DNREC Updates A-Street Ditch PCB Cleanup Pilot Project

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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DNREC Analysis of Brandywine River Dam Sediments Reveals Encouraging Results

Scientists from the Delaware Department of Natural Resources and Environmental Control published research today related to sediment quality behind eight dams in the Brandywine River, which finds there would be low risk of harm to fish or human health from toxic compounds if the sediments were released due to dam modification, removal or failure.

Conducted by DNREC’s Watershed Approach to Toxics Assessment and Restoration (WATAR) team, results of the study indicate that the volume of sediment trapped behind the dams is less than originally predicted, which translates to an overall lack of legacy toxic contaminant buildup. The report compares concentrations of contaminants in accumulated sediment across the eight dams investigated, and describes techniques used to evaluate potential impacts from the contaminants to aquatic life and human health. The overall findings are encouraging, as an increase in risk of adverse effects from the release of trapped sediments is not predicted.

A release of trapped sediments is likely to occur during dam modification/removal, or from catastrophic failure of any of the aged dams during a major storm/high flow event. Understanding potential impacts from the release of these sediments will allow DNREC to effectively influence proposed construction projects in the river to provide regulatory protection to downstream drinking water sources, and to fish health and aquatic habitat.

Brandywine Shad 2020 (BS2020) is a nonprofit led by the Brandywine Conservancy, the Hagley Museum and Library, and the University of Delaware. The nonprofit initiated the sediment study to inform their mission to remove or modify the dams in the Delaware portion of the Brandywine River to promote passage of American Shad and other fish species to “pre-dam” historic spawning grounds.

The Brandywine River surface water, sediment and aquatic species have been impacted by legacy contaminants such as polychlorinated biphenyls (PCBs), dioxins and furans, and chlorinated pesticides. This condition is evidenced by the existence of fish consumption advisories in both the non-tidal and tidal portions of the river. However, recent improvements have been documented, and future improvements are anticipated.

The report noted that opportunities exist to improve the overall water/sediment quality of the Brandywine River system in the future. Data collected in this study show that there are areas of greater relative concentrations of toxic compounds than others. And although increased risk of toxicity due to sediment release may not be predicted, evaluation should be conducted at the time of specific project planning/implementation to determine if a benefit to the ecosystem as a whole could be accomplished as a result of sediment removal or sediment management activities.

“The results of this evaluation provide peace of mind that the City of Wilmington’s drinking water, as well as the aquatic life in the river, should not be negatively affected by any release of contaminants associated with sediments behind the dams.” said John Cargill, hydrologist for DNREC. “Beyond this study, DNREC will continue to monitor the quality of the surface water and the fish in the Brandywine River, along with other water bodies throughout the state.

WATAR is a cooperative approach/project team that draws on the expertise of staff primarily within, but not limited to, the DNREC Division of Watershed Stewardship and the Division of Waste and Hazardous Substances. WATAR creates a framework for assessing potential toxic impacts and then implementing remediation and restoration projects in Delaware watersheds that are affected by toxic pollutants.

DNREC-WATARs partnership with BS2020 resulted in a total state cost of $51,000 for chemical analysis of sediment samples. Analytical services were supported by Hazardous Substance Cleanup Act (HSCA) funds. BS2020 funded the sediment sample collection activities. Visit the program web page at de.gov/WATAR to review/download the report and for additional supporting information.

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

Media Contacts: Nikki Lavoie, nikki.lavoie@delaware.gov; Michael Globetti, michael.globetti@delaware.gov

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DNREC Mirror Lake clean-up earns more national acclaim; innovative approach reduces pollutants in the Christina River

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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