Bioretention: Construction checklist

From LID SWM Planning and Design Guide
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Common construction pitfalls can be avoided with careful construction supervision that focuses on the following aspects:

Erosion and Sediment Control
  Bioretention locations should be blocked from construction traffic and should not be used for erosion and sediment control
Proper erosion and sediment controls should be in place for the drainage area
Materials
  Gravel for the underdrain should be clean and washed; no fines should be present in the material
Underdrain pipe material should be perforated and of the correct size (when specified in design)
A cap should be placed on the upstream (but not the downstream) end of the underdrain (when specified in design)
Biomedia should be tested to confirm that it meets specifications
Mulch composition should be correct
Elevations
  Depth of the gravel and invert of the underdrain
Inverts for inflow and outflow points
Filter media depth
Ponding depth provided between the surface of the filter bed and the overflow structure
Mulch depth
Landscaping and Stabilization
  Correct vegetation should be planted
Pretreatment area should be stabilized
Drainage area should be stabilized prior to directing water to the bioretention
The following items should be checked after the first rainfall event, and adjustments should be made as necessary:
  Outfall protection/energy dissipation at concentrated inflow should be stable
Flow should not concentrate and should spread evenly over the filter bed
Ponded water at the surface of the bioretenton facility must drain within 24 hours of the end of the storm event.
The biomedia should fully drain within a maximum period of 72 hours
Excessive sediment accumulation should not be present