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4 Tools to Moving Dirt on a Project: Shovel Not Included

By Greg Koontz, PE, LS, President, Koontz-Bryant, P.C.

  1. Moving dirt on site work projects has always seemed like a “black box” to most of our clients and many design professionals. Just let the contractor figure out how it works and everything should be okay. This may work some of the time, but what are you leaving on the table as an owner on a low bid proposal with unqualified responses?

  2. With today’s technological advances, dirt work should be less of a design mystery and be more of an opportunity for valuable consulting to our clients. Software programs such as Autodesk Civil 3D, Carlson Software and Microstation process survey data to produce a 3D digital representation of the surface of the site. The 3D surface files, created in either grid or Triangulated Irregular Network (TIN) formats, allow subtraction of topsoil and expansion/contraction factors to be applied. That’s the easy part! Let’s look at a couple of the key areas where, with the right tools, we help our clients the most.

  3. Creating a 3D Surface

  4. Seems like an easy task when reading the computer instructions and working through examples, but I have seen some horrible examples of what can happen if the computer operator does not really understand what they are really doing when creating a 3D surface. In the most basic terms, the 3D surface once created should be capable of either generating or re-generating contours that represent the site. The biggest issue with surfaces is they basically are “invisible” computer data unless the operator takes the time to verify the data through 3D surface models or re-generate contours. It’s important to take the time to make sure both the existing and proposed surfaces are accurate representations of the site or everything else is a waste of time.

  5. Balancing the site

  6. I usually try to grade a road or site to work with existing grades and slope wherever possible with a high emphasis on ending up with a functional and aesthetically pleasing site. One of the tricks to a great road or site design is to grade the whole project to the most optimal functional and aesthetical design. Run the volumes and adjust the whole site to achieve a balance instead of adjusting pieces and parts. This will maintain the overall integrity of the site design.

  7. Project Phasing and Construction Sequence

  8. A design professional needs to understand how important this can be to the overall success of a project. Not paying attention to the dirt numbers for each phase in construction sequence can leave an owner with the untenable situation of either having to haul off dirt needed in future sections or importing unnecessary dirt. In our area, importing or exporting dirt could easily be $20 per cubic yard (CY) either direction which adds up quickly. For example, a small site needing 3000 CY translates into 300 truckloads and $60,000.

  9. Dealing with Topsoil

  10. Over and over again I hear of projects where design professionals have provided dirt numbers for their clients and they balance within yards. Projects get underway and then the large topsoil stockpile is created. Toward the end of the project, the owner asks when that pile goes away. If they are lucky it’s included in the construction price, and if not it’s an extra. But was it really necessary to have to haul it off in the first place? A little extra time trying to find ways to dispose of the topsoil in non- structural areas of the site such as landscape strips, setback areas, and areas mined for structural fill can save the owner major expenses.

  11. Solving the dirt “black box” for clients can be very rewarding. This includes spending the time talking through the issues and making sure the variables are known by all. Working around construction my entire career, I think it’s very important to include the contractor in the process. This may happen during the design if the contractor is known, or once the project has been awarded. We help the owner understand why it is important to find out what assumptions the contractor is making compared to the ones made during the design process. Many of the issues that arise are due to not coordinating assumptions such as strip depth and expansion factors. When we make the effort to find out how the contractor is figuring the dirt on the job and apply the necessary adjustments before construction begins, our clients reap the financial benefit of having a true consultant!

Contact Greg Koontz at Koontz-Bryant, P.C for any further questions.