This document is the HDPE Pipe Installation for Agricultural Drainage Installation Guide. Backfill selection with table and trench construction tips provided.

The recommendations detail how to install a dependable subsurface drainage or groundwater control system. Installation with proper backfill materials, compaction levels, and placement procedures are essential to achieve long term system performance. These recommendations assume that the drainage designer used design criteria available from ASTM F449 and ADS. The designer should discuss installations involving conditions not covered by this documents (poor soils, high loads, or other factors that may affect the performance of the system) with an ADS representative.

Backfill selection clarifying native soil classes, materials to be compacted, pipe diameter compaction and trench shaping are defined. Table 1 lists the acceptable soil classes for backfill & embedment through a description and soil classification for ASTM D2321 or ASTM D2487, minimum and maximum compaction values shown.

Trench construction is important because de-watering is necessary to maintain stability of backfill materials for a safe and effective installation. As with any pipe, groundwater or seasonal high water tables may impede installation. This section of the document explains proper trench installation in varying situations. It features a table for maximum burial depth with Class IVA materials with dimensions for pipe diameter and maximum burial depth.

Backfill envelope construction is described including a figure showing a typical backfill structure. Alternate backfill methods like the shaped trench bottoms may be used in lieu of the standard trench design. Figure 2 shows the shaped trench bottom V Groove, Trapezoidal bottom and circular bottom with corresponding pipe diameters.