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Iron Enhanced Soil Blending Process

January 19, 2017


We are mixing this product for the Hilo Lane Stormwater Improvements.  IESF project. IESF stands for Iron Enhanced Sand Filter.  We utilize fine filter aggregate, (MNDOT 3149.2J) which is a very coarse sand and iron filings that come from Chicago, IL.  The University of MN St. Anthony Falls Laboratory has been developing a sand / iron mixture that removes phosphorous from the water when it is filtered through this soil medium. The application is typically in stormwater ponds that receive runoff from various types of storm sewer piping which delivers unfavorable water to the ponds.  When the ponds fill to a certain level or capacity, the water enters the constructed “bench” of iron / sand mixture, is filtered through the soil mixture and then exits via draintile which resides beneath the soil medium and is connected to the exit structure. The water leaving the stormwater pond, which is  headed to our lakes and rivers is a much cleaner product with less phosphorous and greatly lessens the impact that stormwater has on our lakes and rivers.  Although phosphorous is essential to plant growth, too much of it speeds up eutrophication  (a reduction in dissolved oxygen in water bodies caused by an increase of mineral and organic nutrients) which causes excessive algae growth and is harmful to all types of species within lakes and rivers.  Due to increased urban impacts these types of systems are becoming much more commonplace within the state of Minnesota.

We utilized our soil blender 15000 to precisely mix the sand and iron at 95% sand and 5% iron which is the preferred ratio of sand to iron.  After the soil blending unit combines the correct amount of each material it runs through to onboard mixers (beaters) and then is conveyed to our Wildcat trommel screener which for this application is fitted with guards that do not allow the sand to exit right away through the screens and is the final mixing station which acts much like a large dryer. This material was consistently tested by the owner of the project, a local conservation district and was consistently right on the mark.  The Hilo Lane project site is an existing site and therefore onsite mixing was not an option, these soils will be transported from our facility to the project.