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Mercury Monitoring Under a Trading Program. Ruben Deza, Ph.D. Clean Air Markets Division U.S. Environmental Protection Agency. Mercury Monitoring Language. For the trading portion of the rule: Addition of Subpart I to Part 75 Establishes mercury monitoring methods
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Mercury Monitoring Under a Trading Program Ruben Deza, Ph.D. Clean Air Markets Division U.S. Environmental Protection Agency
Mercury Monitoring Language • For the trading portion of the rule: • Addition of Subpart I to Part 75 • Establishes mercury monitoring methods • Similar to Subpart H for the NOx SIP Call • Adds portions pertinent to other monitoring methodologies • Establishes monitoring QA/QC proposal • Revisions of Part 72 to add some definitions
Two Alternative Monitoring Systems • Continuous Emissions Monitoring System • Similar to current systems in the Acid Rain & SIP Call programs • Sorbent Tubes • Accumulation of Hg over an extended period of time, e.g., a few days or weeks • Lab analysis of the tubes at end of use
Overall Assessment • Under controlled conditions, both monitoring systems are capable of providing adequate measurements • Sorbent traps require comparable quality assurance testing to make them as reliable as CEMS • It is reasonable to expect that full commercialization will be achievable before the rule’s compliance date
One Proposal – Two Alternatives • Alternative one: • Units with the highest emissions install CEMS • Lowest emitters have the option to install sorbent tubes with more relaxed QA requirements • Soliciting comments on threshold points of 1%, 5%, 10%, or 20% of cumulative emissions • The threshold points translate into 228, 435, 565, and 724 units being able to use sorbent traps
One Proposal – Two Alternatives • Alternative two: • All units would have the flexibility to install sorbent tubes or CEMS • Above the threshold point, units using sorbent tubes would be required to conduct one RATA and three RAAs • Soliciting comments on the same threshold points, i.e., 1%, 5%, 10%, and 20%
Additional Flexibility • Consistent with the SO2 and NOx cap-and-trade programs, regulated sources would have the flexibility of proposing other monitoring approaches or variations of these two as long as such approaches meet the performance requirements in Part 75
Installation and certification • CEMS: • Similar to NOx and SO2 • RATA, linearity, calibration check and cycle time • Sorbent Traps: • RATAs and leak checks
QA/QC for Hg CEMS • Similar to Part 75 CEMS Monitoring • Annual RATA and bias tests • Daily calibrations • Quarterly linearity checks • Beyond Part 75 • Monthly converter check (PS- 12A)
QA/QC for Sorbent Traps • One annual RATA • Three Relative Accuracy Audits (RAAs) • At least 168 operating hours in the quarter • Leak check when traps are replaced (overloading of trap also) • Chain of custody procedures for each sorbent trap • Lab testing in accordance with ISO 9000 standards Note: RAAs would not be required for units that emit below the threshold value