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 about the A-Street Ditch project. Additional information about the Mirror Lake-Dover project can also be found on the DNREC-WATAR webpage.

About DNREC
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 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 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.

Media contact: Michael Globetti, michael.globetti@delaware.gov or Nikki Lavoie, nikki.lavoie@delaware.gov

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DOVER, Del. – For Earth Day 2020, DNREC announced it has successfully used an innovative approach to reduce polychlorinated biphenyls (PCBs) in two Delaware waterways. Newly released scientific data are validating the new method of sequestering pollutants with activated carbon, which render them unavailable for uptake by fish and other aquatic organisms.

The first success was with an activated carbon product called SediMite™ at Mirror Lake in Dover in 2013. The project is featured in a new article co-authored by several project participants, including two DNREC scientists, and published in the May issue of Journal of Environmental Engineering. The article, titled “Full-Scale Application of Activated Carbon to Reduce Pollutant Bioavailability in a 5-Acre Lake” presents a summary of the monitoring data collected at the site between 2013 and 2018. Highlights include an approximate 80% reduction in PCB concentrations in sediment porewater, which is the water trapped between grains of sediment in the bottom of a water body. The study also found an approximate 70% reduction in PCB concentrations in Mirror Lake’s resident fish.

“The recognition by the Journal of Environmental Engineering reflects how Delaware is on the leading edge of environmental technology, an area that DNREC is exploring more and more” said DNREC Secretary Shawn Garvin. “Mirror Lake was a successful pilot, so DNREC’s team sought a second opportunity to try the technology.”

The A Street Ditch project became a focus for DNREC’s Watershed Approach to Toxics Assessment and Restoration (WATAR) Team after samples confirmed that drainage ditch sediments were a continuing source of PCBs to the Christina River. The project, in coordination with cleanup efforts at the adjacent South Wilmington Wetland Park site, provided an opportunity to evaluate an enhanced carbon sequestration technology developed by DNREC’s partners at the University of Maryland Baltimore County (UMBC).

The enhanced technology involves the use of SediMite™ with the addition of PCB-destroying micro-organisms (inoculant). In theory, the activated carbon will sequester PCBs, as shown in Mirror Lake. However, the micro-organisms (which exist naturally in the environment in much smaller numbers) will effectively degrade the PCB molecules over time. Initial results, collected only 5 months after the inoculated Sedimite™ was applied to the ditch sediments, show that total PCB concentrations in the top layer of sediments across the A Street Ditch study area dropped by an average of 25%. In addition, surface water PCB concentrations across the site area have dropped by an average of 35%. Most impressive is concentrations of total PCBs in sediment porewater have dropped by an average of 64%. Additional monitoring will occur in July 2020, and again in July 2022.

Another harbinger for clean water in Delaware is that sequestering or destroying legacy PCBs – the primary risk driver for most of the fish consumption advisories issued by DNREC and the Delaware Division of Public Health – prevents these contaminants from entering the food chain. With increasing confidence in these innovative sediment remediation technologies, DNREC is beginning to plan for larger-scale projects, in key watersheds across Delaware, with similar water quality impairments.

“What these projects have achieved brings the longstanding goal of clean water for all Delawareans a little closer,” said Secretary Garvin. “DNREC’s dedicated scientists and staff are committed to improving water quality and making smarter use of resources at our disposal, including the technology that has driven both the Mirror Lake and A Street Ditch projects.”

DNREC’s A Street Ditch pilot project was supported by $188,000 in Hazardous Substance Cleanup Act (HSCA) funds and a $30,000 US Environmental Protection Agency multi-purpose grant. For more information, view the DNREC YouTube video about the WATAR team’s A Street Ditch pilot and another video on the Mirror Lake project or visit the DNREC website.

About DNREC

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. For more information, visit the website and connect with DNREC on Facebook, Twitter or LinkedIn.

Media Contact: Micahael Globetti, michael.globetti@delaware.gov

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WILMINGTON – A new DNREC YouTube Channel video details an innovative remediation project to remove PCBs from sediment in a ditch that discharges into the Christina River in Wilmington.

This spring, DNREC’s Watershed Approach to Toxics Assessment and Restoration (WATAR) Team and its partner University of Maryland, Baltimore County and contractor Brightfields, conducted a full-scale pilot test, using approximately 7 tons of Sedimite pellets inoculated with PCB-degrading micro-organisms to isolate and destroy legacy PCB contamination in a one-acre wetland area on A Street in Wilmington. With PCBs as the main cause of fish consumption advisories in the Christina Basin, the goal of the project is to prevent the contaminants from entering the food chain and impacting fish and other aquatic life.

Sedimite was the same product used for the Mirror Lake Remediation and Restoration Project in Dover in 2013, which has resulted in more than 80 percent reduction of PCBs in resident fish tissue in the five years since it was applied. The difference in this application – the first commercial application of bio-amended Sedimite in the country – was the inclusion of the PCB-destroying micro-organisms.

The WATAR Team expects successful results from the innovative pilot project and that the technology may become another tool that can be utilized in cleaning up legacy PCB contamination in other water bodies in the state.

The video can be found on the DNREC YouTube Channel at A-Street Ditch.

Contact: Joanna Wilson, DNREC Public Affairs, 302-739-9902

Vol. 49, No. 185