1. The Yeo (Blagdon) Reservoir and embankment.
2. The Blagdon Pumping Station and 30" pipeline to carry the water to the Line of Works aqueduct at North Hill.
3. Intakes for the collection of water from Rickford and Langford Springs, downstream of the reservoir, and the associated 27" and 21" pipelines to carry the water to the Blagdon works.
4. Sewage works for the protection of the reservoir.

Construction work started in 1891 and eight years later impounding commenced in 1899.

The reservoir was first filled to top water level in January 1903 and pumping to Barrow Reservoirs via North Hill commenced in December 1904. The works were designed by the Westminster Consulting Engineers, T & C Hawksley.

THE RESERVOIR EMBANKMENT

The embankment was constructed across the River Yeo at Blagdon. The river then continues through Congresbury and into the River Severn between Clevedon and Weston. The construction of the damlembankment comprises a cut-off trench across the valley, which was taken down into solid rock to a maximum depth of 175 ft below the valley bottom. The cut-off trench, filled with concrete, terminates in a concrete shoe to support and contain the puddle clay core of the dam.

The clay core varies in width between 13 ft 6ins at its base and 6 ft at the highest point. Selected consolidated fill on either side of the puddle clay core forms the main embankment together with protective toes and granite masonry pitching on the upstream side.

A draw-off shaft with exposed heads tocks controls the release of water from the reservoir via:-

1. A 24" diameter draw-off pipe leading to the pumping station.
2. A large diameter scour pipe.

Both the draw-off pipe and the scour pipe are each protected by two valves.

A public road runs over the top of the dam replacing the minor road which was submerged by the formation of the reservoir.

An overflow weir measuring 161 ft constructed at the Northern end of the dam enables flood water to be safely conveyed downstream via an overflow channel 1100 ft long to connect with the River Yeo downstream of the compensation channel.

DRAW-OFF ARRANGEMENTS

At the time of construction only a bottom draw-off pipe was provided. Eutrophication and stratification was not a recognised problem and the water pumped from Blagdon had a period of settlement in the Barrow Reservoirs where it was mixed with Line of Works water before being drawn off into the nearby Barrow Treatment Works and slow sand filters.

During recent years, eutrophication and stratification of the Company's impounding reservoirs has increased and counter measures have been taken to combat the problem.

A syphon draw-off arrangement was installed in 1973 to enable better quality water to be drawn off from a total of five inlets, which enabled a choice to be made to give access to the best quality water.

In addition, to combat stratification, a single Helixor unit has been installed which enables compressed air to be released through a perforated pipe laid in the deep water in front of the dam.

THE PUMPING STATION

The imposing red brick late Victorian period building below the embankment formerly housed four engines, two in each wing of the building. The central chimney stack was originally 130 ft high, but in 1954 the top 50 ft was removed. Six horizontal boilers were installed behind the pump house.

To aid construction of the works, a branch railway line was built by the Wrington Vale Light Railway to Yatton junction on the main Bristol Exeter line, a distance of eight miles. The railway line was later used for the conveyance of steam coal and four sidings were laid directly into the coal stores on either side of the boiler house.

When the steam plant was operational, three beam engines were in use capable of pumping a total of 7.5 mgd, the fourth engine either being serviced or on standby. Each engine has a high and low pressure cylinder connected to a 34 ft long beam by connecting rods and links, using Watt's parallel motion principle. Connected to each beam is a bucket pump. The flywheel, driven through a connecting rod from the beam is 20 ft diameter and weighs 20 tons and is provided with a hydraulic baring engine. The pump output was 107 gallons per stroke at a generated head of 235 ft.

Steam was supplied at a pressure of 100 lbfIin2 by four boilers while two were held on standby. With two engines running, the coal consumption was 8.5 tons per day.

In 1949 two beam engines were replaced by two 4 mgd and one 2 mgd electric pumps. Improvements have been carried out to these pumps so that their outputs are now increased to 5 mgd and 4 mdg respectively.

The two remaining beam engines in the south wing of the building are preserved as a museum feature. In 1984, one beam engine was fitted with an electric motor to demonstrate the principle of a beam engine in operation.

The electric pumping station operates unattended. The plant is supervised and can be controlled remotely from the Operations Room at the Company's Head Office in Bristol.