15-3 1500 -10 Measurement and Payment
The general utility construction work will be incidental and will be paid at the contract unit prices of the various utility items included in the contract. EXCAVATION, TRENCHING, PIPE LAYING AND BACKFILLING FOR UTILITIES 1505 -1 DESCRIPTION Perform all excavation, undercut, foundation conditioning, pipe laying, bedding, backfill and pavement, sidewalk and driveway repair necessary for installation of utilities. 1505 -2 MATERIALS Refer to Division 10. Item Section Portland Cement Concrete , Class B 1000 Select Material s 1016 Use Class III, IV, V or VI select material for foundation conditioning and bedding. 1505 -3 CONSTRUCTION METHODS Excavate, trench, lay pipe, bed and backfill utilities in conformance with the applicable requirements of Division 1, Division 2 and Articles 300-1, 300-4, 300-6 and 300- 7. Comply with AWWA and ASTM standards along with the product manufacturer requirements for installing utilities.
A.Shield ing and Shoring Excavate trenches and pits for the installation of utilities that are safe for the workers and roadway users and that protect the roadway and other property from damage. Provide appropriate groundwater and surface water controls to stabili ze the excavation and foundation and to provide a clean working area.
1.Worker Safety Provide any necessary shielding or shoring to protect workers.
2.Roadway Users Provide shielding or shoring as required under Section 150 or as required elsewhere in the cont ract.
3.Roadbed and Foundation Protection Provide shoring of excavations less than one horizontal to one vertical from existing or proposed pavement to prevent failure or weakening of the roadbed. Provide plans and designs demonstrating the methods and techniques proposed and their adequacy to the Engineer . Provide engineered shoring systems as required for the actual conditions.
4.Building and Structure Protection Provide shoring of excavations less than one horizontal to one vertical from existing structure s and buildings, on or off the right of way, to prevent foundation damage. Provide plans and designs demonstrating the methods and techniques proposed and their adequacy to the Engineer . Provide engineered shoring systems as required for the actual condi tions.
15-4 (B) Foundation Conditioning
Undercut and replace weak or saturated soils below the pipe trench with select material to provide a firm foundation.
C.Bedding Provide excavations with sufficient width for placing and compacting bedding around the utility. B ed utilities in select material. Place bedding material to stable ground on both sides and to at least 2 inches below and above the pipe bells. Provide at least 6 inches of bedding material between rock and piping. Shape the bottom of trenches to fit the pipe. Compact bedding material completely in the pipe haunches. Provide recesses in the bedding to accommodate pipe joints.
D.Pipe Laying Lay pipe in accordance with the specifications and the manufacturer's recommendations. Except where necessary in making connections with other lines or as authorized by the Engineer, lay pressurized pipe with the bells facing in the direction of laying. Where possible, keep joints exposed for visual inspection during testing. During the progress of the work and until the completion and final acceptance, keep the pipelines and their appurtenances clean throughout and remove any obstructions or deposits. Provide secure watertight seals on pipe when work is not in progress. Lay gravity sewer pipe upgrade with the spigot ends pointing in the direction of flow. Lay each pipe to form a close concentric joint with the adjoining pipe and to prevent sudden offsets of the flow line.
E.Thrust Restraint Provide thrust restraint for pressurized pipelines and appurtenances. When shown in the plans, construct as specified with modifications to match the actual field conditions. When not shown, engineer the thrust restraint system wit h a factor of safety of 1.25 for the test pressure specified and for the actual fi eld conditions. Provide thrust restraint on the existing piping system as necessary. Use joint restraint methods, such as integral restraining bells and spigots, restraining retainer glands, restraining gaskets or restraining clamps and lugs with tie rods. Use concrete reaction backing and thrust collars where joint restraint is impractical. Where any section of a main is provided with concrete thrust restraint for fittings, controls or hydrants, perform the hydrostatic pressure test after the concrete reaches appropriate strength.
F.Backfilling Backfill in accordance with Article 300 -7 and compact to the density required by Subarticle 235-3(C). 1505 -4 REPAIR OF PAVEMENTS, SIDEWALKS AND DRIVEWAYS Repair sidewalks and driveways that are disturbed by excavation and trenching to an original or better condition in accordance with Section 848 . Use asphalt plant mix to repair or replace pavement damaged by utility work. Perform all work in accordance with Section 654. Immediately upon completion of the utility removal or installation, make repairs to the pavement.
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 729–730 of 857.