The Virginia State Corporation Commission (SCC) has approved underwater construction of an electric transmission project proposed by Virginia Electric and Power (Dominion Energy Virginia).
As noted in the order, the company in February 2016 filed with the SCC an application for a certificate of public convenience and necessity to build and operate an electric transmission line in the counties of Lancaster and Middlesex in Virginia, and across the Rappahannock River.
In the application, the company proposed to rebuild about 2.2 miles of the company’s existing 115-kV transmission line – Harmony Village-Northern Neck Line #65 – located between the Harmony Village substation in Middlesex County and the White Stone substation in Lancaster County.
The SCC added that the portion of Line #65 that the company proposed to rebuild included an approximately 1.9-mile crossing of the river at the Robert O. Norris Bridge, with the remaining 0.3 mile of the project on land.
For the river crossing, the project would replace seven existing wooden H-frame electric transmission structures located east of the bridge in the river, and 14 existing attachments to the bridge, with 10 galvanized steel H-frame structures that would be located in the river.
As proposed, the SCC added, Line #65 would no longer be attached to the bridge. The new structures would be located about 100 feet east of the bridge in a right of way (ROW) permitted by the Virginia Marine Resources Commission (VMRC), the SCC said.
The height of the existing structures in the river is about 83 feet, while the heights of the proposed structures in the river range from about 102 feet to 173 feet.
The SCC also said that on the Lancaster side of the river, the company proposed to replace one existing wooden three-pole structure, about 48 feet in height, with a galvanized steel three-pole structure, about 55 feet in height, that would be located in the existing ROW.
On the Middlesex side of the river, the company proposed to replace four existing wooden monopole structures, with heights ranging from about 61 feet to 70 feet, with one double deadend galvanized steel monopole and two weathering steel monopoles, with heights ranging from 79 feet to 82 feet, that would be located in the existing ROW.
The SCC added that as part of the project, Dominion would also replace 2.2 miles of existing conductor and one static wire on Line #65 with about 2.2 miles of new conductor and two shield wires.
The company estimates the total cost of the project to be about $26.2m.
The SCC added that according to the application, the project is needed to maintain electric transmission system reliability, as well as to address structural and operational deficiencies associated with certain existing structures and bridge attachments. In the application, the company said that the existing structures and bridge attachments, which were originally installed in 1962, must be replaced to address the risk associated with their age, condition, and proximity to the bridge.
In addition to the project, which Dominion requests SCC approval of, the application indicated that the company has identified a 230-kV overhead alternative and an underground alternative for the SCC’s consideration.
The SCC added that a senior hearing examiner, in a report issued last August, recommended, among other things, that the SCC find that there is a need to replace the aging and deteriorating transmission Line #65 as it crosses the river at and on the bridge; and that the underground option, for instance, best satisfies the statutory requirement that the line is needed and that the corridor or route the line is to follow will reasonably minimize adverse impact on the scenic assets, historic districts, and environment of the area concerned.
The SCC said that it finds that there is a need to replace the 2.2-mile segment of the line. As found by the senior hearing examiner, the SCC said, that segment needs to be replaced because of its extensive out-of-service conditions.
Since 2010, the river crossing segment of the line has been de-energized more than 50% of the time due to Virginia Department of Transportation (VDOT) maintenance, and there have been at least seven unplanned outage events that have also occurred on the line, the SCC said.
The segment of the line is not being replaced due to a capacity problem, the SCC said, adding that the current capacity of the river crossing is adequate to meet existing and projected load; the replacement line will continue to be operated at 115 kV.
Due in part to the uniqueness of the project, no less than 15 alternatives for rebuilding that segment were evaluated in the proceeding, the SCC said.
One factor that distinguishes the project is that it does not involve a new line, but a replacement of an existing line that for decades has been attached to a highway bridge instead of being suspended from free-standing towers across the river, the SCC said.
Attachment of the replacement line to the bridge is no longer feasible in that it does not meet the identified need, the SCC said, adding that increased maintenance, inspections, and superstructure study by VDOT will result in extended outages of the line if attached to the bridge, which may further result in violation of mandatory NERC reliability standards.
“Based on the totality of the circumstances established in the record of this case, the commission finds that underwater construction designed for 217 MVA as directed herein satisfies the statutory requirements and best serves the total public interest within the parameters of the statute,” the SCC said. “This finding includes consideration of, among other things: need; cost; reliability; the environment; scenic assets; historic districts; health and safety of the persons in the area; economic development; local comprehensive plans; proposed method of installation; possible impediments to timely construction; and” ROWs.
The SCC said that its approval is conditioned upon Dominion receiving the additional approvals necessary for underwater construction, including authorization from the VMRC, the U.S. Army Corps of Engineers, and the Virginia General Assembly.
The company is to file an update on the status of any additional approvals necessary for the project within 120 days, the SCC said in its Dec. 21, 2017, order.