Expected performance benefits for various dewatering practices File:Parking Lot Scenario Base.PNG > Stormwater models, calculators and modeling > Sediment control practices - Buffer zones > Calculating credits for infiltration > Expected performance benefits for various dewatering practices

Expected performance benefits for various dewatering practices.
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	Dewatering Best Management Practices
	Sedimentation/ Settling Only (Sediment Traps/ Basins)	Filtration Only (Silt Fence, Dewatering Bag, Geotextile, etc.)	Pretreatment1 + Chemical Flocculants + Settling/Filtration
Water quantity
Flow attenuation	Secondary benefit	Little or no benefit	Little or no benefit
Runoff volume reduction	Secondary benefit	Little or no benefit	Little or no benefit
Water quality
Soil erosion	Little or no benefit	Little or no benefit	Little or no benefit
Sediment control	Good results	Better results	Best results
Nutrient loading2	Good results	Better results	Best results
Pollutant removal
Total suspended solids	Good results	Better results	Best results
Total phosphorus2	Good results	Better results	Best results
Heavy metals	Good results	Better results	Best results
Floatables	Little or no benefit3	Good results	Good results3
Oil and grease	Little or no benefit3	Some benefit	Some benefit3

¹ Pretreatment via settling and/or filtration.
² For soil-borne nutrients; i.e., not dissolved forms.
³ Benefit can be significantly improved with the use of a floating skimmer for discharge