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| ==Planning considerations== | | ==Planning considerations== |
| ==Design== | | ==Design== |
| + | {| class="wikitable" |
| + | !Element |
| + | !Design Objective |
| + | !Criteria |
| + | |- |
| + | |Drainage Area |
| + | |Sustaining vegetation, volumetric turnover |
| + | |5 Ha (≥10 Ha preferred) |
| + | |- |
| + | |Treatment Volume |
| + | |Provision of appropriate level of protection (Table 3.2) |
| + | |See Table 3.2 |
| + | |- |
| + | |Active Storage |
| + | |Detention |
| + | |Suspended solids settling 24 hrs (12 hrs if in conflict with min. orifice size) |
| + | |- |
| + | |Forebay |
| + | |Pre-treatment |
| + | |Minimum depth: 1 m; ii) Sized to ensure non-erosive velocities leaving forebay; iii) Maximum area: 20 % of total permanent pool |
| + | |- |
| + | |Length-to-Width Ratio |
| + | |Maximize flow path and minimize short-circuiting potential |
| + | |i) Overall: minimum 3:1; ii) Forebay: minimum 2:1 |
| + | |- |
| + | |Permanent Pool Depth |
| + | |Vegetation requirements, rapid settling |
| + | |The average permanent pool depth should range from 150 mm to 300 mm |
| + | |- |
| + | |Active Storage Depth |
| + | |Storage/flow control, sustaining vegetation |
| + | |Maximum 1.0m for storms < 10 year event |
| + | |- |
| + | |Side Slopes |
| + | |Safety |
| + | |i) 5:1 For 3 m above and below permanent pool (ii) Maximum 3:1 elsewhere |
| + | |- |
| + | |Inlet |
| + | |Avoid clogging/freezing |
| + | |i) Minimum 450 mm; ii) Preferred pipe slope: >1%; iii) If submerged, obvert 150 mm below expected maximum ice depth |
| + | |- |
| + | |Outlet |
| + | |Avoid clogging/freezing |
| + | |i) Minimum: 450mm outlet pipe; ii) Preferred pipe slope: >1%; iii) If orifice control used, 75mm diameter minimum; (iv) Minimum 100mm orifice preferable |
| + | |- |
| + | |Maintenance Access |
| + | |Access for backhoes or dredging equipment |
| + | |(i) Provided to approval of Municipality; (ii) Provision of maintenance drawdown pipe preferred |
| + | |- |
| + | |Buffer |
| + | |Safety |
| + | |Minimum 7.5 m above maximum water quality/erosion control water level |
| + | |} |
| + | |
| ==Performance== | | ==Performance== |
| STEP (under previous name SWAMP) conducted their own research into the performance of stormwater wetlands, the project page and report can be viewed [https://sustainabletechnologies.ca/home/urban-runoff-green-infrastructure/conventional-stormwater-management/constructed-wetlands/performance-assessment-of-an-open-and-covered-stormwater-wetland-system-aurora-ontario/ here]. | | STEP (under previous name SWAMP) conducted their own research into the performance of stormwater wetlands, the project page and report can be viewed [https://sustainabletechnologies.ca/home/urban-runoff-green-infrastructure/conventional-stormwater-management/constructed-wetlands/performance-assessment-of-an-open-and-covered-stormwater-wetland-system-aurora-ontario/ here]. |