Tony,
I'll probably be laying a gravel drive in the near future which will have 2 inspection chambers situated within it. I was thinking of replacing these with recess tray covers, filled with about 50mm of sharp sand(to give the gravel something to bed into) and then gravel. I presumed it would not be suitable to lay the gravel over the existing covers as it would move about. Would my suggestion be in order?
Regards
Gary
Recess tray on gravel drive
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84-1093879891
The idea is sound, but the plan to use sand within the tray is doomed to failure, I'm afraid.
What you need to do is drill half-a-dozen or so 8-10mm diameter holes in the base of the tray, then line it with a piece of permeable membrane such as Terram or TDP115. If you can't get your mitts on any of this stuff, you can use a piece of the fabric cut from one of the bulk bags used to deliver aggregates, the woven polypropylene stuff.
Then, fill the tray to within 25mm of the top with either the sub-base material or a weak grit sand/cement mixture - 10:1 is more than adequate. Compact this into the tray, then dress with the chosen gravel.
The holes act as drainage for the tray and prevent it being permanently saturated. The reason why sand on its own is not a good idea is that, over time, the heavier gravel particles will 'sink' into the sand and the whole will end up looking like a right dog's dinner.
What you need to do is drill half-a-dozen or so 8-10mm diameter holes in the base of the tray, then line it with a piece of permeable membrane such as Terram or TDP115. If you can't get your mitts on any of this stuff, you can use a piece of the fabric cut from one of the bulk bags used to deliver aggregates, the woven polypropylene stuff.
Then, fill the tray to within 25mm of the top with either the sub-base material or a weak grit sand/cement mixture - 10:1 is more than adequate. Compact this into the tray, then dress with the chosen gravel.
The holes act as drainage for the tray and prevent it being permanently saturated. The reason why sand on its own is not a good idea is that, over time, the heavier gravel particles will 'sink' into the sand and the whole will end up looking like a right dog's dinner.