Changes

===How is it being used?===

===How is it being used?===

*The first retrofit  in Ontario to incorporate a red sand filter system was the George Richardson stormwater management pond in Newmarket.<ref name=LSRCA/> Red sand was installed as the last part of a treatment train to function as a final polishing unit. The underground system was first lined with a bentonite clay liner to minimize groundwater exchange, with various layers of clear stone and red sand sandwiched between nonwoven [[geotextiles]]. The water is distributed via a system of perforated pipes embedded in the top layer of the underground system just above the red sand filter media, with collector pipes located near the bottom. The system is estimated to have a reduction in phosphorus of 23 kg/year. <ref name=CVC>Credit Valley Conservation. George Richardson Stormwater Management Pond Retrofit. 2013. http://www.creditvalleyca.ca/wp-content/uploads/2013/08/CVC-Case-Study-George-Richardson_Aug_2013.pdf. Accessed September 8, 2017.</ref>

*The first retrofit  in Ontario to incorporate a red sand filter system was the George Richardson stormwater management pond in Newmarket(LSRCA, 2013)<ref name=LSRCA/>. Red sand was installed as the last part of a treatment train to function as a final polishing unit. The underground system was first lined with a bentonite clay liner to minimize groundwater exchange, with various layers of clear stone and red sand sandwiched between nonwoven [[geotextiles]]. The water is distributed via a system of perforated pipes embedded in the top layer of the underground system just above the red sand filter media, with collector pipes located near the bottom. The system is estimated to have a reduction in phosphorus of 23 kg/year (CVC, 2013)<ref name=CVC>Credit Valley Conservation. 2013. George Richardson Stormwater Management Pond Retrofit. http://www.creditvalleyca.ca/wp-content/uploads/2013/08/CVC-Case-Study-George-Richardson_Aug_2013.pdf. Accessed September 8, 2017.</ref>.

*Another Ontario project was completed by the Upper Thames River Conservation Authority and Luckhart Transportation Limited, in which they retrofit an innovative wetland treatment system to test a red sand filter. This was the first of its kind for an agricultural application. In this project, a clear round stone was added to improve percolation and phosphorus retention.<ref>Upper Thames River Conservation Authority. Red Sand helps Protect Water Quality. 2014. http://thamesriver.on.ca/2014/11/11/red-sand-helps-protect-water-quality-november-11-2014/. Accessed September 8, 2017.</ref>.

*Another Ontario project was completed by the Upper Thames River Conservation Authority and Luckhart Transportation Limited, in which they retrofit an innovative wetland treatment system to test a red sand filter. This was the first of its kind for an agricultural application. In this project, a clear round stone was added to improve percolation and phosphorus retention (Upper Thames River Conservation Authority, 2014)<ref>Upper Thames River Conservation Authority. Red Sand helps Protect Water Quality. 2014. http://thamesriver.on.ca/2014/11/11/red-sand-helps-protect-water-quality-november-11-2014/. Accessed September 8, 2017.</ref>.

*In a two year STEP research study that compared standard bioretention media to red sand and Sorbtive™ amended media, the red sand plot was shown to have significantly lower total and dissolved phosphorus effluent concentrations.  However the phosphorus reductions occurred only in year 2, after fine particulates in the red sand media had been washed out of the system (STEP, 2019)<ref>STEP. 2019. Improving nutrient retention in bioretention. Technical Brief. Accessed: https://sustainabletechnologies.ca/app/uploads/2019/06/improving-nutrient-retention-in-bioretention-tech-brief.pdf</ref>.

*In a two year STEP research study that compared standard bioretention media to red sand and Sorbtive™ amended media, the red sand plot was shown to have significantly lower total and dissolved phosphorus effluent concentrations.  However the phosphorus reductions occurred only in year 2, after fine particulates in the red sand media had been washed out of the system (STEP, 2019)<ref>STEP. 2019. Improving nutrient retention in bioretention. Technical Brief. Accessed: https://sustainabletechnologies.ca/app/uploads/2019/06/improving-nutrient-retention-in-bioretention-tech-brief.pdf</ref>.