Changes

[[File:perf pipe.gif|frame|500 px|Exfiltration trench under high flow and exfiltration conditions]]

{{float right|[[File:perf pipe.gif|border|600 px|Exfiltration trench under high flow and exfiltration conditions]]}}

Exfiltration trenches are similar to [[infiltration trenches]] but differ primarily in the the manner in which stormwater is delivered to the trench.<br>

Exfiltration trenches are similar to [[infiltration trenches]] but differ primarily in the the manner in which stormwater is delivered to the trench.<br>

Runoff enters infiltration trenches directly by infiltration from the surface. In exfiltration systems, surface runoff is collected by drainage [[inlets]] and delivered to the trench via subsurface perforated [[pipes]].

Runoff enters infiltration trenches directly by infiltration from the surface. In exfiltration systems, surface runoff is collected by drainage [[inlets]] and delivered to the trench via subsurface perforated [[pipes]].

*Gravel beds in which exfiltration systems are installed are typically rectangular excavations with a bottom width between 0.6 and 2.4 m <ref>Greater Vancouver Regional District. 2005. Stormwater Source Control Design

*Gravel beds in which exfiltration systems are installed are typically rectangular excavations with a bottom width between 0.6 and 2.4 m <ref>Greater Vancouver Regional District. 2005. Stormwater Source Control Design

Guidelines 2005. Prepared by Lanarc Consultants Limited, Kerr Wood Leidal Associates Limited and Goya Ngan</ref>.  

Guidelines 2005. Prepared by Lanarc Consultants Limited, Kerr Wood Leidal Associates Limited and Goya Ngan</ref>.  

*The gravel beds should have gentle slopes between 0.5 - 1%.

*The gravel beds should have gentle slopes between 0.5 - 1 %.

*Calculate maximum '''[[flow through perforated pipe]]'''

*Calculate maximum '''[[flow through perforated pipe]]'''

===Drawings===

===Drawings===

Standard details for exfiltration trenches have been produced by City of Kitchener and City of Barrie. See [[Drawings]]

Standard details for exfiltration trenches have been produced by City of Kitchener and City of Barrie. See [[Drawings]]