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Houston Airport - United Airlines Terminal C

Houston, Texas

Stormwater Treatment


IAH Airport


Nathelyne Kennedy & Associates


November 2016

Technical Description:

  • (3) CDS® hydrodynamic separators

The United Airlines® Terminal C North project at George Bush Intercontinental Airport (IAH) resulted in a new 265,000 square-foot concourse, improving the traveling experience for millions of travelers.

The $277 million terminal was built by United in partnership with the Houston Airport System and includes floor-to-ceiling windows, passenger lounge areas, and 20 new dining and retail options. It also includes 11 boarding gates to accommodate a mix of United’s narrow, mid, and wide-body planes.

The new terminal and surrounding apron resulted in the need for a stormwater treatment system capable of meeting the City of Houston's stormwater quality regulations of 70% annual sediment removal.

To meet these requirements, Engineers at Nathelyne Kennedy & Associates originally specified 12’ diameter hydrodynamic separators manufactured by a company other than Contech. However, Contech was able to demonstrate, using annual sediment removal calculations, that 8' CDS units would meet the sediment removal requirements. The smaller units designed by Contech provided a more economical option in both material and installation cost. 

The CDS hydrodynamic separator uses swirl concentration and continuous deflective separation to screen, separate and trap trash, debris, sediment, and hydrocarbons from stormwater runoff. A total of three CDS units were needed to treat the water quality flow at the site.

Since the CDS units would be located under the apron, the units were designed to withstand aircraft loading. The aircraft loading assumed 75kip wheel loading which required 18” thick top slabs with flush-mounted extra heavy duty frames and covers for access. Additionally, these units were intended to capture oil and grease in the runoff from the airport apron. They include oil sorbent media placed in the separation cylinder (at the free surface) to ensure the permanent removal of the free oil and grease from stormwater runoff.

The flexible configuration of the CDS allowed multiple pipe inlets to connect with each unit, eliminating the need for junction manholes, resulting in significant cost savings. In addition, the internal weir of the CDS eliminated the need for separate bypass structures.

Ease of maintenance was also a factor in selecting the CDS. Maintaining a CDS is a simple process that can be accomplished in less than 30 minutes for most installations using a vacuum truck, with no requirement to enter the unit.

A Contech Field Representative was onsite to oversee and ensure proper installation of the three CDS units.

Technical Description:

  • (3) CDS® hydrodynamic separators

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