With the liner fully installed work was done on the perimeter of the lake in order to bury the liner overlap in a small trench dug round the edge of the lake for this purpose as it keeps the liner from slipping at the top of the banks. A couple of days were then spent extracting any spill that had slipped into the lake (of which there was quite a lot) prior to starting to fill it.
A multitude of different ways of filling it with the 1.25 million litres of water it required were looked at, but with low water pressure, even on the hydrant system in the area, Anglian Water were unable to offer any way to fill it quickly. Ultimately they settled on us paying a one off charge and using the hose pipe to fill it, a process which ultimately took three months to complete.
As the over spill was cleared and filling began work was being done to shape the berms on the south and east side of the lake which was again a process for the highly skilled digger driver as all the perimeter trees needed to be carefully worked around. After almost exactly 4 weeks on site the digger completed the final berm and its job there was done. The land had stood up phenomenally well to having a digger and dump truck running all over it for four weeks, but partly that was down to the incredibly dry weather for which we were very grateful.
The lake being filled with the newly constructed berms in the background.
The berms were seeded with grass in the Autumn as was much of the land around the lake, but the very edges of the lake were turfed with the turf being pinned on the water’s edge until it ‘knitted’ itself into the soil banks. Where the liner was visible (the parts of the lake where the slope of the banks was more gentle) large decorative stones were used to dress the banks.
One thing we were worried about was the water stagnating and/or becoming overrun with algae over time so we wanted to add some sort of water movement to help with this. Knowing little about water features of this size lots of research was undertaken online and with suppliers who sell water recirculation products. Eventually we decided ion two courses of action:
A submersed pump that will move water via 50mm MDPE pipe from one end of the lake to two ‘waterfalls’ in the two south western extremities of the lake.
A aeration/oxygenation system consisting of a land mounted air pump and pipework going from this to three (sewage treatment grade) aeration heads mounted on the bed of the lake.
To accommodate the pump/waterfall arrangement the pipe was brought out of the lake to a new manhole that houses a valve system that can be used to direct the water to the waterfalls (the default setting) or to the drainage ditch on the east of the property via a temporary hose that can be connected in the manhole. The waterfalls are then supplied by 50mm MDPE that is buried around the perimeter of the lake with the waterfalls being made of decorative stones sat on additional liner to allow the water to cascade freely into the lake.
Submersible pump/waterfalls being installed.
The aeration system was built on land first and then weighted and lowered into the relevant positions in the lake. It consists of a 20mm pipe from the pump that runs (next to the waterfall submersible pump pipe) into the lake and then splits into three ‘arms’ each with an aeration head at its extremity. The heads are positioned far left, far right and central on the lowest part of the lake bed.
Aeration system being built up.
The electricity supply is routed via armoured cable from the mill and terminates in an exterior grade polycarbonate cabinet where all the connections are made. A further cabinet located next to this cabinet houses the air pump.
Once these were installed and operational the lake was left for a few months to allow the banks and surrounding land to become established and the water to become stable in respect of both temperature and chemistry.
The finished article a month or so after the construction work was complete.
Comments