Olsson Associates


Award-winning drainage project mitigates flooding in Phoenix neighborhood

Wednesday, February 18, 2015

Rachel Wiester, Marketing

For its work on the Lafayette Interceptor Drain and Outlet project in the Phoenix neighborhood of Arcadia, Olsson’s Phoenix Water Resources team won a 2014 American Council of Engineering Companies (ACEC) Arizona Engineering Excellence Honor Award. Olsson served as the prime consultant for the project, which was the second segment of this regional stormwater drainage system. Olsson also designed the first segment of the system.

Lafayette Boulevard faced frequent ponding, even during smaller storms.Arcadia is an affluent neighborhood in east Phoenix that experienced frequent flooding. The deluge was due to stormwater that originated from the Camelback Mountains, flowed through the neighborhood, and ponded upstream of the Arizona Canal. To mitigate flooding, the Flood Control District of Maricopa County and the City of Phoenix proposed a regional drainage system to capture and convey stormwater from Arcadia to the Old Cross Cut Canal, which ultimately drains to the Salt River.

The storm drain system consisted of approximately 10,160 linear feet of reinforced concrete pipe varying in size from 24 inches to 102 inches in diameter along the project’s route. The project also included the following:


  • Six specially designed storm drain transition structures
  • 68 catch basins
  • 31 manholes
  • More than 2,600 linear feet of new curb and gutter
  • 1,800 linear feet of new waterline
  • 18,450 square yards of pavement replacement

The system intercepts stormwater before it ponds behind the Arizona Canal, removes stormwater from the local streets, and provides a drain for the floodplain.

The project team faced a number of challenges during design and construction. Arcadia is a well-established area with many historic and distinct neighborhoods. Olsson worked closely with the public to ensure that neighborhoods would maintain access during construction, disruptions would be minimized, the unique character of the neighborhood would be maintained, and mature vegetation would be protected. A custom-catch basin type was designed to blend in with the unique character of the neighborhood.

Through effective value engineering, the project team realigned the storm drain to eliminate major utility conflicts, reduce traffic impacts, and provide a better drainage solution that increased the capacity of the existing storm drain system.

Drainage outlet area at office complex before construction. Drainage outlet area after construction, with a new drop inlet.

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