In this work, we have performed the flume study to analyze the high-order velocity moments of turbulent boundary layer with and without downward seepage. Sediment transport experiments were done in the laboratory for no seepage (NS), 10% seepage (10%S), and 15% seepage (15%S) cases. Measures of streamwise velocity variance were found increasing with seepage, which lead to increase in sediment transport with seepage. Results show that the variance of streamwise velocity fluctuation follows logarithmic law with distance away from the bed, within inner layer. This observation is also valid for even-order moments obtained in this work. The results show that the (2p-order moments)^{1/p} also follows logarithmic law. The slopes A_{p} in the turbulent boundary layer seem fairly unaffected to NS and seepage flow but follows nonuniversal behavior for NS and seepage runs. The computed slope based on the Gaussian statistics does not agree well with the slope obtained from the experimental data and computed slope are reliable with sub-Gaussian performance for NS flow and super-Gaussian behavior for seepage flow.