This document is the TN 2.03 Minimum and Maximum Cover Heights for Single Wall HDPE Pipe. Minimum and maximum covers for traffic applications are discussed.

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. This 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.

For Minimum Cover in Traffic Applications, Pipe diameters from 3- through 24-inch (75-600 mm) installed in traffic areas (AASHTO H-25 or HS-25 loads) must have at least one foot (0.3m) of cover over the pipe crown. The backfill envelope must be constructed in accordance with the Installation section (Section 5) of the Drainage Handbook and the requirements of ASTM D2321.

Table 1 shows the values for Minimum Cover Requirements for ADS Single Wall Highway and Heavy Duty Pipe with AASHTO H-25.

Wall thrust generally governs the maximum cover a pipe can withstand and conservative maximum cover heights will result when using the information presented in the Structures section (Section 2) of the Drainage Handbook. The maximum burial depth is highly influenced by the type of backfill and level of compaction around the pipe.

Table 2 shows the values for Maximum Cover for ADS Single Wall Highway and Heavy Duty Pipe.