Remediation of a jet fuel contaminated aquifer through enhanced chemical desorption

The implementation of a georefereced database provides an integrated management, representation and analysis of diffrent data (geological, hydrogeological, hydrogeochemical and geophysical) along with the creation of a 3D Hydrogeophysical model that represents an effctive “near real time” Decision Support System able to manage and to release data during the diffrent remediation phases, from the characterization to the technique of implementation, were carried out on a site that consists of a large airport area located in central Italy, where about twenty years ago a jet fuel spill occurred. This site is characterized by the alternation of fie and coarse particle size materials with a groundwater depth equal to about 5m showing a high variability throughout the year. The detected contamination, despite being mainly caused by a spill, is quite extensive and has been the subject of years of a Pump & Treat intervention (still operational) that over time has allowed both the reduction of the contaminant mass and a narrowing of the contaminant plume, that progressively has reached an asymptotic trend. Some portions located immediately downstream of the source show the residual presence of contaminants, which are considered irremovable with the technology being performed, due to the presence of phases adsorbed mainly to the less permeable portions of the aquifer. An in situ enhanced chemical desorption strategy was implemented using the Regenesis PetroCleanze™ product with a main technological function to increase the desorption of hydrocarbons adsorbed to saturated soils or at the capillary fringe, and to increase the recoverability of the product in a separate phase while hydrocarbons are made available in the dissolved phase, allowing a subsequent rapid and effctive physical recovery. The intervention was carried out during the pilot phase in 3 diffrent areas, by a direct application in the existing wells and reactivating the Pump & Treat system a few days later. The monitoring carried out made it possible to verify a substantial increase in the concentrations in the post-application phase, with a progressive subsequent decrease as a result of the pumping activities. The speciation analyzes carried out made it possible to detect an increase in the shorter hydrocarbon chains, indicating that the prevailing effct of the treatment was probably of a partial oxidative type with the breaking down of the longer chains. The monitoring data obtained during and after the test activities showed that a signifiant mass of contaminants was recovered (signifiantly increasing the effiency of the system present on the site) and a reduction of the pollutant mass in the area of interest. In addition to the monitoring activities, geophysical tests were performed during the test, which allowed to provide interesting information about the distribution of the reagents in the saturated subsoil. The full-scale project is currently underway. The case study is considered of interest as it illustrates an example of how it is possible to optimize the removal of LNAPL contaminants when they are substantially no longer recoverable by conventional technologies.