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Newport News to Norfolk AC Mitigation Project

Virginia Natural Gas will be initiating a maintenance project within our existing natural gas pipeline easement as a part of our continuing efforts to ensure the safety and reliability of our pipeline within an active high voltage electrical transmission line corridor.

NEWPORT NEWS TO NORFOLK AC MITIGATION PROJECT OVERVIEW

SAVE Plan Project Frequently Asked Questions

What is the Virginia Natural Gas HRX AC Mitigation Maintenance project?
As part of a continuing maintenance program required by the Virginia State Corporation Commission, we will be working to minimize the effects of AC voltage induced overhead from an active high-voltage electrical transmission line corridor along portions of a 21-mile stretch of the Virginia Natural Gas HRX pipeline. Our transmission pipeline crosses several Dominion Virginia Power electrical circuits and is subjected to the effects of AC electrical interference. This project is considered an upgrade to safety measures already in place that ensures the safe operation of the natural gas pipeline.

Why now?
Personal safety is a top priority when it comes to our operating and maintaining a natural gas pipeline system more than 5,500 miles long, and it’s our job to ensure the safe and reliable delivery of natural gas to our more than 279,000 customers in southeast Virginia. In addition to the potential safety concerns, AC voltage induced onto natural gas pipelines, such as the Virginia Natural Gas HRX transmission pipeline, can over time result in the corrosion and leakage of the pipeline. Without proper mitigation, this can adversely impact the operation of our distribution system.

What does this mean for me?
The initial phase of the project will include surveying, environmental studies and soil testing in select locations, to prepare for the necessary mitigation measures on the Virginia Natural Gas HRX transmission pipeline. The 24-inch transmission pipeline runs along an existing Dominion Virginia Power electrical transmission easementand began in late 2013. Temporary restoration measures for yards and streets will be used during construction with final restoration taking place once the zinc ribbon is installed. The main phase of the project will then prepare the existing easement, which may include survey staking and right-of-way flagging, followed by material installation, and finally restoring the disturbed area back to pre-construction conditions. We anticipate the project to be completed by March 2015. As with all of our construction projects, great care is taken in all phases of the project from beginning to end in each community and neighborhood. We make every effort to minimize inconveniences to property owners along the route.

Where will the work take place?
The Virginia Natural Gas HRX transmission pipeline stretches 21 miles from Newport News, Va. to Norfolk, Va. and runs parallel to an existing Dominion Virginia Power electrical transmission right-of-way. Most of the scheduled maintenance work will take place within the electrical corridor on existing easements. While temporary easements might be granted for additional space for construction, we anticipate that no additional permanent easements will be required for this project.

What does construction entail?
Construction will utilize methods known as open trenching, which involves digging a trench in which to install the components of the new AC mitigation system and directional drilling, where the components are installed via subsurface boring between above ground entry and exit points. The construction process consists primarily of installing gradient control wire – zinc ribbon – along the pipeline to protect the pipe from exceeding certain threshold voltages. Roughly 47 structures, known as decoupling devices or DCDs, will also be installed to divert AC current from the pipeline to the zinc grounding system, which is typically installed at a minimum depth of 4 feet.