Changes

* Operation and maintenance (O&M) cost estimates assume annual inspections, removal of trash and debris twice a year, removal of sediment from pretreatment structures annually. Verification inspections are included every 5 years to confirm adequate maintenance, and every 15 years to confirm adequate drainage performance through in-situ trench water level monitoring during natural storm events.

* Operation and maintenance (O&M) cost estimates assume annual inspections, removal of trash and debris twice a year, removal of sediment from pretreatment structures annually. Verification inspections are included every 5 years to confirm adequate maintenance, and every 15 years to confirm adequate drainage performance through in-situ trench water level monitoring during natural storm events.

* Designed with an impervious drainage area to treatment facility area ratio of between 5:1 and a maximum of 20:1.

* Designed with an impervious drainage area to treatment facility area ratio of between 5:1 and a maximum of 20:1.

* Length to width ratio of infiltration trench area recommended from facilities receiving road or parking lot runoff is 10:1.

* Length to width ratio of infiltration trench area recommended from facilities receiving road or parking lot runoff is 10:1.

* Should be set back at least four (4) metres from building foundations.

* Hydrodynamic (oil and grit) separator included upstream of trench to provide pretreatment.

* Default filter media depth of 1.0 metres to accommodate trees in planting plan.

* Default maximum depth of 3 - 4 metres, as there are cost implications with using trench boxes to retain the side walls.

===Notes===

===Notes===