Difference between revisions of "Choker layer"
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[[File:Gravel.jpg|thumb|medium sized granular, free from fines]] | [[File:Gravel.jpg|thumb|medium sized granular, free from fines]] | ||
In [[bioretention]] systems a choking layer of ≥ 100 mm is the recommended method to prevent migration of finer [[filter media]] into an underlying reservoir of [[Reservoir gravel|coarse aggregate]]. | In [[bioretention]] systems a choking layer of ≥ 100 mm is the recommended method to prevent migration of finer [[filter media]] into an underlying reservoir of [[Reservoir gravel|coarse aggregate]]. | ||
These same mid sized granular materials are recommended for use in [[Stormwater planter]] underdrains. | |||
Suitable materials include: | Suitable materials include: | ||
;High performance bedding (HPB) | ;High performance bedding (HPB) | ||
Revision as of 17:59, 19 March 2018
In bioretention systems a choking layer of ≥ 100 mm is the recommended method to prevent migration of finer filter media into an underlying reservoir of coarse aggregate. These same mid sized granular materials are recommended for use in Stormwater planter underdrains.
Suitable materials include:
- High performance bedding (HPB)
- Clean, angular aggregate screened to between 6 - 10 mm. Widely available and designed specifically for drainage applications. Free from fines by definition.
- HL 6
- Is a clean, angular aggregate screened between 10 - 20 mm. Free from fines by definition.
- Pea Gravel
- Rounded natural aggregate, screened between 5 - 15 mm, and washed free from fines.
In most scenarios, a geotextile layer is unnecessary and have been associated with rapid decline and clogging in some circumstances.