Grass ChannelsPretreatment

• Shallow forebay

  • located at inflow point
  • forebay volume = (0.5”)(impervious acres of drainage)

• Pea gravel diaphragm

  • located along top of channel

• Vegetated filter strip

• No minimum volume

• Mild slopes (< 3:1) provide pretreatment for lateral flows

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Pretreatment criteria for grass channels is essentially the same as for dry and wet swales.