Installation Guidelines for PE Pipe
Install PE pressure pipe in accordance with ASTM D2774.
The engineer must evaluate the site conditions, the subsurface conditions, and the application objectives to determine the extent of support the pipe may need from the surrounding soil. Where the pipe burial depth is relatively deep, where subsurface soil conditions are not supportive of pipe, where surface loads or live loads are present, or where the pipe DR is high, the engineer will generally prepare a specific installation specification. The specific engineered installation instructions should be followed.
The following are general guidelines for the installation of 12” and smaller diameter PE pipe with a minimum cover depth of 2 ft (3 ft under traffic loading; up to 5 feet for frost protection) and a maximum depth of cover of 16 feet. For other depths consult the engineer. Other satisfactory methods or specifications may be available. This information should not be substituted for the judgment of a professional engineer in achieving specific requirements.
The length of open trench required for fused pipe sections should be such that bending and lowering the pipe into the ditch does not exceed the manufacturer ’s minimum recommended bend radius and result in kinking. Table 4 lists the recommended lengths of trench openings for placement of continuous lengths of fused pipe, assembled above the trench. When the trench sidewalls are significantly sloped, somewhat shorter trench openings may be used.
The trench width should allow sufficient room for joining the pipe, if required, snaking small diameter from side to side along the bottom of trench for thermal affects, and filling and compacting the side fills.Table 3 gives suggested minimum trench width values.
Principal considerations in trench construction are trench width, length, and depth; soil stability; and groundwater accumulation in the trench. Unstable soils or wet conditions should be controlled by sloping or bracing the trench walls, de-watering the trench bottom, and/or other measures.
Placing Pipe in Trench
Place polyethylene pressure pipe up to 8” in diameter in the trench by hand. Use equipment to lift, move, and lower larger diameter pipe into the trench. Pipe must not be dumped, dropped, pushed, or rolled into the trench.