(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.
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Source Note: The provisions of this §217.54 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254