June 2007, Vol. 19, No.6

Sewer Sociology

Mystery Flow: Part 2

Kevin L. Enfinger and Patrick L. Steven

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 put your sewer
sociology skills to test with a mystery land-use pattern. The challenge continues this month with a new mystery.

A composite hydrograph of flow monitor data from a location in Southern California is provided in the figure. Note that the wastewater flow on weekdays is about the same as the wastewater flow on the weekends. Weekdays are shown in green, and weekends are shown in light blue.

Composite Hydrograph From Mystery Land-Use Area

Click figure for larger view


Based on this information, which of the following do you think this mystery land-use pattern is?
a) a theme park.
b) a military installation.
c) a petrochemical plant.
d) a prison.

Think you know the answer? To enter our contest, click here and select the answer you think best describes this month’s mystery flow. Responses will be accepted until July 1. The winner, who will be drawn at random from correct responses, will receive a WE&T prize. We will announce the correct answer and the name of the contest winner on the Web site and in a future issue. Good luck!

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 1 Revealed

Last month’s mystery land-use pattern was obtained from a shopping mall. Wastewater flow increases during the week and is higher on weekends than weekdays. Also, four distinct diurnal patterns are observed: weekdays (Monday through Thursday), Friday, Saturday, and Sunday. These patterns are closely correlated with the common retail operating hours and shopping habits of the American public. “Black Friday” — the day after Thanksgiving — is shown for comparison.


Click figure for larger view