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→Design
==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
|}
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.