Thirlmere Aqueduct

File:Thirlmere Aqueduct Higher Wheelton.jpg

{{maplink|type=line|frame=yes|frame-height=280|frame-width=200|id=Q7785115|stroke-colour=#5E74F3|text=Interactive map of route}}

The Thirlmere Aqueduct is a 95.9-mile-long (154.3-kilometre-long) pioneering section of water supply system in England, built by the Manchester Corporation Water Works between 1890 and 1925. Often incorrectly thought of as one of the longest tunnels in the world, the aqueduct's tunnel section is not continuous.

The aqueduct was built to carry approximately {{convert|55000000|impgal|m3}} per day of water from Thirlmere Reservoir to Manchester. The construction of the reservoir and aqueduct was authorised by the Manchester Waterworks Act of Parliament. The first phase was completed in 1897 and, for the pipeline sections, subsequent phases were completed in 1925. The first water to arrive in Manchester from the Lake District was marked with an official ceremony on 13 October 1894.

The route of the reservoir passes through Lancashire and then enters Manchester through Salford and Trafford.

History

File:Thirlmere - geograph.org.uk - 19789.jpg

In 1874 John Frederick Bateman advised Manchester Corporation that the increasing demand for water, then averaging {{convert|18000000|impgal|m3}} per day, would soon exhaust the available supply from Longdendale. His first recommendation was to source water from Ullswater, but it was eventually decided to seek powers to acquire Thirlmere and build a dam there. In the face of local oppositionRitvo, Harriet (2003) "Essays on Science and Society: [http://www.sciencemag.org/cgi/reprint/300/5625/1510.pdf Fighting for Thirlmere - The Roots of Environmentalism]", Science, 300 (5625: 6 June), p. 1510–1511, {{doi|10.1126/science.1079920}} {{PMID|12791968}} the project received Royal Assent in 1879. Under this act Manchester was granted priority of right to {{convert|25|impgal|L}} per person per day.

Tunnel under Dunmail Raise Pass

This tunnelled section under Dunmail Raise was dug by two teams mining towards each other. The two tunnel sections joined within 20 cm of centre.{{Citation needed|date=March 2014}}

Thirlmere Dam

File:Thirlmere Dam from Raven Crag.jpg

The dam at Thirlmere {{coord|54.5615|-3.0680|display=title,inline|region:GB|format=dms}} rises {{convert|64|ft|m|0}} above the old stream bed, and the reservoir when full has a surface area of {{convert|814|acre|km2}}, and a holding capacity of {{convert|8235000000|impgal|m3}} above the level to which water may be drawn (540 O.D.) The total dry-weather yield of Thirlmere Reservoir is reckoned at about {{convert|40500000|impgal|m3}} per day, out of which compensation water in respect of the area now draining into the Lake {{convert|10120|acre|km2}}, amounting to {{convert|4658000|impgal|m3}} per day average, is sent down the St. John's Beck. Manchester Corporation has acquired the drainage area of {{convert|10800|acre|km2}} (in addition to other lands).

Aqueduct technical data

File:Thirlmere Aqueduct Stretford.jpg

The aqueduct is 95.9 miles long from Thirlmere reservoir to Heaton Park Reservoir {{coord|53.5421|-2.2614|display=inline|region:GB|format=dms}}, Prestwich.{{cite web | title= Thirlmere Aqueduct Construction Facts | work= The Hodder and Thirlmere Aqueduct Access Gates | url= http://www.jdscomponents.co.uk/gates/thirlmere/facts.asp | format= HTTP | accessdate= 2007-08-24}} Its most common form of construction is cut-and-cover, which consists of a "D" section concrete covered channel, approximately {{convert|7.1|ft|m|1}} wide and between {{convert|7.1|ft|m|1}} and {{convert|7.9|ft|m|1}} high. There are {{convert|37|mi|km|1}}{{cite EB1911 |wstitle=Aqueduct#Masonry aqueducts. |display=Aqueduct § Masonry aqueducts |volume=2 |page=245}} of cut and cover, made up of concrete horseshoe-shaped sections {{convert|12|in}} thick. Typically, the conduit has {{convert|3|ft}} of cover and traverses the contours of hillsides.

It is the longest gravity-fed aqueduct in the country, with no pumps along its route. The water flows at a speed of {{convert|4|mph|km/h|0}} and takes just over a day to reach the city. The level of the aqueduct drops by approximately 20 inches per mile (30 cm/km) of its length.

Construction history

Sections of the route of the aqueduct have over time been modified for the construction of modern motorways. During the construction of the M6 and M61 connection a short section was diverted.{{cite web|title=History of the M61 |work=M61 Motorway |url=http://www.lancashire.gov.uk/environment/historichighways/m61.asp |accessdate=2007-10-27 |url-status=bot: unknown |archiveurl=https://web.archive.org/web/20140827102205/http://www.lancashire.gov.uk/environment/historichighways/m61.asp |archivedate=2014-08-27 }} A short section of the aqueduct near Worsley, Greater Manchester, was also re-routed in the late 1960s during the construction of the M62/M63/M602 motorway interchange.{{cite web|title=The Motorway Archive |work=History of the M602 |url=http://www.lancashire.gov.uk/environment/historichighways/m602.asp |accessdate=2007-10-27 |url-status=bot: unknown |archiveurl=https://web.archive.org/web/20070416190122/http://www.lancashire.gov.uk/environment/historichighways/m602.asp |archivedate=2007-04-16 }}

References

Aqueduct crossing the River Irwell at [[Agecroft|thumb|right]]

External links

[https://archive.today/20121224023241/http://www.nwpho.org.uk/reports/bulletin/jan2001/index.htm North West Public health Observatory: Cryptosporidium in the North West water supply]
[https://archive.org/details/b28062759 Mansergh, James. "The Thirlmere water scheme of the Manchester Corporation : with a few remarks on the Longdendale Works, and water-supply generally." London: Spon, 1879] - popularising lecture, with copious plans & elevations, including map showing aqueduct route

Category:Aqueducts in England

Category:Grade II listed buildings in Greater Manchester

Category:Buildings and structures in Cumbria

Category:Works by John Frederick Bateman

Category:Grade II listed bridges in Greater Manchester