Farmoor Reservoiris a public supplyreservoiratFarmoor,Oxfordshire,England,about 5 miles (8 km) west ofOxford.It is adjacent to theRiver Thames.Like most of the reservoirs in theThames Valley,it is a pumped storage reservoir which was not formed by damming a watercourse in a valley. In this case the banks were raised above the local ground level using material excavated from within the bowl of the reservoir.
| Farmoor Reservoir | |
|---|---|
 | |
  Farmoor Reservoir | |
| Location | Oxfordshire |
| Coordinates | 51°45′20″N1°21′24″W/ 51.75543°N 1.35671°W |
| Type | reservoir |
| Primary inflows | Abstraction from River Thames |
| Primary outflows | Farmoor water treatment works, River Thames |
| Catchment area | 0.77 km2 |
| Basincountries | United Kingdom |
| Max. length | 1.71 km |
| Max. width | 1.10 km |
| Surface area | 1.491 km2 |
| Average depth | 4.898 m |
| Water volume | 9.30 Gl (2.05×109imp gal) |
| Surface elevation | 64 m |
| Website | thameswater.co.uk |
The reservoir is divided into two: Stage 1 to the north and Stage 2 to the south. The two reservoirs stages are separated by a causeway.
| Parameter | Stage 1 | Stage 2 |
|---|---|---|
| Year completed | 1967 | 1976 |
| Capacity, million litres | 4,544 | 9,298 |
| Perimeter, miles (km) | 1.7 (2.74) | 2.4 (3.9) |
| Water outlet to: | Water treatment works | River Thames |
The water improves in quality during its retention in the reservoir as solids settle and organic contaminants areadsorbedand degraded through a combination of natural biological processes aided by sunlight and oxygenation. As well as Oxford and other localities, Farmoor supplies the town ofSwindon,some 25 miles (40 km) to the southwest via a trunk main installed in 1986.[1][2]The reservoir is supplied by water abstracted from the River Thames at a flowrate of about 1.62 m3/s or 140 million litres per day.[3][4]Water enters the reservoir near the western end of the causeway.
Operations
editFarmoor Stage 2 was intended to supplement the flow of the Thames during periods of drought. The reservoir operated in conjunction with Swinford sewage treatment works. The project aimed to ensure that at least 135 million litres of water passed over Eynsham weir per day.[5]The Stage 2 reservoir has twolimnological towersto facilitate the study ofaquatic ecosystems(limnology).
In 1989 an outbreak ofCryptosporidiosisaffecting over 100 people was traced to drinking water supplies from Farmoor water treatment works. Investigations revealed a large build up of bacteria on the filter beds.[2][6]
A report in 2018 suggested that if the reservoir's abstraction point from the Thames was moved 23 km downstream to Abingdon then a better water quality could be achieved.[4]
Recreation
editThe reservoir is used for sports:fishing(especially fly-fishing forrainbowandbrown trout),dinghy sailing,windsurfingand stand up paddle boarding. Oxford SUP Club (stand-up paddle boarding), Oxford Sailing Club and the Oxford Sail Training Trust are based there. The latter offers sailing, windsurfing and powerboat courses. There is also access forbird watchingandwalking.There is a public car park.
Birds of Farmoor Reservoir
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Farmoor Water Treatment Works
editThe Farmoor Water Treatment Works are located on the eastern side of the reservoir just north of the causeway. The works are capable of treating 98 million litres per day of raw water from the Farmoor reservoir. The works were originally constructed at the same time as the Farmoor reservoir: Stage 1 in 1963 and stage 2 in 1975. Further extensions were constructed in 1990 and 2009.[5]The plant comprises:[7]
- Slow sand filtersfor the primary removal of solids from reservoir water
- Rapid Gravity Filters(RGF) in which water flows through a medium, such as sand, where solids are retained. Periodic backwashing and air scouring remove the accumulated sludge.
- Granulated Activated Carbon Filters (GAC) for the filtration of partly treated water
- Sludge system including waste water plant, sludge thickening plant, sludge press room, andpolyelectrolyteplant
- High lift pumps capable of pumping up to 98 million litres per day
- Chemical dosing including storage tanks and pumps for:
- Sulphuric Acid
- PaCl (polyaluminium chloride) dosing
- Caustic dosing
References
edit- ^"£32m water scheme in final stage".BBC News.24 May 2004.Retrieved7 August2020.
- ^abYoung, John (22 February 1989). "Hunt for source of bacteria in contaminated water supplies".The Times.p. 5.
- ^Benke, Mike (26 November 2014)."Water pipeline to preserve Kennet".Swindon Advertiser.Retrieved7 August2020.
- ^abHutchins, M G. "Balancing water demand needs with protection of river water quality by minimising stream residence time: an example from the Thames, UK".Water Resources Management.32 (7).
- ^ab"Farmoor Reservoir Intake".Retrieved19 November2024.
- ^Fletcher, Martin (29 July 1989). "Minister warns of danger in water".The Times.p. 16.
- ^Knight, Keith (2009). "Farmoor WTW combined upgrades to meet SOSI compliance".Water Treatment and Supply:171–174.
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