Sand Filter PretreatmentAlternative Techniques for Different Filter Options

• Surface sand and organic filters

  • dry detention for 24 hours, or
  • wet pool with dry detention above

• Underground sand filter

  • wet pool at least 3 feet deep & dry detention above

• Perimeter sand filter

  • wet pool with 2 foot depth & dry detention above

• Pocket sand filter

  • concrete level spreader, filter strip & plunge pool

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Pretreatment is necessary for stormwater filters to remove excessive sediment that contributes to premature failure of these practices. Pretreatment may be in the form of sedimentation basins, vegetative filter strips, grass swales, storm drain structures with sumps, or water quality (oil/grit separator) inlets. Alternative techniques for different filter options are provided in this slide.