Depending on your job and the conditions of the site, you may wish to opt for either reverse circulation drilling or diamond drilling. Let’s take a brief look at how they stack up against one another:
Reverse circulation (RC) drilling is faster
One thing that makes RC drilling popular is that it’s faster than diamond drilling. However, RC drilling is only good for the first 300m. After that, you’ll want to switch to diamond core drilling or another method for the deeper portion of the hole. This can save you around two or three working days per hole.
RC is easier on the wallet
While diamond core drilling is excellent for rock with high silica content, the equipment and materials can get a bit pricey. Reverse circulation drilling works well and quickly through broken or overburdened rock formations, but it really shines when it comes to hard composite rock. In most cases, reverse circulation drilling is from 25% to 40% less expensive than diamond drilling.
Diamond drilling will get you a core sample
Diamond drilling is preferable when you need a sample of soil at depth. This is due to the difference in how these drilling methods create a hole. Reverse circulation drilling simply creates a hole in the ground rather than extracting a sample. The face of the bit pulverises the rock, and the chips are pushed by air pressure to the top of the hole. These cuttings are then bagged by an assistant. Not all will be used by a geologist, as only 6% to 25% are required for analysis.
While the drill cuttings can be analysed to provide a limited amount of information, the scope of these tests is limited and their locations are less precise. Core samples, on the other hand, will identify actual veins of materials and give you their precise location.
Diamond drilling is more accurate
When accuracy is an issue, such as with geotechnical drilling, reverse circulation may not be your ideal choice. Since RC holes tend to corkscrew into the ground, you will also want to use diamond core drilling if you need a straight pilot hole.
No two drilling jobs are the same. To get the best results, and to have your job done quickly, safely, and well, it’s important to use the methods that suit the project. If you have any questions about your drilling job or you’d like to know more about our services, feel free to contact us. At BG Drilling, we know how to get the job done right.