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EAB Rejects Requirement for Digital Camera Optical Technology

In In re Salt River Project Agricultural Improvement and Power District – Navajo Generating Station, NSR Appeal No. 16-01, EPA’s Environmental Appeals Board (EAB) considered an argument that the “digital camera opacity technique” (DCOT) should be required to monitor opacity from a proposed refined coal treatment system at a power plant. The EAB affirmed EPA Region 9’s decision that DCOT is not required.


In April 2016, EPA Region 9 issued a minor NSR permit to the Salt River Project Agricultural and Improvement District (SRP) to construct and operate a refined coal treatment system at its Navajo Generating Station in northern Arizona. The treatment system mixes coal with cement and calcium bromide to control mercury emissions. The treatment system includes silos, day bins and a tank for the calcium bromide. All reagents are delivered by truck. Use of the system increases particulate matter (PM10) emissions primarily due to truck traffic. EPA Region 9 required use of baghouses and dust collectors to minimize dust emissions on transfer points in the system and required monitoring with weekly Method 22 observations, followed by a Method 9 observation is any opacity is observed. A petitioner challenged this decision, arguing that Methods 9 and 22 are inadequate and that the minor NSR permit should be revised “to require use of the ‘Digital Camera Opacity Technique,’ referred to as ‘Alternative Method 082’ or ‘ALT-082.’”


The first question presented to the EAB was the standard for reviewing petitions under the Tribal minor NSR rule codified in 40 C.F.R. Part 49. Ultimately, the EAB resolved this by holding that “the Board’s decisions under part 124 serve as relevant precedent in this NSR context.” Slip op. at 3. Turning to the merits, the EAB noted that the petition sought relief on many sources of PM10, but that only the refined coal treatment system was presently before it. EAB noted that Methods 22 and 9 are presently approved and that ALT-082 has received “limited approval” for determining opacity in lieu of Method 9. The Board explained that “ALT-082 uses a digital camera to record images and a certified human operator to review those images with analysis software to determine the opacity.” The petitioner challenged the use of Method 9, arguing that it had allowed opacity exceedances and was “clearly not adequate.” Region 9 rejected this comment, stating that since Method 9 was already in use at Navajo Generating Station, an alternative was not needed for the minor sources at issue in this permit and that the alleged opacity exceedances occurred at other sources not related to the one included in the permit. The EAB found that this conclusion was adequately supported in the record. The EAB also noted that “the Agency made clear in approving the use of ALT-082, however, that the use of this and other alternative test methods are not mandatory, but permissive” and that there is “nothing in the record or applicable regulations to support Petitioner’s argument that [ALT-082’ is superior to EPA Method 9.” Slip op. at 8. Accordingly, the EAB denied the petition for review.


This decision is important primarily for determining that decisions under Part 49 will follow prior precedent from Part 124. On the monitoring issue raised by petitioner, the decision is important for the proposition that a permitting authority is not required to use ALT-082 even if commenters request its use.

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