| (a) Pipe Embedment.
(1) A rigid pipe must be laid with bedding, haunching,
and initial backfill that will meet the appropriate standards and
will support the anticipated load. The bedding classes that are allowed
are A, B, or C, as described in American Society for Testing and Materials
(ASTM) C 12, American National Standards Institute (ANSI) A 106.2,
Water Environment Federation Manual of Practice No. 9, or American
Society of Civil Engineers (ASCE) MOP 37.
(2) A flexible pipe must be laid with bedding, haunching,
and initial backfill that will meet the appropriate standards and
will support the anticipated load. The bedding classes that are allowed
are IA, IB, II, or III, as described in ASTM D-2321 or ANSI K65.171.
(3) Debris, large clods, stones that are greater than
six inches in diameter, organic matter, and other unstable materials
are prohibited as bedding, haunching, or initial backfill.
(4) Backfill must not disturb the alignment of a collection
system pipe.
(5) If a fracture, fault zone, cave, or solutional
modification to the rock strata that would prevent pipe bedding is
encountered during construction, an owner must halt construction until
an engineer prepares a written report, which must be submitted with
the final engineering report, detailing how construction will accommodate
these site conditions.
(b) Compaction.
(1) Compaction of the pipe embedment must meet the
manufacturer's recommendations for the collection system pipes used
in a project.
(2) Compaction of the pipe embedment must provide the
modulus of soil reaction for the bedding material necessary to ensure
a collection system pipe's structural integrity as required by §217.53
of this title (relating to Pipe Design).
(3) The placement of the backfill above a pipe must
not affect the structural integrity of a pipe.
(c) Embedment Thickness.
(1) A minimum clearance of 6.0 inches below and on
each side of the bell of all pipes to the trench walls and floor is
required.
(2) The embedment material used for haunching and initial
backfill must be installed to a minimum depth of 12 inches above the
crown of a pipe.
(d) Trench Width.
(1) The width of a trench must allow a pipe to be laid
and jointed properly and must allow the backfill to be placed and
compacted as needed.
(2) The maximum and minimum trench width needed for
safety and a pipe's structural integrity must be included in the engineering
report.
(3) The width of a trench must allow proper and safe
placement and compaction of haunching materials in accordance with
the standards in subsection (a) of this section.
(4) The space between a pipe and a trench wall must
be wider than the compaction equipment used in the pipe zone.
Attached Graphic
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