Trench Excavation. Trenches for all pipe lines and culverts shall be excavated to required lines and bottoms taken out to the exact gradients using profiles and boning rods or other suitable devices. The trench shall be of sufficient width to enable the pipes to be properly laid and jointed. No excavation shall be filled in or covered with concrete until the Engineer has inspected it and the Contractor has been authorised to proceed with the works. All surplus excavated materials from such excavation not required for refilling shall be carted away to tips or otherwise disposed of, as directed. All excavations shall be kept dry and all bating and pumping timbering shoring and supporting of sides that may be required, and any refilling, ramming and disposal of surplus materials necessary in carrying out the excavations and back filling of trenches shall be included in the prices of excavations. Special care shall be taken to provide a solid bed for the barrels of the pipes and where a concrete bed is not specified, the floor of the trench shall be properly shaped to receive the socket. The length of the trench open ahead of pipe laying shall not exceed 200 m. Trenches shall have a width not less than that shown on the drawings and shall have vertical sides unless the Engineer has approved the use of sloping sides in lieu of timbering. The bottom 50 mm of trench shall be left undisturbed until immediately before the pipe is to be laid when it shall be trimmed accurately by hand to the correct grade. If no bedding is required joint holes shall be formed as necessary so that the pipe, when laid is bedded on the entire length of its barrel on the firm and undisturbed bottom of the trench.
Trench Excavation. 13.7.1 Trenches Greater Than Five Feet Pursuant to Labor Code section 6705, if the Contract Price exceeds $25,000 and involves the excavation of any trench or trenches five (5) feet or more in depth, the Contractor shall, in advance of excavation, submit to the Owner or a registered civil or structural engineer employed by the Owner a detailed plan showing the design of shoring for protection from the hazard of caving ground during the excavation of such trench or trenches.
Trench Excavation. This Section shall apply to the Contract only if the Contract Amount exceeds twenty-five thousand dollars and the Work requires or involves excavation of any trench or trenches five feet or more in depth. The Contractor, in conformance with Labor Code Section 6705 and other applicable law, and prior to any such excavation, shall submit to the District for review and approval a detailed plan showing the design of shoring, bracing, sloping, or other provisions to be made for worker protection from the hazard of caving ground during the excavation of such trench or trenches. The plan must be prepared by a registered civil or structural engineer and if the plan varies from the requirements of applicable Cal-Osha Construction Safety Orders, the Contractor must obtain Cal-Osha approval of the plan. Nothing in this Section, and no District or other approval of any plan prepared pursuant to this Section, shall relieve the Contractor of any responsibility, or result in District liability for hazards resulting from excavations performed by the Contractor.
Trench Excavation. Dig trench to lines and grades established on the drawings or as directed. Trench width shall be as shown on the drawings. If not shown on the drawings, trench width shall be as follows:
Trench Excavation. If the Contractor encounters unsuitable soils materials at the specified depths during trench excavation, he shall contact the Owner’s Representative and request instructions from the Geotechnical Engineer before proceeding further.
Trench Excavation. Before excavating any trench 5 feet or more in depth, the Contractor is to submit to JWA a detailed plan showing the design of shoring, bracing, sloping, or other provisions to be made for the protection from the hazards of caving ground during the excavation of such trench. If the plan varies from the Construction Safety Orders for shoring systems, then it will be prepared and stamped by a registered Civil Engineer. No excavation will start until JWA has accepted the plan and the Contractor obtains a permit from the state's Division of Industrial Safety. A copy of the permit is to be submitted to JWA. All excavation and trenching activities at JWA must be supervised by a competent person as defined by CAL-OSHA and conducted in accordance with Title 8 CCR, Subchapter 4. Construction Safety Orders, Article 6 Excavations (Sections 1539-1547). The Contractor is responsible for contacting the local utility locating agency. The Contractor shall have an additional second independent entity conduct utility locations to confirm the local utility locating agencies’ initial analysis. The Contractor must follow all erosion control procedures and ensure all dust mitigation measures are in place.
Trench Excavation. Excavation of soil for the purpose of installing water and sewer mains, water services, house drains, their appurtenances, and for the restoration of surface features. The excavated material may be classified as either clay or xxxxx soil, a mixture of each, and may contain varying amounts of loam, silt, gravel, organic material, or rock fragments less than one (1) cu yd. in volume. Trench excavation excludes all material defined as Rock Excavation and Unsuitable Soil.
Trench Excavation. Pursuant to Labor Code section 6705, if the Contract Sum exceeds $25,000 and involves the excavation of any trench or trenches five (5) feet or more in depth, Contractor shall, in advance of excavation, submit to Owner or a registered civil or structural engineer employed by Owner a detailed plan showing the design of shoring for protection from the hazard of caving ground during the excavation of such trench or trenches. If such plan varies from the Shoring System Standards established by the Construction Safety Orders, the plan shall be prepared by a registered civil or structural engineer, but in no case shall such plan be less effective than that required by the Construction Safety Orders. Pursuant to Labor Code section 6705, nothing in this Article shall impose tort liability upon Owner or any of its employees.
Trench Excavation. A. Trenching Guidelines: Excavate the trench to the approximate level of the top of the utility line to be installed, using adequate trench width and side slopes to safely accommodate worker access. Continue excavating for the utility line, to a width not greater than is shown on the appropriate trench detail.
Trench Excavation. Dredging techniques including grab dredging, cutter suction and trailer suction dredging are considered and chosen depending on the engineering, environmental and risks conditions. As the submarine watermain will be located across the Yau Ma Tei, Central and Southern Fairway, grab dredging is selected, as cutter suction and trailer suction dredging which requires a working area of over 150m in width, will result in an unacceptable impact on marine traffic and thus are not feasible. Suction dredging will also produce more marine sediment by volume when compared with grab dredging. Grab dredging is therefore the best practicable and feasible method to minimize dredging and dumping requirements and demand for fill sources. Submarine Pipeline Installation In the bottom pull method, pipes are joined to form pipe strings which are progressively pulled from a landfall site into a pre-dredged trench underwater by a winch set up at the landfall site at the other side of the waters until the crossing is complete. This method is one of the most common method for installation of medium to large diameter pipelines. In the lay barge method, while the work barge moves along the pipeline, the pipes are progressively added to form a string, which are hung in a catenary from at the back of the barge, and are gradually lowered into the pre-dredged trench. As the lay barge method will introduce intolerable marine traffic impact due to its long suspended pipeline at sea during the installation, this method is considered not a feasible option. In the float and sink method, lengths of pipe are made up into strings at a fabrication yard and these strings are launched to seabed from one of the landfall sites. These prefabricated pipe strings are temporarily stored on the seabed before towed by work barge at or below the water surface to the pre-dredged trench. By removing or filling water to the supporting buoyancy tanks, the pipe strings are sunk to its final position. This method is also one of the most common method for installation of medium to large diameter pipelines.
