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==Design==
==Design==
+{|{| class="wikitable"
+|+Design parameters for dry ponds <ref>https://www.ontario.ca/document/stormwater-management-planning-and-design-manual/stormwater-management-plan-and-swmp-design</ref>
+!Element
+!Design Objective
+!Criteria
+|-
+|Drainage Area
+|Minimum orifice size (see [[flow control]])
+|style="text-align: left|5 Ha (≥10 Ha preferred)
+|-
+|Treatment Volume
+|Provision of appropriate level of protection
+|style="text-align: left|See [[#.|below]]
+|-
+|Active Storage
+|Detention
+|style="text-align: left|[[Total Suspended solids|Suspended solids]] settling 24 hrs (48 hrs preferred)
+|-
+|Forebay
+|Pre-treatment
+|style="text-align: left|
+*Minimum depth: 1 m;
+*Sized to ensure non-erosive velocities leaving forebay;
+|-
+|Length-to-Width Ratio
+|Maximize flow path and minimize short-circuiting potential
+|style="text-align: left|
+*Overall: minimum 3:1;
+*4:1 preferred
+|-
+|Depth
+|Safety
+|style="text-align: left|Maximum 3 m
+|-
+|Side slopes (See also [[berms]])
+|Safety
+|style="text-align: left|
+*4:1 average
+|-
+|Inlet
+|Avoid clogging/freezing
+|style="text-align: left|
+*Minimum 450 mm;
+*Preferred pipe slope: > 1 %;
+*If submerged, obvert 150 mm below expected maximum ice depth
+|-
+|Outlet (See also [[flow control]])
+|Avoid clogging/freezing
+|style="text-align: left|
+*Minimum: 450 mm outlet pipe;
+*Preferred pipe slope: > 1 %;
+*If orifice control used, 75 mm diameter minimum;
+*Minimum 100 mm orifice preferable
+|-
+|Maintenance access
+|Access for backhoes or dredging equipment
+|style="text-align: left|
+*Provided to approval of Municipality;
+*Provision of maintenance drawdown pipe preferred
+|-
+|Buffer
+|Safety
+|style="text-align: left|Minimum 3 m above maximum water quality/erosion control water level
+|}
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The bottom of a dry pond should be flat to encourage uniform ponding and infiltration across the entire surface. Recommended tolerance on base levels 10 mm in 3m.
The bottom of a dry pond should be flat to encourage uniform ponding and infiltration across the entire surface. Recommended tolerance on base levels 10 mm in 3m.