Full-Scale Application of STAR (In Situ) to Treat Coal-Tar Impacted Soils
Former Industrial Site in New Jersey
The fill and alluvium units underneath a 37-acre site located in Newark, New Jersey, are contaminated with residual and free-phases of coal tar from the historic operations of a former industrial facility. The soil remedial objective is the removal of non-aqueous phase liquid (NAPL) to the extent practicable. A cost effect remediation strategy was developed for STAR based on results from Pre-Design Evaluation (PDE) studies.
Full Scale Design
PDEs were conducted to collect data regarding: 1) contaminant mass destruction rates; 2) radius of influence (ROI); 3) propagation rates; and 4) vapor emissions levels.
The application of STAR at full scale requires approximately 1500 surficial fill ignition points and 500 alluvium/sand aquifer ignition points. Rather than attempting to establish all ignition points simultaneously, STAR is being deployed in ‘leapfrogging cells’ that are made up of 20 ignition direct push points. Each cell is serviced by centralized equipment ‘nodes’ containing an air distribution and vapor collection/treatment system. After treatment is complete, the heaters are removed and deployed to another pre-installed cell, while the treated cell ignition wells are removed and installed in another location. Two parallel treatment systems are currently operating in this ‘leapfrog’ pattern.
Full Scale Implementation
System operation began in 2014 and is anticipated to continue through 2018. Data collected to date indicates that mass destruction rates from a single operating cell within the deep sand unit (6 ignition wells) are on the order of a ton of coal tar per day. Post-treatment soil concentrations are consistent with PDE results.
Conceptual Site Model of Contaminant Distribution
Pre-design Evaluation (PDE)
Full Scale Design and Implementation
- PDEs determined treatment levels, cycle times and radius of influence
- Full scale design approved by NJDEP
- Field deployment has begun with operations to be completed in 2018