Drivers traveling through St. Louis will soon find it easier to cross between Missouri and Illinois, where the third longest cable-stayed bridge in the U.S. will open on Feb. 9. The Stan Musial Veterans Memorial Bridge, initially known as the New Mississippi River Bridge, is part of a $694 million project that involves rerouting traffic from the nearby Poplar Street Bridge to alleviate congestion.
Two lanes of Interstate 70 will travel over the bridge in each direction, with room to expand to three in the future. Construction, featuring a 1,500-foot structural steel main span with a concrete deck, 400-foot-tall reinforced concrete piers, and 68 pairs of stay cables, began in January 2010.
When ready-mix producer Jay Riley heard about plans for the bridge in 2009, he dismissed the idea of bidding. Riley has owned Riley Ready Mix & Materials in St. Louis for 15 years. With 25 employees and a fleet of 25 trucks, he assumed the project was beyond the scope of his resources.
But Riley’s perspective changed when he attended an informational meeting held by the Missouri Department of Transportation (MoDOT). “MoDOT encourages its partners to think outside the box,” he says. “I never would have attempted a project of this magnitude on my own, but I realized that a partnership might work.”
For the small producer, finding a creative way to collaborate was the key to surviving—and thriving—in a slow construction market. Riley talked to the management team at Kienstra Enterprises, a concrete producer with operations in Missouri and Illinois.
The producers formed a mutually beneficial arrangement that would provide expertise on both sides of the river, and keep the work local. Riley formed Riley Illinois LLC with Kienstra President Danny Bruns, CFO Pat Wessels, and Scott Maberry, general manager of Kienstra Illinois. MoDOT supported the idea and, when the agency accepted Riley Illinois’ bid, the real work began.
The logistics of spanning a river
After securing funding, the partners began to hash out the details of supplying massive amounts of concrete to a high profile, fast-paced project in two different states.
“Considering there were two different DOTs involved, the process wasn’t as stressful as I thought it would be,” Riley says. MoDOT and the Illinois Department of Transportation (IDOT) have a long-standing partnership when it comes to projects involving both states. The two agencies hold an annual Border Bridge meeting to coordinate maintenance on the bridges they share.
The agencies alternate responsibility for each new project, and determine financing based on the percentage of the project that falls within each state. MoDOT coordinated construction and managed contracts, while IDOT was responsible for roughly two-thirds of the funding because most of the roadwork falls on its side of the Mississippi River. Maintenance costs will be split evenly.
Jointly funded portions of the project, including the bridge itself and approaches on each side, were designed to MoDOT specifications although IDOT oversaw construction on its side. “It’s easier for each state to oversee certain portions, to handle procurement, different regulatory agencies, and other state-specific logistics,” says Randy Hitt, MoDOT engineer and project director.
From the producer’s perspective, the process went smoothly. “Pre-pour meetings with the general contractor and representatives from both DOTs were essential,” says Riley. “It helped that everyone knew what his role was ahead of time.”
Riley set up a new base of operations for the project on three acres in Granite City, Ill., about four miles away. He hired a full-time plant manager to oversee a fleet of eight ready-mix trucks running from a portable wet batch plant that produced 10 yards every 2 ½ minutes, and a back-up dry batch plant that could batch 10 yards in 3 ½ minutes. For the entire project, Riley Illinois supplied 46,000 cubic yards of concrete.
The producer’s work began at a demanding pace in August 2010 to ensure the bridge’s concrete foundations and piers could be built up above high water level by spring. “Flooding is one of our biggest risks on any river bridge project,” says Tom Tavernaro, project manager for general contractor Massman, Traylor, Alberici (MTA). “We worked two shifts throughout the drilled shaft installation, footing construction, and pier shaft construction, roughly the first year of the project.”
With its pooled resources, Riley Illinois ran up to 20 trucks at a time, including eight from Granite City, some from Riley’s St. Louis plant, and several Kienstra trucks from Alton and Collinsville, Ill. “The biggest challenge was coordinating all of the trucks from different locations and figuring out the drivers’ availability to meet the contractor’s schedule,” says Riley.
The traffic pattern was also a concern. Loaded ready-mix trucks from Granite City took an indirect route around the city to avoid crossing a levy, then returned via the levy once emptied.
One of the most time-critical phases was completing the bridge’s two pier footings, founded on six 11 ½-foot diameter drilled shafts with 11-foot diameter rock sockets. Each 55-foot-by-88-foot-by-20-foot footing took about 40 hours to place, while the producer’s trucks ran continuously up and down a riverbank access road. The trucks discharged into truck-mounted concrete pumps that delivered the concrete through slick lines to the footings.
As the piers rose above the water, the contractors scaled back to one shift a day and Riley ran an average of eight to 10 trucks. To supply bridge elements further from the river bank, the trucks unloaded onto a barge that delivered the concrete to a crane and bucket setup on the river.
Losing heat, gaining time
In addition to keeping the trucks running on time, Riley Illinois contributed significantly to the project’s success by designing a slag cement concrete mix that kept construction on schedule and exceeded compressive strength requirements. Jay Riley and quality control technicians Jeff Schaefer from Kienstra and Alphonso Rice, a new hire for Riley Ready Mix & Material, consulted with cement supplier Holcim to develop a 70% slag cement, 30% portland cement mass concrete mix.
To meet the unique factors involved in constructing mass concrete elements, MTA also commissioned a thermal control plan from CTLGroup. “We needed to develop and implement a good plan to reduce the thermal control period for the mass concrete elements. A key factor to our success was the use of Riley’s low heat of hydration slag mix,” says Tavernaro.
MTA took extra measures to cool the concrete, following CTL’s recommendations. The contractor assembled a system of cooling tubes by installing more than 1.5 miles of polyethylene pipe in a 5-by-5-foot grid within the pier footings. Ice-cold water from the Mississippi River was pumped through the tubes and then returned to the river.
“With the combination of insulation on the sides of the forms and on top of the footing and using the cold river water, we were able to keep the temperature differential within an acceptable range,” says Tavernaro. The contractor also used maturity meters and temperature sensors embedded in the concrete placements to monitor the concrete’s temperature and performance.
Because the concrete gained strength quickly, the contractors were able to build the piers above the high water level before spring 2011, when the Mississippi River crested at record levels in St. Louis. “If the mix hadn’t achieved strength so quickly, the project could have been set back for two or three months,” says Mark Luther, a senior technical service engineer for Holcim (US) Inc.