A new report prepared for the Delaware Department of Natural Resources and Environmental Control indicates that the innovative technology being tested in Wilmington’s A-Street Ditch cleanup pilot project continues to show promise. The report summarizes data collected one year after biologically-enhanced carbon pellets were applied to sediments in the ditch to clean up polychlorinated biphenyls (PCBs).
Conducted by the DNREC’s Watershed Approach to Toxics Assessment and Restoration (WATAR) program, the technology deployed in the A-Street Ditch project uses an activated carbon product (SediMite™) with the addition of PCB-destroying micro-organisms. The activated carbon sequesters PCBs and over time the micro-organisms degrade and destroy PCB molecules. A similar technology was successfully demonstrated in an earlier DNREC project at Mirror Lake in Dover.
PCBs are persistent, bioaccumulative and toxic legacy industrial compounds. They pose ecological and human health risks and are the largest contributor to fish consumption advisories issued periodically by DNREC and the Delaware Division of Public Health.
Results of DNREC’s July 2020 sampling of the A-Street Ditch show reduced concentrations of dissolved PCBs in the sediment porewater – the water trapped between grains of sediment in the bottom of a water body – across the entire project area. Results from two of the nine samples that were collected in July 2020 (one surface water sample and one sediment sample) showed localized increases in PCB concentrations. The WATAR team is evaluating potential reasons for these increases and will make their findings public when available. DNREC is planning to assess PCB concentrations in sediment, surface water and sediment porewater again in July.
DNREC’s A-Street Ditch pilot project was supported by Hazardous Substance Cleanup Act (HSCA) funds and a U.S. Environmental Protection Agency multi-purpose grant. Visit the DNREC-WATAR webpage for monitoring reports and a DNREC YouTube video about the A-Street Ditch project. Additional information about the Mirror Lake-Dover project can also be found on the DNREC-WATAR webpage.
The Delaware Department of Natural Resources and Environmental Control protects and manages the state’s natural resources, protects public health, provides outdoor recreational opportunities and educates Delawareans about the environment. The Division of Watershed Stewardship develops and implements innovative watershed assessment, monitoring and implementation activities. The Division of Waste and Hazardous Substances ensures Delaware’s wastes are managed to protect human life, health, safety and the environment. For more information, visit the website and connect with DNREC on Facebook, Twitter or LinkedIn.