What is graded fill?

[pilsbury]

laid my new drains on pea gravel and have filled to just covering the top of the pipe. Should I fill with more pea gravel - if so, how deep?

Advice then states graded fill before fully filling. What is graded fill? Soil with big lumps and stones removed?

 

[Doggit]

Try this site for more info, and look under bedding types. Essentially you're on the right path.

 

[tomfe]

It'll say something like graded fill stones less than x

 

[stuart45]

Graded means that there are various sizes of the particles of the fill as with a graded sand, meaning the voids are filled. An example is gravel from 20mm to dust.

 

[Blagard]

I'll back up what stuart45 says.

To make it more interesting there are so many similar terms it can all get confusing. One I saw often in specifications was "selected excavated material" in other words the best you can get from what you have dug out of the ground! meaning if there are nasty bits there that could cause a problem you remove them first. What makes the fill important is where the drains are - So under a road (or say a driveway) you need material that compacts extremely well whereas in landscaped areas almost anything above the bed and surround.

 

[Ian H]

When I do repairs I bed in pea gravel as you have and the first foot of backfill I make sure there are no big/hard/sharp things that could damage the pipe when compacted.

I use the same stuff I dig out to backfill.

 

[pilsbury]

Thanks all - In the interests of my budget mentality, I shall just cover the pipes with pea gravel once BC have had a look (currently 3/4 covered) then backfill with the soil I dug out removing any large stones.

 

[nuzuki]

I suggested pea gravel to my builder when we had the drainage connection to the main sewer. He opted for limestone scalpings as they compacted better. But as Ian says its all about just avoiding damage to the pipework.