Geospatial Analysis of Onsite Wastewater Treatment System Density, Pollution Potential, and Social Vulnerability in Coastal Mississippi and Alabama

Abstract

Proper wastewater infrastructure management is essential in preventing negative health outcomes for humans and the environment, and geospatial tools can serve as a tool to identify and bridge shortcomings. Recently, several studies have investigated onsite wastewater treatment systems (OWTSs), a commonly used method of wastewater treatment and disposal. Despite the prevalence of OWTS research, some gaps persist. Thus, the primary objective of this thesis was to use geospatial tools to understand shortcomings in OWTS management and inform more equitable decision-making. This objective is addressed in two chapters. Chapter 1 leverages a GIS-based multi-criteria decision analysis (GIS-MCDA) to estimate the potential for pollutant exposure from OWTSs across coastal counties of Mississippi (MS) and Alabama (AL). Moreover, Chapter 1 explores social vulnerability indicators to identify the most practical OWTS pollutant exposure intervention strategies across localized case study regions. This manuscript underscored inequities in OWTS usage and presented recommendations that could guide more targeted and equitable decision-making regarding OWTS pollutant exposure interventions. Chapter 2 uses limited OWTS permitting data with random forest regression to estimate OWTS density across regions where data are incomplete. Results highlight complex dynamics in urban periphery areas that may not be effectively captured by modeling alone. This work represents among the first efforts to estimate OWTS presence and presents opportunities for improvement and scalability.