Assessing the Socio-Environmental Risk of Onsite Wastewater Treatment Systems to Inform Management Decisions

Area of Science:

• Environmental science
• Public health
• Environmental justice

Background:

• Onsite waste treatment systems (OWTS), commonly known as septic systems, are crucial for managing wastewater in many areas.
• Assessing the risks posed by failing OWTS to human health and natural resources is vital for effective environmental management.
• Existing research often lacks a comprehensive approach integrating environmental and socio-demographic factors to evaluate OWTS risks.

Purpose of the Study:

• To develop and apply a framework for assessing environmental risks and environmental justice concerns associated with septic infrastructure.
• To identify the primary factors contributing to OWTS environmental risk, differentiating between system placement and system age.
• To inform strategies for proactive environmental monitoring and mitigation of risks, particularly in vulnerable communities.

Main Methods:

• Integration of environmental data (topographic, hydrologic, edaphic characteristics) with socio-demographic information.
• Geospatial analysis to map and quantify the risk associated with registered OWTS based on placement and age.
• Statistical analysis to correlate high-risk OWTS locations with socio-demographic indicators such as poverty and race.

Main Results:

• Only 8% of OWTS posed environmental risks due to placement characteristics.
• Nearly 70% of OWTS presented potential environmental risks primarily due to their age (25 years or older).
• Approximately 60% of high-risk OWTS were located in disadvantaged census blocks (impoverished, nonwhite, or both).

Conclusions:

• Septic system age is a more significant predictor of environmental risk than placement in the studied jurisdiction.
• There is a clear environmental justice dimension to OWTS risk, with disadvantaged communities disproportionately affected.
• The developed framework using integrated geospatial data can guide proactive monitoring and management of OWTS to address environmental justice concerns.