For construction excavation to be successful, there are various things required. These include preparation, control and the use of proper equipment. Note what each entails.
Preparation
First, it is essential to clear the area of perishable material that includes the removal of such things as stumps, weeds, sod and agricultural debris among others. Secondly, make sure that sections are checked and matched to the plan. Thirdly, the contractor should scalp or strip the areas where excavations or embankments will be placed. Stripping or scalping is the removal of a layer of soil usually about four inches. Removal of this layer helps to get rid of decayable vegetation that should not be present when embankments are placed.
There might be some pronounced depressions left in some areas; therefore, the fourth thing to do is fill them with acceptable materials and then compact them using a roller or other approved compacting machine. The fifth and final step is proof rolling. Usually, a pneumatic tyre roller is used to check for unstable areas, spongy areas or yielding materials that are not compacted.
Placement of Embankment and Control
Ditches should be dug first because the excavation from them is used as material for embankments before sourcing additional materials. The ditches also act as drainage. However, they should be protected from erosion. This includes perimeter protection, slope protection, inlet protection and construction of a drainage barrier. Additionally, sediment control strategies should be implemented, which include culvert pipe protection, sediment trap and straw bale checks among others.
When constructing the embankment, care should be taken to ensure the outside slopes are compacted and so is the middle. This is achieved by having lifts extend transversely over the embankment area. As filling occurs, it is crucial to look out for bellied or fat slopes (slopes containing excess materials exceeding what was planned).
Correct Equipment
Equipment required for embankment can be categorised to hauling, spreading, compacting and moisture control equipment.
Hauling equipment that can be used may include dump trucks, earthmovers or quarry trucks. The method to be used will, however, depend on the material and presence of obstacles. Earthmovers will commonly be used for soil materials. Quarry trucks will be used for rock excavation while dump trucks are used when getting additional or borrow material from a remote area. Spreading equipment is used to achieve uniform layers and may include bulldozers and motor graders. For moisture control and to break up clods, lumps or slabs, a disc may be used.
Compacting equipment has been mentioned above, but it may vary depending on the contractor, material, embankment and availability.