Trench backfill material is considered to be all material placed in the trench between the pipe embedment and the road bed or ground surface.
(A) Backfill in public rights-of-way, district easements, public utility easements or in existing or future paved areas. The material, placement and compaction shall be done in accordance with the requirements and inspection of the District, city or county as applicable.
(B) Backfill in existing and future unpaved private property areas. The material placed must meet the following requirements:
(1) Native backfill. Backfill shall be”approved native backfill material” compacted to the same degree of compaction as the adjacent ground or a minimum of 90% relative compaction per ASTM D-1557, whichever is greater.
(2) Imported backfill. In areas where the excavated material does not meet the requirements for “approved native backfill material”, material meeting the requirements for “import backfill material” or “trench excavated material” under § 33.193 may be used. It shall be compacted to the same degree of compaction as the adjacent ground or a minimum of 95% relative compaction, whichever is greater.
(C) Compaction. The method the contractor uses to meet compaction requirements is not specified except for the following limitations.
(1) Compaction shall be achieved by mechanical means. Water settling, jetting, ponding and other water compaction methods are prohibited. Compaction testing shall be done in accordance with the requirements of the city or agency having jurisdiction.
(2) For sloped trenches or when heavy-impact compaction equipment is used, such as sheep-foot wheels and self-propelled compactors, the contractor shall protect the pipe from being damaged during mechanical compaction. The remainder of the backfill shall be in accordance with the requirements of the city or county.
(Ord. 2019-02, passed 4-25-2019)