Posted on October 13, 2022
Decades of silt build-up has left the Queen Pool at risk of drying out completely.
A flotilla of floating diggers has carefully removed 100,000 cubic metres of silt from the lake – marking the first stage in the epic nine-month rescue mission.
The dredge is believed to be one of the largest civil engineering projects ever undertaken at a UK heritage site.
Leading wet civil engineering contractor, Land & Water will eventually remove 300,000 cubic metres of silt, enough to fill Wembley Stadium, and return the ‘Capability’ Brown-designed lake to its original depth of two metres from its current shallows of 30cm.
Dubbed the finest view in England by Winston Churchill’s father, the vista across the lake and over the Vanbrugh-designed Grand Bridge to the 18th century Baroque Palace is under serious threat of disappearing.
Blenheim Estate director Roy Cox said: “The Queen Pool is an iconic part of the World Heritage Site, it’s a SSSI, a fishery and a national treasure seen by over a million people each year.
“Over 70 per cent of the lake now has a depth of just 30cms or less. It is silting up at a rate of one to two centimetres per year but, during severe storms, deposits can reach up to 20cm.
“Without this drastic intervention the Queen Pool would revert to a wetland in the next 5-10 years and the nation’s ‘Finest View’ will be lost,” he added.
Floating diggers move slowly across the full surface of the lake, dredging over the course of about nine months. Along with the diggers are six hoppers which go backwards and forwards, bringing the silt from the platform to land.
This removed silt is being relocated to an area of the estate known as Great Park to create a new 16-hectare grassland mound.
Land & Water’s Project Manager Charlie Oakes said: “We are thrilled to have reached the 100,000m3 milestone. The Blenheim project has been an incredible undertaking and we have valued the chance to work on such an iconic landscape.
“We are now a third of the way through our dredging journey at Blenheim Palace, with the final dredge anticipated to finish early next year,” he added.
The last major dredging operation was in 1895-1897 when 150,000m3 of silt was removed.
Queen Pool is the upper lake at Blenheim and was created by ‘Capability’ Brown around 1763 as part of his extensive re-landscaping of the Park and Gardens.
The man-made lake gets its name from a 14th century fish pool that was known to be a favourite place of Queen Philippa, wife of Edward III.
The Dredge by numbers
Total lorry loads to date– 10,707
Lorry load in m3 – 9.4
Tonnes – 150,968.7
Volume of silt removed (m3) to date – 100,645.8
Days dredging – 93
Average volume (m3) of silt remover per day – 1,082
Average truck loads deposited per day – 115
