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Available as an eBook only. This study evaluates the impacts of blending practices at municipal wastewater treatment plants on effluent and receiving water quality, and estimates public health risks associated with recreation in surface waters receiving blended flows. Field samples were collected at four municipal wastewater treatment plants for in-plant processes and receiving waters during wet weather blending, wet weather non-blending, and dry weather events. Laboratory analyses for Giardia, Cryptosporidium, viruses (adenovirus, enteric viruses, rotavirus, norovirus), pathogen indicator organisms (fecal coliform, E. coli, enterococcus, and male specific coliphage), and other water quality parameters were performed on these samples. Field sample results for the East Bay Municipal Utility District's (EBMUD) Main Wastewater Treatment Plant were used to develop a hydrodynamic and water quality computer models to predict receiving water conditions and a quantitative microbial risk assessment (MRA) to evaluate increased risks of gastrointestinal and respiratory infections for people recreating in waters receiving blended flows. EBMUD field sampling results indicated that Giardia and adenovirus concentrations in plant final effluent increased during wet weather blending events in comparison to non-blending events, and so receiving water modeling was conducted for these organisms. T-test results indicated that the differences between blending and non-blending were not considered to be statistically significant for any of the pathogen and indicator organisms except Giardia cysts (enumeration). Additionally, TSS, cBOD5 and particle concentrations from final effluent grab samples also appeared higher during blending events, but no increase was observed in VOC levels during these periods, and no NPDES permit limits were exceeded. An estimate of the incremental annual number of infections associated with blending practices at EBMUD's wastewater treatment plant was developed based on two pathogens (adenovirus and Giardia spp.) and three exposure sites. Estimated individual risk per exposure event for people recreating in waters receiving blended flows were greater by about an order-of-magnitude (10x) at the EBMUD MWWTP Outfall location and less than an order-of-magnitude (10x) at three other exposure sites, than if these blended flows received full secondary biological treatment during wet weather conditions. Thus the relative increase of annualized risk appeared negligible, at less than one infection annually assuming 100 exposure events per day for 30 blending days per year.

Water services include water supply, sewerage and stormwater drainage. The facilities needed for these services are pipelines, reservoirs and treatment works; but the service goes beyond the infrastructure. It includes economics, billing, and business management. Although these services exist in every city, being advanced by the growing use of automation and information technology, costs are also increasing without many consumers seeing increased benefits. Customer service is therefore becoming important to the industry. Water Services Management is intended to educate engineers to manage and improve water services, rather than simply designing and constructing treatment works and distribution systems. The text covers water supply and drainage from the hydraulic and economic points of view, and while design and construction practices are reviewed, the focus of the book is on improving existing systems to turn the emerging industry into an attractive business. Topics covered include: Potable water supply, sewerage and stormwater drainage. Hydraulic management: storage, peak flow attenuation and pumping. Water quality: standards, pollution control and treatment. Infrastructure management: rehabilitation, reconstruction, upgrading and maintenance. Economic efficiency: asset management, privatization, and risk analysis. Improving economic viability via efficient use of energy and construction project management. Characteristics encountered in developing countries are also considered, including: Low cost sanitation, water supply standards and off-grid energy sources. Capacity building and appropriate technologies. Financing, operation and benchmarking.