City of Richmond, Virginia conducts Bacteriological Monitoring in the James River asIndicator of the Effectiveness of its Established Long Term Combined Sewer Overflow(CSO) Control Program

摘要

The City of Richmond, Virginia conducted in 2000 a bacteriological monitoring program tocomplement the existing data collected in previous bacteriological sampling programs conductedin the 1980’s and 1990s. The James River in the study area is a “Tier I” protected river whichrequires maintenance and protection of existing aquatic uses. The Virginia Department ofEnvironmental Quality (DEQ) is currently considering E. coli and enterococci as potentiallybetter suited for predicting the presence of gastrointestinal illness-causing pathogens infreshwater. The study included all microbial organisms considered as probable indicators ofhuman contact related health effects. Understanding the population levels of these organismsupstream and downstream of a wet weather CSO discharge is critical in the application of waterquality based controls. Evaluating the combined effects of all interacting bacteriological sourcesis paramount to all municipalities addressing CSO control in assigning properly designedengineering control measures. This monitoring program was conducted as part of the City’sLong Term CSO Control Program under a Special Order agreed upon with the DEQ as issuedOctober 8, 1999. This study also provides Richmond, other localities and the Commonwealth ofVirginia sound scientific basis to indicate if attainment of the present bacterial water qualitystandard is possible or if movement towards an alternative based on water quality improvementsfrom a well designed and operated CSO Long Term Control Program is needed.Utilization of actual river bacterial monitoring information as input to both the combined sewersystem model and the James River tidal model provided the basis to conduct the necessary longrange CSO planning analysis based on gains in river bacterial water quality.