If special bedding material is required due to poor local soil conditions, the material should not contain granular material greater than what size?

When dealing with special bedding materials in water distribution systems, the size of granular material is critical, especially in areas with poor soil conditions. The intention behind restricting the size of the granular material is to ensure stability and compaction and to minimize movement or settling over time.

The correct answer indicates that granular materials greater than 1 inch can lead to voids in the bedding, potentially causing instability in the pipeline. Larger aggregates can prevent the proper compaction needed for adequate support, which is essential under varying loads and conditions. By limiting the size to 1 inch or smaller, the bedding material can better conform to the shape of the pipe and provide consistent support, reducing the likelihood of future issues such as misalignments or fractures in the pipe.

In areas with poor soil, using appropriate bedding material helps to distribute the load more evenly and accommodate any soil movement that may occur. Thus, having granular material restricted to a maximum size of 1 inch assists in achieving a reliable foundation for the water distribution system.