Work is soon to start on the Catchpit which is north of Mixed Pond. In this location a 5.6m dry dam is to be built in a natural valley which was cleared of vegetation last year. This structure will remain dry, except in large storm events, and will look like a grassy slope when completed. In a storm it will hold back water in the valley and store it temporarily. The water will then be released slowly into the ponds beneath it (Mixed Pond, Hampstead No. 2 and No. 1 Ponds). The decision to build this structure here means that further down the chain, less work is required.
You can see a plan of the works and the environmental mitigation which will take place on the environmental masterplan: Catchpit PDF
The following image is a before and after computer generated elevation of the works.
You can view this as a PDF (which you can zoom in on) here: Elevations of catchpit
The clay material to build this dam is being found in a borrow pit in Pryor’s Field. This borrow pit will then be filled in with silt extracted from the ponds on the Hampstead Chain, plus material which is being excavated from the Sports Field area.
The work in this location will be taking place from later this month until August, with the reinstatement of the borrow pits and the sports field, and environmental mitigation work taking place after that.