Land Application Monitoring Needs for Long Term Sustainability.

Land application treatment of wastewater has been a viable alternative for sustainable wastewater treatment and reuse.  It is an important alternative treatment technology for industries such as food processors and dairies, as a means to maintain a low energy, lower cost treatment process for organic and nutrient rich wastewaters.  For municipalities, it offers a means to reuse a valuable resource and conserve scarce potable water supplies.  Instead of direct discharge to surface waters, land application is a discharge to soils, crops, and groundwater on a macro scale making performance monitoring and data interpretation a challenge.  Interpretations of operational monitoring data for groundwater quality protection is typically by inference through computations of water and nutrient balances and review of soil residual nutrient content.  Regulatory agency personnel often lack the agronomic training and skills to understand  the monitoring data and must rely on groundwater monitoring results for evidence that land application is being protective of groundwater quality.  Where groundwater is deep, or not highly responsive to surface inputs, groundwater sampling and analysis is ineffective for documenting compliance.  The regulatory acceptability and operational feasibility of land application treatment often hinders the ability to confidently and practically monitor the fate and transport of nutrients in the vadose zone before it reaches groundwater.  New and improved, practical, cost-effective methods are needed to quantify nutrient balances and fate of nitrogen, phosphorus, salts, and other contaminants on a macro scale in the vadose zone on a timely basis.  This presentation explores the current state of land application system monitoring and identifies specific concerns and needs for developing practical monitoring systems and techniques to provide direct interpretation and management of potential impacts to groundwater quality.  Once commercialized, these techniques could be implemented for not only wastewater reuse, but agriculture, and agricultural waste management, as well.