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Construction Standards for Water/Sewer Transmission
Mains
Located Wholly or Partially in an Agricultural District
Pipelines Less Than Eight Inches Outer - Diameter
The following standards focus on measures, which minimize or mitigate the impacts on farmland from
small pipeline trenching/construction. These standards cover practical agricultural issues including:
pipeline depth-of-cover, topsoil protection, waste stone/rock materials, soil rutting and compaction, and
existing and future farm drainage.
Pipeline Depth-of-Cover
Pipeline depth within the soil profile is important from the farming standpoint due to the permanence of a
pipe's position in the soil profile. Inappropriate depth of a water/sewer line will diminish the current and
future farm operators' capacities to administer the scope of land-fitting practices required to meet
specialized cropping needs. Such practices can range from deep tillage to the installation of subsurface
tile drain lines.
From the pipeline operator's standpoint, appropriate depth-of-cover is essential for protection against
puncture from surface disturbance and against bursting due to frost penetration and freeze up. A common
minimum depth-of-cover employed in water/sewer pipelines is 4.5 feet.
Standard: In agricultural land, the minimum depth-of-cover from restored ground surface to top of
the buried pipe will be 4.0 feet. (See "Existing and Future Farm Drainage" regarding depth
adjustment.)
Topsoil Resource
The topsoil layer of the soil profile is the fertile material needed for sustained crop productivity and must
be protected against degradation and loss due to pipeline construction activity.
Standard: For small pipelines to be constructed in agricultural land the "ditch and spoil-side"
topsoil stripping practice should be employed:
The topsoil ("A" horizon) of the trench and adjacent trench-spoil storage zones should be stripped
down to the top of the subsoil zone. The stripped topsoil should be segregated from all other
materials in its separate stockpile at the edge of the construction right-of-way. At least two feet of
open buffer shall be maintained between the respective toe of the topsoil stockpile and the
nearest toe of the trench-spoil stockpile.
Trench Backfill
It is important to restore the original soil profile during the trench backfilling stage. Also, if the backfilling
phase is completed while there is water in the pipeline trench, long stretches of right-of-way with
prolonged soil saturation conditions can occur. Such saturated soil conditions can result in significant
restoration difficulties and delays.
Standard: The trench should be backfilled with the excavated spoil material. (For areas with
stones/rocks, see "Waste Rock.")