Mississippi PSC approves Entergy Mississippi’s proposed 25-mile line

The Mississippi Public Service Commission (PSC) has granted Entergy’s (NYSE:ETR) Entergy Mississippi a certificate of public convenience and necessity in relation to the company’s proposed 25-mile transmission line that would run from the Franklin 500/115-kV substation in Franklin County, Miss., to the McComb 115-kV substation in Pike County, Miss.

As noted in the PSC’s Feb. 29 final recommended order, Entergy Mississippi last October filed a petition seeking authorization from the PSC to acquire, expand, build, operate and maintain the proposed facilities in Franklin, Lincoln and Pike counties, including:

  • Build the new transmission line, built to 230-kV design specifications, but initially operated at 115-kV, between the Franklin and McComb substations
  • Build a new double breaker bus 115-kV bay at the Franklin substation for the proposed transmission line at an open bay position
  • Build a new 115-kV bay at the McComb substation for the proposed transmission line; the line terminal and bay would be located to accommodate future 230-kV expansion on a seven-acre site directly adjacent to the McComb substation
  • Reroute 0.67 mile of the existing 115-kV Franklin to Liberty Line to accommodate the routing of the proposed transmission line on existing Entergy property at the Franklin substation
  • Rebuild about 0.51 mile to install double circuit structures that would accommodate the existing Brookhaven to McComb 115-kV line and the proposed transmission line

The total estimated cost of the project, which has an in-service date of November 2017, is about $39m.

The PSC also noted that in addition to meeting mandatory federal reliability requirements for the continued delivery of reliable electric service to customers, the proposed facilities are designed to significantly improve the reliability of service to customers in south Mississippi and allow Entergy Mississippi to increase the transmission system’s load serving ability in the Brookhaven area.

The company’s requirement to comply with federal reliability standards drives the need for significant transmission capital investment over the next five years, the PSC said. Entergy’s transmission system must comply with NERC’s mandatory reliability requirements, the PSC said, adding that with integration into the Midcontinent ISO (MISO) now complete, functional control of Entergy Mississippi’s transmission assets lies with MISO. Entergy Mississippi still has responsibility for local reliability planning, the PSC said.

As part of the MISO Transmission Expansion Plan (MTEP 14) process, the project was reviewed by the MISO Transmission Provider Board and determined to provide the most effective alternative to remedy the limitations identified in that process. As a result, the PSC added, the project was included in Appendix A of the MTEP 14 as a project needed within the next five years.

After careful review and an alternative route analysis that included an environmental assessment, a route was designed to have minimal impact on the community and environment while balancing costs to customers, the PSC said.

Entergy Mississippi selected the second-highest ranked route in POWER Engineers’ study – Route 8 – rather than the highest-ranked route – Route 2 – for the proposed line. The PSC added that the two routes are identical except for the last approximately one-half to one mile of transmission line as it approaches the McComb substation.

The existing right of way (ROW) in that area contains three existing 115-kV lines, and two of the existing 115-kV lines would need to be rebuilt to accommodate the construction of the proposed line if Route 2 were used in that existing ROW. Rebuilding the existing 115-kV lines in that area carries with it an elevated operational risk associated with outages needed to rebuild the lines, and the potential for impacts on customers, the PSC added.

Entergy Mississippi determined that using Route 8 would have no significant impact on customers in the McComb area and would avoid the elevated operational risks from rebuilding the existing lines. The PSC also said that fewer landowners would be affected by using Route 8.

The PSC said that after reviewing the evidence, it finds that the company acted reasonably in performing its route analysis, considering alternatives and associated costs, as well as in developing and choosing its preferred route.

Among other things, the PSC noted that parties could file – within 15 days from the date of entry of the recommended order – exceptions to the recommended order for review, and if no exceptions are filed, the recommended order is to become a PSC order.

About Corina Rivera-Linares 3273 Articles
Corina Rivera-Linares, chief editor for TransmissionHub, has covered the U.S. power industry for the past 16 years. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial. She has also covered such topics as health, politics, and education for weekly newspapers and national magazines. She can be reached at clinares@endeavorb2b.com.