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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 inthe 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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Systems should be located below shoulders of roadways, [[permeable pavements]] or [[swales]] where they can be readily excavated for servicing. An adequate subsurface area outside of the 4 m setback from building foundations and suitable distance from other underground utilities must be available.
Systems should be located below shoulders of roadways, [[permeable pavements]] or [[swales]] where they can be readily excavated for servicing. An adequate subsurface area outside of the 4 m setback from building foundations and suitable distance from other underground utilities must be available.
===Infiltration===
For information about constraints to infiltration practices, and approaches and tools for identifying and designing within them see [[Infiltration]].
===Native Soil===
Exfiltration trench systems can be constructed over any soil type, but hydrologic soil group (HSG) A or B soils are best for achieving water balance and erosion control objectives. Facilities should be located on portions of the site with the highest infiltration rates. Native soil infiltration rate at the proposed facility location and depth should be confirmed through in-situ measurements of hydraulic conductivity under field saturated conditions. For guidance on infiltration testing and selecting a design infiltration rate see [[Design infiltration rate]].
===Site Topography===
===Site Topography===
Systems cannot be located on natural slopes > 15 %.
Systems cannot be located on natural slopes > 15 %.
For more information on planning considerations and site constraints see [[Infiltration trenches]].
For a table summarizing information on planning considerations and site constraints see [[Site considerations]].
==Design==
==Design==
===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]]
==Inspection and Maintenance==
Routine inspection and maintenance consists of checking and cleaning trash, debris and sediment from [[pretreatment]] devices, [[inlets]] and [[overflow|outlets]] twice a year in the spring and/or late fall, or when pretreatment device sump is half full. Use hydro-vac truck to remove sediment from catch basin sumps, [[OGS]] and isolated chamber row filter pre-treatment devices. To clean isolated chamber row filters use a vacuum truck equipped with rear-facing jet nozzle for cleaning large diameter pipes or culverts.
Monitoring of storage reservoir water level during and after natural or simulated storm events using the monitoring well should be performed periodically to verify the facility drains within the required drainage time (typically 72 hours). Should be performed as part of inspections following construction or major rehabilitation prior to assumption, and every 15 years at a minimum, to track drainage performance over time and determine when replacement is needed. <br>
</br>
Take a look at the [[Inspection and Maintenance: Underground Infiltration Systems]] page by clicking below for further details about proper inspection and maintenance practices:
{{Clickable button|[[File:Cover page underground.PNG|150px|link=https://wiki.sustainabletechnologies.ca/wiki/Inspection_and_Maintenance:_Underground_Infiltration_System]]}}
==Gallery==
==Gallery==
{{:Exfiltration:_Gallery}}
{{:Exfiltration:_Gallery}}
==Materials==
==Materials==
{{:Reservoir aggregate}}
{{:Reservoir aggregate}}
*https://www.chijournal.org/C390
*https://www.chijournal.org/C390
*http://www.civil.ryerson.ca/seminar/Papers/Draft%20Design%20manual%20of%20EES%20by%20Tran%20and%20Li%207-24-2015.pdf
*http://www.civil.ryerson.ca/seminar/Papers/Draft%20Design%20manual%20of%20EES%20by%20Tran%20and%20Li%207-24-2015.pdf
==References==
[[Category:Infiltration]]
[[Category: Green infrastructure]]