How long does geothermal borehole drilling usually take?

A common question that business and homeowners want to know about geothermal borehole drilling is how long the whole process will take. People are understandably keen to avoid too much disruption on-site, and will want to know how long to factor in for the whole project. 

The actual drilling of a borehole itself doesn’t take long – just a few days in most cases. However, that’s not the only part of the process to keep in mind – let’s take a closer look at what you can expect.

Planning

Before the geothermal borehole can actually be drilled, some planning will need to be done in order to ascertain how many holes need to be drilled and to what depth.

Some basic details will need to be assessed, such as the size of the space that needs to be heated, the energy efficiency of that space, and the temperature difference between the internal and external spaces. 

It can take a few days to get all of these details down. Once confirmed, a drilling team can be put together, and appropriate drilling equipment can be brought to the site.

The actual drilling

Once a suitable length and location have been determined and an appropriate drilling rig has been brought to the site, the actual drilling process shouldn’t take long at all. 

In most cases, each borehole should take around 1-2 days; if your premises require multiple boreholes in order to meet their energy needs, then you can simply multiply that out to include all of the boreholes.

This is based on a drill rate of around 100m per day, with a standard rig. IT might end up being slightly quicker or slower, depending on the ground material that needs to be drilled through, but this rough estimate should end up being broadly applicable.

As the borehole is drilled, the team will also need to install a casing, to ensure that the sides of the borehole don’t collapse in on themselves.

Loop insertion + grouting

Once the borehole has been drilled to its full depth, the loop can be dropped into it. This loop is essentially a long polyethylene pipe with a U-bend at the bottom, through which a liquid can be pumped in order to bring up some of the ambient heat from below.

A grout material will be poured around the loop, to make sure that energy is able to efficiently transfer between the ground and the heat transfer liquid. 

That liquid can then be pumped through the loop, bringing energy up from the ground below and running it through a heat pump, allowing for that energy to be concentrated and used for the property’s heating needs.

The actual amount of time that you can expect the drilling team to be onsite will generally be about 3-6 days. With the right provider and proper planning, you can get the whole project completed with minimal disruption, leaving you with an energy solution that keeps your property heated for decades to come.