Slide 66 of 119
Notes:
The majority of filtering practices, with the exception of bioretention, are sand filters. Sand filters are usually two-chambered stormwater practices; the first is a settling chamber, and the second is a filter bed filled with sand or another filtering media. As stormwater flows into the first chamber large particles settle out, and then finer particles and other pollutants are removed as stormwater flows through filtering media. There are several modifications of the basic sand filter design, including the surface sand filter, underground sand filter, perimeter sand filter, organic media filter, and the pocket sand filter. All of these filtering practices operate on the same basic principle. Modifications to the traditional surface sand filter were made primarily to fit sand filters into more challenging design sites or to improve pollutant removal.
Sand filters can be applied in most regions of the country. There are some restrictions at the site level, however, that may restrict the use of sand filters as a stormwater management practice, such as available hydraulic head.