Extraction rates can vary greatly depending upon the amount of steam injected, the total vacuum applied, and cycle times. Permitting of air discharges from both aboveground treatment units and equipment used to supply steam energy is an issue requiring early attention. DUS is a labor intensive process requiring significant field expertise to implement. ERT proved to be the most effective method for monitoring the DUS process in real time. Alternative geophysical techniques could be used for other applications.
Treated soils can remain at elevated temperatures for months and even years after cleanup.
This could impact site reuse plans. Soil venting can greatly accelerate the cooling process. DUS is not applicable at depths less than five feet. At greater depths, the steam injection pressure can be increased, which produces higher efficiencies and extracts more work from each well. Future Technology Selection Considerations DUS was effective at quickly removing concentrated free-product contaminants, including materials sorbed to saturated sediments, without mobilizing contaminants outside the treatment zone.