Sediment and gross solids in stormwater | Minnesota Stormwater Manual

This page currently in development.

Solids transported in stormwater come in many shapes and sizes ranges from microscopic particulates to large pieces of trash and vegetative debris.

General size classifications for particulate pollutants found in stormwater¹.
Fines			Coarse
Clay		Silt	Sand	Pebble	cobble
0.45um-2um		2um-75um	75um-4.25mm	> 4mm-6.4cm	6.4cm-25.6cm
				Gross solids
				>4.25mm
Nanoplastics²		Microplastics²		Macroplastics²
<1um	1um-5mm			>5mm
Fine organic matter			Coarse organic matter
<75um			>75um
¹ AASHO classifications. Classification boundaries vary somewhat among soil classification systems (e.g., USCS, USDA). ² USEPA