Have you thought about using your GPS machine control system for structural excavation? It might not be common place, yet, but we have more clients requesting structural excavation models every year.
Depending on your needs and equipment, there are a couple ways we can set up the files for you.
The first is simple. We put the 2D linework in your GPS file for stakeout or to double check your manual measurements. Here is a picture of what it might look like:
You can use your rover to stakeout to the linework and check elevations vs. the project plans. It is similar to how you would use the linework to stakeout a utility like a watermain. It sure beats staking the whole project or pulling a tape measure from batter boards. While 2D is great there is still room for improvement.
The most progressive contractors are moving to 3D modeling for their structural excavations, just like they use a 3D surface model to grade the rest of the project. Quantum's experts take the location and depth information from the Engineer's design to build a 3D model of the structural plans. That 3D model then guides your excavator to dig in the correct location and depth required by the plans, no more, no less. You can use your rover to stakeout locations and depth, too.
The 3D model can show all of the elements of foundation excavation like stoops, continuous footings, pad footings, thickened slabs and even foundation drainage. Your excavator operator can dig with confidence knowing they are doing the work right the first time. There is no need for a grade checker to continuously check grade with a laser, or even slower, a tape measure.
The 3D model can be set up to match the over-dig required by the concrete contractor or to match your machine's bucket width. If your excavation requires shoring or safe back slopes we can build the model to take that into account. On some projects, part of the foundation may require over excavation due to poor soil conditions. Just let our experts know what you need when you request the model.
Often, the biggest pay off comes when it is time to place concrete. Small over excavations are easy to make without the continuous grade control provided by a GPS excavator and 3D model. Let's make the math easy. Assume we have a small 300' long by 3' wide x 3' deep trench footing. The entire trench will be filled with concrete. It should take 100cy of concrete. If it is over excavated by only 3" it will take an extra 8.3 yards of concrete to pour the trench footing - that is an entire extra mixer truck - over $1,000 in concrete. Keep in mind you will have an extra dump truck load of dirt to export or waste onsite, too. Seemingly small structural excavation errors can quickly add up to big bucks.
A word from the wise…. DO NOT blindly use linework from the civil plans to stake out or excavate for any structure. You need to verify that the linework matches the structural plans. Often times, the building outlines or even bridge abutments in the civil CAD file are not kept up to date with the latest structural engineering changes. For this reason, Quantum's experts only build structural excavation models from the structural plans, the "S" sheets in most plan sets.
It might seem complicated at first, but once you have your first 3D structural excavation job under your belt you will never go back. To take the leap Email or call us at 515-505-3510.