Utilities, enviros battle over proposed power line near Tucson

Phoenix-based Salt River Project (SRP) has joined the debate over a proposed power line for a proposed copper mine southeast of Tucson, citing concerns over expanding the scope of review to include environmental impacts beyond those of the proposed power line and the precedent such a decision could create.

At issue is the Arizona Corporation Commission’s (ACC) decision to consider evidence about the potential environmental impacts of the Rosemont Mine as it considers the application by Tucson Electric Power (TEP) to build a 13-mile, 138-kV line to the mine’s site in the Santa Rita Mountains (Docket No. L-00000C-11-0400-00164).

In a May 3 letter signed by its outside counsel, SRP said it is concerned that the ACC’s decision will set a precedent by allowing the introduction of evidence about the environmental impact of the loads to be served by future lines. “Such a standard would make sitings difficult, confusing, and expensive,” the utility said. 

SRP said it takes no position on the merits of the power line project itself.

In December 2011, the state’s Power Plant and Transmission Line Siting Committee refused to consider a broad range of issues about the potential environmental impacts of the mine, concluding that state law did not authorize it to consider issues beyond the effect of the power line itself.

The committee is an independent, 11-member body that evaluates applications to build power plants of 100 MW or more and transmission projects of 115-kV or higher. It decides whether to grant or deny a certificate of environmental compatibility (CEC) for any project that comes before it. Its decisions then go to the ACC, which can confirm, deny or modify the committee’s decisions.

In March, the ACC conditionally approved the CEC but stayed its approval pending a review of information the line siting committee had excluded. Although it noted that its “task is not to site the mine,” the ACC said discussing the mine’s “environmental impacts would provide a helpful context for our full consideration” of the application.

SRP countered, stating that the standards of materiality and relevance would “prohibit evidence that does not relate to a determination of the environmental impact of the line or the purpose and need for the line,” adding that, “a siting case is not the forum to debate the issues.”

TEP has also asserted that a siting case is not the forum to debate issues beyond the effects of the power line itself.

In its prehearing brief, mine developer Rosemont Copper Company noted that the commission’s approval of the CEC included 26 separate conditions that balance “the need for electricity with the desire to minimize the environmental impacts of a 138-kV transmission line on the environment and ecology of the surrounding area.”

The CEC prohibits construction of the proposed transmission line until Rosemont receives approval from the U.S. Forest Service, which is the lead federal agency with oversight over Rosemont’s mining development. “This one condition alone should address the concerns of mine opponents, who claim that the mine will never be built,” the company said in its brief.

Rosemont said the case “serves as a prime example of how the public process can be twisted to serve political agendas that have nothing to do with balancing the need for power with the desire to minimize environmental impacts of electric facilities.”

The case has attracted attention from a broad range of constituents, an ACC spokesperson told TransmissionHub on May 9.

For instance, Arizona State Mine Inspector Joe Hart has also weighed in. In a letter to ACC Commissioner Sandra Kennedy, Hart objected to the ACC’s intention to “allow consideration of evidence that is in any way related to environmental impacts of [the] Rosemont mine … [a]s compared to evidence that is related to the impacts of the power line.”

Hart also referred to the federal process to review the mine impacts, stating that he had monitored the environmental impact statement hearing and the 120-day comment period.

“Anybody who had any comment on the mine should have already had their say,” Hart said.

The ACC will address the issue at its May 10 open meeting in Phoenix.

TEP is a subsidiary of UniSource Energy Corporation (NYSE: UNS).