Modeling, Impacts, and Effects Review Dom Ruggeri, P.E., Manager Technical Program Support Section TCEQ, Air Permits Division Austin, Texas September 27, 2006

Introduction Introduction Discuss general approach to modeling, impacts, and effects review Discuss general approach to modeling, impacts, and effects review Prepare to evaluate impacts of MSS emissions Prepare to evaluate impacts of MSS emissions

Applicant Submits Application Identifies all emissions from production and planned MSS Identifies all emissions from production and planned MSS Provides scenarios, emission factors, control technologies, representations Provides scenarios, emission factors, control technologies, representations Provides all supporting documentation Provides all supporting documentation Addresses known concerns Addresses known concerns

Table 1 (a) Includes all normal operation scenarios Provides separate scenarios for short- term, long-term operations Includes all facilities and related activities and frequency Includes hours of production and MSS and the number of startups and shutdowns

Permit Reviewer Duties Agrees to BACT or BMP Agrees to BACT or BMP Agrees with proposed emission rates and stack parameters Agrees with proposed emission rates and stack parameters Conducts preliminary impacts evaluation Conducts preliminary impacts evaluation Requests modeling as needed Requests modeling as needed

Impacts Evaluation Look at all contaminants, project emissions Look at all contaminants, project emissions Include MSS not previously evaluated Include MSS not previously evaluated Include PBRs and standard permits Include PBRs and standard permits Compare to de minimis, SIL, 10% ESL Compare to de minimis, SIL, 10% ESL Conduct applicable modeling Conduct applicable modeling Modeling sitewide? Include everything! Modeling sitewide? Include everything!

Basic Questions Do I have to evaluate all emissions from normal operations? Do I have to evaluate all emissions from normal operations? –Yes Can I evaluate planned MSS separately from production? Can I evaluate planned MSS separately from production? –Maybe Is there a de minimis for MSS? Is there a de minimis for MSS? –Yes and no

If Modeling is Requested Which Model? Which Model? –Staff prefer SCREEN3 and AERMOD When do we switch from ISCST3? When do we switch from ISCST3? –Federally required December 2006 Could we use ISCST3 instead of AERMOD? Could we use ISCST3 instead of AERMOD? –Maybe

Modeling Process Try Conservative, Worst-Case Approach First Modeling Process Try Conservative, Worst-Case Approach First Continuous emissions; max hourly rate Continuous emissions; max hourly rate Simultaneous PMSS Simultaneous PMSS Set model for overall max and individual source concentrations Set model for overall max and individual source concentrations Pass: site meets standards and/or ESLs Pass: site meets standards and/or ESLs

Modeling Process Failed? Are Impacts “Possible” or “Probable”? Identify likely worst-case scenario (s) Identify likely worst-case scenario (s) Emissions at max hourly rate for short- term, average hourly rate for long-term Emissions at max hourly rate for short- term, average hourly rate for long-term Use emission rate scaling factors Use emission rate scaling factors Set model for overall max and individual source concentrations Set model for overall max and individual source concentrations Pass: site meets standards and/or ESLs Pass: site meets standards and/or ESLs

Modeling Process Modeling Process Still failed? Are Impacts Possible? Apply appropriate post-modeling techniques For example: – –Consider buildings, obstructions – –Particle size – –Stability class and wind speed

Modeling Process Modeling Process Impacts Possible But Not Probable Are the emissions continuous? Rate based on spikes or steady state? If steady state, then meteorology not an adjustment factor for single source If noncontinuous, probability approach may be appropriate

Modeling Process Impacts Possible, Analyze Operations Identify the issues Identify the issues What are the culpable sources? What are the culpable sources? How are the culpable sources authorized? How are the culpable sources authorized? What are the applicable scenarios, hours of operation, emission rates? What are the applicable scenarios, hours of operation, emission rates? Are the emissions from production or MSS? Are the emissions from production or MSS?

Modeling Process Options to Reduce Impacts  Modify stack parameters  Reduce emissions with proposed BACT  Propose new BACT  Limit normal operations Limit use of standard permits and PBRs Limit use of standard permits and PBRs

Show Air Quality Benefit Still Can’t Demonstrate Compliance? Can we show an air quality benefit? Assumes: Standards met; issue related to ESLs Standards met; issue related to ESLs All refined modeling, control, emission and scenario options fully explored All refined modeling, control, emission and scenario options fully explored No backsliding No backsliding No significant air quality impact No significant air quality impact

Air Benefit Analysis Basic Questions What is the ESL issue? What is the ESL issue? –Acute or chronic health –Nuisance –APWL or mobile monitoring What are the BACT issues? What are the BACT issues? –Technical reasonableness –Economic feasibility –Timing –Timing

Air Benefit Analysis More Basic Questions Does the source of emissions exist? Does the source of emissions exist? What are the operational issues? What are the operational issues? –Production or MSS? –Existing PBRs and/or standard permits? Should we limit future PBRs, standard permits? Should we limit future PBRs, standard permits?

Air Benefit Analysis Still More Basic Questions What is the compliance history? What is the compliance history? What is the region’s input? What is the region’s input? What is toxicology’s input? What is toxicology’s input? What is the public’s input? What is the public’s input? Is there a net air quality improvement from the project? Is there a net air quality improvement from the project?

Summary Applicants provide technical information Applicants provide technical information Permit reviewers evaluate Permit reviewers evaluate –BACT –Compliance with rules/regulations –Protectiveness Models are tools Models are tools Engineering judgment can be used to weigh air quality benefits Engineering judgment can be used to weigh air quality benefits

Questions