Acid Tar Impoundment Remediation at Legacy Industrial Site

This site in New Jersey faced significant environmental threats, including contamination of soil, surface water, sediments, and both shallow and deep aquifers. These hazards stemmed from 16 surface impoundments holding approximately 877,000 tons of waste material. The project team was tasked with proving and scaling a concept design to remove and process acid tar from two 4-acre impoundments—an essential step toward site closure. The effort required meeting evolving debris standards for cement kiln end-use, proving operational scalability, and gathering air monitoring data under tight regulatory deadlines. Complicating factors included the site’s expedited schedule, failure of the original long-term operations design, and safety risks associated with low pH acid tar and benzene air emissions.

Mobilization for tar removal began in February 2023 following winter vegetation clearing and concluded in August 2023. The team employed specialized equipment and innovative methodologies to meet the project’s complex demands. Key equipment included a 150-ton Manitowoc MLC150 crane with a 2-cubic-yard clamshell bucket and a REMU bucket attachment—newly applied to acid tar—for debris conditioning. Paper mulch and custom-built processing systems were used for dewatering and conditioning the material. Navigation and excavation were guided by bathymetric surveys and RTK GPS to ensure precision and verify removal depths and volumes. The REMU bucket application, developed by the project team, proved especially critical, allowing operations to meet and exceed the target of four truckloads per day and comply with updated cement kiln debris standards.

The project achieved key outcomes, including the successful demonstration of a scalable acid tar removal process that met air monitoring and processing requirements. Experience gained from earlier phases in 2021 and 2022—combined with the leadership of our technical staff familiar with in-situ solidification (ISS) pilot studies at the site—was instrumental in overcoming the challenges. The REMU bucket technique, never before used for acid tar, represents a breakthrough approach for processing and stabilizing waste, positioning the site for future ISS remediation and full closure. This milestone marks significant progress in addressing one of the most persistent environmental challenges on site.