A better way to design street inlets: New version of UD-Inlet workbook now available!

[Ken MacKenzie (UDFCD)]

In 2006, UDFCD commissioned a study to investigate the hydraulic
efficiencies of street inlets commonly used in the UDFCD region,
including the CDOT Type 13 and Denver No. 16 grated inlets in valley
and combination configuration, and the CDOT Type R curb opening inlets
for street and roadway drainage.

The study was completed at the Colorado State University (CSU)
hydraulics laboratory, where a 1/3 scale physical model was
constructed to study the hydraulics of these inlets. The project was
financially supported by the Urban Drainage and Flood Control
District, the Colorado Department of Transportation, Denver, Adams
County, Arapahoe County, Arvada, Douglas County, Jefferson County,
Boulder, Golden, Lafayette, Lakewood, Littleton, and Lone Tree. My
special thanks go out to these entities who made this costly but
important work possible.

The findings of that four-year long study resulted in new equations,
modified equations, and calibrated coefficients to better approximate
the true capacity of street inlets commonly used in the UDFCD region.
All of this work has now been coded into an Excel workbook we call UD-
Inlet_v3.00.xls, which is available as freeware at:
http://www.udfcd.org/downloads/down_disclaimer.htm.

The workbook is accompanied by a technical memorandum describing the
CSU study, the results, and the new computational methods. This paper
also contains simplified empirical equations for inlets in sump
conditions in the appendix, which can be used in place of the workbook
for inlets in sump or sag locations.

The full study report from CSU to UDFCD is also available at:
http://www.udfcd.org/downloads/down_hydra_design.htm.

I hope you find this new tool useful, and will appreciate any comments
you have to offer.

Best Regards, Ken.