Outfall
{{Short description|Discharge point of a waste stream into a body of water}}
{{Refimprove|date=August 2012}}
File:Bell Wharf CSO outfall in London.jpg in London{{cite web |title=Structure: Outfall |url=https://environment.data.gov.uk/asset-management/drl-app/revision/current/categories/Structure/asset-types/Outfall |publisher=United Kingdom Department for Environment Food & Rural Affairs |access-date=7 April 2024}}]]
An outfall is the discharge point of a waste stream into a body of water; alternatively it may be the outlet of a river, drain or a sewer where it discharges into the sea, a lake or ocean.
United States of America
In the United States, industrial facilities that discharge storm water which was exposed to industrial activities at the site are required to have a multi-sector general permit.{{cite web |title=Request Access |url=https://www.ecfr.gov/current/title-40/chapter-I/subchapter-D/part-122/subpart-B/section-122.26 |website=unblock.federalregister.gov |publisher=Code of Federal Regulations |access-date=12 July 2023}} Issuing permits for storm water is delegated to the individual states that are authorized by the Environmental Protection Agency (EPA). Facilities that apply for a permit must specify the number of outfalls at the site. According to the EPA's Multi-Sector General Permit For Stormwater Discharges Associated With Industrial Activity, outfalls are locations where the stormwater exits the facility, including pipes, ditches, swales, and other structures that transport stormwater. If there is more than one outfall present, measure at the primary outfall (i.e., the outfall with the largest volume of stormwater discharge associated with industrial activity).{{cite book |title=Multi-Sector General Permit For Stormwater Discharges Associated With Industrial Activity|date=2009 |publisher=United States Environmental Protection Agency |location=Washington |url=https://www3.epa.gov/npdes/pubs/msgp2008_finalpermit.pdf |access-date=12 July 2023}}
File:FlorhamParkSewerageUtilityOutfall.webm in New Jersey]]
Outfalls from sewage plants can be up to {{convert|20|ft|m}} in diameter and release {{convert|4000|USgal/s|m3/h}} of treated human waste miles from the shore.
A wastewater treatment system discharges treated effluent to a water body from an outfall. An ocean outfall may be conveyed several miles offshore, to discharge by nozzles at the end of a spreader or T-shaped structure. Outfalls may also be constructed as an outfall tunnel or subsea tunnel and discharge effluent to the ocean via one or more marine risers with nozzles.