Portland International Airport (PDX) is the 34th largest airport in the U.S., serving over 14 million travelers annually with flights to 42 domestic and four international cities. It ranks as the 24th largest cargo airport in the country and is also home to the 142nd Fighter Wing of the Oregon Air National Guard.
A vital element for providing safe aviation service at PDX is deicing airplanes during periods when air temperatures are below 40°F with actual or potential freezing precipitation. The Port of Portland, which operates PDX, constructed a $31 million system to collect, treat, monitor, and discharge deicing runoff. The system was placed into operation in 2003. Deicing runoff is collected and safely treated prior to controlled discharge.
In 2006, under a Mutual Agreement and Order with the Oregon Department of Environmental Quality, the decision was made to further enhance the deicing system to treat additional volumes of runoff from the western half of the airfield, and to ensure compliance with new environmental requirements. Part of the new collection system required new 24” and 6” piping to be installed under the crosswind runway and cargo center to convey deicing runoff to the treatment facility.
CDM, the Port’s design engineer, evaluated different options for the pipeline construction to minimize environmental impact and disruption to airport operations. Horizontal directional drilling (HDD) was selected with a bore alignment of 3,820 LF and a maximum depth of 75 feet. FPVC® pipe, provided by Underground Solutions Inc. (UGSI), was selected for its high tensile strength, superior buckling pressure, and ability to minimize the size and cost of the HDD bore hole.
High pipe buckling strength was a key design criterion since the collection pipes are empty most of the year when the deicing systems are not in operation. Other thermoplastic pipe materials were unable to meet the long-term deflection requirements of the design.
Due to the complexity and risk of the directional drill, project construction manager JE Dunn pre-qualified HDD contractors prior to the bid. The successful low bid was submitted by the team of Northwest Underwater Construction, LLC of Vancouver, WA, and Kinnan Engineering, Inc. of Camas Valley, OR.
During drilling, Kinnan encountered difficult and complicated drilling conditions. Due to airport security and access concerns, the perimeter road and surrounding fence needed to remain intact. Kinnan installed a temporary corrugated metal culvert under the fence and road which met both security and continuous access needs. Finally, the lay-down area for the fused pipe also presented a challenge due to wetlands that could not be disturbed. JE Dunn, CDM, The Port of Portland, Kinnan, and UGSI ultimately identified an alternate alignment that did not disturb the wetlands.
Kinnan custom fabricated a pull head to pull the 6” and 24” pipes simultaneously. Pullback commenced on July 27, 2010, with the pipe ballasted with water to reduce frictional force. The pull was completed in 13 hours, exerting a maximum pull force of 117,000 pounds. A successful pressure test was completed several weeks later.
“UGSI provided us with great support and assistance during the entire project. The pipe pulled in really well and didn’t stretch during pullback operation which typically occurs when pulling HDPE,” said Keith Kinnan, Kinnan Engineering. “FPVC® pipe had a better than expected bend radius that worked well in the lay down field adjacent to the airport where we had to avoid wetlands. We were really impressed with the 225 psi pressure test and our ability to drill deep with the pipe.”
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