Contractor Shall Design
Every heavy civil specification has a few sentences that move engineering from the designer's desk to the Contractor's. At one of our projects along the Sacramento River, those sentences covered cofferdams, dewatering, temporary shoring, soil nails, helical piles, aggregate piers, pile drivability, and top-of-weir grouting. Between April 2025 and August 2026, we prepared several submittals and memos for the Contractor.
The project rehabilitates the weir and adds a fish passage gate structure. In-water work is limited to a window between April 15 and November 1 each year, and anything that isn't finished by November waits for next spring. In Season 1, the Contractor built the gatehouse and part of the connection channel. In Season 2, the crew connected the channel to the river, rebuilt the energy dissipation basin, and improved the weir foundation.
Deferred submittals make sense. The Owner defines what the finished work must do, and the Contractor decides how to build it. Often, nobody knows better than the Contractor which rig, hammer, and sheet pile inventory will show up. The temporary works still have to be engineered, stamped, reviewed, and approved before the crew can start. When the work window is fixed by the river, every week matters.
Here's what was reinforced for us.
Buy Back the Schedule
The contract drawings showed the Season 1 cofferdam in the river, which meant it couldn't be built until water in the river was low enough. We suggested pulling the cofferdam inland, through the existing embankment. The inland alignment required no in-water work, so the crew could drive sheets ahead of the window and start excavating sooner. That one move gained the Contractor weeks of schedule in a season that had little to spare.
Design for the Crew that will Build It
Our drawings say it plainly: the design relies on the Contractor's equipment and expertise. We started each design from the sheet piles in their yard, the rigs they planned to mobilize, and the order they wanted to build in. We set the Season 2 cofferdam high enough that full-length sheets could go in uncut. Nobody likes torch-cutting good steel.
Verify, Adjust, and Verify Again
The loose sands and silts beneath the new gatehouse could liquefy in the design earthquake. We designed aggregate piers to densify that ground. The piers work together with the driven displacement piles in the structural design. An early RFI to the Owner clarified what the ground improvement needed to achieve. Post-installation CPTs at the first test array showed very little improvement. Rather than abandon the method, the crew changed how they built the piers: a stiffer base, more aggregate, thinner compacted lifts, and a steady pace for each lift. A second test array, installed and tested in about four days, densified the clean sands enough to mitigate liquefaction. The silts were more stubborn, as fine-grained soils usually are. Instead of chasing improvement the soil couldn't give, we showed that the piers, the improved ground between them, and the driven piles together make ground failure very unlikely, and we proposed a down drag check of the pile foundations to close out acceptance.
Match the Intent, Not the Template
Project specifications described the kind of pressure grouting used to cut off seepage through fractured rock beneath dams. The scope here was different: filling a shallow void between the weir crest slab and the slab beneath it. Following the specification as written meant specialty drilling and mixing equipment, plus grout pressures that could lift the very slab we were trying to support. So we challenged it. Our variance memo explained, item by item, why gravity grouting with a conventional non-shrink grout through simple cored holes better fit the design intent. With the Owner's acceptance, the crew grouted the weir to the more relevant procedure, and the work was completed successfully.
Test to Learn Something
Helical pile load tests are more than a box to check. The Contractor loaded the test piles all the way to geotechnical failure, so the results would tell us how these piles behave in this ground. They did. The data let us refine our design assumptions and lower the minimum installation torque. Testing also showed the piles could be installed deeper without field cutting, which preserved the bolt-on cap plates. When one test was lost to a hydraulic jack problem, the Contractor added another test pile and kept the program on track.
Stay Involved through Construction
Partway through Season 2, the south end of the energy dissipation basin was holding water, and the subgrade couldn't be approved until it dried out. The Contractor proposed a gravel-filled subdrain along the east side of the weir, feeding a few sumps. We checked that it would draw the water down far enough, documented it in a short supplemental memo, and the crew kept working. A field change like that should be a quick memo, not a new design cycle.
The Point
A deferred submittal is the Contractor's plan for building the work, designed and written to meet performance requirements so a reviewer can approve it. Starting from the means and methods gives the reviewer a plan that matches how the work will be built. It also gives the crew comprehensive working drawings they can follow. And when the ground surprises everyone, a design built around the real construction sequence is easier to adjust.
Thanks to the Contractor's crew, whose measurements and photos from the field drove several design changes on this project, and to the Owner's reviewers for comments that made each submittal sharper.
These deferred submittals are Atlas’ bread and butter if your submittal says the Contractor shall design, give us a call.
Located just outside of New York City, Mike is an avid New England Patriots fan, golfer, and aspiring woodworker. He earned a B.S. in Civil Engineering from the University of Hartford. While studying for an online M.S. in Geotechnical Engineering from the University of Oklahoma, he performed construction engineering on many projects throughout New England, with the majority located in and around New York City. Mike’s practical engineering approach has led to having experience in bulkhead & trestle designs, cofferdams, excavation support systems, deep foundation design, and constructability evaluations. In additional to his geotechnical engineering toolbox, he has a fundamental background in structural engineering and erection & demolition engineering.