# Study of Noise Effect of Slag Storage Technology on Surrounding Environment
## 2 Materials and Methods
### Methods
#### 2.2.1 Design of a Methodology for Minimizing the Effects of Slag Storage Technology
The long-term time-averaged value of the sound pressure A \(L_{AT}(LT)\) is calculated according to the following equation:  
\[L_{AT}(LT)=L_{AT}(DW)-C_{met}\,\,[\cdot], \tag{4}\]  
where \(C_{met}\)--meteorological correction described in Section Corrections. Corrections  
1. Geometric divergence \(A_{div}\)  
Geometric divergence is given by the spherical propagation of sound waves generated by a point source of sound in the open field. The attenuation due to geometric divergence is given by the following equation:  
\[A_{div}=20\text{log}\left(\frac{d}{d_{0}}\right)+11\,\,[\text{dB}], \tag{5}\]  
where \(d\)--distance from the sound source to the receiver (m);  
\(d_{0}\)--reference distance of 1 m.  
2. Sound absorption in the atmosphere \(A_{atm}\)  
The attenuation due to sound absorption in the atmosphere \(A_{atm}\) when propagating at distance \(d\) is given by the following equation:  
\[A_{atm}=\alpha d/1000\,\,[\cdot], \tag{6}\]  
where \(\alpha\)--the attenuation coefficient due to sound absorption in the atmosphere (dB/km) determined in each octave band for the middle frequencies of that band [25; 26; 27]. 3. Ground surface effect \(A_{gr}\)  
The attenuation due to the ground surface \(A_{gr}\) is primarily the result of the interference of sound waves reflected from the ground surface and sound waves propagating directly from the source to the point of immission. The curvature of the propagation path towards the ground (propagation in the downwind direction) causes this attenuation to be determined primarily by the ground surface in the vicinity of the source and in the vicinity of the point of immission. This method of calculating the ground surface effect is only applied to a surface that is relatively flat and is horizontal or has a constant slope. Three distinct regions are defined for the attenuation due to the ground surface effect:  
1. the source area is in the space from the source towards the immission point at a distance of 30 hs, with a maximum distance of dp, where hs is the height of the source and dp is the projection of the distance from the source to the immission point onto the ground plane; 2. the area of the immission point is in space from the immission point towards the source at a distance of 30 hr, with a maximum distance of dp, where hr is the height of the receiver; 3. the median area is at the distance between the source area and the immission point area; if dp < (30 hs + 30 hr), the source area and the immission point area overlap and there is no median area. To calculate the attenuation due to the ground surface for a particular octave band, the following is required:  
* to calculate the attenuation component \(A_{s}\) for the source area specified by the ground index \(G_{s}\);
* to calculate the \(A_{r}\) component for the receiver area specified by the ground surface index \(G_{r}\);
* and to calculate the \(A_{m}\) component for the median area specified by the ground surface index \(G_{m}\). The total attenuation due to the ground surface for the octave band is calculated according to the following equation:  
\[A_{gr}=A_{s}+A_{r}+A_{m}\;[\cdot], \tag{7}\]
4. Attenuation due to the barrier \(A_{bar}\) shall be expressed in terms of the insertion loss. Diffraction at the upper horizontal edge of the barrier and at its vertical edges can be significant. For sound propagation in the downwind direction and for diffraction at the upper horizontal edge, the attenuation shall be calculated according to the equation  
Figure 2:0  
And for diffraction at the vertical edges by the equation  
Figure 2:1  
where \(D_{z}\)--insertion loss of the barrier in each octave band;  
\(A_{gr}\)--attenuation due to the ground surface without the barrier. 5. Additional attenuation \(A_{misc}\)  
The \(A_{misc}\) component contains the contributions to attenuation due to various effects not included in the general methods for calculating attenuation.