*3.6. Consequences for Sand Trap Design*

Based on the analysis results it is found that the tested rib design improves the trap efficiency and can be recommended for new sand traps and retrofitting of existing sand traps. The tested design was recently developed and presented in Richter et al. [5] and has not previously been installed in a hydropower plant. The tested v-shaped rakes were found to decrease the trap efficiency and, in addition, have a larger negative effect on the head loss. Such v-shaped rakes are installed in several existing hydropower plants, but this practice should be reconsidered. However, it is noted that only one design of the v-shaped rakes were tested and other designs may prove to have a positive effect on the trap efficiency.
