Sanitary sewer overflow: Difference between revisions

Revision as of 16:56, 6 September 2015

Revision as of 22:36, 6 September 2015

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==Blockage==

Decentralized failures in dry weather mainly occur from collection sewer line blockages, which can arise from a [[debris]] clog, line rupture or tree root intrusion into the line itself. Approximately half of SSOs in the United States are caused by blockage.<ref name="EPARTC"/>{{rp|p. 4–26}} Approximately[[Brown grease|Grease]] is the blocking agent in approximately half of United States SSOs attributed to blockage, wereand causedsolid bydebris cookingis fatsthe dissolvedblocking inagent hotfor wateranother for25 dischargepercent. to[[Root]]s sanitaryare sewersa whichcontributing congealedfactor asin greaseapproximately depositsone-quarter inof theUnited coolerStates sewer.SSOs attributed Solidto debrisblockage. including ragsGrease anddeposits clothingare wascaused responsibleby forcooking approximatelyfats one-quarterliquified ofwith Unitedhot Stateswater SSOsfor attributeddischarge to blockagessanitary sewers. RootsThese werefats acongeal contributingas factorsolid deposits in approximatelythe one-quartercooler ofsewer. United StatesSolid SSOsdebris attributedincludes tosoiled blockageclothing, [[diaper]]s, and [[sanitary napkin]]s flushed into toilets. <ref name="EPARTC"/>{{rp|p. 4–28}}

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 it has been said that this practice has permitted the reduction of pollution events by up to 60%.

Dry weather blockage is less likely within combined sewers; because combined sewers designed for the additional volume of surface runoff are so much larger than sanitary sewers. Combined sewers may be vulnerable to blockage at the storm water regulator, but discharges from such blockage typically enter the diversion [[outfall]] to avoid flooding private or public property.

==Infiltration/inflow==