The Minimum and Maximum Cover Heights for Corrugated HDPE Pipe technical note provides information about traffic applications with figures and tables.

The information in this document is designed to provide answers to general cover height questions; the data provided is not intended to be used for project design. The design procedure should be utilized for project specific designs.

The two common cover height concerns are minimum cover in areas exposed to vehicular traffic and maximum cover heights. Either may be considered “worst case” scenario from a loading perspective, depending on the project conditions. Minimum Cover in Traffic Applications Pipe diameters from 100-1200 mm (4”- 48”) installed in traffic areas (CHBDC CL-625 Loads, AASHTO H-25 or HS-25 loads) must have at least 0.3 m (1’) of cover over the pipe crown, while 1500 mm (60”) pipe must have at least 600 mm (24”) of cover. The backfill envelope must be constructed in accordance with the Installation standard.

Structural backfill material should extend to the crown of the pipe; the remaining cover should be appropriate for the installation and as specified by the design engineer. If settlement or rutting is a concern, it may be appropriate to extend the structural backfill to grade. Where pavement is involved, sub-base material can be considered in the minimum burial depth. While rigid pavements can be included in the minimum cover, the thickness of flexible pavements should not be included in the minimum cover. A table for Minimum Cover Requirements for N-12 and Mega Green Pipes (per ASTM F2648) with AASHTO H-25 or HS-25 Load is provided.

Wall thrust generally governs the maximum cover a pipe can withstand and conservative maximum cover heights. The maximum burial depth is highly influenced by the type of backfill and level of compaction around the pipe. General maximum cover limits for N-12 and Mega Green (per ASTM F2648) pipe are for a variety of backfill conditions. Figures and a table for Maximum Cover for ADS N-12 and Mega Green Pipes (per ASTM F2648), m (ft) are provided.