Rehabilitation of 800 year old dam
After reducing water levels in the pond by siphoning over several weeks, work commenced by carefully gaining access by protecting roots of the trees and acid grassland by using aluminium trackway. Under the strict control of Surrey wildlife/bats/reptiles a borrow area was slowly cleared. (Borrow area was basically the source of material required for the project as very few materials could be brought onto the SSSI site.)
Once access to the dam had been obtained, drilling and chemical injection of the masonry walls and arch was started. At the same time a dewatering system was installed to allow the spillway works to commence. It was at this point there was a sudden self ignition of an old WWII phosphorus grenade 0.5m away from the public footpath where it must have lain undisturbed for 60 years. The bomb squad arrived in force along with a fleet of members of the fire service, ambulance crew & police. The site was shut down and the grenade was destroyed on site with a controlled explosion.
The concrete spillway finally was constructed and faced with brickwork and the wooden bridge was installed by National Trust Rangers. Soil from the borrow area was used to backfill and raise the levels to those required for the adjoining paths. Whilst all the works were being carried out our site agent was responsible for monitoring movement of the masonry structure to within 0.01mm.
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