AGENCY: Port of Portland, Ore.
GENERAL CONTRACTOR: JE Dunn Construction
ENGINEERING AND DESIGN: Gresham, Smith & Partners
SCOPE: Adding several large storage tanks, pump stations, and a 12,000-square-foot anaerobic treatment facility
COST: $74 million
|FEDERAL WATER QUALITY GUIDELINES FOR AIRPORTS|
This year, the U.S. EPA issued new guidelines and source performance standards for discharges from airport deicing operations that will impact all airports built in the future. (Existing airports will continue to be regulated by state guidelines.)
The requirements generally apply to wastewater associated with the deicing of airfield pavement at primary airports, in accordance with the Clean Water Act. Visit http://water.epa.gov and search “aviation guidelines” for detailed information, including:
TIMELINE: 2009 – 2011
Like any organization that releases effluent directly into U.S. waters, airports must meet certain discharge requirements. The U.S. EPA has asked the air transportation industry to voluntarily control pollutants from deicing operations. These federal water quality standards, plus Oregon Department of Environmental Quality effluent limitations , prompted Portland International Airport (PDX) managers to upgrade their deicing runoff system.
Owned by the Port of Portland, PDX was one of the nation's first airports to build and implement a system to capture and process stormwater runoff containing dilute concentrations of deicing materials from both aircraft and pavement. Activated for the 2011–2012 winter season, the system is comprised of several large storage tanks, pump stations, and an onsite, 12,000-square-foot anaerobic treatment facility. The result: an effluent discharge treatment process that protects the nearby Columbia Slough and Columbia River.
Such a major infrastructure expansion at a high-traffic airport posed many challenges.
“For construction to be efficient and yet allow the airport to operate, the solutions we provided had to be innovative,” says Bruce Van Hine, project manager for general contractor JE Dunn. “Not only were our efforts successful, they were fun to be a part of.”
Complying with discharge standards
Before 2003, the airport's primary runoff controls were best management practices to capture, collect, and ship off to appropriate facilities that could handle the overflow. Previously, discharge was metered out to the Columbia Slough when the flow in the slough was active. When the slough was low or had no flow, or when the discharge amount was greater than the Port's permit would allow, the effluent went into the municipal sanitary sewer system or occasionally exceeded the permit limits. Although the airport effectively collected runoff, it couldn't meet state requirements 100% of the time.
The new system doubles the Port's existing treatment capacity. More than 200 new inlets collect ramp and runway runoff. The contaminated runoff is conveyed to storage tanks and reservoirs, then goes through through an anaerobic treatment process.
“A state-of-the-art, onsite anaerobic processing facility in the new treatment building is at the heart of the project,” says Susan Aha, Port of Portland deicing program manager. “It is the largest of its kind in the United States, and one of three in the world to use this specific treatment technology.”
Working in the flight path
The contractors installed more than six miles of underground conveyance piping to move stormwater from one side of the airport to the other. The project team chose the long bore method of underground horizontal directional drilling (HDD) for some sections of pipe, rather than cut-and-cover underground installation, to avoid interference and disruption to active airport operations and tenants, avoid critical utility and navigation systems, and to mitigate environmental impacts.
JE Dunn used building information modeling (BIM) to coordinate the pipe routing and alignment underground. To ensure all project teams were on the same page, all BIM efforts were compiled into a single model.
“It definitely wasn't a typical construction project,” says Jason Schaumberg, BIM coordinator for JE Dunn. “The quantity of underground and above-ground piping was intense, and we couldn't risk coming up short and drilling through a runway. The only way to coordinate accurately and efficiently was by using BIM.”
The combination of BIM and HDD allowed the project team to successfully pull more than 3,700 feet of heavy-duty polyvinyl chloride pipes through a 40-inch bored hole, making this the longest dual-pipe HDD installation completed in the U.S. in 2010. Placing the river discharge section of pipe entailed drilling under a Columbia River dike with a busy highway on top. The river work had to be coordinated within a narrow window of time to avoid conflict with fish migration. To meet this requirement, the HDPE piping was prefabricated and fusion welded offsite. After the hole to the river was bored, contractors floated the pipe up the river and pulled it through the hole.
Because the new facility and storage tanks are located at the end of active runways, the project team coordinated with airport operations personnel daily to sequence their work and meet construction schedules. Equipment such as cranes, concrete pumps, and lift equipment were limited to a height restriction due to air traffic. Any time a crane boom had to be raised or lowered more than 40 feet, contractors contacted the control tower for permission. Certain operations were scheduled during slower traffic periods. For instance, the process reactors were set with a large crane in the middle of the night, during a coordinated runway shutdown.
Communicating with all of the airport's numerous stakeholders — including the airlines themselves — kept the project on schedule. Specifications were clear about coordinating with airport departments including wildlife, security, TSA, environmental, and deicing operations. The project team held regular open meetings, allowing stakeholders to voice any concerns and discuss possible solutions immediately. Weekly meetings also were conducted to integrate this stakeholder information into a working model that JE Dunn, the designers, and the Port of Portland could implement.
Additionally, environmental reports were required after rain events or when the team used any hazardous materials. The Port Fire & Rescue Department had to be notified before any work involving open flame. Port security wanted thorough criminal history background checks on laborers and adequate security badge management. Finally, the construction team kept the Port inspection team informed of work activities on a daily basis.
The project provided the Port of Portland with a long-term solution to improve water quality in the Columbia Slough while minimizing energy use — and it met all regulatory milestones established by the Oregon Department of Environmental Quality.
The new water treatment facility also reduces energy costs. Methane biogas produced by the microbes in the anaerobic system is collected and used to fuel the hot-water system. The heating system then heats the reactors and building via a hot-water heating loop. The treatment site's 540 square feet of solar panels reduce energy demand by providing approximately 6,700 kilowatt-hours per year.
Construction took 761 days and did not incur a single lost-time accident. The project was completed under budget and 12 weeks ahead of schedule to allow for an extended start-up and commissioning period. This ensured the plant would be completely ready for any early winter season weather events and the start of the 2011 –2012 deicing season.
— Laizure (firstname.lastname@example.org) is vice president and business development director for JE Dunn Construction.
PDX ENHANCED DEICER MANAGEMENT SYSTEM
At the core of the water treatment facility are two anaerobic fluidized bed reactors, designed by Gresham, Smith & Partners. Deicer runoff is passed through a bed of granular-activated carbon, suspending and mixing the media. This allows microorganisms to grow on the entire outer surface of the carbon, which absorb the organic compounds from the deicer fluid and break them down. They convert the effluent to water, carbon dioxide, and methane, which then flow into a separator where gravity forces denser solids to the bottom, and lighter solids and water migrate to the top. The water is clarified and discharged.
After treatment, the system discharges the treated effluent to the Columbia River or to the sanitary system in compliance with permit requirements. On average, the new system will reduce discharge to the Columbia Slough by 89% and meet National Pollutant Discharge Elimination System permit requirements.
The entire process — storage, conveyance, treatment, and discharge — is remotely monitored using a Supervisory Control and Data Acquisition (SCADA) system. Specialized instruments monitor biochemical oxygen demand (BOD) to identify chemical concentration, flow rates, and permit limits. This real-time monitoring and automation helps plant operators determine and control the options for water storage, treatment, and release.