Sanitary sewer overflow
Sanitary sewer overflow (SSO) is a condition in which untreated
SSOs can cause
Magnitude of the problem
Developed countries such as the United States, Canada, most Western European nations (e.g. Italy and France), Australia, Singapore, South Korea and Japan are struggling with public health problems of SSO prevention. The magnitude of the problem is much greater in most developing countries.
United States
The
Worldwide perspective
Developed European countries and Japan have similar or somewhat larger percentages of SSO events compared to the U.S.[citation needed]
In
In many countries there are obligations to measure and report SSO occurrence using real-time telemetry to warn the public, bathers and shellfishery operators.[citation needed]
Causes
Engineering aspects
Sewers that were built in the early stages of urbanization were usually built before
Blockages
Decentralized failures in dry weather mainly occur from collection sewer line blockages, which can arise from a
Many U.S. municipalities require restaurants and food processing businesses to use
One of the main problems of a decentralized line failure is the difficulty of defining the location of overflow, since a typical urban system contains thousands of miles of collection pipes, and the central treatment plant has no way of communicating with all the lines, unless expensive monitoring equipment has been installed. Companies in the UK have widely deployed bulk dielectric transducers suspended in the sewers to detect high levels and to report the events back over fixed wireless data networks. In certain locations this practice has permitted the reduction of pollution events by up to 60 percent.[citation needed]
Dry weather blockage is less likely within combined sewers; because combined sewers designed for the additional volume of surface runoff are much larger than sanitary sewers. Combined sewer storm water regulators may be vulnerable to blockage by debris, but overflow from such blockage typically enters the diversion outfall to avoid flooding private or public property.
Infiltration/inflow
Approximately one-quarter of United States SSOs occur during heavy
Malfunctions
Another mode of system failure can include
Power failure, human error, or mechanical failure may cause similar discharge of untreated or partially treated sewage from a sewage treatment plant; but this is typically regarded as a sewage treatment plant malfunction rather than a sanitary sewer overflow. Sewage treatment plants may be designed to capture overflow from malfunctioning units and discharge it to alternative treatment facilities. Flooding of private or public property is typically avoided by discharging the overflow to an outfall designed for discharge of treated sewage.[2]: p. ES–3
Human health and ecological consequences
Human health impacts include significant numbers of
Mitigation techniques
The concept of SSO containment valves has been pioneered in the UK and they are installed to mitigate dry spills, by correlating rainfall data with SSO spill activity.[citation needed]
History
Since medieval times rulers have been aware of the impact of raw sewage improperly discharged to the environment. Before treatment systems existed in 16th century
In the 19th century, sewage treatment plants were first developed and installed in the U.S. and parts of Europe, and the concept of SSO was identified. SSOs were not recognized as a widespread environmental problem until the rise of environmental awareness in the 1960s. Around that time government agencies in the U.S. began identifying locations and frequencies of SSOs in a systematic way. Local governments heard complaints of citizens, and beach closure protocols were systematised to reduce risks to public health.
After passage of the Clean Water Act in 1972, the U.S. spent billions of dollars on upgrades to sewage treatment plants, with some associated repairs and improvements to the associated collection systems, where the overflows occur. EPA continues to provide funding for low-interest loans to communities for addressing SSO problems, through the Clean Water State Revolving Fund.[13]
In the 1990s
See also
- Fatberg (sewer blockage)
- Water pollution
References
- ^ "Sanitary Sewer Overflows". National Pollutant Discharge Elimination System. Washington, D.C.: U.S. Environmental Protection Agency (EPA). 2015-11-16. Retrieved 2023-02-17.
- ^ a b c d e f g Report to Congress: Impacts and Control of CSOs and SSOs (Report). EPA. August 2004. EPA-833-R-04-001. Retrieved 2023-02-17.
- ^ "World Bank Supports China's Wastewater Treatment", The People’s Daily, November 30, 2001, Beijing
- Water Conservation, Reuse, and Recycling: Proceedings of the Iranian-American Workshop, National Academies Press (2005)
- ^ Appropriate Technology for Sewage Pollution Control in the Wider Caribbean Region, Caribbean Environment Programme Technical Report #40 1998
- ^ See History of water supply and sanitation.
- ^ Okun, Daniel A. (1959). Sewage Treatment Plant Design. American Society of Civil Engineers and Water Pollution Control Federation. p. 6.
- ^ "Combined Sewer Overflow Frequent Questions". National Pollutant Discharge Elimination System. EPA. 2017-12-20.
- ^ For example, the Washington Suburban Sanitary Commission (WSSC) in Maryland, U.S.: "Fats, Oils, & Grease". Special Wastewater Discharge Requirements. Laurel, MD: WSSC. 2023-12-29.
- ^ Monica Spendilow, Impeller Magazine, ITT Flygt AB, SE-174 87 Sundbyberg, Sweden (2004)
- ^ Environmental Impact Statement for the East Bay Municipal Utility District Wet Weather Overflow Project, Earth Metrics Incorporated, prepared for the U.S. EPA and East Bay Municipal Utility District, Oakland, Ca. (1985)
- ^ Johnson, S. P., Jang, S., Gulland, F.M.D., Miller, M., Casper, D., Lawrence, J., Herrera, J., "Characterization and clinical manifestations of Arcanobacterium phocae infections in marine mammals stranded along the central California coast", Journal of Wildlife Diseases, 39:136-144 (2003).
- ^ "Sanitary Sewer Overflow (SSO) Frequent Questions". EPA. 2015-11-16.