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− | [[File:perf pipe.gif|border|400 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]]. |
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| *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]] |