STAR (In Situ) Pilot Test to Treat Coal Tar Impacting Two Hydrogeologic Units
Former Industrial Site in New Jersey
STAR was evaluated as an alternative to excavation and disposal and Low Temperature Thermal Desorption (LTTD) at a 37-acre former manufacturing facility in New Jersey impacted with coal tar. A Pre-Design Evaluation (PDE) was conducted within two hydrogeologic units (i.e., surficial fill and underlying sand units) to evaluate key design parameters such as: 1) contaminant mass destruction rates; 2) STAR well radius of influence (ROI); and, 3) vapor emissions levels, in preparation for the design of a full-scale remedy for the site.
Pre-Design Evaluation (PDE)
The PDE within the surficial fill unit demonstrated sustained destruction rates in excess of 800 kg/day resulting and the destruction of more than 4,500 kg of coal tar. This treatment was supported solely through air injection at a single well following a 90-minute ignition period. Deep sand unit testing (twenty-five feet below the water table) resulted in the treatment of a targeted six-foot layer of impacted fine sands to a radial distance of approximately twelve feet. Analysis of collected vapors showed that approximately 1% of the total remediated mass was volatilized (and collected for subsequent treatment); whereas approximately 99% of the coal tar was destroyed via smoldering combustion. Post-pilot sampling for both units demonstrated a substantial reduction in coal tar volume within the target treatment zones, with volatile and semi-volatile organic compound concentrations reduced (on average) by greater than 99% in zones where combustion was observed or detected. These results (and additional parameters) were used to develop a full-scale STAR design for the site.
Soil Cores Before and After Pilot Test
Selection of STAR for Full-scale Application
The PDE results were used to develop a full-scale STAR design consisting of approximately 1500 surficial fill ignition points and 500 deep sand ignition points and two treatment systems (air distribution and vapor collection/treatment system).
The STAR technology is a rapid, safe, and low cost remedial alternative for source areas.
- Resulted in the destruction of more than 4,500 kilograms of coal tar within the surficial fill unit and more than 800 kilograms of coal tar within the deep sand unit.
Showed radii of influence from a single point of ignition up to 30 feet in the shallow fill unit and up to 12 feet in the deep sand unit.
- The full-scale design incorporated key design parameters evaluated during field testing and integrated a detailed Conceptual Site Model (CSM)
- Full scale remediation began in early 2014 and is anticipated to continue through 2016.