back filling buried water lines

[skiwest]

iv'e got my trench all done and the power cable , telephone and water  are all in on a bed of sand 2-3 " but I know I am going to run out of sand as some of the piles got buried by backhoe.  I have to use sand around power cable but was wondering if it would be a good idea to use scrap lumber , 2x4s along the poly water line.

My ground is river gravel, mostly small , all round, some sand to seams of pure sand.  Where I have sand I "mined" it to backfill until the trench walls couldn't take any more undercutting.

Or can I put the gravel by hand directly on water line 4"  and then back fill with skid steer?

[glenn kangiser]

The last is what I would do -- smooth gravel won't hurt much -- I shaded in clay then backfilled with clay and rocks with the Bobcat.  Should not be a problem if you are gentle.