The Three Valleys Municipal Water District (TVMWD) faced several concurrent challenges atthe Miramar Water Treatment Plant (MWTP). Residuals management was a cumbersomeaspect of operations. On-site lagoons that collected solids-bearing streams from filter backwashesand clarification had to be cleaned on a more frequent than desired basis, which requiredcomplex logistics. The complexity of the operations required a balance of maintaining arepository for the solids-bearing streams while the MWTP remained in operation, while at thesame time minimizing the impact on recycled water. TVMWD decided to simultaneously address all three of thesechallenges. A residuals audit was conducted, which characterized the solids-bearing streams andenumerated the amount of residuals generated by the facility. The residuals audit also evaluatedmanagement alternatives, which maximized the use of existing facilities yet utilized new processes amenable to the available space and human resource limitations. The alternativesevaluation was further calibrated by the desire to improve on-site storm water management andmaximize the recharge of groundwater using storm water and the liquid fraction from residualsmanagement.Ultimately, TVMWD selected a belt filter press as a mechanical dewatering method. Theexisting lagoons were retrofitted with features to provide contingency residuals management andmaximize the use of existing infrastructure. A novel mixing system was retrofitted into one ofthe lagoons to help assure a consistent quality feed stream to the belt filter press. The area thathad been used to consolidate liquid residuals was converted to an engineered infiltration basin,so that storm water collected on-site and liquid fractions from residuals management could berecharged to the local aquifer. Includes tables, figures.
