Timeline of visibility and regional haze-related actions affecting the Navajo Generating Station
The regional haze program is designed to achieve reasonable progress in 10-year planning periods. To that end, the states (or the Environmental Protection Agency (EPA), in the case of facilities on Native American lands such as NGS and Four Corners Power Plant (FCPP)) must complete revised regional haze plans in 2018 and every 10 years thereafter. Although Best Available Retrofit Technology (BART) determinations are to occur within the first planning period, the rules do not require maximum possible reductions in visibility impairing emissions during each 10-year review period. Instead, the regional haze program seeks to achieve reasonable towards the eventual goal of achieving visibility equivalent to natural conditions in 2064.
The EPA issued a proposed BART rule for NGS on Jan. 18.
SRP submitted to EPA, for its consideration in developing a BART proposal for NGS, a report on the results of additional visibility modeling conducted using the newest release of the CALPUFF model. CALPUFF is the regulatory model that is recommended by EPA for use in predicting visibility improvements from each control option. The upgraded model predicts less visibility benefit from SCR than the previous modeling conducted by SRP, which further supports SRP's conclusion that SCR cannot be justified as BART.
In recognition of the importance of the cost estimates for potential BART control technologies, SRP retained Sargent & Lundy, an engineering firm with extensive experience with the design and installation of power plant emission controls, to refine the cost estimates for the installation of controls at NGS. The purpose of the study was to develop cost estimates that could be accepted by even the most critical evaluators as accurate and representative of the real costs of installing emission controls at NGS. To develop accurate estimates, a significant level of effort was required, involving a detailed evaluation of site-specific factors affecting the design and constructability of emission control equipment. The total cost of the study exceeded $700,000, and included over 4,000 hours of work. The study showed that SCRs on all three units would cost approximately $544 million, and if baghouses were required to mitigate increases in emissions of other pollutants, the total capital cost of controls would be in excess of $1.1 billion.
SRP voluntarily initiated a stakeholder negotiation process, facilitated by EN3Professionals, to develop a consensus for phasing in environmental controls while keeping the plant in operation. The goal was to provide a negotiated agreement to EPA for their consideration in the development of the BART proposal for NGS. This process included over 100 participants and over 30 different organizations. Information regarding this process is available at www.en3pro.com.
EPA issued an Advanced Notice of Proposed Rulemaking (ANPR) for Navajo Generating Station and FCPP. The ANPR sought comment on the propriety of several BART controls options under consideration by EPA for reducing NOx emissions from the two plants, including combustion controls and much more expensive post-combustion controls, such as SCR. SRP submitted extensive comments on the ANPR, noting among other things that the NGS participants were already in the process of voluntarily installing combustion controls on all three units at NGS, and that such controls would reduce emissions to levels that are below EPA's presumptive NOx emission limits. SRP also argued that post-combustions controls were not cost effective and would not result in meaningful improvements in visibility beyond that achievable with combustion controls alone. CAWCD submitted comments in support of SRP's position and emphasized the importance of NGS as the principal source of power for pumping Colorado River water through the Central Arizona Project (CAP). CAWCD also argued that a requirement to install post-combustion controls at NGS would at best increase costs to CAP water users substantially and at worst could lead to plant closure. The Navajo Nation and the Hopi Tribe argued that a requirement to install post-combustion controls at NGS would cause the two tribes enormous harm if that led to plant closure.
EPA provided comments on SRP's BART modeling protocol in July 2008. SRP submitted an updated BART report that addressed EPA's comments in December 2008. The updated report supported SRP's earlier proposal that BART for NGS can be achieved by installing LNB/SOFA on all three units, and that SCR cannot be justified as BART.
SRP submitted a proposed BART modeling protocol to EPA in September 2007, and submitted an initial BART report to EPA in November 2007. Based on an evaluation of the five statutory factors, SRP concluded that BART for NGS can be achieved by installing Low-NOx Burners and Separated Overfire Air (LNB/SOFA) on all three units at NGS. The primary basis for this conclusion is that the cost of the more stringent NOx control option, selective catalytic reduction (SCR), is more than 10 times the cost of LNB/SOFA, and is only predicted to result in a small visibility improvement relative to LNB/SOFA. Accordingly, SRP concluded that SCR cannot be justified as BART.
EPA revised its regional haze rule and issued guidelines for making BART determinations. The rule calls for imposition of BART if a source "may reasonably be anticipated to cause or contribute to any impairment of visibility in any mandatory Class I Federal area." In determining what constitutes BART for a particular source, the states (and EPA) must consider five factors, including the cost of compliance and the degree of visibility improvement which may reasonably be anticipated to result from the use of the technology. The guidelines include presumptive limits for nitrogen oxide (NOx) emissions from large coal-fired power plants, and say that these presumptive limits "are extremely likely to be appropriate" for such plants. "Based on our analysis of emissions from power plants," EPA said, "we believe that applying these highly cost-effective controls at the large power plants covered by the guidelines would result in significant improvements in visibility and help to ensure reasonable progress toward the national visibility goal." EPA's presumptive limits are based on the use of combustion controls, such as low-NOx burners, at such plants.
The United States Court of Appeals for the District of Columbia Circuit found EPA's regional haze rule contrary to the Clean Air Act in important respects, including because it forced the states to require BART controls at sources without any empirical evidence of the particular source's contribution to visibility impairment in a class I area.
EPA issued its final regional haze rule. The rule required that all states submit an implementation plan that provides for reasonable progress toward achieving "natural background conditions" in national parks and wilderness areas by 2064. The rule required that the states identify those sources that are subject to BART requirements and then determine what constitutes BART for such sources.
EPA issued a notice of proposed rulemaking for regional haze, and received more than 1,300 comments on its proposed rule.
The GCVTC issued its report to EPA. The report included a series of recommendations for reducing visibility impairment attributable to man-made sources.
EPA proposed to revise the federal implementation plan for Arizona to address winter visibility impairment at the Grand Canyon that it claimed was associated with sulfur dioxide (SO2) emissions from Navajo Generating Station (NGS). In October of that year, EPA issued a final rule that required a 90 percent reduction in SO2 emissions from NGS. The Central Arizona Water Conservation District (CAWCD), which operates the Central Arizona Project (CAP), challenged that rule, but the rule was upheld by the United States Court of Appeals for the Ninth Circuit. In order to comply with the rule, Salt River Project (SRP), the operator of NGS, installed SO2 scrubbers at NGS at a cost of more than $400 million.
Congress again amended the Clean Air Act, adding section 169B, which required, among other things, that EPA undertake research to identify "sources" and "source regions" of visibility impairment in Class I areas and establish a visibility transport commission for Grand Canyon National Park. EPA established the Grand Canyon Visibility Transport Commission (GCVTC) in 1991.
EPA disapproved the state implementation plans of 29 states, including Arizona, for failing to comply with the visibility regulations. Over the next few years, EPA investigated visibility impairment at several class I areas, including Grand Canyon National Park.
Environmental groups sued EPA to compel it to adopt federal implementation plans for those states that had failed to submit revised state plans. The parties reached a settlement agreement in 1984 that required EPA to review all state implementation plans for deficiencies and allow states to cure those deficiencies. If the states failed to cure the deficiencies, the consent decree required EPA to issue its own visibility implementation plans for such states.
EPA adopted visibility regulations under section 169A of the Act. The regulations adopted a "phased approach to visibility protection." Phase I was directed at visibility impairment "that can be traced to a single stationary facility or a small group of stationary facilities." EPA required all states to submit revised visibility implementation plans within nine months. Most states failed to do so. EPA deferred addressing other types of visibility impairment, such as "regional haze" caused by a multitude of sources.
EPA identified 156 mandatory class I Federal areas, including Grand Canyon National Park.
Congress substantially amended the Clean Air Act. The amendments included section 169A, which declared "as a national goal the prevention of any future, and the remedying of any existing, impairment of visibility in mandatory class I Federal areas," such as national parks. Congress required EPA to adopt regulations to assure "reasonable progress toward meeting this national goal." Measures for achieving reasonable progress were to include best available retrofit technology or "BART" for certain existing stationary sources and a long-term strategy.