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| ===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: |
| <ul>
| | *[[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! |
| </ul>
| | ==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: |
| <ul>
| | *[[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== |
| </ul>
| |
| ===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" |
| <tr class ='success'>
| | |+ 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 |
| <tr>
| | !style="background: darkcyan; color: white"|Other products (not verified) |
| | |- |
| | !OGS Baffles |
| | |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> |