Agenda - 03-02-2006-7b - Laserfiche WebLink

Browse Search

Does Conservation and Improved Efficiency Save Capacity at the Wastewater Plant? The effects of increased development densities on wastewater treatment capacity are more complex than on the water system. Wastewater plant capacity is substantially affected by both the volume of flow (which is mostly water) acid the strength or amount of the waste contained in that flow. Using water more efficiently through practices such as those outlined above can help reduce the volume of wastewater, but the amount of pollutants in the untreated sewage that must be treated will remain the same. Waste loads (the actual amount of pollutants) will generally increase with increased development density. OWASA addresses wastewater treatment and capacity issues though the selection of specific processes or combinations of processes needed to produce a high quality effluent (treated wastewater released to the enviromnent) that meets applicable environmental and water reuse standards. Those decisions are made in the context of capital improvement projects needed to periodically increase treatment capacity and/or to respond to new or anticipated regulatory requirements. The estimated buildout capacity and future plans for OWASA's Mason Farm Wastewater Treatment Plant are based on our best projections of future flow, wastewater strength, and regulatory requirements. Long-teen plans for the wastewater plant will continue to evolve as treatment technology evolves and as other assumptions change or become better defined. Although increased development density may increase the amount of waste that OWASA must ultimately treat, it is w4ikely that this will affect total capacity or future treahnent plant decisions as signif candy as new or more stringent regulatory requirements, such as the total maximum daily load (TMDL) restrictions for nitrogen and phosphorus that will be set forth in .Jordan Lake rules that the North Carolina Enviromnental Management Commission is expected to consider later this year. Pipes in the Ground OWASA's overall water and sewer infrastructure -the pipes in the ground - is adequate to accommodate reasonable increases in development density. The water distribution system (pumps, pipes, and storage tanks) is generally designed to meet fire flow requirements that are substantially higher than everyday needs. The wastewater collection system, with a minimum pipe diameter of eight inches, is able to accommodate flows from most foreseeable residential or commercial development. The capacity of downstream sewer outfalls and interceptors is reviewed systematically through capital improvements projects such as those underway or about to begin in the Morgan Creels and Upper Bolin Creels sewer subbasins, These evaluations rely extensively on existing or proposed land use, zoning, and density scenarios to estimate the capacity needs of downstream sewers. OWASA -Water and Sewer Capacit)~ hnplrcations oJGicrensed Development Densiry~ Page 1? of 2/