ABCW-4 Under Technical Review Engine v0.9.0
Bioretention Swale calculator
Combined conveyance (swale above the filter), filtration capacity of the bioretention trench, underdrain and perforation capacity, and overflow pit checks.
Not a PUB approval. This calculator is under technical review and is not yet validated against PUB's official calculation template. A passing calculation does not establish compliance with PUB requirements. ABC Waters design calculations must be prepared and endorsed by an ABC Waters Professional / Qualified Person and submitted to PUB in the required format.
Available after technical review
This module will open once it has been validated against PUB's official ABC Waters calculation template and independently reviewed. The method, inputs and references are listed below.
Inputs
- Project / feature reference
- Contributing catchment area (ha)
- Impervious fraction (-)
- Target filter area (% of impervious area) (%)
- Runoff coefficient (treatment flow)
- Rainfall intensity for design treatment flow (mm/h)
- Swale base width (= filter width) (m)
- Side slope (H:1V)
- Swale depth above filter surface (m)
- Longitudinal slope (%)
- Length of filter (m)
- Manning n at minor / major flow
- Minor flow (5-yr ARI) (m3/s)
- Major flow (m3/s)
- Filter media depth (m)
- Design saturated hydraulic conductivity (mm/h)
- Extended detention depth (m)
- Filter media effective porosity (information) (-)
- Underdrain pipe internal diameter (mm)
- Number of underdrain pipes (no.)
- Manning n of underdrain pipe
- Perforation open area per metre of pipe (mm2/m)
- Orifice discharge coefficient
- Perforation blockage factor (fraction open)
- Overflow pit weir length (m)
- Overflow pit grate open area (m2)
- Available head above overflow crest (m)
- Weir coefficient
- Overflow grate blockage factor (fraction open)
- Minimum freeboard at minor flow (m)
- Maximum velocity at minor flow (m/s)
- Maximum velocity at major flow (m/s)
- Maximum velocity x depth at major flow (m2/s)