# 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 final sound propagation model includes  
* calculation of attenuation under favorable conditions;
* calculation of attenuation under homogeneous conditions;
* geometric divergences;
* the influence of the terrain surface and its properties;
* diffractions;
* reflections. Source Description and Basic Equations  
The computational assessment of industrial noise is based on the use of the ISO 9613-2 methodology. The CadnaA calculation program works on this methodology, and its algorithms correspond to the methodology used. The calculation model has been specified for favorable sound propagation conditions. The distribution of the noise load in the areas of interest was calculated on a 1 \(\times\) 1 m grid at heights of 1.5 and 4.0 m above ground level. The calculation of noise from industrial sources was validated at reference calculation points at predefined heights corresponding to the calibration points at the time of the in situ measurements. These points were chosen for model validation at different distances from the processing plant. The noise map expresses the situation for the reference time intervals day, evening, and night. Non-point sources of sound such as railway traffic or an industrial area must therefore be represented by a set of components, each of which has a certain acoustic power and vector. The attenuation calculated for the sound from a reference point within a part is taken to be representative of the sound attenuation for the whole part. Line sources can be divided into line parts and area sources into area parts, each of which is represented by a point source at its center. Point sources are assumed to be represented by the sound power obtained by standard measurement methods. The equivalent sound pressure level in the downwind octave band at the receiving point \(L_{fT}(DW)\) is calculated for each point source and its mirror sources and for each octave band of the audible spectrum according to the following equation:  
\[L_{fT}(DW)=L_{W}+D_{c}-A\ [\mathrm{dB}], \tag{1}\]  
where \(L_{W}\) --the sound power level in the octave band emitted by the point source and determined with respect to a reference sound power of 1 pW. \(D_{c}\)--a directionality correction describing the degree by which the equivalent sound pressure level from the point source deviates in a specified direction from that of the multidirectional source generating the L\({}_{W}\) sound power level. D\({}_{c}\) is the sum of the directionality index D\({}_{l}\) of the point source and the index D\({}_{\Omega}\), which takes into account the radiation of the sound source into a solid angle of less than 4\(\pi\); for a multidirectional sound source radiating into free space, D\({}_{c}\) = 0 dB. \(A\)--sound attenuation in the octave band when propagating from a point sound source to an immission point. The attenuation A in Equation (1) is given by the relation  
\[A=A_{div}+A_{atm}+A_{gr}+A_{bar}+A_{misc}\ [\cdot], \tag{2}\]where \(A_{div}\)--attenuation due to geometric divergence;  
\(A_{atm}\)--attenuation due to sound absorption in the atmosphere;  
\(A_{gr}\)--attenuation caused by the ground surface;  
\(A_{bar}\)--attenuation caused by a barrier;  
\(A_{misc}\)--attenuation caused by various other phenomena. The individual corrections are described in Section Corrections. The equivalent sound pressure level A in the downwind direction shall be calculated according to Equation (3) by summing the time-averaged squares of the respective sound pressures calculated using Equations (1) and (2) for each point source, for all their mirror sources, and for each octave band, as determined by Equation (3):  
\[L_{AT}(DW)=10\text{log}\left[\sum_{i=1}^{n}\left[\sum_{j=1}^{8}10^{0.1[L_{T}( ij)+A_{L(j)}]}\right]\right]\,[\text{dB}], \tag{3}\]  
where n--number of contributions of the i-th source;  
j--an index indicating an octave band with a center frequency of 63 Hz to 8 kHz;  
\(A_{Lif(j)}\)--correction of the normalized A weighted sound pressure level.