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Section 19 – Trench Excavation, Bedding and Backfill

Full compensation for trench excavation, including all equipment, labor, materials, control of

water, shoring and bracing, and other safety measures required, is included in the prices paid

per linear foot of the respective sizes, grades, and types of pipes listed in the Contract, and no

additional compensation will be paid.

19-2 PIPE BEDDING AND BACKFILLING OF TRENCHES

19-2.01 Pipe Bedding

Pipe bedding shall be furnished and placed as shown on the Plans and in accordance with

the requirements in these Specifications. Pipe shall be placed on a firm layer of bedding

material, and shall be bedded uniformly throughout its length. Pipe bedding material for storm

drain construction shall conform to the requirements of Section 50-16, "Clean Crushed Rock”, of

these Specifications. Pipe bedding material for water distribution systems shall conform to the

requirements in Section 50-13.02, “Graded Sand”, of these Specifications.

Pipe bedding material for sewer construction shall conform to the requirements as detailed

on Standard Drawing 7-4, and in conformance with these Specifications. At least three inches

(3”) of bedding material shall be placed beneath the pipe. An additional minimum three inches

(3”) of bedding material shall be placed in contact with and beneath all pipe joint and couplings.

The bedding material shall provide uniform support to a width of at least sixty percent (60%) of

the pipe’s external diameter. This support shall be achieved by shaping the bedding or by

lightly bouncing the pipe to set it into the bedding. In lieu of shaping the bedding materials, the

Contractor may place bedding material to the spring line of the pipe, and compact it by light

tamping to provide the support. Care shall be used not to disturb the alignment or grade of the

19-2.01.B Storm Drain

Unless otherwise indicated in the Contract, storm drain pipe bedding shall be furnished and

placed as detailed in Standard Drawing 9-1 and in conformance with these Specifications.

Storm drain pipe bedding material shall conform to Section 50-16, "Clean Crushed Rock", of

these Specifications.

The Pipe shall be bedded uniformly throughout its length. The bearing shall be achieved by

shaping the bedding or by lightly "bouncing" the pipe to set it into the bedding. Pipe bedding

material shall be placed at a minimum thickness meeting the greater of the following criteria:

1. The minimum bedding thickness shall be three inches (3”) for pipe with internal diameter

ten inches (10”) or less, and four inches (4”) for pipe with internal diameter twelve inches

(12”) and greater; or

2. The minimum bedding thickness shall be equal to the difference between the outside

diameter of the pipe barrel and bell plus one and one-half inches (1-1/2”); or

3. When soil conditions in the trench bottom are unstable, rocky, or otherwise unsuitable as

a foundation for pipe bedding, the minimum bedding thickness shall conform to Section

19-1.07, "Trench Excavation - Special Foundation Treatment", in this Section.

19-2.01.C Water Distribution Systems

Polyvinyl Chloride (PVC) water distribution mains shall have four inches (4”) of sand

bedding material that conforms to the requirements of Section 50-13.02, “Graded Sand”, of

these Specifications. If existing soil is too porous to hold sand, four inches (4”) of crushed

aggregate or a geotextile fabric placed on the trench bottom and covered with four inches (4”) of

sand may be used. The Agency must approve the use and type of geotextile, and crushed