On October 3rd, board members the Sassafras River Association gathered on a farm near the headwaters of the Sassafras River to celebrate construction of SRA’s first vertical flow treatment wetland.
SRA initially became interested in this project site while studying “high phosphorus” sub-watersheds based on an MDE stream survey. Upstream from this particular sampling site, located on Wards Hill Rd, there is a major egg laying CAFO (concentrated animal feeding operation) consisting of approximately 15 acres of impervious surface (larger than a Wal-Mart parking lot), eight 500+ ft layer houses, and an egg washing/packing facility. Wastewater from the facility is spray irrigated on surrounding crop fields. Site visits to the downstream Crawford Farm revealed significant erosion and degradation of the grassed waterway, forested wetlands, and blue-line stream that receive storm flow from the facility. Hundreds of tons of sediment have been transported downstream to the Sassafras River as the waterway, field, and stream have scoured away. SRA conducted surface water sampling throughout the spring of 2011 and documented extremely elevated nutrient levels. In addition, several wells were established to enable groundwater testing, which revealed elevated levels of phosphorus.
SRA has partnered with Sustainable Science, LLC, Natural Resource Conservation Service, Ridge to Reefs, LLC, and Cecil Soil Conservation District to develop a solution to the high nutrient and sediment loads being exported downstream. It was determined that an innovative system of shallow wetlands, planted with a thick stand of emergent vegetation, could be utilized to cycle and remove nutrients from the water before reaching the stream, while a sediment pond at the head of the project would capture and slowly release flow from storm events, protecting the wetland system. Considerable effort was spent to design a method of capturing groundwater to be treated in a separate wetland cell. A “cutoff trench” utilizing an HDPE liner buried 11 ft deep, will be constructed to back water up into a tile system that will carry the groundwater to the separate cell. The original grassed waterway will be repaired, and an underground pipe, originating in a rock basin at the head of the project, will be utilized to convey base flow from the upstream CAFO property down to the sediment pond. This practice will prevent future erosion of the waterway.
The Crawford wetland project will be subject to intensive monitoring for its effectiveness at removal of both nitrogen and phosphorus. Automated monitoring stations will be deployed at the inflow and outflow of both the surface and ground water treatment systems, and samples will be submitted to a private lab for rigorous analysis. Data collected from this project will be compiled, analyzed, and presented to the Chesapeake Bay Program for review to be utilized as a practice in the 2017 water quality model run. The data will also be presented to the State NRCS technical review panel for possible adoption as a standard practice that would be eligible for cost share funding. SRA will be constructing a second treatment wetland in Kent County in the spring of 2013, and has a goal of completing 10 wetlands in identified high nutrient export areas to meet the Sassafras River TMDL.
At the groundbreaking, SRA recognized the funders who made this project possible, including the National Fish and Wildlife Foundation, Chesapeake Bay Trust, and the Chesapeake and Atlantic Coastal Bays Trust Fund.
“It is really exciting to be part of this program and to see this project finally breaking ground,” said SRA Board President John Burke. “At SRA, we like our reputation as the ‘Little Association that Gets things done.’”
For more information on the vertical flow treatment wetland technology, visit www.sassafrasriver.org.
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