July2021

7 Buckden Roundabout July 2021 Grafham Water Pt.1 : Construction Grafham Water. Part 1 - Construction Richard Storey, Secretary to Buckden Local History Society It ’ s hard to believe that in the 1950s this part of the country suffered from constant water shortages. In 1958 the daily con- sumption of water from the existing reservoirs 1 was 12.5 mil- lion gallons per day. However, the planned expansion in the 1970s of Corby, Northampton, Wellingborough and Peterbor- ough, plus the new town at Milton Keynes, was expected to substantially increase the demand for water, with a forecast daily consumption of 20 million gallons. It was clear that something had to be done and in 1959 a re- port recommended improving water supplies, leading to the Great Ouse Water Act in 1961. A Joint project was formed between Bedfordshire County Council, the Great Ouse Water Authority and the Mid Northants Water Board to build a new reservoir in the Diddington Valley to provide 40 million gallons of water per day for Huntingdonshire, Bedfordshire, North- amptonshire and Hertfordshire. Grafham was chosen for a number of reasons: it was close to the river Great Ouse, which was an ideal source for abstraction; the materials for the dam were readily available; the heavy clay was an ideal substrate for a reservoir bed; and it was sparsely populated, although a few properties would have to be sacrificed. The top map ’ s hill shading shows the outline of the current Grafham Water as can be seen in the lower map. A natural valley runs through the site but it needed a dam at the east end to enclose it. Two roads originally traversed the site to West Perry, one from Grafham village and one from Hill Farm, now long gone but still evidenced in both villages by short stretches of road running down to the water. Also, parts of the Buckden to West Perry road were diverted to allow con- struction of the dam and both Rectory and Low Farms disap- peared under the reservoir. Designed by Binnie and Partners and at a cost of approximate- ly £2M, plus £7M for the treatment works and delivery pipe- lines, W and C French Ltd started work on the new Diddington Reservoir in 1962. Unfortunately, the name of the contract gave rise to problems with many site deliveries arriving in Did- dington village rather than at Grafham; a problem solved when in 1963 the name was changed by popular demand to Grafham Water. In 1962 sourcing labour, and subcontractors was an issue so accommodation was erected on the main site com- pound in the area local to the Buckden end of the dam where workers could eat, drink and sleep. For the workers entertain- ment was in the form of challenges for darts and cricket matches, issued to the H.M. Borstal Institution staff and in- mates now known as Littlehey Prison. No results are known, nor whether all equipment was returned! The Diddington brook was diverted before work could begin and a new tunnel excavated to carry the pipes to bring water to and from the completed reservoir. A pumping station was built on the bank of the river Great Ouse at Offord to lift and carry the water 3 miles. The enormous culvert, i.e. pipe/ tun- nel, was built under the dam containing pipes carrying water from the River Ouse into the reservoir. The water was sent to the pumping station below the dam for pumping to the treat- ment works. The dam, 80 feet high and a mile long, built with rolled boulder and Oxford clays with a central rolled clay core was completed in late 1964. The first water was pumped into the reservoir that December, ten months ahead of programme - quite an achievement at the time. The mild winter of 1963 - 64 and working round the clock seven days a week for more than a year made up for the hard winter conditions during the ‘ Big Freeze ’ of 1962 at the start of the contract. Filling the reservoir took fifteen months of continuous pumping to lift 13,500 mil- lion gallons of water, mostly from the River Ouse to the new reservoir . (Continued on page 12) Extract from OS 6 inch 1888 - 1913 1 Pitsford, Hollowell, Ravensthorpe, Cransley and Thorpe Malsor The dam under construction New culvert under construction