Establishing Base Ambient Odor Impact Levels Using Air Dispersion Modeling for Odor Control Planning

In 2003, the District of Columbia Water and Sewer Authority (DC Water) published an Odor Control Master Plan (OCMP) for the Blue Plains Advanced Wastewater Treatment Plant (Blue Plains) with the intent of developing a long-term strategy for mitigating odor. While facility modifications have been made over the past ten years, continued concerns of offsite odor impacts prompted a subsequent OCMP study in 2011. The goals of the OCMP study were to estimate offsite impacts and facilitate selection of odor mitigation measures and process changes.Assessment of potential odor on the surrounding community was conducted through a dispersion modeling analysis using the US EPA’s AERMOD program. The dispersion environment surrounding Blue Plains varies from residential communities and commercial establishments to the north and west to tidal wetland and residential areas to the south and east. The plant terrain is generally flat to gently rolling with an elevation of 2-5 meters above sea level. The river to the east combined with elevated terrain to the west influence the wind patterns that influences the odor transport from sources the plant.Detailed model set-up is presented and discussed. Example unit-level and facility-wide modeling results are also presented in order to demonstrate the power of dispersion modeling as a tool for estimating odor reduction potentials of various engineering solutions.