Sanitary sewer overflow: Difference between revisions

Revision as of 13:01, 13 June 2017

Revision as of 17:49, 13 June 2017

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: ''Not to be confused with [[Combined sewer#Combined sewer overflows (CSOs)|combined sewer overflow (CSO)]]''

[[File:Sewer overflow RI EPA.jpg|thumb|right|A [[manhole]] cover unable to contain a sanitary sewer overflow]]

'''Sanitary sewer overflow''' ('''SSO''') is a condition in which untreated [[sewage]] is discharged from a [[sanitary sewer]] into the environment prior to reaching [[sewage treatment]] facilities. When caused by rainfall it is also known as '''wet weather overflow'''. It is primarily meaningful in [[developed countries]], which have extensive treatment facilities. Frequent causes of SSO spills include:

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* Malfunction of [[pumping station]] lifts or electrical [[power failure]]

* Broken sewer lines.

SSOs can cause [[gastrointestinal illness]]es, beach closures and restrictions on fish and shellfish consumption.

==Magnitude of the problem==

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[[Image:Overflowepa.gif|thumb|230px|Decentralized wet weather overflow event]]

Human health impacts include significant numbers of [[gastrointestinal illness]] each year, although death from one overflow event is uncommon. Additional human impacts include [[beach]] closures, [[human swimming|swimming]] restrictions and prohibition of the consumption of certain aquatic animals (particularly certain [[mollusc]]s) after overflow events. Ecological consequences include [[fish kill]]s, harm to [[plankton]] and other aquatic microflora and microfauna. Turbidity increase and dissolved oxygen decrease in receiving waters can lead to accentuated effects beyond the obvious [[pathogen]]ic induced damage to aquatic [[ecosystem]]s. It is possible that higher life forms such as [[marine mammal]]s can be affected since certain seals and [[sea lion]]s are known to experience peaks in pathogenic harm.<ref>Johnson, S. P., Jang, S., Gulland, F.M.D., Miller, M., Casper, D., Lawrence, J., Herrera, J., [http://www.jwildlifedis.org/cgi/reprint/39/1/136.pdf "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).</ref>

==Mitigation techniques==