What does an approved hydraulic loading rate of 1.6 gpm/sq. ft. mean for stormwater design?

What does an approved hydraulic loading rate of 1.6 gpm/sq. ft. mean for stormwater design?

For FocalPoint® HPMBS, it means 1.6 gallons per minute of treatment flow per square foot of media surface area, subject to the conditions of Washington Ecology’s General Use Level Designation for Basic (TSS) Treatment.

For engineers, that rate connects required treatment flow to preliminary media sizing:

Required treatment flow ÷ hydraulic loading rate = media surface area.

For example, 160 gpm ÷ 1.6 gpm/sq. ft. = 100 sq. ft. of media surface area. That illustrates the sizing relationship; final design must also account for applicable sizing requirements, pretreatment, hydraulics, bypass configuration and local approval.

The practical benefit? A compact treatment area can give designers more flexibility on constrained sites.
FocalPoint’s space-efficient footprint and flexible configuration are established advantages. GULD adds a Washington Ecology-reviewed pathway for specifying the system in Basic Treatment applications.

Have a treatment-flow requirement or a challenging site layout? Convergent’s technical team can help evaluate sizing and configuration.

Review the designation, approved conditions and design resources: https://bit.ly/47iYml0