Difference between revisions of "Stormwater wetland design criteria"
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<table class="sortable"> | <table class="sortable"> | ||
<tr> | <tr> | ||
| − | <th width="12%" | + | <th width="12%">'''Design Criteria'''</th> |
| − | <th width="12%" | + | <th width="12%">'''Shallow Wetland'''</th> |
| − | <th width="12%" | + | <th width="12%">'''Pond/Wetland'''</th> |
| − | <th width="12%" | + | <th width="12%">'''ED Shallow Wetland<sup>*</sup>'''</th> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td width="12%">Wetland/Watershed Ratio (Ac/Ac)</td> | <td width="12%">Wetland/Watershed Ratio (Ac/Ac)</td> | ||
| − | <td width="12%" | + | <td width="12%">0.2</td> |
| − | <td width="12%" | + | <td width="12%">0.1</td> |
| − | <td width="12%" | + | <td width="12%">0.1</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Minimum Drainage Area (Ac)</td> | <td>Minimum Drainage Area (Ac)</td> | ||
| − | <td | + | <td>25</td> |
| − | <td | + | <td>10</td> |
| − | <td | + | <td>25</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Length to Width Ratio (minimum)(ft/ft)</td> | <td>Length to Width Ratio (minimum)(ft/ft)</td> | ||
| − | <td | + | <td>2:1</td> |
| − | <td | + | <td>2:1</td> |
| − | <td | + | <td>2:1</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Extended Detention (ED)</td> | <td>Extended Detention (ED)</td> | ||
| − | <td | + | <td>No</td> |
| − | <td | + | <td>Optional</td> |
| − | <td | + | <td>Yes</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Allocation of V<sub>wq</sub> (pool/marsh/ED) in %</td> | <td>Allocation of V<sub>wq</sub> (pool/marsh/ED) in %</td> | ||
| − | <td | + | <td>25/75/0</td> |
| − | <td | + | <td>70/30/0(includes pond volume)</td> |
| − | <td | + | <td>25/25/50</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Allocation of Surface Area (deepwater/low marsh/high marsh/semi-wet) in %</td> | <td>Allocation of Surface Area (deepwater/low marsh/high marsh/semi-wet) in %</td> | ||
| − | <td | + | <td>20/35/40/5</td> |
| − | <td | + | <td>45/25/25/5 (includes pond surface area)</td> |
| − | <td | + | <td<center>10/35/45/10</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Forebay</td> | <td>Forebay</td> | ||
| − | <td | + | <td>Required</td> |
| − | <td | + | <td>Required</td> |
| − | <td | + | <td>Required</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Micropool</td> | <td>Micropool</td> | ||
| − | <td | + | <td>Required</td> |
| − | <td | + | <td>Required</td> |
| − | <td | + | <td>Required</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Outlet Configuration</td> | <td>Outlet Configuration</td> | ||
| − | <td | + | <td>Reverse-slope pipe or hooded broad-crested weir</td> |
| − | <td | + | <td>Reverse-slope pipe or hooded broad-crested weir</td> |
| − | <td | + | <td>Reverse-slope pipe or hooded broad-crested weir</td> |
</tr> | </tr> | ||
</table> | </table> | ||
<font size="1">*Note: The ED Shallow Wetland design guidance does not meet the MPCA requirements for permanent volume. The guidance may be applied in a stormwater retrofit situation where area requirements preclude the use of a Shallow Wetland</font size> | <font size="1">*Note: The ED Shallow Wetland design guidance does not meet the MPCA requirements for permanent volume. The guidance may be applied in a stormwater retrofit situation where area requirements preclude the use of a Shallow Wetland</font size> | ||
Revision as of 14:04, 22 January 2013
Link to this table
| Design Criteria | Shallow Wetland | Pond/Wetland | ED Shallow Wetland* |
|---|---|---|---|
| Wetland/Watershed Ratio (Ac/Ac) | 0.2 | 0.1 | 0.1 |
| Minimum Drainage Area (Ac) | 25 | 10 | 25 |
| Length to Width Ratio (minimum)(ft/ft) | 2:1 | 2:1 | 2:1 |
| Extended Detention (ED) | No | Optional | Yes |
| Allocation of Vwq (pool/marsh/ED) in % | 25/75/0 | 70/30/0(includes pond volume) | 25/25/50 |
| Allocation of Surface Area (deepwater/low marsh/high marsh/semi-wet) in % | 20/35/40/5 | 45/25/25/5 (includes pond surface area) | |
| Forebay | Required | Required | Required |
| Micropool | Required | Required | Required |
| Outlet Configuration | Reverse-slope pipe or hooded broad-crested weir | Reverse-slope pipe or hooded broad-crested weir | Reverse-slope pipe or hooded broad-crested weir |
*Note: The ED Shallow Wetland design guidance does not meet the MPCA requirements for permanent volume. The guidance may be applied in a stormwater retrofit situation where area requirements preclude the use of a Shallow Wetland