Site Preparation for Construction: What to Expect (+ What You Need to Do)

Site preparation may sound simple. But in reality, it is a complex task that involves LOTS of activity – and we’re not talking about just shovelling this or moving that.

Whether you are planning a residential, or commercial construction project, proper site prep is a must before the engineering work begins at the site.

Building site preparation involves site clearing, excavation, demolition, grading, and soil compaction using heavy equipment. What happens if you fail to conduct proper site preparation? It will result in poor quality of construction and delays in project completion. 

Time to dig deeper into the topic (pun fully intended!) to understand more about the site preparation process.

3 Basic Factors for Site Preparations Works

The goal of any site preparation activity is to ensure a stable and level work area for the construction to progress safely. But the methods needed for preparing the site aren’t always the same. They’ll depend on multiple factors.

Scope of the Project

A simple residential project will not require in-depth site preparation compared to a large industrial or commercial project. The size of the construction and the design of the foundation will also determine the nature of the process, the cost, and the time it takes.

For example, if you’re building a detached garage or adding a small patio, you’ll only need to clear the area, level the ground, do some basic excavation and pour the simplest concrete slab. It wouldn’t take more than several days.

While more complicated than building a shed, even a farm dam or a similar rural project will only require several steps.

Compare that to things like in-depth soil testing and re-testing, site surveys, extensive clearing, demolition and excavation that are required even for simplest commercial projects, and you’ll get the picture.

Location of the Construction Site 

By location we mean where it stands, but also its topography – that is, what the land looks like and how it changes from place to place.

The factors here are things like slope, soil conditions, and drainage patterns. Other factors are the depth of the water table, the position of nearby structures, and weather conditions.

But there’s more to location than just its whereabouts. Another question is, what or who lives there.

In other words, site preparation should not disturb the ecosystem and needs to preserve the environment. For many sites, a low-impact site preparation methodology is used to preserve the biological and hydrological characteristics of the soil.

Keep an eye out for environmental concerns and local laws. Local zoning regulations and future project development plans should be considered as well. 

Soil Type

One essential activity before site preparation is evaluating the soil type and properties through site soil testing.

In plain English, this means determining the soil composition, density, moisture content, and load-bearing capacity. It all helps to figure out the depth and extent of the excavation work and the necessity of implementing soil stabilisation techniques.

Then again, the type of residues and the competing plant species on a piece of land will affect the site preparation methods. Beyond that, plant rooting can affect the movement of earth-moving machinery throughout the site. 

How to Prepare a Building Site?

We’d love to tell you that you can do it alone. But that’s almost never the case as it requires much more than being handy.

What you’ll need is an experienced team, skilled in handling heavy equipment. The team not only prepares the site but also disposes of the waste materials effectively. 

Now, the time needed for site preparation can vary between a few days to months depending on the project’s complexity, soil conditions, and weather. Optimising the timeline requires proper planning and coordination between the working teams.

Time to list the main steps involved in the process of site preparation!

Site Evaluation Through Testing & Examining the Soil

Evaluating the site is not just a visual check, but a geotechnical test to determine how much load it can hold. The soil strength and bearing capacity determined through the test will help the experts understand how the soil will behave. 

There are many examples – like this tunnel digging in NSW that went horribly wrong – that prove that going ahead without evaluating the ground conditions can be disastrous.

(It also shows that big omissions can happen even in gigantic projects of great public significance.)

On a sloping or hilly terrain, a contour survey is also done for site evaluation. This data is of immense importance to civil and structural designers and helps to identify any excavation-related dangers. 

Clearly, there is no one-size-fits-all approach for land clearing and site preparation. Based on the soil condition and the type – whether it has streams, a floodplain, a wetland, or steep slopes – the process will vary.

Based on these, the choice of heavy machinery required for the site preparation is made. For example, you may decide to use a bulldozer to level the soil in a site with steep slopes.

Clearing and Demolition

For starters, there need to be clear site access points for the heavy machinery that needs to remove all rubbish, rocks, and other undesirable materials.

And if this sounds meta, it’s because it is. The equipment first needs to clear up its own way so that it can go on and clear the terrain!

If there’s old construction on the site, it needs to be demolished. But that’s more to it than just knocking it down. Of course, it requires some sound planning. If the topsoil is not suitable for the planned construction, it’ll have to be replaced with more suitable soil.

Proper disposal areas for all the cleared material is fixed along with the arrangement of unhindered access to these spots from the site. In some sites, drainage channels are dug for conducting dewatering operations within the site.

The next step is the clearing of vegetation and trees on site. This is where you absolutely need to look closely into the environmental laws and guidelines of the area. There have been multiple incidents where companies were penalised for clearing ecologically sensitive areas!

Managing Underground Obstructions

Time to look underground and identify any and all obstructions that could impede the construction work! These can be anything from underground rocks to underground utilities like electricity or sewer lines.

Of course, you don’t want to damage any lines, so you’ll need an underground survey of the site to pinpoint where the obstructions extend and how to tackle them, if at all. Before handling any subsurface service assets related to power, natural gas, or communication, you’ll need to consult the authorities in charge.

Excavation, Grading, and Compaction

Site excavation is done by using tools or explosives. While the soil is removed by using backhoe loaders, excavators, or trenchers, bedrock removal is done by blasting. 

After excavation, the soil is levelled or graded. In some sites, the soil is levelled by the cut-and-fill method where soil from the higher level is transferred to the lower level. The other option is using a split-level design where the construction follows the land slope.

The next step is soil compaction which provides stability for the foundation. The exact process used depends on the nature of the soil and the moisture content. Static or vibratory forces are used for soil compaction. There are various types of rollers used for this process.

What Are the Costs of Site Preparation for Construction?

The site preparation costs depend on the size and condition of the site. Unfortunately, there is no stock formula for calculating it as Australian site conditions can vary a lot. So copy-pasting the figures from any past projects may not work either.

A site in a rural or hilly area where transportation of materials is difficult will raise the costs. Likewise, developing some sites with specific soil types, like those with clay soil, is more expensive. Lastly, the layout of the project and the design of the foundation will impact the costs. The timeframe for the work also matters.

But what about the actual site preparation costs?

Depending on the conditions, the excavation cost per cubic metre of soil is currently between $50 and $200. Site preparation for a small home on a flat piece of land that needs little preparation can cost $2,500. For a large commercial site, the cost can be around $12,000 on flat terrain. On hilly terrain, the cost can rise to $25,000 or more.

Site Preparation for Construction: FAQs

What is the site preparation method?

The site preparation method prepares a site for construction works by surveying and testing the soil and clearing the site. This is followed by soil excavation, grading and compaction- a series of activities to stabilise the soil.

What is the sequence of site preparation?

The first step of soil preparation is site survey and soil testing. Based on the results, the site is cleared of all unnecessary materials and debris. This is followed by excavation, grading, and soil compaction in sequence. 

What safety precautions should be taken during site preparation?

The first step for ensuring safety during site preparation is to minimise all risks and conduct an induction for all workers. Ensure strict site security to restrict unauthorised entry into the site. Workers should wear PPE at all times and follow the safety signs and precautions. Lastly, keep the site tidy and prevent any tampering with equipment.