§ 63.848 Emission monitoring requirements.

(a) TF and PM emissions from potlines. Using the procedures in § 63.847 and in the approved test plan, the owner or operator shall monitor emissions of TF and PM from each potline by conducting annual performance tests on the primary control system and semiannual performance tests on the secondary emissions. The owner or operator shall compute and record the average semiannually from at least three runs for secondary emissions and the average from at least three runs for the primary control system to determine compliance with the applicable emission limit. The owner or operator must include all valid runs in the semiannual average. The duration of each run for secondary emissions must represent a complete operating cycle. Potline emissions shall be recorded as the sum of the average of at least three runs from the primary control system and the average of at least three runs from the roof monitor or secondary emissions control device.

(b) POM emissions from potlines. Using the procedures in § 63.847 and in the approved test plan, the owner or operator must monitor emissions of POM from each potline stack annually and secondary potline POM emissions semiannually. The owner or operator must compute and record the semiannual average from at least three runs for secondary emissions and at least three runs for the primary control systems to determine compliance with the applicable emission limit. The owner or operator must include all valid runs in the semiannual average. The duration of each run for secondary emissions must represent a complete operating cycle. The primary control system must be sampled over an 8-hour period, unless site-specific factors dictate an alternative sampling time subject to the approval of the regulatory authority. Potline emissions shall be recorded as the sum of the average of at least three runs from the primary control system and the average of at least three runs from the roof monitor or secondary emissions control device.

(c) TF, PM, Hg and POM emissions from anode bake furnaces. Using the procedures in § 63.847 and in the approved test plan, the owner or operator shall determine TF, PM, Hg and POM emissions from each anode bake furnace on an annual basis. The owner or operator shall compute and record the annual average of TF, PM, Hg and POM emissions from at least three runs to determine compliance with the applicable emission limits. A minimum of four dscm per run must be collected for monitoring of Hg emissions. The owner or operator must include all valid runs in the annual average.

(d) Similar potlines. As an alternative to semiannual monitoring of TF, POM or PM secondary emissions from each potline using the methods in § 63.849, the owner or operator may perform semiannual monitoring of TF, POM or PM secondary emissions from one potline using the test methods in § 63.849(a) or (b) to represent the performance of similar potline(s). The similar potline(s) must be monitored using an alternative method that meets the requirements of paragraphs (d)(1) through (7) of this section. Two or more potlines are similar if the owner or operator demonstrates that their structure, operability, type of emissions, volume of emissions and concentration of emissions are substantially equivalent.

(1) To demonstrate (to the satisfaction of the regulatory authority) that the level of emission control performance is the same or better, the owner or operator shall perform an emission test using an alternative monitoring procedure for the similar potline simultaneously with an emission test using the applicable test methods. The results of the emission test using the applicable test methods must be in compliance with the applicable emission limit for existing or new potlines in § 63.843 or § 63.844. An alternative method: