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Facts and figures
Below are some facts and figures relating to our work in and around Preston.
Pressure balancing systems
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The volume of air that will be exhausted is 1,087m3.
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The maximum velocity of the exhausted air will be 17.2 metres per second. This is equivalent to approx 38 mph.
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The time during which air will exhaust is dependant on the storm but could be as little as 98 seconds.
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The pressure balancing systems will exhaust air up to 20 times a year.
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Air will only be exhausted during storm conditions when most people will be sheltering from the weather rather than enjoying recreational activities.
Terminal Pumping Station
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Terminal Pumping Station is a term used for the last pumping station on the United Utilities network before the stormwater in our pipes reaches our treatment works.
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During construction 71,000m3 of surplus materials will be generated. The surplus materials will be used to elevate the site above the 1 in 200 year flood level.
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The Terminal Pumping Station will be 35 metres underground.
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Once in operation the pumping station will pump the stored stormwater 5.2km to Preston Wastewater Treatment Works for treatment.
The Storm StorageTunnel
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The tunnel will be 3.5km long and 2.85 metres in diameter.
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The average depth of the tunnel is approximately 26 metres below ground and will include two crossings of the River Ribble.
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The tunnel will be constructed using a Tunnel Boring Machine. Although smaller, this is similar to the type that was used to construct the Channel Tunnel.
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The tunnel will provide 40,500 cubic metres storage for stormwater – this is equivalent to 16 Olympic swimming pools.