Geostatistical analysis was then undertaken to assess the uncertainty in the monitoring data. Variogram analysis showed that the monitoring network needed to be expanded in order to develop a justifiable range of data extrapolation. Interpolation of the plume extents was undertaken using the Kriging mythology. Further groundwater model simulations were undertaken to assess groundwater flow conditions and long term movement of the plume.

Finally, this information was used to develop a site remediation strategy. A network of remediation wells were designed and installed (Figure 2).

As of 2018, Earthfx continues to host the data management system for the Ministry of Environment and the Ontario Clean Water Agency (OCWA).