Changes

{{TOClimit|2}}

{{TOClimit|2}}

===Overland sheet flow===

==Overland sheet flow==

<p>The following pretreatements are recommended where sheet flow  is being directed to a BMP (typically a [[Bioretention cells| bioretention cell]]) from the edge of an impermeable surface such as an asphalt parking lot or a paved plaza:

The following pretreatements are recommended where sheet flow  is being directed to a BMP (typically a [[Bioretention cells| bioretention cell]]) from the edge of an impermeable surface such as an asphalt parking lot or a paved plaza:

*[[Gravel diaphragms]]

<li>[[Gravel diaphragms]]</li>

*[[Vegetated filter strips]]

<li>[[Vegetated filter strips]]</li>

A gravel diaphragm typically requires less setback between the catchment and the BMP.  Where space permits, these two designs can be used in combination to even greater effect!

==Concentrated overland flow==

A gravel diaphragm typically requires less setback between the catchment and the BMP.  Where space permits, these two designs can be used in combination to even greater effect!</p>

===Concentrated overland flow===

Where a [[Curb cuts| curb cut]], [[Downspout disconnection| a disconnected downspout]] or a [[Swales| swale]] directs surface water to a point, increasing the flow rate, one or more of the following pretreatments should be considered:

Where a [[Curb cuts| curb cut]], [[Downspout disconnection| a disconnected downspout]] or a [[Swales| swale]] directs surface water to a point, increasing the flow rate, one or more of the following pretreatments should be considered:

*[[Forebays]] (well suited for bioretention cells)

<li>[[Forebays]] (well suited for bioretention cells)</li>

*[[Sand filters]] (well suited for underground infiltration)

<li>[[Sand filters]] (well suited for underground infiltration)</li>

*[[Screens and racks]]

<li>[[Screens and racks]]</li>

==Concentrated underground flow==

===Concentrated underground flow===

This type of pretreatement is dominated by proprietary systems, some of which have undergone verification under the [http://etvcanada.ca/ Environmental Technology Verification (ETV)] program.  

This type of pretreatement is dominated by proprietary systems, some of which have undergone verification under the [http://etvcanada.ca/ Environmental Technology Verification (ETV)] program.  

<table class = "table table-striped table-responsive">

 

<caption><strong>Inline pretreatment options</strong></caption>

{|class="wikitable"

|+ Inline pretreatment options

  <th width = 20%>Type</th>

  <th width = 40%>Description</th>

!style="background: darkcyan; color: white"|Type

  <th width = 20%>ETV products</th>

!style="background: darkcyan; color: white"|Description

  <th width = 20%>Other products (not verified)</th></tr>

!style="background: darkcyan; color: white"|ETV products

!style="background: darkcyan; color: white"|Other products (not verified)

|Baffles slow flow, encouraging larger, heavier particles to drop out of the water column. A skimmer may also trap floating debris, oils and grease.||-||[http://upstreamtechnologies.us/products/safl.shtml SAFL baffle]

 

 

 

<td>OGS Baffles</td>

<td>OGS Baffles</td>

<td>Baffles slow flow, encouraging larger, heavier particles to drop out of the water column. A skimmer may also trap floating debris, oils and grease. </td>

<td>Baffles slow flow, encouraging larger, heavier particles to drop out of the water column. A skimmer may also trap floating debris, oils and grease. </td>

<td>-</td>

<td>-</td>

<td>[http://upstreamtechnologies.us/products/safl.shtml SAFL baffle]</td></tr>

<td></td></tr>

<tr>

<tr>

<td>Hydrodynamic OGS</td>

<td>Hydrodynamic OGS</td>