Changes

[[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 depth is the recommended method to prevent migration of finer [[filter media]] into an underlying reservoir of [[Reservoir gravel|coarse aggregate]].

In [[bioretention]] systems a choker layer of ≥ 100 mm depth is the recommended method to prevent migration of finer [[filter media]] into the underlying [[Reservoir gravel|storage reservoir aggregate]].

These same mid sized granular materials are recommended for use in [[Stormwater planter]] underdrains and may be useful in the fine grading of foundations courses for [[permeable paving]].

These same mid-sized granular materials are recommended for use in [[Stormwater planter]] underdrains and may be useful in the fine grading of foundations courses for [[permeable pavements]].

Suitable materials include:

Suitable materials include:

;High performance bedding (HPB)

;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.   

:Clean, angular aggregate screened to between 6 and 10 mm. Widely available and designed specifically for drainage applications. Free from fines by definition.   

;HL 6

;HL 6

:Is a clean, angular aggregate screened between 10 - 20 mm. Free from fines by definition.  

:Is a clean, angular aggregate screened between 10 and 20 mm. Free from fines by definition.  

;Pea Gravel

;Pea Gravel

:Rounded natural aggregate, screened between 5 - 15 mm, and washed free from fines.  

:Rounded natural aggregate, screened between 5 and 15 mm, and washed free from fines.  

In most scenarios, a [[geotextiles|geotextile]] layer is unnecessary and have been associated with rapid decline and [[Clogging#Filter fabric|clogging]] in some circumstances.  

In most scenarios, a [[geotextiles|geotextile]] layer is unnecessary and has been associated with rapid decline and [[Clogging#Filter fabric|clogging]] in some circumstances.  

[[category: materials]]

[[category: materials]]