Emission InventoryQuality Assurance/Quality Control

(QA/QC)

Melinda Ronca-Battista

ITEP

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• Quality Control (QC) • Documenting data sources• Rechecking calculations• Accuracy checks • Use approved standardized procedures for

emissions calculations

• Quality Assurance (QA)• External review and audit procedures by third

party

Quality Control Terminology

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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 example QAPP handout

• 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 Emissions Inventory Improvement Program (EIIP) Vol. 6, page 2.1-5

See Emissions Inventory Levels handout

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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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Unit Example

Asks for data in units of 1000 gallons

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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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Calculator Methodology

• Scroll down on summary screen to get to Reference and Online Link

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Why Review the Methodology?

• What do I select here?

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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

QC Methods: Typical Errors

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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

• 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

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Homework

• Read EIIP Volume 3, Chapter 1: Introduction to Area Source Emission Inventory Development, Sections 6.1 and 6.2

• Answer questions on handout