This paper reports two discrete-event simulation studies to model the activities of a residential waste treatment facility and prepare it to accept additional wastewaters through tanker trucks. The first simulation study models the wastewater treatment facility to ensure its ability to handle the planned added capacity arriving through the pit, while the second study simulates various managerial strategies to handle the traffic, testing, and unload procedures of tanker trucks arriving at the facility. The simulation models were statistically validated and the outcomes of the study were implemented in reality. The wastewater treatment facility extension suggested by this study was implemented and launched in mid 2008 to accept residential wastewater tanker trucks. This has saved the environment over 6,000 m 3 daily from being dumped into the open unlined terrestrial landfills. Simulation proved to be an excellent tool in the facility planning effort, as it ensured smooth flow lines of tanker truck load discharge and the best utilization of facilities on site.