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Home My WebLink About20181638 Ver 2_Appdx I Standard Pipeline Construction Procedures_20190208MMMountain Valley PIPELINE «c Standard Pipeline Construction Procedures Appendix I Standard Pipeline Construction Procedures February 2019 MountainValley PIPELINE «c Standard Pipeline Construction Procedures Clearing After the right-of-way has been surveyed and property rights have been secured (for the permanent and temporary construction right-of-way, and any existing right-of-way if necessary), the Project will clear the right-of-way of obstructions (e.g., trees and stumps, brush, logs, large rocks) according to the FERC Plan, the Project -specific E&SCP and applicable regulatory approvals. The Southgate Project will conduct construction across waterbodies and through riparian corridors in accordance with the FERC Procedures. In most instances, the corridor will be reduced from 100 -feet to 75 -feet for work conducted within Zones 1 and 2 of the riparian buffer (50 feet from top of stream bank). To facilitate future inspection and maintenance of the pipeline, trees will be cut to grade, and stumps will be removed within the proposed 50 -foot permanent maintenance corridor. Within the proposed 25 -foot temporary workspace, vegetation will be replanted and restored, trees will be cut to grade, but stumps will not be removed. In forested wetlands, trees will be cut to grade, but stumps will only be removed within 15 feet of the edge of the pipe trench, or where safety concerns dictate otherwise. The Project will clear the right-of-way to the width required for construction, but not more than specified on the pipeline alignment sheets and approved by the FERC. These right-of-way widths indicate the maximum width necessary for construction, operation, and maintenance of the pipeline. At no time will the Project clear or alter any areas outside of the boundaries of DEQ and FERC -approved workspace areas. Should additional areas be required, the Project will request approval from the landowner, the DEQ, and the FERC. Merchantable timber will be stacked outside of the work area alongside the edge of the right-of- way, and outside of the riparian buffers. Merchantable timber will be cut into lengths and stacked along the edge of the right-of-way or ATWS in areas that have previously been agreed upon by the landowner The Project will dispose of brush and slash through burning, windrowing, or chipping. Burning will be conducted on a case-by-case basis and in compliance with permit conditions, and subject to local ordinances, but will not occur within riparian buffers. The Project may windrow, burn, or haul off cleared vegetation depending on the terrain and landowner request. The Project will dispose of, split, grind, or burn stumps to the satisfaction of the property owner and/or company representative in accordance with applicable law. Grading Once clearing operations have been completed, grading operations will commence. Topsoil will be stripped and segregated into piles that maybe used as BMP's. Segregated topsoil piles will be temporally seeded with noninvasive approved seed mixes, and subgrades will be cut to a workable right-of-way. Subgrade soil piles will also be segregated into piles that maybe used as BMP's and temporally seeded with noninvasive approved seed mixes. Grading will need to be completed with track -mounted heavy equipment. MountainValley PIPELINE «c Standard Pipeline Construction Procedures Trenching The Project will excavate a pipeline trench that is on average approximately 4 feet wide and 4-5 feet deep with a track -mounted backhoe or similar equipment and only use explosives when necessary in areas where rock substrates are at depths that interfere with conventional excavation or rock -trenching methods. On actively cultivated agricultural tracts, at wetland crossings, and in residential areas, subsoil will be segregated and stockpiled separately from topsoil per the FERC Plan. The Project will stockpile excavated soils along the right-of-way on the side of the trench (the "spoil" side) away from the construction traffic and pipe assembly area (the "working" side). Where the pipeline route is collocated adjacent to an existing infrastructure, the spoil will generally be placed on the same side of the trench as the existing infrastructure. Stringing New steel pipe for the pipeline will be procured and protected with an epoxy coating applied at the factory or at a coating yard (the beveled ends will be left uncoated for welding) and shipped to strategically located materials storage areas, contractor yards, or "pipe yards." The Project will transport the individual joints to the right-of-way by truck and place along the excavated trench in a single, continuous line that is easily accessible to the construction personnel on the working side of the trench (typically opposite the spoil side). This will allow the subsequent lineup and welding operations to proceed efficiently. Pipe Bending The Project will deliver the pipe to the Project workspace in straight joints, typically 40 to 60 feet in length. The use of controlled internal diameter fittings, in addition to the bending of pipe, will be required to allow the pipeline to follow natural grade changes and directional changes of the right-of-way. Prior to welding, track -mounted hydraulic bending machines will bend selected joints in the field. Pipe Assembly and Welding Following stringing and bending, the Project will place the joints of pipe on temporary supports adjacent to the trench. The ends will be aligned and welded together using multiple passes for a full penetration weld. Only qualified welders can perform the welding. Automated welding techniques may be used in flatter areas if the terrain is suitable. The Project will employ qualified welders and implement welding procedures in accordance with applicable American Society for Mechanical Engineers, API, and 49 CFR Part 192 Standards including the latest edition of API Standard 1104. MountainValley PIPELINE «c Standard Pipeline Construction Procedures Non -Destructive Examination and Weld Repair To ensure that the assembled pipe will meet or exceed the design strength requirements, the completed welds will be visually inspected and tested for integrity using non-destructive examination methods such as radiography (X-ray), or ultrasound, in accordance with API 1104. Welds displaying unacceptable slag inclusions, void spaces, or other defects will be repaired or replaced. Coating Field Welds, Inspection, and Repair Following welding, the Project will sandblastthe previously uncoated ends of the pipe atthejoints and cover them in epoxy. The coating on the completed pipe section will be inspected, and damaged areas will be repaired prior to lowering in accordance with applicable industry standards. Pipe Lowering The completed section of pipe will be lifted off temporary supports and lowered into the trench by side -boom tractors or equivalent equipment. Prior to lowering the pipe, the Project will inspect the trench to ensure that it is free of rocks and other debris that could damage the pipe or the coating. In rocky areas, if the bottom is not smooth, a layer of soil or sand may be placed on the bottom of the trench to protect the pipe using a padding machine or excavator with a "shaker bucket," which separates rocks from satisfactory padding materials. Concrete -coated pipe or aggregate filled sacks (pipe weights) will be used if necessary for negative buoyancy in areas prone to flooding or with a high groundwater table. Padding and Backfilling After the pipe is lowered into the trench, the Project will backfill the trench. Previously excavated materials will be pushed back into the trench using equipment or backhoes. Where the previously excavated material contains large rocks or other materials that could damage the pipe or coating, clean fill will be used as backfill to protect the pipe. Due to concerns about the acidity of fly ash and its potential impacts on cathodic protection, fly ash will not be used as backfill material. However, limestone dust or sand, which is typically non -acidic and will often aid in the cathodic protection of the pipeline, may be used as backfill material. The remaining fill in the trench will be the aggregate of the excavation material removed at the time of the excavation. If additional fill is required, it will be either flowable fill or clean fill. After the subsoil is placed in the trench, segregated topsoil will be placed in the trench above the subsoil. Following backfilling in agricultural land, and open land, a small crown may be left to account for any future soil settling that might occur. In wetlands, a crown will not be left to ensure restoration of ground and surface water hydrology to pre-existing conditions. Excess soil will be distributed evenly on the right-of-way in accordance with landowner and agency requirements, only in upland areas and only to meet the pre -construction surface elevations. Standard Pipeline Construction Procedures _1'YP AL X31PEI._NE 39 a'rr r��rd'�k,us. �r kru .ywn nr xrR e+fj I5—Y —Y Typical Riparian Construction The Southgate Project will conduct construction across waterbodies and through riparian corridors in accordance with the FERC Procedures. In most instances, the corridor will be reduced from 100 -feet to 75 -feet for work conducted within Zones 1 and 2 of the riparian buffer. To facilitate future inspection and maintenance of the pipeline, trees will be cut to grade, and stumps will be removed within the proposed 50 -foot permanent maintenance corridor. Within the proposed 25 -foot temporary workspace that will be replanted and restored, trees will be cut to grade, but stumps will not be removed. In forested wetlands, trees will be cut to grade, but stumps will only be removed within 15 feet of the edge of the pipe trench, or where safety concerns dictate otherwise. Restoration The Project will conduct post -construction restoration activities in accordance with the measures specified in the FERC Plan and Procedures, and as applicable to meet buffer requirements. After a segment of pipe is installed, backfilled, and successfully tested, the Project will final -grade the right-of-way, temporary ATWS, and other disturbed areas, and construction debris will be disposed of properly. The Project will grade the surface of the right-of-way disturbed by construction activities to match original contours and to be compatible with surrounding drainage patterns, except at those locations where permanent changes in drainage will be required to prevent erosion, scour, and possible exposure of the pipeline. The Project will return segregated topsoil to its original horizons in agricultural areas wetlands, and other sensitive areas and re -install temporary and permanent erosion and sediment control measures where necessary, including silt fencing, MountainValley PIPELINE «c Standard Pipeline Construction Procedures diversion trenches, and vegetation. Forested areas of the 25 -foot temporary workspace will be revegetated with native trees, while non -forested temporary workspaces will be returned to their previous conditions. The 50 -foot operational corridor will be revegetated using approved seed mix in previously forested areas, while non -forested areas in the operational corridor will be returned to their previous conditions. Riparian buffer restoration will occur in accordance with 26.0295 (n)(2).