November 2008, Vol. 20, No.11

Affluent Effluent

Kevin L. Enfinger and Patrick L. Stevens

sew´•ẽr sō•ci•ol´ō•gy, the science of society, social institutions, and social relationships viewed through the eyes of a sewer; specifically, the systematic study of the development, structure, interaction, and collective sewer use of organized groups of human beings.

Most sewer flows are characterized by repeatable diurnal patterns that vary across weekdays, weekends, and holidays. Differences in land use are also apparent. Last month, we concluded our mystery land-use series. Thanks to all who participated. We hope that you were both enlightened and entertained.

This month, we take a closer look at our most recent find — variations in diurnal patterns from four different residential areas, as shown in the figure to the below.

Most sewer flows are characterized by repeatable diurnal patterns that vary across weekdays, weekends, and holidays. Differences in land use are also apparent. Last month, we concluded our mystery land-use series. Thanks to all who participated. We hope that you were both enlightened and entertained.This month, we take a closer look at our most recent find — variations in diurnal patterns from four different residential areas, as shown in the figure to the below.

 

These composite hydrographs display flow monitor data from communities in California, Georgia, Tennessee, and Indiana, respectively. Weekdays are shown in green, and weekends are shown in light blue. The differences observed are believed to be a direct result of socioeconomic differences.

The first example (a) originates from an affluent area and is characterized by a much lower evening peak and lower flows on the weekend. The second example (b) originates from a white-collar middle-class area and is the “classic” residential pattern. The third example (c) originates from a blue-collar middle-class area and is characterized by an evening peak that is higher than the morning peak. The fourth example (d) originates from a middle-class area with a high percentage of dual-income households with no children. This pattern is characterized by an afternoon minimum flow that drops nearly as low as the nighttime minimum.

Take a few minutes to study these examples, and see if you can identify the reasons for the observed differences. We have a hunch or two and even have consulted with a sociology professor for further insight.

Send your comments and theories to magazine@wef.org. The results will be shared in a future issue.

Kevin L. Enfinger is senior project engineer, and Patrick L. Stevens is vice president of engineering at ADS Environmental Services, a division of ADS LLC (Huntsville, Ala.).

Mystery Flow: Part 6 Revealed

The final mystery land-use pattern was obtained downstream from an
automobile assembly plant located in the Northeast. Production activities
are only conducted on the first shift.

Mystery Flow: Part5 Winner

Last September mystery flow contest apparently stumped our readers. No one correctly identified the land-use pattern as a mental health hospital