Entergy Arkansas applies for new transmission project near Hot Springs

Entergy Arkansas on May 14 filed an application with the Arkansas Public Service Commission (PSC), seeking a certificate of environmental compatibility and public need (CECPN) for a new 17-mile, 115-kV transmission line in the southeast corner of its service territory, about six miles south of Hot Springs, Ark. (Docket No. 13-056-U).

The line would connect the existing Hot Springs Milton substation and the Carpenter Dam substation. The proposed project, which would also include high-voltage circuit breaker equipment and related electronic relay and metering control systems, would also connect a new proposed 115/13.8-kV distribution substation near the midpoint of the line, and would provide service to the city of Lake Hamilton, Ark., and the surrounding Garland County area south of Hot Springs, Ark.

“These improvements will protect west-central Arkansas from potential under-voltages and thermal overload problems,” an Entergy Arkansas spokesperson told TransmissionHub May 15. “By making these improvements, Entergy Arkansas will also have much needed back-up power when maintenance outages are necessary. The upgrades will also provide a needed 115-kV source for a new planned substation for the west-central region of Entergy Arkansas’ service territory” in the area south of Lake Hamilton and Hot Springs.

Total cost of the project is estimated at $58.5m, which Entergy Arkansas said it would finance with funds available from various sources, including retained earnings, debt, and capital securities.

According to the application, the project line is needed “to relieve existing area transmission line overloads during certain contingencies in the west-central Arkansas service area.” Those contingencies include the loss of three different 115-kV power lines. The loss of the Blakely Dam to Mt. Pine South line and the Carpenter Dam to Hot Springs South line cause low voltages at area substations and overloads adjacent 115-kV lines, while the loss of the Arklahoma to Tigre Bay line causes the Carpenter Dam to Hot Springs South line to overload.

The associated transmission facilities are needed “to improve operational reliability and low voltage conditions during certain contingencies in the west-central Arkansas service area,” the company said. In its application, the company noted that its major concern is a projected 5% overload on the Carpenter Dam substation transformer in the summer of 2015. Further, the company said it has “insufficient capacity in the area to reduce load at the Carpenter Dam substation by switching to other sources.”

The application included a map of the company’s preferred route.

Despite being one of the longer routes evaluated, the proposed route detailed in the application “should offer the least amount of adverse environmental impact to the natural, cultural, agricultural, recreational, and industrial environment as compared to the alternative routes,” the company said, noting that it had evaluated 73 separate line segments and 10 primary alternative transmission routes before choosing its preferred route.

The company plans to employ its standard design for the 115-kV kV over-head, three-phase, shielded, transmission line design using a delta conductor configuration on single-pole steel or concrete structures within a 100 foot right-of-way (ROW), according to the application.

The supporting structures would be single-pole design and would be directly buried in the ground. Aluminum conductor, steel reinforced (ACSR), would be attached to the poles with polymer/fiberglass type post insulators to insulate and support the conductors.

Entergy Arkansas expects the proposed facilities to have a useful life of 40 years. If approved, the project would enter service in 2015.

Entergy Arkansas is one of the operating companies of Entergy (NYSE:ETR).