Modeling analyses to evaluate the impacts of proposed subsurface injection of disinfected wastewater
The City of Malibu is assessing the viability of groundwater injection as a means of disposing of highly treated effluent from a centralized wastewater treatment facility. The centralized treatment facility would receive wastewater flows from the Civic Center area of Malibu in phases that are stipulated as part of an agreement between the City and the Los Angeles Regional Water Quality Control Board. The assessment is based upon a combination of field investigations, hydraulic testing and groundwater flow modeling.
MMA conducted modeling analyses for this study to evaluate the impacts of proposed subsurface injection of treated disinfected wastewater into deep coarse-grained alluvial deposits on groundwater levels and directions of groundwater flow in the alluvial aquifer that lies along Malibu Creek and Lagoon in the Civic Center area of Malibu. Injection capacity was evaluated using groundwater modeling optimization modeling. Density dependent modeling was done to evaluate the position of the salt water / fresh water interface in subsurface alluvial deposits.