CRISP 2.0 Type 1: Interdependent Water Infrastructure in a Potable Reuse System

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The overall objective of this Critical Resilient Interdependent Infrastructure Systems and Processes (CRISP) research is to characterize the interdependence and resilience of flood control, wastewater, and drinking water infrastructure, and, in particular, the impact on water quality of unsheltered homeless encampments with insufficient sanitation facilities and management. Homelessness is one of the most significant issues affecting human health, well-being, and ecosystem services in the United States. The problem is particularly evident in Las Vegas where 67 percent of the homeless population is unsheltered. This raises concerns related to the public and environmental health implications of human fecal contamination of local water systems, specifically flood control infrastructure. Similar to many cities throughout the US, Las Vegas also discharges treated wastewater effluent upstream of its drinking water intakes. Therefore, if the wastewater and drinking water infrastructure are not sufficiently resilient, the added stress from flood control infrastructure may create a positive feedback loop leading to greater exposure to contaminants of emerging concern and more frequent outbreaks of waterborne disease. This research targets two long-term outcomes related to these issues: (1) generation of data and models that can be used to increase understanding of the broader public health implications of homelessness and (2) development of tools and products to effectively disseminate this knowledge to contribute to more effective measures to address homelessness and mitigate related impacts on public and environmental health. Although this research focuses on Las Vegas, concerns related to the nexus of homelessness and water quality exist in numerous cities throughout the country, thereby offering ample opportunity for replication in other regions.This research employs a transdisciplinary systems-level approach to characterize the interdependence and resilience of flood control, wastewater, and drinking water infrastructure in the context of potable reuse. The overall objective of the research is to fully characterize the nexus of water quality and public health implications of unsheltered homeless encampments. This research addresses the following environmental engineering and social science hypotheses. (1) Inadequate sanitation practices within the unsheltered homeless population result in significant deterioration of surface ater quality. These impacts are characterized using advanced chemical methods (gas chromatography/mass spectroscopy and liquid chromatography/mass spectroscopy) for the detection of pharmaceuticals, illicit drugs, and other indicator trace organic compounds. The chemical data are complemented by advanced microbiological methods [16S rRNA gene sequencing, quantitative polymerase chain reaction, and microbial source tracking] for the detection of fecal indicators, human-specific markers, and pathogens. (2) Flood control and wastewater infrastructure contribute pathogen and disinfection byproduct (DBP) precursor loadings that may lead to adverse public health impacts in drinking water infrastructure systems. Pathogen monitoring data are integrated into a system dynamics model in a quantitative microbial risk assessment (QMRA) framework. The relative contributions of DBP precursors from surface water, wastewater, and flood control infrastructure are based on trihalomethane (THM), haloacetic acid (HAA), and nitrosamine formation potentials using free chlorine, chloramines, and ozone as the target disinfectants. (3) Advanced treatment with ozone-biofiltration can be optimized to improve the resiliency of drinking water infrastructure as a DBP barrier by increasing the removal of N-nitrosodimethylamine (NDMA)which typically is elevated during and after rainstorms in urban areas. This effort is best informed by quantitative stable isotope probing to identify the microbial taxa responsible for NDMA biodegradation. The research team also uses ethnographic methods to characterize the homeless experience and their decision making processes, thereby allowing for the development of targeted outputs that can inform stakeholders and decision makers. Finally, through collaboration with the UNLV Department of Film, the research team also produces a short documentary on the nexus of homelessness and water quality in Southern Nevada. In addition to exposing film students to modern issues in engineering and social science, the documentary serves as the foundation of future outreach and education activities aimed at raising awareness.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.