Changes

* Native soil infiltration rates for Full, and Partial Infiltration Design scenarios were assumed to be 20 mm/h and 10 mm/h respectively, and a safety factor of 2.5 was applied to calculate the design infiltration rate.  

* Native soil infiltration rates for Full, and Partial Infiltration Design scenarios were assumed to be 20 mm/h and 10 mm/h respectively, and a safety factor of 2.5 was applied to calculate the design infiltration rate.  

* 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.

* Trench width of 2.0 metres.

* Maximum impervious drainage area to permeable surface area (I:P area) ratio of 20:1.

===Notes===

===Notes===

* Designs include [[pretreatment]] through hydrodynamic separator ([[Oil and Grit Separator]]).

* Designs include [[pretreatment]] through two (2) hydrodynamic separators ([[Oil and Grit Separator]]) located upstream of trench inlets, and two (2) 150 mm diameter monitoring wells per trench.

* The tool calculates costs for new (greenfield) development contexts and includes costs for contractor overhead and profit, material, delivery, labour, equipment (rental, operating and operator costs), hauling and disposal.  

* The tool calculates costs for new (greenfield) development contexts and includes costs for contractor overhead and profit, material, delivery, labour, equipment (rental, operating and operator costs), hauling and disposal.  

** Land value and equipment mobilization and demobilization costs are not included, assuming BMP construction is part of overall development site construction.

** Land value and equipment mobilization and demobilization costs are not included, assuming BMP construction is part of overall development site construction.