STAR is an innovative in situ thermal technology based on smoldering combustion, where the contaminants are the fuel. The process is sustained by the addition of air through a well to the target treatment zone and is initiated through a short duration, low energy “ignition event.” Once the process is initiated (ignited), the energy of the reacting contaminants is used to pre-heat and initiate combustion of contaminants in adjacent areas, propagating a combustion front through the contaminated zone in a self-sustaining manner (i.e., no external energy or added fuel input following ignition) provided a sufficient flux of air is supplied. Active control of the combustion front is maintained by the air supply. This efficient recycling of energy is made possible by the presence of the porous matrix (i.e., contaminated aquifer) that is being remediated.
The above ground equipment used to implement the technology is similar to that used in Air Sparge (AS) / Soil Vapor Extraction (SVE) systems and includes compressors for sub-surface air delivery, blowers for ground surface vapor collection, and vapor phase activated carbon or a thermal oxidizer for vapor treatment. The specialized equipment associated with the STAR process includes the use of 2-inch diameter, carbon steel direct push ignition wells with a stainless steel screen, temporary in-well heaters to initiate the process, and subsurface multi-level thermocouple bundles to track the combustion process.