The build

Exciting times with a digger. Are these pipes to drain water off the land? If so where to? The water table looks well low.
Measurements of stones? My cartoon mind has an image of you and Bob sitting in the bottom of a very wet ditch measuring each stone and pebble with Verniers before chucking it back or away.

That particular ditch is for surface water pipes (what comes off your roof & down your gutter). As ever with red tape and the rules it’s all expensive and a bit of a joke! When it’s finished going through those pipes it’s goes through 5 metres of filter. Which is basically a bigger ditch lined with plastic. Part filter with gravel (of the correct size) then a slotted pipe and topped up with more gravel and the plastic wrapped round it all. From there it goes back into normal pipe. Then it has to go through an entinuation / intuattion tank ( not idea who to spell that). Basically it’s a tank with a small hole ( of the correct diameter to allow a flow rate of ……are you board yet, I am ) in so if there’s a lot of water it won’t flood people down stream. But then if the weather is really really bad it just over flows and floods people down stream!! That incredibly pointless piece of kit, that we have to put in cost use over £500! Then the water goes through its last bit of pipe and away into the burn at the corner of our plot. 

Frankly your idea/ suggestion of using the gravel we already have in the bottom of the ditch is just outrageous. Can you please stop using common sense. It really doesn’t apply. We have to now get pea gravel for the bottom of the trenches. Because after doing more research we don’t have to concentrate all the pipes in. Another long boring story.

This is the stuff we have to use for the gravel filters.