Concrete and Flexible Pipe Installation Considerations:
For Inspectors and Contractors
This document lays out installation parameters required by AASHTO and the costs associated with them that contractors must consider prior to bidding a project. Installation is critical to the strength of the flexible soil / pipe system. In this example HDPE pipe only contributes 5% whereas RCP contributes 90% of the structural strength of the soil/pipe system. Therefore, post installation inspection is imperative to ensure the constructed flexible soil/ pipe system was properly built. The Engineer of Record must approve any deviation from the requirements in the Contract Documents due to the high dependence of the HDPE pipe system strength on the compacted soil and other installation requirements. Examples would include, but not be limited to soil type, density requirements, trench width, use of trench boxes, water table or wet trench conditions, and minimum cover before allowing construction equipment to cross over the trench.