Environmental groups want federal regulators to place a partly coal-fired power plant in Tucson under regional regulations designed to curb regional haze.

The Sierra Club and other groups say two generating units at the H. Wilson Sundt Generating Station were improperly exempted from the regional haze rules - which can require costly upgrades to cut emissions - by the Arizona Department of Environmental Quality.

The groups want the U.S. Environmental Protection Agency to review Sundt's status and impose emission-control requirements on the plant's Unit 3 and Unit 4 generators.

Sundt's Unit 3, along with Units 1 and 2, can burn natural gas, landfill gas or liquid fuel. Unit 4 can use gas but was converted to also burn coal in the 1980s, to comply with a federal law passed in 1978 aimed at reducing the nation's dependence on foreign oil.

In a recent letter to the EPA, the environmental groups contended that the ADEQ erred in not including Sundt in its state haze-rule implementation plan, filed with the EPA last year. The EPA can reject the state's plan and impose its own requirements.

The letter was filed by Earthjustice, a nonprofit environmental law firm based in Denver, on behalf of the National Parks Conservation Association; the Sierra Club; the state chapter of Physicians for Social Responsibility; Diné Citizens Against Ruining Our Environment; the Grand Canyon Trust; and the San Juan Citizens Alliance.

The groups contend that the ADEQ erroneously concluded that the Sundt units began operations outside of a 15-year time period that would make them subject to the haze rules.

They say Sundt Units 3 and 4 are, in fact, subject to anti-haze rules that require power plant operators to comply by installing so-called "Best Available Retrofit Technology" (BART) upgrades.

The groups contend that both of the Sundt units were in operation between Aug. 7, 1962, and Aug. 7, 1977, which along with other factors would make them subject to the haze rules.

The idea behind the eligibility window was that plants built before mid-1962 are likely reaching the end of their useful life, while plants built after mid-1977 were built with technology to meet more-stringent pollution-control standards.

In the case of Unit 3, the groups said, the ADEQ erroneously concluded that the generator began operations in June 1962 based on a "work log" and other correspondence from TEP.

ADEQ exempted Unit 4 because it was reconstructed to burn coal in 1987, a determination the groups called "illegal."

According to TEP and Star archives, the first generating unit at the plant - originally known as the Irvington Generating Station - went into service in 1958 and three more were added by 1967. The plant was renamed for a prominent former board member in 2003.

TEP stands by its assertion that the Sundt units began operations outside the time period that would make them subject to the anti-haze regulations, spokesman Joe Barrios said, adding the utility has not decided whether to formally respond to the environmental groups' letter.

The utility faces potentially millions of dollars in costs for anti-haze controls at other Arizona plants through its partial ownership in those plants, including the Navajo and San Juan generating stations, Barrios said.

"We're looking at alternatives, because in many cases these costs will ultimately be passed down to the consumer," he said, adding that the utility will comply with any final rule.

Trevor Baggiore, deputy director of ADEQ's air-quality division, said the agency stands by its findings regarding Sundt and its overall state haze plan.

Baggiore said the agency has not decided whether to file a response or wait for the EPA to file its ruling on the state's plan, which is expected by mid-November.

The EPA can either approve the state agency's plan or reject all or parts of it and impose its own requirements, Baggiore said.

"We expect they will disapprove some things they find problematic, and this may be one of them," he said.

On Friday, the ADEQ announced it had filed a lawsuit against the EPA for failing to approve the state's anti-haze plan in a timely manner. Under a settlement of a similar lawsuit filed by environmental groups last year, the EPA must rule on haze rules for three Arizona power plants by Nov. 15.

Baggiore said the EPA has agreed with ADEQ's plans for regulation of particulates and sulfur dioxide at three Arizona coal-fired power plants, the Apache Generating Station, Coronado Generating Station and Cholla Generating Station.

But the EPA has not approved ADEQ's plans for control of nitrogen oxide emissions for those plants, he said.

The EPA is considering imposing anti-haze controls on two other coal plants serving the state: the Navajo Generating Station near Page and the Four Corners Generating Station in northwestern New Mexico, which are under sole EPA jurisdiction because of their location on the Navajo Nation.

The environmental groups' petition to the EPA comes as local activists have been pressing TEP to stop burning coal at Sundt, citing local public-health effects.

Efforts by the Tucson Climate Action Alliance and others have included street theater in front of TEP's downtown headquarters and a protest at the Sundt plant last week that resulted in the trespassing arrests of three activists.

Did you know?

While utilities now face stepped-up environmental scrutiny of coal-fired power generation, a federal mandate about 30 years ago pushed Tucson Electric Power Co.'s local power plant into coal operation.

In 1981, TEP was ordered by the U.S. Department of Energy to convert its Irvington Generating Station (now known as the H. Wilson Sundt Generating Station) from fuel oil or gas to coal-fired capability. That mandate came under the Power Plant and Industrial Fuels Act of 1978, which sought to cut America's reliance on foreign oil amid the energy crisis. That law was rescinded in 1987.

The coal conversion was completed on the plant's Unit 4 in 1988; a project to convert a second unit was later abandoned.

Contact Assistant Business Editor David Wichner at dwichner@azstarnet.com or 573-4181.