Block paving around a drain

[D4N1EL]

Hi,

I've just won 2 packs of red block on eBay for £20, I've spent all day moving them.

Now here is the questions I should of asked before.

When I pull the current flags up, how far down to I dig for the base?

How do I go around a drain? (See pic)

Thanks.

 

[Ian H]

They normally lay a single row of blocks along the side of the house and simply square them out around the gully.