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How to Estimate Commercial Excavation and Backfill

How to Estimate Commercial Excavation and Backfill

Estimating the cost of your commercial excavation can be a challenge. Determined by a list of factors such as lot tree coverage, grade, remoteness and climate, getting a quote early will help you align your budget to avoid unexpected costs down the line. Working with a commercial excavation contractor is a must; besides being experts at the dirty work, they’re familiar with local laws regarding excavation and know which permits a site must secure prior to construction. So, what is the role of an excavator and how do you choose the best one for your project?

Sitework

Sitework is a crucial step in the construction process, responsible for both initial site preparation and finishing touches. In both residential and commercial construction, any part of the project that is not directly part of erecting a structure is considered sitework. Sitework often includes:

  •      Grading: creating a level piece of land upon which a structure will sit.
  •      Excavation: removing soil or rock to create a trench, wall shaft, tunnel or foundation for a construction project.
  •      Backfill: using a combination of soil and rocks to replace soil that has been removed during construction.
  •      Septic & sewer system installation: a structure in a remote area will likely require a septic system to remove waste.
  •      Water: drilling a well or hooking a building up to city water
  •     Permit processing and fees: this varies by city and type of construction project.
  •      Tree removal and land clearing: trees and boulders often must be removed before construction can begin. Simply cutting a tree at the base is not sufficient. Stumps and root systems must be removed completely by a professional.
  •      Driveway and pathway installation

Landslide clean-up, debris removal and erosion control may also be part of sitework depending on the condition of the lot and whether or not parts of the lot have been compromised by extreme weather or other phenomena.

Commercial Excavation and Backfill

The costs accumulated through sitework can easily push your budget up so it’s important to understand what sitework your commercial construction site requires before nailing down a budget.

A sloping lot will likely need to be leveled before construction can start, while a heavily wooded lot will likely need to be cleared of trees.

Much more goes into commercial excavation and backfill than you might think. First, a contractor conducts a site visit to evaluate how much preparation the lot will need before the foundation dig can start. Surveyors calculate grading (or what areas of the lot require leveling) and confirm lot and building size. These meticulous measurements are calculated for the the excavation contractor to ensure a level foundation and determine factors such as sewer and water-line placement.

Excavation contractors are part of the subcontracting team and work under a general contractor. After a site is cleared, an excavation contractor works with a foundation contractor to remove earth to the depth required for a secure foundation. Soil is tested for stability—ensuring a foundation is stable and will not sink—and foundation is laid.

The building’s foundation acts as a footprint, determining the shape and size of the entire structure. Cinder blocks, cement and steel rods create stem walls that anchor the foundation to the ground. Once stem walls and footings are complete, the commercial excavation contractor backfills the site, filling the space around the structure with soil and rocks.

Commercial Excavation and Erosion Prevention

Many state and local governments have regulations addressing erosion control on construction sites. Construction can be halted by an inspector if erosion control concerns arise. Erosion can cause flooding when streams fill with excess sediment; it can lower municipal water quality by polluting water with yard run-off and can clog culverts. Over time, erosion sediment can ruin lawns and landscaping, too.

Rain falling on bare soil triggers erosion and is a major concern in places with high annual rainfall, as well as dry areas where the soil cannot absorb sudden bursts of significant rainfall. Grading and removing vegetation from the immediate construction area will reduce the risk of erosion. Trench drains that run underground can also be built by excavation contractors to divert water away from high-risk erosion areas.

Getting an Estimate

Because excavation can be a costly necessity, it’s important to get your quote in writing and to work with a contractor that is licensed and insured—cutting corners will end up costing significantly more in the long run and could lead to an unsafe building.

Here are a few guidelines to follow when choosing a contractor for your commercial excavation:

  •      Hire one contractor who can perform lot clearing, demolition (if necessary), excavation and backfill work. Working with one company on both lot clearing and excavation can expedite the process, which can easily get derailed by slow-moving communication. You’ll also avoid paying multiple base or new client fees.
  •      Work with a contractor that’s been around for a while. More experienced contractors will better understand the challenges you can expect. For example, lots in the Pacific Northwest often require significant tree removal and specialized excavation techniques to combat challenges that arise when encountering perpetually wet soil.
  •      Choose a contractor that doesn’t charge extra for holiday and weekend work. Ask this question up front and move on if the answer is yes. These added costs multiply quickly and there are plenty of reputable companies that won’t take advantage of you.
  •      Ask if the company owns the necessary equipment to get the job done. If not, make sure you’re informed upfront about any additional rental costs.