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The pipeline trench should be thoroughly dewatered prior to backfilling. Topsoil should not be used as trench-backfill. After backfilling the trench with the spoil material, the stripped topsoil should be replaced uniformly over the area from which it was removed. Waste Rock The upper portion of the soil profile (topsoil and upper subsoil) on tillable land contains a relatively low concentration of stones and rocks. Trench excavation for pipelines can unearth substantial quantities of stone and rock spoil from deeper portions of the soil profile. It is important to prevent either large rocks or concentrations of stone material used as backfill from obstructing normal farm tillage operations and disabling farm machinery. Standard: In agricultural land, blasted or excavated bedrock, boulders and concentrations of excavated stone or rock materials should not be returned to the trench any closer than 24 inches from the exposed work surface of the stripped portion of right-of-way. The remainder of the backfill should be limited to suitable subsoil material, backfilled up to top of the exposed work surface. Excess waste/rock stone materials should be removed and then disposed of safely. Soil Rutting and Compaction The construction work/traffic zone of the right-of-way for a small diameter pipeline is not generally stripped of the topsoil. However, construction equipment can seriously rut, compact and damage the topsoil and upper subsoil. Damage from small-diameter pipeline construction is usually the result of work when soils are too wet after rains, or from seasonal saturation. Standard: Project traffic over topsoil on unstripped agricultural land should not be scheduled during seasonally wet soil conditions in early spring or late fall. During the period of right-of-way construction/restoration, the movement of project vehicles and equipment over unstripped topsoil should be halted through periods of soil saturation from rainfall, until the soils are drained sufficiently to avoid rutting. Likewise, vehicle and equipment traffic should be prohibited during periods of thaw, until the upper soil profile is sufficiently frozen to avoid rutting. Existing and Future Farm Drainage Surface drainage ways for storm runoff as well as for the outletting of subsurface drain lines are afforded agricultural lands by natural creeks, swales, ditches, diversion terraces, etc. Subsurface drainage is managed through installed practices of random and pattern tile drain lines. Protection of existing surface and subsurface drainage is important for crop production as is the capability to install future tile drain lines and maintain ditches. Standard: Existing drainage Surface drainage systems affected by the pipeline project should be protected and their function maintained by temporary fluming. Earthen berms of surface drainage systems (e.g. diversion terraces) should not be breached. Where breaching is unavoidable, the earthen berm