2,681
edits
Changes
Jump to navigation
Jump to search
Line 48:
Line 48: − + − + + + + + + + + + + + + + + + +
no edit summary
| 0.4
| 0.4
|}
|}
Before you begin you will need to know the following;<br>
* Catchment area (i.e. contributing drainage area), A<sub>c (m<sup>2)
* Catchment impervious area, A<sub>i (m<sup>2)
* Catchment runoff coefficient, C
* Design storm intensity, i (mm/h)
* Design storm duration, D (h)
* Infiltration target for design storm event, I<sub>d (mm)
* Drainage time target to fully drain the active storage, t (h), based on long-term average inter-event period for the location or local criteria
* Field infiltration rate of the underlying native soil f<sub>f (mm/h), median of field measurements or based on interpolation from median grain-size distribution results
* Design infiltration rate of the underlying native soil f' (mm/h), median field measured value divided by a safety factor (z)
* Safety factor, z (dimensionless value between 2 and 3) chosen by designer
* Proposed surface grade elevation at the practice location (metres above sea level, masl)
* Elevation of the seasonally high water table or bedrock surface (metres above sea level, masl), below the practice location
* Effective porosity of any void-producing structure system (e.g. soil cells, chambers and associated aggregate) included, n' (if applicable)
* Types of plants to be supported by the filter media bed (i.e. grasses vs. mix of grasses, plants and shrubs vs. trees)
* How runoff will be delivered to the practice (i.e. to filter bed surface; to storage reservoir; or both)
==Calculate the maximum overall depth==
==Calculate the maximum overall depth==
*Step 1: Determine what the planting needs are and assign appropriate depth of media, using the table above.
*Step 1: Determine what the planting needs are and assign appropriate depth of media, using the table above.