AWWA ACE69076

A large majority of clearwells must be modified while maintaining the original baffles, since they were built underground with materials like concrete. Therefore, it is unreasonable to apply the previous research in clearwell modification which assumed that distance between baffles is constant. In this study, the internal short-circuiting estimation method (ISEM), which has the advantage of being applicable under any conditions, is applied to evaluate modification of an A clearwell and to modify B and C clearwells which have unusual characteristics. After analyzing the hydraulic efficiency of the original state, modifications, where baffles, intra-basins and diffuser walls are additionally installed, are considered and evaluated using the ISEM. The effect of intra-basin and diffuser walls on T₁₀/T is estimated and the application feasibility of ISEM is evaluated. The improvement provided by intra-basins is almost the same as that of baffles. Also, short-circuiting in the effluent zone can be reduced with the same level of channel zone if an intra-basin is added in the effluent zone. However, the effect range is restricted to the next channel zone. A diffuser wall can obtain a lower ISI than is possible in cases where baffles and intra-basins are installed. Therefore, additional improvement of the T₁₀/T value can be expected after the T₁₀/T value converges maximum using only baffles Includes 13 references, tables, figures.