**3.3 Green barrier**

#### *3.3.1 Description*

The green barrier under study is *Eucalyptus dunii*, with a width of 61 m and a length of approximately 239 m, covering a total area of 1.46 104 m<sup>2</sup> . It is placed between the coal processing mill and Point P1, 278 m from the mill (see **Figure 6**).

*E. dunii* is a tree with straight trunk, with dense and drooping foliage. The projected planting technique was staggered diagonally, which is the technique commonly used from the agronomic point of view for planting such species of trees. It is based on the formation of an equilateral triangle between trees. In this case, a variant was made in such a way that the distance between trees in each row was 2.0 m and the distance between rows was 4.0 m. In any case, it can be considered that it is a regular planting pattern, as shown in **Figure 7**. Based on this configuration, there is a surface density of 0.3125 trees/m<sup>2</sup> .

**Figure 6.** *Location of the tree barrier.*

**Figure 7.** *Staggered planting pattern.*

The height of the tree barrier was measured, and the following results were obtained:


Since the plantation was not created for commercial use, no pruning of root sprouts was done. This practice increases the density of the barrier.


*sound level on scale C with the sound level A, allows determining whether or not there are significant low-frequency components. Indeed, since curve A attenuates low frequencies and curve C does not, if the difference between dBA and dBC values is not huge (C-A* ≤ *10), it will be considered that the low frequency components are not important [27].*

**Table 6.** *Tree barrier initial check.* *Evaluation of Industrial Noise Reduction Achieved with a Green Barrier: Case Study DOI: http://dx.doi.org/10.5772/intechopen.108835*
