This document is the 108 Shaped Trench Installation Detail (Agriculture). Diagrams, tables and notes provide descriptions and measurements.

The detail shows the <1” between pipe OD and spoon trench sidewall, compacted fill material, springline, corrugated HDPE or PP pipe, cover height, stable native soil foundation and various trench width/height.

Table 1 for rounded trench dimensions shows the values for pipe diameter and X. Table 2 is allowable fill material (per ASTM D2321) with descriptions of soils, ASTM D2321 and ASTM D487.

Note 1 states that shaped trench installation recommendations are for use as subsurface drainage and groundwater control using ADS HDPE or PP pipes. Not recommended for sanitary or storm sewer, commercial conveyance or road crossing. Note 2 says that the ADS pipe products may be installed in a shaped trench. Note 3 explains that native soil is suitable in-situ material with adequate strength to withstand trenching operations and maintain the final trench shape. Note 4 is about the shaped trench that shall be cut to a depth such that the top of the shaped trench bottom extends to pipe springline or higher. Note 5 clarifies that the fill material should be of suitable material and compacted around the pipe after placement in the shaped trench. Note 6 states that minimum cover depth of backfill above the pipe should be maintained before allowing vehicles or equipment to travel over pipe. Note 7 specifies that maximum cover should be product specific fill heights based on fill type and compaction density.