Trenchers in a wind farm: do they make sense?

In a nutshell, the answer is yes – at least if you are able to find one nearby at a reasonable price.

In general, you will have several alternatives to dig your cable trenches:

  • Backhoe
  • Backhoe with hydraulic breaker hammer
  • Explosives
  • Trencher

The smarter choice will depend on the hardness of the rock.

In general, the use of explosive for trenches in wind farms is extremely rare – it is normally limited to foundation excavation.

Backhoe is always an easy solution, above all in situation where the trenches follow a very irregular path with a lot of change of direction.

However, it’s production is lower when you have compact, very hard rock (for instance, basalts and granites).

On top of that you can have a border of the trench which is not very “clean”, as it could be difficult to open a truly rectangular section.

All in all, it will usually be a better choice in small wind farms on soils or soft,, fractured rock.

The biggest problem with trenchers is that it’s not always easy (or cheap) to find one for your project. They are very performant with long distances, as they can easily open from 1 to 3 meters per minutes in soils (e.g. silts and clays).

Obviously they are somehow slower in rocks. In a very soft one (e.g. gypsum) you should work at a pace of around 1 meter per minute (from 40 to 80 m/h), going all the way down to few meters per hour while you go up in  the Mohs scale.

As an order of magnitude, in limestone you would get from 15 to 40 meters per hours, in sandstone from 10 to 30 m/h and in gneiss less than 10 m/h.

This entry was posted in Trenches and cabling by Francesco Miceli. Bookmark the permalink.

About Francesco Miceli

Hello!My name is Francesco and I'm a civil engineer specialized in EPC (that is, "turnkey") wind farms projects.I'm currently based in Hamburg, Germany and I'm developing several interesting project all around the world - southern Europe, LATAM and various other countries.If you want to contact me please don't leave a comment in the blog (I don't check them very often) - you can use the contact form.You can write me in English, Spanish and Italian.To find a (somewhat concise) description of my non-wind business activities you can visit my webpage - www.francescomiceli.comIf you want to know more about my work, here you can download my CV - www.windfarmbop.com/CV_Francesco_Miceli.pdfHope you like the blog!Francesco

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