Measurements for Excavating

Size of the Excavation

• The contractor must identify the proper size of the excavated hole. An excavation opens a hole in the ground for installation of a building foundation, a septic field, a drainage system or any number of underground mechanical systems. The contractor must know the size of the installed system and plan to excavate a larger hole than needed in order to give the workers room to perform their work. The takeoff should also considering whether wall bracing is needed and include the additional hole size and construction time the bracing will require.

Volume of Removed Earth

• Digging a large hole in the ground is a complicated process; one of the more important details is determining where to store the excavated earth. In some instances the job site has enough clear area to store the dirt until the hole is filled back in, but in many cases the earth must be transported away from the site by truck. The contractor must estimate the total volume of unpacked earth, make plans for its storage or transportation and return it at the end of the project, if needed.

Labor Required

• The most expensive aspect of an excavating project is not the equipment or the machinery -- its the amount of time a project requires. For this reason, the contractor must also calculate how long the job will take and how many workers are required to complete the task. In most large construction jobs, after the hole is excavated other crews arrive on site to pour the foundation or begin to install the equipment. The contractor must estimate how much dirt his crew can excavate per hour and then use that information to calculate the amount of time the project will take.

Ground Load Capacity

• Excavation equipment weights multiple tons; when a crane is removing huge amounts of earth from the ground, its center of gravity shifts dynamically. The excavation process creates torque, compression and momentum forces on the ground under the excavation equipment. Consequently, as he prepares for the excavation, the contractor must measure the ground load capacity under the equipment to verify the work site is safe before he can begin pulling dirt out of the ground.

Line Item Costs

• Each of these measurements translates into costs. The amount of time required, the equipment required and the number of men required to operate the equipment all contribute to the overall cost of a project. Therefore, each measured line item must be converted into costs so that the total cost of an excavation project can be calculated.