This study focuses on scientific literacy and how we can extend our findings from our previous work on socioscientific engagement, where Meta-Epistemic Reasoning Practices (MERPs) are defined as a situated epistemic resource model that indicates that participants may be shifting between aims, ideals, and reliable processes (AIR model) as they work through a situation. Since MERPs could interact on the domain-general strategic knowledge for mechanistic reasoning, we decided to focus on epistemic heuristics for mechanistic reasoning, how these can be applied with the use of MERPs, and with the science ideas citizens used to construct a mechanism to evaluate contextual relevance of an authentic SSI. WE conducted interviews with 7 members of a town that had recently experienced hurricane-induced flooding. Participants included activists, policy makers, planners, scientists, and infrastructural managers, rather than students in order to explore diversity. We included "levels," like levels of description, to characterize a system, as well as the analysis of science-related ideas for mechanistic reasoning of each participant. WE found that participants used a combination of science and situational knowledge for evaluating causal propositions, that MERPs guide the use of a diverse set of aims and ideals, and that different individuals integrate different science ideas, where together the community rises to a more sophisticated evaluation of the SSI proposal. By studying the real world we aim to incorporate constructive civic engagement into the classrooms, and empower the next generation of citizens, not only future scientists.