Project file can refer here
Normally, the contractor will provide an as-built drawing for Earthwork progress and C&S engineer will be required to check the EW volume submitted by the contractor. Hence, we will have two survey groups which represent our Original Ground Level (OGL) and As-Built Level.
In this project, we have the OGL and we import to the project file named “Survey Points 1” as per image below.
Next, we have the second group of survey points named “Survey Points 2” which is our As-Built Level as per image below.
If we were to overlap both Survey Points, the visual is as per image below.
Before we proceed to compute the earthwork volume, we will first need to ensure that the base surface and comparison surface has been chosen correctly as highlighted in the image below. You can go to;
Earthwork > Cut/Fill > Surface > Base: Survey Points 1
Earthwork > Cut/Fill > Surface > Comparison: Survey Points 2
In this project file, Survey Points 1 or OGL should be our base surface. Whereas, our Survey Points 2 or As-Built Level should be set as the comparison surface. This is because we are comparing the OGL with our As-Built Level. Then, you can proceed to compute the earthwork volume using any method you prefer.
The output for each method is shown as follow:
1. DTM Method
2. Grid Method
3. End-Area Method
The discrepancy between each method for the earthwork computation is less than 1%. However, if you encounter a large discrepancy between each method, you can refer to our blogpost on how to reduce the discrepancy between each method. Hence, this proof that any method can be used for comparison of earthwork cut and fill for as-built.