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Bioretention can be constructed over any soil type, but hydrologic soil group A and B are best for achieving water balance objectives. Facilities designed to infiltrate water should be located on portions of the site with the highest infiltration rates.
For small LID facilities:*Apply soil media in 150-300 mm lifts until desired top elevation of bioretention, bioswale or rain garden area is achieved*Thoroughly wet each lift before adding the next and wait until water has drained through the soil before adding the next lift. For large LID facilities:*Apply soil media in 150-300 mm lifts with slinger trucks. This type of equipment will reduce the need to move soil media manually or by backhoe.*Thoroughly wet each lift before adding the next and wait until water has drained through the soil before adding the next lift.
*All exposed soil areas that are not being actively worked must have temporary erosion protection or permanent cover within 7 days for slopes 3:1 or greater and 14 days for slopes 3:1 or greater and 14 days for slopes 3:1 or flatter. This should apply to all exposed soil areas year-round and until the site is stabilized.
→Backfill Granular and Pipes (SPC)
'''Soil Media / Filter Media'''<br>
'''Soil Media / Filter Media'''<br>
Construction Steps
Bioretention can be constructed over any soil type, but hydrologic soil group A and B are best for achieving water balance objectives. Facilities designed to infiltrate water should be located on portions of the site with the highest infiltration rates. STEP has detailed construction guidance on soil amendments available on its [[https://sustainabletechnologies.ca/home/urban-runoff-green-infrastructure/healthy-soils/construction-specifications-for-implementing-compost-amended-planting-soil-in-ontario/ Construction Specifications for Implementing Compost Amended Planting Soil in Ontario]] webpage. These resources include specification details and a spreadsheet calculator for determining soil and amendment volumes.
Construction Steps:
#Apply soil media in 150-300 mm lifts until desired top elevation of bioretention, bioswale or rain garden area is achieved.
#Apply soil media with slinger trucks when possible. This type of equipment will reduce the need to move soil media manually or by backhoe.
#Thoroughly wet each lift before adding the next and wait until water has drained through the soil before adding the next lift.
#If amending soils:
**Stockpile native soils in designated areas.
**Mix selected additives with native soils using a plumbus.
**Sling soils into the LID feature whenever possible.
Key Inspection Points:
Key Inspection Points:
*When material arrives to the site: perform chain of custody, visual inspection and ribbon test to ensure that material meets design requirements.
*When material arrives to the site: perform chain of custody, visual inspection and ribbon test to ensure that material meets design requirements.
*Ensure that soil media is being applied to the correct depth
*Soil/filter media’s design parameters and assumptions should be confirmed through in-situ permeability testing (e.g., permeameter measurements to determine hydraulic conductivity). Results of permeability testing should be reviewed by the designer and, if required, changes to the LID design may be needed. See [[Testing]] for more information regarding testing procedures.
*Ensure that soil media is being applied to the correct depth.
*Ensure that the native soil and amended material are well blended.
*Measure potentially compacted soils using a cone penetration test or a cone penetrometer.
Mistakes to Avoid:
Mistakes to Avoid:
*Machine compaction: Equipment should not be operated within the infiltration practice.
*Machine compaction - equipment should not be operated within the infiltration practice.
*Soil material: Accepting material that does not meet design specifications and requirements
*Soil material: Accepting material that does not meet design specifications and requirements.
*Soil material application: Applying the next lift without letting the previous lift of filter material dry.
*Application: Applying the next lift without letting dry the previous lift of filter material.
===Finishing Grades: Inlet, Outlet, Biomedia, Plants (SPC)===
===Finishing Grades: Inlet, Outlet, Biomedia, Plants (SPC)===