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SECTION 19 TRENCH EXCAVATION, BEDDING AND BACKFILL

19-1 TRENCH EXCAVATION

Trench excavation shall include the removal of all materials or obstructions and the control

of water as necessary to construct the Work as shown or specified in the Contract. Unless

otherwise shown or specified in the Contract, excavation shall be by open cut or as directed by

Attention is directed to Section 10-5, “Control of Water in the Work”, and Section 14,

“Restoration of Surfaces”, of these Specifications, for additional requirements. Surface water

shall not be allowed to enter any pipe trench and shall not be permitted to enter the existing

downstream pipe system.

19-1.01 Exploratory Excavation

An encroachment permit shall be obtained from the Agency prior to any exploratory

excavation within highway rights-of-way or other public easements. Prior to the end of each

Working Day, exploratory excavations made outside the paved surface during that Working Day

shall be backfilled with sand or native excavated materials as directed by Agency and

mechanically compacted to prevent subsequent settlement. Excavations made within the paved

surface shall be permanently restored per Standard Drawing 4-31.

19-1.02 Trench Width

Minimum and maximum trench widths at the top of the pipe shall be shown or specified

elsewhere under the specific facility sections in the Contract or as specified in these

19-1.02.A Storm Drain Pipe

Unless otherwise shown or specified in the Contract, for storm drain pipe the minimum and

maximum trench width shall be as shown on Standard Drawing 9-1. If trench widths at the top

of the pipe are exceeded by any amount, the Contractor shall provide stronger pipe or improved

bedding and backfill conditions, as approved by the Agency to meet the changed load

requirements. If the trench width is exceeded for any reason within the Contractor's control, the

stronger pipe or improved bedding and backfill shall be provided at the Contractor's expense.

19-1.02.B Sewer Pipe

Unless otherwise shown or specified in the Contract, minimum and maximum trench widths

at the top of the pipe shall be as shown on the Plans for the designated type of bedding. For

rigid pipes, the maximum trench width at the top of the pipe shall be as follows:

Pipe sizes less than eighteen inches (<18”):

Maximum trench width = pipe outside diameter + twenty-four inches (24”)

Pipe sizes eighteen inches (18”) and larger:

Maximum trench width = outside diameter + thirty-six inches (36”)

If no minimum trench width is shown on the Plans, the minimum trench width at the top of

the pipe shall be as follows:

Vitrified clay pipe:

Minimum trench width = outside diameter plus twelve inches (12”)

Minimum trench width = outside diameter plus twenty-four inches (24”)

If trench widths at the top of the pipe are exceeded by any amount, the Contractor shall

provide stronger pipe or improved bedding and backfill conditions, as approved by the Agency

to meet the changed load requirements. If the trench width is exceeded for any reason within