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What are they?
- Shallow trenches filled with rubble or stone to create subsurface runoff storage
Where can they be used?
- Best used when run along an impermeable surface and receive inflow along the length of the trench
- Ideal locations include playing fields, other public open space, roadways and parking lots
Who commonly uses them?
- High Density Areas
How do they work?
- Create subsurface runoff storage
- Water exfiltrates into surrounding soil from bottom and sides of the trench
- Cleans water through physical filtration, adsorption, and biochemical reactions in the soil
- Enhances natural capacity of ground to store and filter water
- Reduces runoff rates and volumes
- Reduces volume of runoff pollutants
- Fits well beside roads
- Easy integration
- Low maintenance
- High potential for clogging without pre-treatment, since they don’t trap sediments
- Volume of water depends on the infiltration potential of the soil underneath the trench
- Quality of water treatment depends on the size of the fill material and pre-treatment
- Need to be regularly inspected for signs of clogging
- Need to perform removal and cleaning or replacement of stone