Cut and Fill Is the Process of Earth Moving

15

Estimating VolumE of Cut and fill using Contour mEthod

In this chapter you will learn about:

• How to determine areas in a site-grading plan that will result in cut and those that will result in fill

• How to calculate the quantity of cut and fill based on the site-grading plan by determining area of cut and fill, using square inches based on a scaled site-grading plan • The difference between a square foot and cubic yard, and how both are used to determine cut and fill quantities

Cut and Fill is the ProCess oF earth Moving

The topography of a site is not always opportune for the purposes of project. In most cases portions of a site’s topography will need to be modified so as to accommodate the uses and activities envisioned in the site design. What this means is that the designer will need to shift soil around from some parts of the site to others in order to create topography suitable for the designed elements. To achieve the topographic modifications detailed in the site grading plan, earth—and in some cases, rock—may need to be removed (cut) from areas of the site then used to build up other places requiring additional material (fill). In other situations, it may be necessary to transport excess earth material from the project site and dispose of it at an off-site location. In other instances,

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New Landform

Fill Cut

Figure 15.1 Section of a slope showing area of cut and area of fill. The dashed line represents existing slope and the solid line the proposed newly created shape or section of the modified slope.

soil may need to be transported from an off-site location to supplement areas where additional fill is needed. Both disposing of and purchasing material will add to the project budget. The process of moving and shifting earth around a site involves cutting and filling. Cutting away a portion of a hill slope to create a gently sloping area and placing the cut material at another area on the site is common. However, the goal is to balance cut and fill whenever feasible to minimize costs of taking away or importing material. Figure 15.1 should help viewers visualize the concept of cutting a slope in one area then moving the earth to another area. Cutting and filling creates a level area to build a structure such as a house, picnic shelter, or playing field. The Figures 15.2-A and 15.2-B visually represent the concept of cut and fill by modifying or changing contours on a site. Notice that when contours are adjusted in an uphill direction, as in Figure 15.2-A, one is creating cut. The dashed lines are existing contours, and the solid lines are the same contours in their new position as shown in the site plan prepared by the designer. Notice the lower contours moved uphill with—for instance—the 104 contour was repositioned to cover the 105 and 106 contours. Conversely, by adjusting the contours downhill, as in Figure 15.2-B, one is filling. In Figure 15.2-B, the higher-elevation contours are moved to cover over the lower-elevation contours. For instance, the 106 contour was repositioned to fill over (or raise the elevation of) the old 105 and 104 contours.