North Davis Sewer District WWTP Plant Wide Odor Review and Solution Implementation

The North Davis Sewer District (NDSD) operates a regional 34 MGD WWTP in Syracuse, UT. After undergoing a facility wide upgrade to the wastewater process, improvement in treatment and solids capture lead to increased odor emission from the facility. The facility has a substantial buffer zone and the neighbors consisted mostly of long standing residents. During more than 20 years of operation there have been fewer than five odor complaints. The facility employs turned outdoor biosolids drying beds and with the beginning of the turning operation in the spring of 2007 neighbors complained vehemently in force. What at first appeared to be a single process odor issue was in fact turned the straw that broke the camel's back for neighbors who had lived with a low level of for years.While traditional methods were employed to conduct the facility wide odor review, (i.e. sampling and modeling), less conventional solutions were employed. Because a low level of odor was tolerable in the short term, a phased approach to solving the odor issues could be pursued. This involved the following:A key element was enlisting and welcoming community comment and involvement in recognizing the problem and developing fast implementation solutions;Developing contingency options for day-to-day operations;Piloting various solutions; andUsing existing facility assets and operational adjustment to provide quick relief and avoid costly solutions.Neighbor involvement proved critical in allowing the staged approach to solving the odor problems. Public meetings and tours helped to alleviate public fears and allow for a reasonable phased approach to solving the emissions. Piloting of various dosing schemes identified solutions that used existing facility assets. In addition, operational adjustments and community notification saved hundreds of thousands of dollars in costs at the biosolids drying operations.Although most of the current neighbors are long time residents, new residential development has been moving closer to the facility including a new school and 20 new homes near the eastern boundary of the facility. NDSD is currently moving forward on biosolids process reviews to stay ahead of the coming greater demand for increasing levels of odor control.