We need help to overcome a clay lined pond problem before 22nd July.
Work has now stopped on a two pond project because we cannot seal pond 1,which is clay-lined. We have spent countless hours with teams of committed students and staff puddling close to 20 tons of Essex Blue Clay – using hand tools and barrows. We have put in £3,500 worth of hard-earned sponsorship and we took expert advice on pond location. The results are
We need help and advice on site. I suspect, if we get to 22nd July, without help, 8 months of commitment will have been in vain. This area will wither and die in the summer holiday period. The sadness is that the hard work has actually been done.
It was our intention to use this pond project to create an educational
Resource for our students and to provide learning experiences for hundreds of local primary school students. There are plans to film underwater life as it develops, to record research data on ph levels and developing eco-systems and the students involved were to provide primary schools with environmental science learning materials linked to on-line support. Our hope is that this project might be an interesting departure from the norm for you and it would be of reader interest. If completed the site could yield further information on ecological development in the future. We live in hope.
How was the excavation consolidated?
Essentially a JCB cut into heavy ?orange ? clay with flints ? the clayhold its shape ? vertical sides. Tapered depth 4 ft to 1 ft.
How steep are the sides?
Steepness of sides ? deepest area it is vertical ? shallower 20 degrees slope.
Did a geotextile go down on top under the clay?
No geotextile fabric is under the clay.
How was the Essex blue clay prepared?
The Essex clay arrived late September in dry form By October it as wet.
Clay was dug out and barrowed to the pond and puddled by feet ? pushed onto the walls by feet from spades.
How thick was it when it went down? Did you manage to get it all down in one day? If not did any of it dry out during the process?
No ? we did not get it done in one day. We tried to create an 8 inch thick layer ? layers were added weekly, It did begin to dry out in March/April.
We simply added more clay over the cracks as another layer.
Pete asked How many layers?
I should guess there were 4 layers applied October ? April.
How was it puddled?
It was puddled by foot with the same methodical team.
Did a geotextile go down on top?
No geotextile went on top.
Is there a loam or gravel layer over the clay?
Have you engineered a 'capillary barrier' around the top edge?
There is no loam or gravel over the clay and no capillary barrier around the top edge.
We may need to raise part of the down slope side of the pond as the upslope side exposes 1-2 ft of dry wall. This would increase the volume. It takes 2 days with a garden hose to pill the pond.
Sadly Peter we began this journey with honest endeavour and learned as we went along. We are encouraged to develop projects like this but you quickly discover that you are very much on your own from design through to problem solving to completion.
We will reluctantly replace the clay with an artificial skin if need be? But it is not what we wanted to do. We wanted this pond to be a natural pond.
Here is a list of guidelines that relate to the construction of clay ponds that will help to ensure that you have a watertight liner at the end of it.
PHEW! Is there no wonder the world and his dog have resort to the convenience of a pvc and rubber pool liners.
As a remedy for your particular problem at the moment, I would let the water go down for as long as dare. Where the clay is exposed, I would moisten it an keep it covered with plastic. Keep checking it.
Then get a ‘whacker plate’ on a rope and let it vibrate down as far as you dare. Get the two strongest folks on the team to do this, because they are heavy tools. It may take plenty of wetting an several runs of the ‘whacker’ plate to get the clay elastic again. Once you have done this all round, fill it up whilst ensuring the clay is covered still. If the slope is shallow enough in places to have some soil or gravel, then cover it with this. (Don’t use geomembrane with out the capillary barrier, because this will act as a wick.)
If there are any nearby buildings, sheds would it be possible to divert the runoff into the pool to keep the water level up? Your exposed bank of clay may best be converted to a rock face. Raising one side at this late stage sounds like asking for trouble. But this I cannot truly tell without seeing it.
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