Modeling stormwater facilities accurately in hydraulic programs depends greatly on facility specific characteristics, including stage-storage and elevation-discharge curves. It is typically assumed that these facilities are in ‘good’ operating condition with full design capacity. True field conditions, however, may uncover factors prohibiting these facilities from achieving true design capacities.

It is imperative that best management practices, or BMPS, are maintained to provide their design level of service. Field inspections provide critical information on the state of the facilities’ infrastructure. Plans and previous inspection reports are helpful to determine if the facility is operating as intended or if maintenance items are being addressed as needed.

Modeling true field conditions provides data that can drastically change the results of a proposed drainage study. Examples of this include; basins filling with sediment (thus altering stage-storage relations), pipes filling with debris (reducing the effective pipe diameter) and roadside ditches not being maintained (decreasing capacity and potentially increasing water surface elevation).