How to Put Grading Around a Concrete Pipe

A concrete pipe is the most stable and durable type of pipe for underground installations. It's a conduit that's also structural -- 85 percent of its strength is in the pipe itself, and 15 percent is on soil support. Concrete pipe can be laid on uneven ground without affecting flow through the pipe and can be installed with less stringent attention to soil quality and preparation than flexible pipes, which rely mostly on soil support for strength. Specifications for installation are set by engineers, though local building officials may have standard requirements for grading around concrete pipes.

Concrete pipe
Bedding material, to specifications
Backfill, to specifications
Plate compactor

Instructions

- 1
  Excavate your trench to specified depth and slope for the sides. Spread bedding material to an even width on the bottom, sloping the length for drainage. Compact as required for concrete pipe. Check the slope of the pipe bed as each section of pipe is laid, and adjust as necessary.
- 2
  Place backfill around the pipe carefully, in 6-inch layers, to the top of the pipe. Don't allow rocks 3 inches and larger to touch the pipe. Compact each layer thoroughly with the compactor, for the full length of the layer.
- 3
  Place backfill on top of the pipe in 12-inch layers, compacting each layer. Backfill to the top of the trench.
- 4
  Add soil to a depth of at least 2 feet -- including the depth of the backfill -- to cover the pipe for the width of the trench. Maintain the cover during construction activities that follow.

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