9-13 The Development and Deployment of a National Septic Soil Mapping Tool

Session: Advances in Geologic Mapping, Databases, and Dissemination: Student Posters

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Abstract:

Septic systems are a cornerstone of wastewater infrastructure in the United States, serving millions of households in rural and peri-urban areas where centralized sewer systems are impractical or cost-prohibitive. When properly sited and designed, these systems are critical for protecting public health, environmental quality, and local economies. However, septic installers and environmental health professionals frequently arrive at project sites with limited prior knowledge of subsurface soil conditions, leading to design inefficiencies, unexpected site rejections, and increased project costs.

This project addresses these challenges by developing a streamlined, web-based geospatial decision-support tool that provides installers with site-specific soil suitability information prior to field visits. The tool was designed for statewide to national-scale application across the contiguous United States (lower 48 states), enabling consistent pre-site evaluation regardless of jurisdiction. The technical framework leverages the Gridded National Soil Geographic Database (gNATSGO), the highest-resolution national soil dataset available from the USDA Natural Resources Conservation Service. Complex relational joins were performed on gNATSGO tabular datasets to extract and synthesize key soil attributes relevant to septic system performance, including permeability limitations, depth to restrictive layers, and slope constraints. These processed datasets were deployed within an ArcGIS Experience Builder environment, transforming multi-layered soil survey data into a mobile- and desktop-accessible interactive interface.

The resulting application allows users to query specific locations and visualize septic-relevant soil limitations before arriving on site. This pre-site intelligence supports improved system design, more accurate cost estimation, optimized equipment selection, and clearer communication with homeowners regarding site feasibility. By bridging soil science and field-level decision making, this tool promotes more sustainable land use practices and reduces the risk of inappropriate septic system siting. From a policy perspective, this approach supports proactive infrastructure planning and aligns with emerging state-level resilience and wastewater management strategies, demonstrating how applied GIS can modernize essential wastewater infrastructure workflows at scale.

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