Proposed Best Practices for the Design and Management for Subsurface Drip Irrigation Fields in Tennessee

Subsurface drip irrigation (SDI) systems are widely used for onsite wastewater dispersal, offering advantages such as improved effluent distribution and reduced surface contamination risks. However, variations in design, maintenance, and regulatory oversight contribute to inconsistent performance. This study evaluates SDI system design and management in Tennessee, comparing them with national regulations and manufacturer recommendations to develop Best Management Practices (BMPs) aimed at improving system efficiency and longevity.

A survey of SDI regulations across 31 states found that 20 states mandate reserve areas, 26 require or recommend flow meters with totalizing features, and 11 require telemetry-based monitoring, showing regulation of SDI systems exists across the US. Manufacturer recommendations and state regulation support drip line spacing between 12 to 24 inches as well as the use of flow monitoring and alarm systems to detect failures. In Tennessee, inconsistent inspections, design practices, an operator oversights can lead to system failures, highlighting the need for standardized regulations.

The proposed BMPs focus on drip line spacing, hydraulic loading rates, inspection protocols, operator accountability, and reserve areas. Key recommendations include biweekly visual inspections, monthly system performance checks, and annual inspections by the Tennessee Department of Environment and Conservation. Additionally, large SDI systems should designate a 100% reserve area to prevent catastrophic failures. Implementing these BMPs will align Tennessee’s SDI management with national standards, ensuring long-term system reliability, regulatory compliance, and improved environmental protection.