Theme: 06. Petroleum and Heavy Hydrocarbon Site Strategies

Topic Area: 6b. In Situ Remediation of Petroleum Hydrocarbons

Formatted Title:

Remediation at a Remote Petroleum Hydrocarbon-Contaminated Site

Background/Objectives:

This project was undertaken to support the cleanup of a remote northern property in northern Ontario (ice road or float plane access only). The property exhibited a large fuel oil spill area which resulted in soil and groundwater petroleum hydrocarbon (PHC) contamination. AEL’s specific objectives were to remediate soil and groundwater contamination to the applicable criteria.

Approach/Activities:

In order to facilitate remediation for such a large volume of contaminated soil, AEL used a combination of excavation and disposal for soil treatment and in situ chemical oxidation (ISCO) for groundwater treatment. Soils were excavated and screened on site. Soil that failed screening was loaded into large sling bags and transported via helicopter to barges which carried the contaminated soil to landfill. Soils that passes screening were recycled for reuse via backfilling. Excavation extents were determined in real time using a combination of a photoionization detector (PID) calibrated for PHCs and a ultraviolet fluorescence (UVF) site laboratory and verified via laboratory samples, flown out in batches. It has been AEL’s experience that the combined screening modality provides significantly increased accuracy of screening relative to simply relying on a PID. Groundwater was treated using sodium persulfate activated by a combination of sodium hydroxide (i.e., base activation) and a simple carbohydrate mixture. Due to the remote nature of the Site, all remedial injection materials were flown out to the site in 5-gallon pails.

Currently, the contaminated soil has been all removed and two (2) rounds of post remediation groundwater sampling have been carried out from wells within and surrounding the excavation. As of the second round of sampling, no exceedances were noted in groundwater.

Results/Lessons Learned:

Due to the remote nature of the Site, many standard remediation methods were ruled out due to mobilization costs and the short summer season, which makes cost effective remedial methods such as bioremediation proceed at an reduced pace. Even when cost effective remedial methods are investigated, care must be taken to ensure redundancies and the unknowns associated with travel to remote sites. For ISCO remedial amendments, specialized transportation was required to ship the large quantity of sodium persulfate and sodium hydroxide. When dealing with remote sites, an up front comprehensive cost analysis of multiple remedial approaches which consider the remote nature of the Site is integral to project success.

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Simon Huddart