Difference between revisions of "Pretreatment features"

From LID SWM Planning and Design Guide
Jump to navigation Jump to search
Line 12: Line 12:
 
<div class="col-md-4">
 
<div class="col-md-4">
 
     <panelInfo>
 
     <panelInfo>
         <gallery mode="packed" height = 300 px>
+
         <gallery mode="packed" widths=300px heights=300px>
 
             Forebays.png| Without a forebay (top) the flow is concentrated around the inlet, potentially causing erosion and not optimally spread for infiltration; A three sided forebay (centre) with a level spreader on all sides will distribute the water and reduce the energy, sediment will collect in the pad of the forebay (shown darker); In a narrow cell, the forebay may extend across the whole facility (bottom).
 
             Forebays.png| Without a forebay (top) the flow is concentrated around the inlet, potentially causing erosion and not optimally spread for infiltration; A three sided forebay (centre) with a level spreader on all sides will distribute the water and reduce the energy, sediment will collect in the pad of the forebay (shown darker); In a narrow cell, the forebay may extend across the whole facility (bottom).
 
         </gallery>
 
         </gallery>

Revision as of 13:55, 13 July 2017

Forebays are a form of pretreatment for open inlets. Energy of the incoming flow is dissipated, causing suspended particles to drop out of the water. These accumulated particles/sediment can then be easily swept or vacuumed during routine maintenance and doesn't end up clogging downstream biomedia or filter material.

A well designed forebay will also spread the flow somewhat, reducing erosion around the inlet. One effective way of achieving this is by surrounding the pad with some level spreader on all sides. The level spreading could take the form of a shard crested weir in metal or concrete, or be more like a soft edged, rocky check dam.

   <panelSuccess>
   </panelSuccess>
   <panelInfo>
   </panelInfo>