Line 1:
Line 1:
[[File:Gravel.jpg|thumb]]
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]].
Suitable materials include:
Suitable materials include: