Triple Play Pumping – Speeds Bridge Construction
Concrete pumping is playing an important part in the replacement of the Hwy 52 Bridge connecting Illinois to Iowa over the Mississippi River. The connection is critical to the residents of Sabula, IA, which is the only town in the state located on an island that is linked to Illinois by the existing span. The aging bridge is listed on the National Register of Historic Places. The 520-foot main span steel bridge was constructed by the Savanna-Sabula Bridge Company in 1932. It is considered to be structurally deficient. A new steel tied arch bridge with 546-foot main span will replace the existing structure. Sun Concrete Pumping, Grimes, IA developed an innovative system to build the cast-in-place caissons which will support the new bridge. The new bridge will be 40 feet wide between a central barrier, with 8 feet of shoulder on each side to accommodate disabled vehicles and still leave room for cyclists. It will be located 100-feet downstream from the existing bridge.
Because of the environmental issues of working on the river and extensive coordination with railroads and utilities, planning has been on going since 2011. Because the detour is 36-miles with the aging span out of commission, the State determined to implement Accelerated Bridge Construction (ABC). The Iowa DOT has a strong desire to minimize this disruption and inconvenience to traffic during the bridge replacement. Environmental and permitting factors all but eliminated other conventional methods for maintaining traffic such as staged construction leaving ABC techniques as the only reasonable alternative to minimize traffic disruption.
The use of ABC techniques is still an emerging technology. The Iowa DOT has completed nearly a dozen ABC projects to date using various ABC technologies including Slide-In Bridge Construction (SIBC), modular units, precast concrete substructure components and full-depth precast concrete deck panels. Selection of the use of ABC technologies are on a case-by-case basis with about 5% of bridge replacement projects selecting ABC as the preferred construction alternative.
Sun Concrete Pumping has been on the job since early 2016. Kraemer North America. LLC, with offices in Plain, IA is the general contractor. “The original concrete placement plan for the caissons was to bucket the concrete into a tremie, “ according to Shawn Jackson, project manager for Sun in Eastern Iowa, “ But we proposed a pump to pump to pump scenario that has worked out to be a much faster method.” The speed of construction using concrete pumps suits the ABC concept that the State is following.
Sun has placed their Schwing S 58 SX concrete pump on the Iowa side of the river and is utilizing the 187’9” reach to hook into 250-feet of barge-mounted line that feeds the hopper of an S 46 SX concrete pump which is utilizing its 149‘7” of reach to pump directly into an S 41 SX concrete pump. The final pump in the triple play is feeding a crane-supported tremie pipe inserted into the caisson forms.
“All the pumps have the Super X front outriggers which helps set-up in tight areas,” Jackson explains. He has been an operator for more than 20 years and the S 41 SX is painted blue unlike the red color of the Sun fleet. Jackson owned the S 41 SX when he had his own concrete pumping company. Jackson Concrete Pumping, headquartered in Dubuque, IA, was acquired in 2014 by Sun. “I put more than 20,000 yards through the S 41 SX in less than six months back in 2007 when I first got it and it has been very reliable.” Jackson states that the four-section Roll and Fold boom has been excellent for tremie pours. “The key reason a Roll and Fold boom works best for tremie applications is the full 180 degrees articulation at the 2/3 knuckle is on the working side of the boom.”
The S 58 SX and S 46 SX concrete pumps utilize four-section Overhead Roll and Fold Booms and all of the pumps are equipped with Big Rock Valves with extended housings. “The coordination of the three pumps requires that all of the operators monitor the concrete in each pump’s hoppers, “ explains Jackson, “The large volume of the Big Rock housings helps keep the pumping smooth.” The company is able to maintain 100 yards per hour with the system. Typical pours are 250-400 yards. “Occasionally we will get an 800 yard pour and that can take 10 hours because ready-mix access is not great and the truck mixer deliveries can’t keep up,“ according to Jackson.
All of the pumps were serviced before they were put into service on the project and simple maintenance is performed by the operators on the barges. Washout pans are positioned under the valves for clean-out at the end of the day. Two cranes are on the job and they transfer the pans to shore. The only factor not following the Accelerated Bridge Construction method is Mother Nature. It has been very wet in the Midwest and when the river hits 17-feet above its normal level, there is no access for the S 58 SX. “We only have one more pier to pour but we haven’t been able to get down to the river in two weeks because of high water,” Jackson notes. He says that the company will be on the project through 2017. The project is expected to be completed in Spring of 2018 at a cost of $80,600,000.
Owner – State of Illinois, State of Iowa
General Contractor: Kraemer North America. LLC, Plain, IA
Pumping Contractor: Sun Concrete Pumping, Grimes, IA
Pumping Equipment: Schwing S 58 SX, Schwing S 46 SX, Schwing S 41 SX truck-mounted concrete pumps with placing booms