Hydrocarbon Spill – Project Profile
The work included site assessment, conceptual site model development, and risk management plan implementation to address a historic petroleum hydrocarbon spill with an on-site and off-site approximate area of 2,900 m2 that. The site is an active industrial site located in Edmonton Alberta. Benzene and ethylbenzene in soil and groundwater were the primary contaminants of concern.
Pipelines within the impacted zone were first suspected of being the source of the hydrocarbon contamination but was later excluded based on additional site assessment and establishment of a more detailed site conceptual model. The contamination appeared to originate from a garage near the shared property line and pipeline right of way.
Based on integrity concerns expressed by the pipeline company related to excavation close and provided the existing site infrastructure, geotechnical issues related to excavations, and ongoing business activities at the site, an in-situ remedy for petroleum hydrocarbons was selected. The hydrocarbon source zone was treated with 6,000L of combined sodium persulfate activated with calcium peroxide (Klozur® CR) in 30 temporary injection points.
A Risk Management Plan was implemented after the in-situ program was completed. Groundwater was monitored for in-situ remedy effectiveness and for verification of monitored natural attenuation. Pre-remediation, the approximate area of groundwater concentrations higher than Alberta Tier 1 guidelines was 3,100 m2 and was 1,600 m2 two years later. The benzene concentrations both on-site and off-site decreased by approximately 80% between 2015 and 2017. In this same time period, the ethylbenzene concentrations on-site dropped between 65% to 90% and by approximately 50% off-site. The frequency of groundwater monitoring has been decreased following the success of the remediation program.