Formatted Title
Optimizing the Remedial Approach to Accelerate the Remediation Timeline while Managing Client Expectations: Remediating a Complex Former Manufacturing Site
Background/Objectives
The Site is a historical manufacturing site in northern New Jersey impacted by chlorinated volatile organic compounds (CVOCs). An interdisciplinary team of environmental consultants, technology vendors, and injection contractors developed a treatment-train option to accelerate the remediation timeframe at the site. Comprehensive site characterization prompted a kinetically aggressive in situ approach in the source area while limiting disruptions to site operations. A combined remedy initiative (CRI) was undertaken to achieve short-term goals of mass reduction in the source area and mitigation of plume concentrations using reductive technologies. Continuous evaluation of site geochemical conditions informs the need for additional remedial measures and helps to identify when the transition to monitored natural attenuation (MNA) should occur.
Approach/Activities
Direct excavation around the historical discharge source area was completed to remove contaminant/source mass that was physically accessible. This task included a significant investment in structural support and off-site disposal of significant volumes of hazardous soil and groundwater. These costs triggered the transition to In-Situ treatment.
To address the remaining mass, a chemical oxidation (ISCO) pilot test was conducted using activated sodium persulfate. The goal of this pilot was to evaluate in situ remedial options and gain an understanding of the geological and logistical challenges at the site. As part of the CRI, residuals sulfate from persulfate decomposition could potentially be tapped to promote in situ biological and biogeochemical reduction mechanisms in the immediate downgradient plumes.
While remediation optimization decisions are often driven by technical considerations and site data, remediation projects are also subject to additional constraints including client expectations, logistical challenges and regulatory framework. These aspects are equally important and must be incorporated into the remediation planning, design, and optimization process.
In this presentation, we provide a case study that illustrates a holistic approach to remediation, balancing technical, financial, and logistic considerations to reach site-specific goals. We will discuss the process used to incorporate accelerated site remediation tools, applied both spatially and temporally, to develop a realistic end goal given regulatory, operational, and budgetary constraints that often accompany complex sites.
Results/Lessons Learned
- The project goal was to achieve as much mass reduction as possible given the constraints of challenging subsurface conditions, site operational constraints, regulatory timeframe concerns, and budgetary constraints.
- The constraints have the potential to negatively affect remediation compared to a site with ideal conditions. A phased CRI approach allows for maximizing available technologies to overcome constraints and develop an overall effective remedial strategy.
- Balancing the use of direct push technologies and permanent injection wells was used to overcome the challenges with each approach and build a hybrid injection strategy in shallow aquifers. Continuous field evaluation and monitoring for challenges was used to optimize the method of chemical delivery and can focus subsequent treatment(s) to achieve the greatest overall effect for the least effort/cost.
- The phased CRI approach allows for continuous adaptation based on site data during remedial execution and transition to subsequent technologies once the point of diminishing returns is identified. This strategy improves the ability to reach project end goals.
- Clear identification of remedial objectives and metrics were used to establish technology transition points, thereby promoting a synergistic remediation pathway to improve performance that saved time and resources for the client.
- Determination of the appropriate time to consider long-term MNA is not always clear. It is necessary to demonstrate progress to clients and regulatory agencies.