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Phosphorus is the chemical that supports rapid algal growth and it is a challenging task to find ways to remove dissolved phosphorus from bodies of water. A new and promising management practice to control phosphorus is using an iron enhanced sand filter (IESF).
Sand filters have been used for a number of years to remove solids and some pollutants from stormwater, but it has been found that adding iron filings to the sand removes dissolved phosphorus in a cost effective way.
Thanks to a partnership with the Anoka Conservation District and Rice Creek Watershed District, the city was able to install an IESF in Centennial Greens Park. The park was chosen after a study was completed showing a need for dissolved phosphorus treatment in the area. Since the installation of the IESF in 2015, water monitoring is showing that the IESF is effectively removing phosphorus. The IESF is maintained by the city. This includes raking it on a regular basis during the summer months. As long as the system is maintained, it is projected to last up to 30 years before needing reconstruction.
The city has an opportunity to partner with the Coon Creek Watershed District to construct another IESF in the Pleasure Creek neighborhood near the intersection of Clover Leaf Parkway and East Pleasure Creek Parkway. This project would take the design a step further by adding a substance called biochar to the mix. Biochar functions to remove E. coli, which is the bacteria found in animal waste. E. coli contamination is a problem in the Pleasure Creek watershed. The funding for the project will be a combination of grants, funds from the Clean Water Fund Watershed Based funding, Coon Creek Watershed District and the city. More information will be released in the near future regarding the timing and logistics of the project.