Emission Inventory Quality Assurance/Quality Control (QA/QC) Melinda Ronca-Battista ITEP/TAMS...
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Transcript of Emission Inventory Quality Assurance/Quality Control (QA/QC) Melinda Ronca-Battista ITEP/TAMS...
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• Quality Control (QC) • Documenting data sources• Rechecking calculations• Accuracy checks • Use of approved standardized procedures for
emissions calculations
• Quality Assurance (QA)• External review and audit procedures by a third
party
Definitions
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QA/QC: Where to Start?• Prepare QAPP that answers
• What are you going to report in EI?• What will you use the EI data for?• How are you going to review the data?
See template QAPP
• Potential uses of EI data will define minimum level of QA/QC
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QA/QC Levels
• Level 1 – supports enforcement, compliance, or litigation
• Level 2 – supports strategic decision making• Level 3 – general assessment or research• Level 4 – Inventory compiled entirely from
previously published data or other inventories
From US EPA’s Emission Inventory Improvement Program (EIIP) Vol. 6, page 2.1-5
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Data Quality Objectives (DQOs)
• DQOs• Broad statement on how “good” or “true”
your EI results will be• EI ESTIMATES emissions. You can’t
know exact “truth” about quantity or type of pollutants from a given source
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DQOs: Examples
• EI DQO for Accuracy• 100% of data transcribed from paper
forms to TEISS will be verified• EPA methods used to estimate emissions,
ensure estimates as close to “truth” as possible
• Track Accuracy Checks with TEISS QA/QC functions
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DQOs: Examples
• DQO for Completeness• 100% of largest point sources of PM
included in EI
• DQO for Comparability:• Emissions calculated represent “truth” on
your reservation• Emissions comparable to similar sources
or areas
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DQOs are set, now what’s the plan?
• QC should be included in each EI task• QC for data collection• QC for calculations• QC for choosing estimation methods
• Allocate at least 10% of resources for QA activities
• Don’t wait until the end!
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• Check transcription of data during inventory preparation and reporting• Transcription of data from raw data
collection sheets into electronic spreadsheets or TEISS calculators
• Transcription of data results from TEISS summary tables to EI report
QC: What is included?
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• Check calculations• Including calculation of throughput, if
necessary• If not calculating emissions with TEISS
calculator, check that throughput multiplied by EF equals emissions
• Verify that unit conversions are correct• Verify that units of your data match units
TEISS or equation asks for
QC: What is included? (cont.)
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• Verify you’ve documented all data sources
• Completeness checks• Consistency checks• Double counting• Reasonableness
QC: What is included? (cont.)
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• Keep a file for each source• Use checklist to monitor person and
date for• Data collection• Data calculations• Evaluation of data reasonableness• Evaluation of data completeness• Data coding and recording• Data tracking
QC: How to track it
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• Most commonly used• Is this number reasonable? Does it make
sense?
• Never use the reality check as the sole criterion of quality
• Find data for similar sources on EPA’s EIS Gateway system
QC Methods: Reality Checks
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• Independent review of calculations, assumptions, and/or documentation by person with moderate to high level of technical experience
• QA is a form of peer review• Can also be included as part of QC
QC Methods: Peer Review
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• Most reliable way to detect computational errors
• General rule, minimum of 10% of calculations checked, depending on• Complexity of calculations• Inventory DQOs• Rate of errors encountered
QC Methods: Replication of Calculations
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• Automated data checks can be• Built-in functions of databases, models, or
spreadsheets, or stand-alone programs• Automate to
• Check for data format errors (like Export to NEI component of TEISS)
• Conduct range checks• Provide look-up tables to define permissible
entries (like TEISS selection boxes)
QC Methods: Computerized Checks
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TEISS needs a Human Touch
• TEISS is an excellent tool; however, it needs your guidance
• Be familiar with emission methodologies on which TEISS calculators are based
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Finding Calculator Methodology
• Scroll down on summary screen to get to Reference and Online Link
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Methodology Has Answers• Methodology: used to calculate emissions for 4
different “station operations” (in most cases)
• Underground tank filling
• Underground tank breathing
• Vehicle refueling displacement losses
• Vehicle refueling spillage
• Each operation should be included as a different Process in TEISS
• If using an EPA model to calculate onroad emissions, make sure vehicle refueling emissions are not double counted
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• Missing or duplicate facilities• Improper facility locations• Missing operating or technical data• Erroneous technical data• Double counting• Errors in calculations• Data entry and transposition errors; data
coding errors
Typical Errors in EIs
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Most Typical QC Error
Letting it slide• Make sure to include time for QA/QC• Pressure to gather data and “get it
done” can harm documentation & verification
• Putting it off to project’s end
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• Ensure final written compilation of data accurately reflects inventory effort
• Support QA assessments of inventory
• Ensure reproducibility of inventory estimates
• Enable inventory user or reviewer to assess quality of emission estimates and identify data references
• Foundation for future inventories
QC Documentation
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What about QA?
• Independent review by third party, ITEP for example
• Checks effectiveness of your QC
• Allocate 10% of project resources to QA
• Again, don’t wait until the end
• QA person checks a fraction of data entry, calculations, documentation, etc.
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Are You Hungry For More?
• Excellent resource and source for some of this presentation material
• EIIP Volume 6: Quality
Assurance/Quality Control -
http://www.epa.gov/ttn/chief/eiip/techreport/volume06/index.html