Major project to repair and restore the Blenheim Dam completed Oct 09
This year a major restoration project took place to repair the Blenheim Dam. The Blenheim Dam works were needed in the interest of safety as required under the Reservoir Act 1975. The Dam was constructed between 1760 and 1774 by Lancelot 'Capability' Brown to hold back the waters of the River Glyme and create the centre of his landscape, the Blenheim Lake. Unfortunately due to the age of the dam and the stringent requirements of the Reservoirs Act, repairs and re-engineering strengthening works to the dam were essential
[UKPRwire, Tue Nov 17 2009] This year a major restoration project took place to repair the Blenheim Dam. The Blenheim Dam works were needed in the interest of safety as required under the Reservoir Act 1975.
The Dam was constructed between 1760 and 1774 by Lancelot 'Capability' Brown to hold back the waters of the River Glyme and create the centre of his landscape, the Blenheim Lake. Unfortunately due to the age of the dam and the stringent requirements of the Reservoirs Act, repairs and re-engineering strengthening works to the dam were essential.
The works began in mid May and were completed in October, they address two main areas. Firstly, essential repairs were required to the core along the length of the crest of the dam to stop a number of significant leaks. Secondly, upgrading and strengthening works as required under the Reservoirs’ Act to allow the Dam to withstand a 1 in 10,000 year flood event.
The core of the dam is formed from boulders and clay, and over the years water has gradually found its way through and eroded small pathways in the core. If these had been allowed to continue, they would increase in size creating areas of weakness that could ultimately, have lead to the failure of the Dam.
The Reservoir Act became statute in 1975 and it is enforced by the Environment Agency. Under its provisions all retained bodies of water are classified A to C, dependent upon the consequence of a major failure. The bodies of water are inspected every 10 years by an engineer appointed by the Institute of Civil Engineers on behalf of the Environment Agency. Depending upon the classification, the dam retaining the water is required to be structurally designed to withstand certain flood events. In the case of the Blenheim Dam it is a category B and the Act therefore states that the dam must be of a design to hold back the water levels that would result in a 1 in 1,000 year flood and withstand over-topping in a 1 in 10,000 year flood event (to put this in context, 10,000 years ago we were in the ice ages).
Summarised below are the works undertaken:
• Remediate the clay core by digging a 1m wide trench to remove eroded and breached sections of the clay core and back filling with bentonite (a form of clay) slurry.
• Create a new 80m wide spillway on the downstream face of the Blenheim Dam. Involving the removal of all planting, stripping off the top soil, laying a bed of Armorloc concrete blocks, replacing the top soil and reseeding. To reinforce the sides of the cascades with concrete and limestone boulders.
• To carry out repairs to the “penstock” or underground sluice gates and associate tunnels.
Despite Blenheim Palace and Park being one of the first World Heritage Sites designated in the UK, it is the only one that does not attract any form of public or Heritage Lottery Fund funding, this is due to it effectively being in private ownership. The Estate believes this position is inequitable and is lobbying hard to try change this position but, without success to date. The Palace and Park are generally in good repair and condition as the Duke and Trustees take their roles as custodians of a part of the countries heritage very seriously, however, the current project places severe strains on the Estates’ ability to continue with its ongoing program of conservation works and maintenance, many of which may now have to be delayed for 3 to 5 years.
The essential work on the dam has however created many additional benefits from the point of view of visitors to Blenheim Palace. A walkway has been created around the dam creating a viewing stand which overlooks the Cascade from above. The path has been levelled at a gradient which enables wheelchair access to the view point. As the project neared completion, 36,000 daffodil bulbs were planted in the area surrounding the dam to ensure the Cascade provides a wonderful attraction and destination point for visitors to enjoy in the spring of 2010.
Notes to Editors
• The restoration project has taken approximately 20 weeks from mid May to mid October 2009.
• For more information about J.N. Bentley Ltd please call Kate Crawford 01756 799425 or email firstname.lastname@example.org,uk or visit www.jnbentley.co.uk
• Access to the Cascade will be re-opened to visitors from 28th October 2009 (included within a Park & Garden or Palace Park and Gardens ticket during normal opening times).
For media information contact: Hannah Payne or Victoria Bellamy, Blenheim Palace Marketing Department. Telephone: +44 (0) 1993 810 524/510 Email: Marketing@blenheimpalace.com