Airport Expansion Flies with PreCast Pipe

by Paul M. Heffern, PE., Corporate Engineer Independent Concrete Pipe Co., Sylvania, Ohio

A $600 million expansion and modernization project at the Louisville International Airport relied on the strength and dependability of precast reinforced concrete pipe as a critical component of the new facility.

In the trench, alignment of the 108-inch RCP included four curves totaling 1,580 feet.

Situated within 500 miles of nearly 50 percent of the nation's consumer markets, Louisville, KY., is a growing city and major commerce center in the Southeast and Midwest. To ensure continued growth and prosperity, efficient and effective air service was clear. A substantial portion of Louisville's economic vitality stems from the United Parcel Service, which has made the airport its hub for international shipments. UPS employs more than 14,000 people there - a number expected to increase to 27,000 by 2010. Louisville International, located just six miles from the city's central business district, is a world renowned cargo hub. In 1995, it handled close to 3 billion pounds of cargo making it the fourth-busiest cargo airport in the country and the sixth-busiest in the world.

The airport expansion project was initiated in 1988 by the community and the airport's owner and operator, the Regional Airport Authority of Louisville and Jefferson County (RAA). The centerpiece of the project are two new parallel runways. One runway, measuring 7,775 feet, is located on the airport's east side and was completed in the fall of 1995. The second and most recent project is located on the airport's west side and measures 10,000 feet. The new project also included associated taxiways and aprons.

These new surfaces, when combined with the 3,000-acre facility, drastically increased the airport's rainfall runoff. The new facility depended on a closed drainage system capable of handling discharge of more than 1,200 cubic feet per second at the outlet end.

In the original plan for the west runway, the primary storm interceptor was designed to consist of single, double and triple lines of 10' x 5' and 12' x 5' cast-in­place boxes. However, prior to bid-letting, the Kentucky division of Independent Concrete Pipe Company, an American Concrete Pipe Association member, presented an alternative plan based on the use of specially designed 108-inch and 96-inch precast reinforced concrete pipe.

A triple line of 108-inch RCP was used with as many as 50 pieces of 8-foot length pipe installed in a single day.

It's not just about doing it right, it is about doing it right and on-time.

Independent Concrete's General Manager Mike Pepper and Corporate Engineer Paul Heffern met with Robert A. Brown, RAA's Director of Engineering, and local design firm Howard Needles Tamman & Bergendoff's Project Design Engineer, Daniel E. Beyke, and engineer, Todd Tabor, to detail the two major advantages to their plan.

Heffern and Pepper, in a direct comparison of precast concrete pipe to cast-in-place box, showed that using precast concrete pipe would provide an immediate savings of several million dollars. Equally as important was the ability to meet the project's tight production schedule, in part because UPS contributed $1 million to help get the runway open prior to the carrier's peak 1997 Christmas season. Independent Concrete was able to prove that precast concrete pipe would expedite the project's completion date significantly.

Independent Concrete's plan to use precast reinforced concrete pipe won out over cast-in-place boxes with an installed savings of $3.4 million. The airport authority awarded the contract to MAC Construction & Excavating Inc. of New Albany, Ind., which submitted the low bid of $10.2 million out of four bidding contractors. The project's completion date was set for October 30, 1997.

Working closely Independent Concrete with HNT&B engineers, and airport authority engineers revised the plan to include roughly 13,300 linear feet of precast pipe. The plan included 11,440 linear feet of 108-inch diameter RCP and 1,550 linear feet of 96-inch RCP in eight-foot segments.

A key selling point of the plan was the commitment by all parties to adhere to an aggressive installation schedule. To assure adequate productivity, Independent Concrete formed a joint venture with CSR Hydro Conduit, in Louisville, for production of the 96­inch RCP. Art Cannon, sales manager for CSR Hydro Conduit, coordinated production of the 96-inch pipe.

The 108-inch pipe was produced in Independent Concrete's McCracken VIERa-MAC Dry Cast Machine at the company's Louisville plant.

The pipe was specially designed for the installed conditions of loading and bedding using the American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Highway Bridges, Section 17, "Soil-Reinforced Concrete Structure Interaction Systems." The pipe was designed to accommodate a 1 million pound aircraft loading in case future expansion placed a new taxiway over or near the drainage pipe. PIPECAR, design software developed by Simpson Gumpertz & Heger Inc. in cooperation with the Federal Highway Administration and the ACPA, was used in this phase of the project. PIPECAR was used to design for installed conditions of loading and bedding rather than the indirect design method. "The PIPECAR software provides a computerized method to perform structural analysis and rein­forcing design of concrete pipe." Heffern said. "This allows the user to obtain reinforcing steel areas for specified pipe geometry, material properties and loading data."

A dump truck bed equipped with an air controlled gate was used to control placement of the bedding material, #57 crushed stone.

Inlet structures were formed and cast-in­place by MAC Construction.

Single line of 108-inch RCP on straight alignment.

In order to evaluate the million-pound aircraft live load on the pipe, the load distribution through the 17­inch thick concrete pavement and backfill was based on the load distribution analysis presented in Design Data #15, "Aircraft Loads" published by the ACPA. Load Analysis and Structural Designs were performed at 21 locations along the 96-inch and 108-inch diameter pipe alignment to determine the most critical combination of live and earth load. All pipe was manufactured in accordance with ASTM Standard c76 with ASTM C443 joints utilizing oil resistant gaskets. Steel reinforcement cage configurations were full, circular inner and outer cages with quadrant mats - with and without stirrups at the pipe invert.

The outlet end of the triple 108-inch line shows the bedding and baclifill as detailed in Figure G.

To stay within the tight production schedule, Independent Concrete's Plant Manager Sonny Gollar and General Manager Pepper established a demanding work schedule beginning at 4 a.m. and often not ending until 5:30 p.m. To assure the production schedule could be met and enable the manufacture of a close­tolerance joint, new joint ring forms were ordered. After receiving the new forms, as many as 24 pieces of 108-inch pipe were manufactured per day, using only 12 sets of rings.

"We would cure the day's early production so it could be handled, then we recycled the pallets and headers and used them again that same day" Pepper said.

Independent Concrete was able to adhere to that schedule because of the versatility of the VIBRO-MAC equipment, he said. A large hydraulic pipe tipper was used to pick up each finished pipe after three or four hours of curing, and then the pallet was pulled off. The pipe was set down, the header was removed with a bridge crane and the joint-forming rings were used again.

"It just goes to show you that you can make more pipe than you have pallets and headers for in a day with this type of equipment." Pepper said.

Once the construction phase was underway, Independent Concrete was able to ship as many as 59 pieces of 108-inch pipe per day to the job site under the supervision of Scott Holzapfel, Independent Concrete's Transportation Manager. In the trench, alignment of the 108-inch pieces included four curves totaling 1,580 feet. In order to fit these curves, special radius pipe was manufactured with a 3 1/2-inch bevel at the spigot ends.

"We had to maintain tight quality control in order for the radii pipe to layout correctly." Pepper said. The project also set a precedent for MAC Construction. "This is the largest pipe the company has ever installed." said Dennis Coffman, MAC's Vice President of Construction. The installation was led by Steve Stinnett, project manager, and Ed Calvert, project superintendent.

While MAC Construction was installing the 108-inch storm sewer, the Harper Company of Hebron, Ky., was in the midst of a separate but related $30 million project to place more than 600,000 tons of concrete pavement and aggregate base courses for the runway, taxiways and roadways. Harper's runway paving project also included more than 23,700 feet of RCP, manufactured by CSR Hydro Conduit and Independent Concrete Pipe, ranging from 18-inch to 108-inch diameter for related drainage facilities.

In addition, Gohmann Asphalt, of Clarksville, Ind., was completing construction of ramps and sitework for UPS, which included more than 14,000 feet of l2-inch to 72-inch diameter RCP.

Independent Concrete shipped the last of the 108-inch pipe in mid-October and the installation phase for the big pipe concluded at the end of that month. The project was completed on schedule and under budget and the new runway is currently being used, enabling simultaneous takeoffs and landings, doubling the airport's capacity. "The success of the project relied on the hard work and expertise the numerous participants brought to the job." said Barry Bundrant, Independent Concrete's President. "This project will have a positive impact on the growth and prosperity of the city of Louisville for many years to come."