How do I reduce the size of my pond.

[Ventura]

My Natural clay pond is 12mtrs x 5 mtrs, It has been there for 100 years +. Originally it was much smaller, but was increased to be used as a soakaway for the rainwater from the new house built 25 years ago. It was very deep once dug out to 14 feet, but fill in to a depth of 4 feet with hardcore. Over the years it has eroded at the sides and silt form the soakaway has reduced the level to 18 inches and dries out totally in the summer.
What I want to do is reduce the size. I thought I could dig out half to a depth of 4 feet and put the silt in the other half. I don't know how to section it off to make it water tight. Can anyone help.

 

[Stephen Noble]

Welcome Ventura! I would consult a professional before doing anything. They can do a do a Percolation test ('Perc test') to test the rate that water passes through your soil. Your pond is historic and special so I would proceed very carefully and again, seek professional advice. Do you keep fish in the pond?

 

[Mmathis]

Hello and welcome! Agree with @Stephen Noble — get professional advice and go from there. So much will depend on the makeup of the soil as well as your local laws. Would love to see pictures if you have some to share.

 

[JamieB]

Agreed. If, for some reason, you can’t get the test done, you need to research local laws and see what they say about it. If it’s not considered historical, and there are no laws saying you can’t, then you have three options: 1) dig it out, use brick or stone to form a barrier wall, and hope there’s enough clay left to slow down water draining away. 2) consult with an expert on the clay. I’m not familiar with clay ponds, but from what I gather, a certain depth of clay is needed to prevent water draining off too fast. 3) dig your hole, put in a liner, and turn the rest into a garden of water loving plants. This option lets you have the drainage, and a pond, but you’ll have to fill the pond back up as needed.