Hang on a minute. I don't know the area you are going to excavate but lets say its 5m x 5m and you dig down 1m. Thats a 25m^3 void. But you said you were pumping nearly 5m^3 per hour (based on 80L/min) for three days with no noticeable impact. Something still doesn't stack up, but if this company has done a site visit they presumably know whats happening. I wish you good luck. I too would be interested to know it turns out.
So, Friday I took advise from a water management company. They suggest creating a negative void deep under the bed and below the tile level all the way along. This will create a a sink away that can then have a bed planted above. This water will soak naturally away as the ground water falls. Then under the tiles I lay a sort of rockwool system that will hold more water volume than sand or soil again acts as a buffer and water soaks back out into the ground below when levels naturally fall. Adding a small drain will not overload the drainage system and therefore I can get a subsidy. Its a lot of digging thick, wet clay, to 60 cm deep, lets hope it works.
I may have misunderstood the situation, but I’m querying how it’ll “soak naturally away” if it’s below the water table?
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
From what I have understood from the guy who visited; the water table is still lower than even the lowest part of my garden. The water I have been pumping last week is via a ground pipe, that we do not know the actual depth of, he suspects at least 2 mtrs. I assumed this area is below water table because because there is so much pressure that it freely flows out, even without the need to pump. So pumping from so deep will have little effect during winter compared to summer. The standing water in the bed is run off from above he assures me, as others have said. So to create a void under flower bed will create a reservoir, and will hold more water per volume than the clay can currently hold. Then raise the level of the flower bed as others have suggested, with a more substantial wall. It all seems confusing, but I have to take his knowledge as I have no idea any more. Thanks everyone for your input.
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Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
Thanks everyone for your input.