Treatment of Oil-Impacted Soil and Oily Waste: Overview of Two Field Demonstration Projects
Authors: Sabadell Gabriel , Thomas David , Bireta Paul , Scholes Grant , Murray Cody , Boulay Benoit , Grant Gavin , Major Dave 
Published: April 2018

Treatment of oil-impacted soil and management of oily waste are often significant challenges of environmental stewardship at E&P facilities. Both oil-impacted soil and oily waste (e.g. tank bottoms, clarifier or pit sludge) result from E&P activities at sites that are distant from waste disposal or treatment facilities, or may not have such facilities available. A technology to effectively treat these materials onsite has been developed and field demonstrated at two different sites. One field demonstration project was specific to sludge treatment, while the other project assessed the treatment of oil-impacted soil from active remediation sites.

The treatment technology that has been developed is an ex situ method for treating oil containing materials on a flat working surface, referred to here as Hottpad. The process utilizes the oil content in the material to be treated as the primary fuel for treatment via smoldering combustion. Hottpad is an innovative technology to initiate and sustain the treatment process. Each Hottpad unit is equipped with a heat source to initiate the reaction, and an air distribution system to keep the smoldering reaction active and propagating upward in the direction of air flow. The heat source is only required for a short duration, after which time it is turned off and the supply of air is sufficient for the treatment to continue to completion without the need of additional external energy (i.e. self-sustaining). The current Hottpad configuration is the culmination of more than 5 years of collaborative research and technology development. The resulting technology is cost-effective and robust, applicable to a broad range of materials.

The initial scale-up of the technology was performed in 2016, when a full-size unit was operated for the treatment of large volumes of sludge (&gt; 45 m3 per batch). The initial project was to demonstrate the viability of the technology at large scale. The favorable results prompted additional modifications of the test system, essentially converting the system to a more practical configuration representative of an actual remediation unit. The modifications included the addition of vertical walls around the perimeter and testing of different emissions treatment methods. The second demonstration project focused on assessing the treatability of high clay, oil, and moisture content oil-impacted soil from an active remediation site. Leveraging learnings from the first field demonstration project, most notably that a small prototype unit can be used to scale up to large systems, a cost-effective small scale Hottpad system was used to run the treatability tests. The small-scale units were also equipped with vertical walls. The smaller units allowed for more runs in a shorter time, using less material, yielding more information.

The additional field tests have improved our understanding of the technology and provided results that will help improve its application in the future. Of significance, the results confirm the technology is very robust, both in terms of the range of materials that can be treated and from an operations perspective; the technology is very cost-effective; the technology may be implemented on site, reducing off-site transportation and eliminating safety concerns, while simultaneously reducing the overall remediation carbon footprint; and the treatment will meet even the most stringent remediation requirements. In addition, these projects confirm that small-scale treatability testing, when necessary for potentially difficult to treat materials, will provide the necessary information to assess site-specific technology applicability.