# Sand: A Critical Component for Beach Volleyball Courts
## 4 Results
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Site**} & \multicolumn{4}{c}{**Mean**} & \multicolumn{2}{c}{**Sorting**} & \multicolumn{2}{c}{**Skewness**} & \multicolumn{2}{c}{**Kurtosis**} \\ \hline
**ID** & **Name** & \(\mathbf{\mu}\)**m** & **Description** & \(\mathbf{\mu}\)**m** & **Description** & \(\mathbf{\mu}\)**m** & **Description** & \(\mathbf{\mu}\)**m** & **Description** \\ \hline
1 & Skowroni Park & 372.9 & Medium sand & 1.641 & Moderate & 0.146 & Coarse & \multirow{2}{*}{1.162} & Leptokurtic \\  & & & & & & & skewed & 1.162 & Leptokurtic \\ \hline
2 & KS AZS Wratislavia & 369.3 & Medium sand & 1.977 & Moderate & \(-\)0.035 & Symmetrical & 1.044 & Mesokurtic \\ \hline
3 & \
\begin{tabular}{c} Wroclaw University of \\ Science and Technology \\ \end{tabular} & 479.9 & Medium sand & 2.019 & Poor & 0.162 &
\begin{tabular}{c} Coarse \\ skewed \\ \end{tabular} & 1.131 & Leptokurtic \\ \hline
4 &
\begin{tabular}{c} Wroclaw University of \\ Health and Sport Sciences \\ \end{tabular} & 383.4 & Medium sand & 1.665 & Moderate & \(-\)0.070 & Symmetrical & 1.051 & Mesokurtic \\ \hline
5 &
\begin{tabular}{c} 'Morslie Oko' swimming \\ facility \\ \end{tabular} & 390.9 & Medium sand & 1.841 & Moderate & \(-\)0.031 & Symmetrical & 1.161 & Leptokurtic \\ \hline
6 & GEM Sports Complex & 502.2 & Coarse Sand & 1.702 & Moderate & 0.108 &
\begin{tabular}{c} Coarse \\ skewed \\ \end{tabular} & 1.181 & Leptokurtic \\ \hline
7 & Millennium Park & 360.2 & Medium sand & 1.766 & Moderate & \(-\)0.032 & Symmetrical & 1.127 & Leptokurtic \\ \hline
8 & \begin{tabular}{c} 'Glinianki' swimming \\ facility \\ \end{tabular} & 548.4 & Coarse Sand & 1.526 & \
\begin{tabular}{c} Moderate \\ well \\ \end{tabular} & 0.123 &
\begin{tabular}{c} Coarse \\ skewed \\ \end{tabular} & 1.027 & Mesokurtic \\ \hline
10 & Primary School No. 95 & 385.0 & Medium sand & 1.806 & Moderate & 0.008 & Symmetrical & 1.239 & Leptokurtic \\ \hline
11 & K69 (hall) & 534.0 & Coarse Sand & 1.520 & \
\begin{tabular}{c} Moderate \\ well \\ \end{tabular} & 0.142 &
\begin{tabular}{c} Coarse \\ skewed \\ \end{tabular} & 1.077 & Mesokurtic \\ \hline
12 & \
\begin{tabular}{c} Olympic Preparation \\ Centre in Spata (hall) \\ \end{tabular} & 315.7 & Medium sand & 1.415 &
\begin{tabular}{c} Moderately \\ well \\ \end{tabular} & \(-\)0.133 & Fine skewed & 0.871 & Platykurtic \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Statistical parameters of the grain size distribution of collected samples according to Folk and Ward [24]. The sorting of the samples ranges from poorly (1/12) through moderately (8/12) to moderately-well sorted (3/12), and the most homogeneous was the sample from the CSC-OPC court (no. 12). Half of the samples are characterised by symmetrical grain size distribution, which means that they contain equal amounts of sand of all fractions, and 5/12 courts are characterised by a skewed grain size distribution in the direction of coarse grains. The distinctive sample is the one from the CSC-OPC court, which is skewed towards the fine grains and has a platykurtic distribution. The platykurtic distribution is defined as the flattest, but in this case, this parameter is strongly influenced by the lack of silt and gravel in the sample. Furthermore, it is the best sorted of all the samples. The kurtosis of the remaining samples is either meso- (4/12) or leptokurtic (7/12) when the majority of grains are close to the sample mean grain size. The consistency of the grain size results with FIVB standards for beach volleyball courts is shown in Table 4. None of the courts surveyed comply with FIVB standards, with very fine sand (9/12 samples) and fine gravel (12/12 samples) being the most frequently violated norms. In the case of very fine sand, the excesses are significant, reaching more than 7%, often referring to the scale of deficiency in the medium and coarse sand class, which according to the standards should dominate the weight content of the sample (80-92%).