As mentioned in my previous blog post, the fencing around the work compound at Model Boating Pond has now been put up and the size of this area is now apparent. This area needs to be this size as material (clay) to build the new dam structure must be found here. This means that material does not need to be brought onto the Heath, which saves many thousands of vehicle journeys onto and over the Heath.
The material will be found by digging borrow pits on the hillside and extracting clay to build the dam. These pits will then be filled with silt which has been removed from Model Boating Pond, and also Stock Pond, Kenwood Ladies Pond and Men’s Bathing Pond. The silt will be treated in the work compound before it is placed in the borrow pits. This treatment includes drying the silt in a centrifuge.
The clay required for the dam must be of a quality only found at a certain depth, so top soil and the top layer of clay (which is unsuitable for the dam) will be placed to one side, within the compound, while the suitable clay is extracted. There will be three borrow pits in total and after the suitable clay has been extracted and the treated silt placed in the hole, the unsuitable clay and topsoil are then placed back to return the ground to a similar level as before, then the area is reseeded with grass and wild flowers. A similar sequence will then be repeated at the other two borrow pits. This will mean lots of earth movements within the work compound.
The following plan gives an indication of how the work site is to be laid out.
These earth movements will start in June 2015 and will take approximately one year to complete.