Rough grading is typically the first trade in land development. It’s the process of shaping the site. To do this, the rough graders have to move a TON of dirt to make leveled pads for the homes. These graders have to cut into some areas of the site as well as fill in some other spots. But before we dive in further, there are some terms you need to learn to understand this process better. See below.
In this post we will be discussing:
- The basic grading terms:
- Cut
- Fill
- Transition Lot
- Site Clearing / Demo
- Mass Excavation
- Over-Excavation
- Drainage in Rough Grading
CUT / FILL
Typically, raw land naturally has a lot of terrain and is very uneven. There are areas within the site that the grader needs to fill in with dirt as other areas need to be cut down because the elevation is too high. You can see these areas on a “Cut/Fill” Map (see example below by Mesa General Engineering, Inc). All the blue represents the areas that need fill, and the red represents all the area that needs to be cut. (NOTE: the dirt from the cut areas in red will generally fill the low areas in blue.)
The Cut/Fill map will calculate (in cubic yards) how much dirt exactly the grader needs to cut and how much to fill (see close-up below). If there is more dirt that needs to be filled than there is to cut, then the site will be an “IMPORT” job since there will not be enough dirt to fill the low areas. If there is more cut than there is fill, then the site is considered an “EXPORT” job since there won’t be enough low areas to take all the excess cut dirt.
TRANSITION LOT
A lot that falls on both a cut area and a fill area.
SITE CLEARING & DEMO
The first phase of the actual rough grading process is the “clearing & grubbing” and “demo” stage. Depending on how long raw land is sitting for, they typically become overgrown with vegetation and other sorts of trash/debris. So the grader will come through and remove all of this from the site. These things can really get in the way of your grader moving dirt if not removed and can delay your operation.
MASS EXCAVATION
The large volume of dirt that the grader must excavate and move using large pieces of equipment known as“scrapers”. (See video below or click here to watch this process in action!)
OVER-EXCAVATION (“OX”) / REMOVALS
Once the grader finally gets to final pad elevation (or “design”grade) there is still one more step they need to take to be able to build a house on it. This step is known as “over-excavation” and will prep the foundation for the home. To do this, the rough grader will have to dig even further below the finished pad elevation (hence the term “OVER-EXCAVATE”) in order to remove the soil completely and/or to rework it. If the soil is “unsuitable” per the soils tech, then the grader needs to replace it with “competent” material. The soil is then moisturized and compacted per the soils engineer’s satisfaction to make a suitable foundation. (See below for a small soils report excerpt by Geotek).
DRAINAGE
The rough grader is also responsible for installing proper drainage on the site. The moment you purchase a site and begin developing, storm water run-off is YOUR responsibility. For one, it can ruin your site and erode all your grading. Also, once the water leaves your site you are responsible if it were to cause any damages to any other surrounding sites (floods, carrying large objects and debris, etc). Drainage consists of v-ditches, down drains, benched terrace drains, and more.
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