In article ,
Chris Hogg wrote:

On Tue, 05 Feb 2019 10:49:20 +0000, Another John
wrote:

A chap I do a bit of gardening for had a couple of his borders flooded
last year by a change in subterranean water flow. That has been fixed,
but the borders are still "sticky".

He wants to dig sand into the borders. Fine, but he has specified
"horticultural sand". I think it would save him money if I just used
ordinary sharp (concreting) sand from a builder's merchant. What does
the team think?

Just another thought: are you sure the 'sticky' border isn't just due
to poor drainage and/or a high water table? I'm not sure what you mean
by 'change in subterranean water flow', and how it was 'fixed'?

Yes - it was a "high water table". He and his next door neighbour are on
land that was a field before they made their gardens; in fact half of
next door's still _is_ a field. The whole plot (3 or 4 acres) is on
the side of a gently domed hill (agricultural pasture), which has
springs. The water springs forth when it has forced its way up through
the clay, which is about 18" down. Last year, heavy rain forced the
water up through the land just "uphill" from my man's garden, hence his
borders were swamped. He has dealt with it by trenching along his
fence, and channelling the water around the garden.

[The proper way to do it would be to get a drainage man in, with the
right "heavy plant", but that will cost too much.]

And so: the soil is sticky because it was sodden -- under water -- for
months.

John