Dropshaft Eduction: Ventilation Impacts on the Design of Vapor Phase Odor Control

The use of vapor phase odor control facilities within the collection system has become increasingly frequent in recent years. This is particularly true in large diameter interceptors and deep tunnels, where large volumes of potentially odorous air are emitted at points of pressurization. The ventilation dynamics of the collection system, and the desired zone of influence of the odor control facility, will dictate the necessary airflow capacity for an effective vapor phase odor control system. Properly sizing and locating vapor phase odor control facilities requires an understanding of the two major factors involved in the natural ventilation of large diameter sewer systems: natural friction drag; and dropshafts.