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*Rake surface with a steel rake to break up oxidized iron clumps or crust | *Rake surface with a steel rake to break up oxidized iron clumps or crust | ||
*For Pond-Perimeter IESF Trenches, remove duckweed, algae, and other organic material weekly, or as buildup occurs | *For Pond-Perimeter IESF Trenches, remove duckweed, algae, and other organic material weekly, or as buildup occurs | ||
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+ | <td colspan=3>Recommended links | ||
+ | *[[Design criteria for iron enhanced sand filter]] | ||
+ | *[[Assessing the performance of iron enhanced sand filter]] | ||
+ | *[https://stormwater.pca.state.mn.us/index.php?title=Category:Sand_filter_schematic Sand filter schematics] | ||
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Do's and Don'ts of Iron Enhanced Sand Filters (IESFs)
Link to this table
Don't | Do | Comments |
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Don’t assume iron is pure or harmless. | Request mineral analysis of iron-based material. |
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Don’t assume iron is reactive with phosphate. | Expose iron material to a solution of soluble phosphate and measure adsorption (e.g., batch studies). | |
Don’t undersize the IESF for the contributing drainage area. | Design the IESF with the appropriate size and dimensions for the contributing area. | Undersized IESFs will run out of sorption capacity quickly. |
Don’t install an IESF in areas that become inundated. | Select locations for IESF that receive intermittent flow, adequately dry out between rainfall events, and such that the outlet is above the downstream high-water level | |
Don’t install IESF where the contributing area lacks phosphate in the runoff. | Measure the phosphate concentration in the runoff where the IESF is intended to be installed. | IESF are most cost-effective when the influent phosphate concentration is > 0.1 mg/L. |
Don’t specify too much or too little iron in the IESF media mix. | Design IESF with the appropriate amount of iron | IESFs are most efficient and successful when the iron content is between 3% and 8% iron by weight. Using > 8% iron by weight can result in iron solidification and reduced hydraulic and sorption capacity. |
If mixing with a roto-tiller, don’t assume that the media is well mixed by appearance. | If mixing by roto-tiller, mix, mix, and mix 3 to 4 times the appearance of a well-mixed media. | |
Don’t ignore inspection and maintenance! | Inspect and maintain IESFs. | Recommended Inspection and maintenance of IESF includes:
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Recommended links |