Image Credit: Montgomery County, MD, 2018
Photograph Image Credit: Montgomery County, MD, 2018

Sand Filter


A sand filter is a depression in the ground used to capture, infiltrate, and filter pollutants before discharging. Sand filters are similar to infiltration basins in design. The primary difference is that sand filters can have vegetative cover and are less aesthetically obtrusive. Sand filters can be constructed with or without underdrains.

Like bioretention systems and infiltration basins, sand filters are more effective at providing water quality treatment and groundwater recharge for small drainage areas. The NJDEP requires a variance for sand filters with large drainage areas to count for water quality and groundwater recharge.

Sand Filter Diagram
Image Credit: NJ BMP Manual, 2020

Considerations:

  • Upstream slopes must be stabilized before the sand filter system is made operational
  • Construction equipment should not be placed within the sand filter in order to avoid compaction.

Cost: Infiltration systems are more efficient at meeting stormwater requirements and can therefore have smaller footprints. Maintenance costs are comparable to traditional detention basins.

Maintenance: Maintenance for sand filters requires regular raking, repair of structural components, and inspections. The sand layer will need to be removed and replaced with sediment accumulation.

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