| Nitrate is one of the most significant documented threats to groundwater quality from on-site wastewater treatment systems. With more than one million septic systems in Ontario, assessing nitrate-N impact on groundwater and improving septic systems practices are essential.; An examination and evaluation of available methodologies through application of these methods on three selected septic systems (or clusters) were conducted in this study to determine the complexity, suitability, accuracy, and data required of different approaches, which include the mass balance method, index and overlay method, and numerical modeling. The mass balance method was demonstrated as a simple and reliable tool to evaluate nitrate-N in groundwater from septic systems. Based on these findings, a modified mass balance calculation tool combined with the estimation of evapotranspiration has been developed in this research. Application of the modified method will improve septic system practices and minimize potential health and water quality problems. |
