ISG Provides Innovative Groundwater Solutions for Rare Wetlands

January 20, 2016 (Mankato, Minnesota) – Minnesota’s fourth Calcareous Fen Management Plan (CFMP), developed by ISG for a mining client, was recently approved by the Minnesota Department of Natural Resources (DNR) in cooperation with several state and local agencies. It was the first of its kind aimed at maintaining hydrogeological (groundwater) levels. Calcareous fens are rare and distinctive wetlands that receive continuous groundwater discharge that is calcium enriched through contact with bedrock or glacial deposits.

Known to be one of the rarest natural communities in the United States, there are only 10 states reporting their existence with approximately 200 sites located in Minnesota. They are identified in part by the presence of peat—a saturated soillike material—and are often located at the base of terraces along river valleys. According to ISG Senior Environmental Scientist, Nick McCabe, “Calcareous fens are highly susceptible to disturbance, which required ISG to design a mitigation system that prevents water table fluctuations that occur with standard mining practices.

As part of the CFMP, ISG designed a 460 x 14 foot infiltration trench system to maintain groundwater levels and conducted testing at an alternate location as part of a case study and pre-mining field test. One year of research allowed data to be collected to measure the trench’s ability to maintain an adequate groundwater level and chemistry to support a calcareous fen. Upon successful completion of the study, the trench was constructed at the intended location along the Minnesota River in southern Minnesota and now provides adequate water supply for the calcareous fen.

The State’s approval of the CFMP includes an ongoing monitoring program, and the project successfully passed the first annual review. ISG Environmental Services staff will continue to monitor this sensitive ecosystem annually, along with five-year reviews for several parameters including water and peat levels, native plant species, as well as inspections for potential invasive species. According to ISG Principal and Executive Vice President, Lynn Bruns, “By navigating the complex regulatory process with state and local agencies, this project shows that effective design solutions can be used to protect conditions for fragile environmental communities while also meeting industry demands.” For more information about calcareous fens, visit, http://www.bwsr.state.mn.us/wetlands/Calc_fenfactsheet.pdf.