Rigging Spotlight
By Mike Larson Handling Specialty Concrete Pipe
Easy Does It
Engineered lifts and rigging gently handle specially made precast piping
Dearborn Engineers & Constructors Inc.( Dearborn) recently teamed up with Ballard Marine Construction and Bay Crane Companies to plan the lifting and placement of special precast concrete pipe that will form the business end of a new freshwater intake for a city in metropolitan Chicago.
The precast-concrete intake pipe will reach about a mile out into Lake Michigan and lie on the lake bed about 50 feet below the water’ s surface.
The outer end of the intake pipe will connect to three huge three-fingered intakes called tridents that will provide a total of nine water-intake openings.
This part of the project staged the tridents and their“ Center Cross T” connecting section on a lakeside lot, then set all the pieces onto the barge that will float them to their installation site.
Ballard is the project’ s prime contractor, Bay Crane Midwest is providing crane services, LGH is supplying rigging components and Dearborn companies provided ground analysis, engineered the rigging and collaborated with Ballard on lift planning.“ It was a total team effort,” said Dearborn CEO Michael Walsh.
Special Pipe Needs Kid-Glove Treatment
Each trident consists of three pipes that connect to each other at one end and spread out like three up-curling fingers.
Each pipe, or finger, is about 5 feet in diameter, nearly 20 feet long and made of precast concrete.
Though this specialty precast concrete is strong, it can crack if over stressed.
The tridents’ sensitivity to stress, their
A 550-U. S.-ton all-terrain crane and engineered rigging gently lifted each of the three concrete tridents and their Cross T connector from onshore locations to a barge.
unique shape and the one-year replacement time if one were damaged dictated that every aspect rigging, lifting and handling them had to be meticulously planned and carefully engineered.
“ This job presented some really interesting challenges,” said Walsh.“ The first was developing and engineering the load-handling concept and rigging to move asymmetrical, stress-sensitive, long-leadtime elements. The second was making sure the same rigging would work equally well both for the crane that would load the pieces from land onto the barge and for the barge-mounted crane that would later lower them to the lake bed for final assembly by divers. The third challenge was making sure that the land-based crane could work safely near the earth-and-sheet-pile dock.”
Firm Footing
One of Dearborn’ s key jobs on this project was making sure the ground at the barge-loading site would support the
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October 2025 • www. cranehotline. com