USING FIELD DATA AND MATHEMATICAL MODELING TO EVALUATE POTENTIAL NITROGEN POLLUTION FROM ONSITE WASTEWATER SYSTEMS

Onsite wastewater systems (OWS) serve to treat domestic wastewater for approximately 25% of the U.S. population, and is also common in Europe and other western countries. OWS are also an attractive solution for wastewater treatment in developing countries. Ground-water pollution from nitrogen is a major concern associated with OWS. Mathematical models can be useful to help assess potential pollution from OWS. However, it is difficult to predict the performance of the soil-treatment unit component of OWS using models because very few data have been archived and reported. This research uses data collected from several operating OWS sites in Colorado, and also from a field-scale wastewater infiltration and treatment research facility at Colorado School of Mines called the Mines Park Test Site. Data is used to calibrate and/or evaluate the performance of mathematical models that can subsequently be used to evaluate the nitrogen pollution potential of OWS. Both ground-water and vadose-zone models are considered. The type and amount of data needed to calibrate these models is discussed, as well as the type of information that can be reliably used from models that are constructed using varying types and amounts of data.