BrightFields, Inc. was retained by the Delaware Department of Natural Resources and Environmental Control (DNREC) to plan and manage the remediation, restoration and maintenance activities at Mirror Lake in Dover, Delaware.  DNREC’s goal is to lift the current fish advisory at Mirror Lake, by the in-situ remediation placement of a layer of activated carbon onto the lake bottom sediments to sequester the existing contaminants so they are no longer bio-available to fish and aquatic organisms.  Restoration activities included creating an intertidal wetland, bank stabilization, installation of grade control structures, and riparian buffer planting.

The remediation of the lake sediments was done by uniformly spreading SediMite™ throughout the lake and the surrounding up and down stream areas.  SediMite™ was spread from the bank of the lake using a telebelt, as well as from boats on the lake through the use of an induction air horn, Vortex spreaders, and by hand.  SediMite™ was spread by three different methods to overcome access and water depth issues.

• A total of 79 tons of SediMite™ was used to cover the entire lake and stream bottoms in the project area.
• Volunteer hours were used to spread SediMite™.

The restoration of the lake and surrounding areas included the pruning of plants along the east and west banks, the enhancement of the existing sandbar on the east side, the creation of an intertidal wetlands, the reinforcement of the west bank with coir logs and mulch. Two rock vanes were constructed upstream of the wetlands to assist in directing the natural flow of the Thalweg.

• The intertidal wetland was created over an area of approximately 20,000 square feet using over 1,325 tons of sand.
• The two rock vanes were installed using 120 tons of large stone and riprap.
• 800 linear feet of 16-inch diameter coir logs were placed along the west bank.
• Over 3,000 plants were planted and 7 rolls of coir matting were placed to create wetland habitat.

To learn more about the Mirror Lake project, please check out the video on DNREC’s YouTube channel.