Year-End CEMS Checklist: How to Prepare for Stack Testing Season
- Oct 31, 2025
- 4 min read
Updated: Jun 25
The end of the year is the right time to get ahead of stack testing season — not the beginning of January when contractors are already booked and procurement is back-logged. Most of what makes Q1 testing go smoothly gets decided in Q4.
This checklist covers the year-end actions that protect your compliance schedule, reduce last-minute scrambling, and set your CEMS up for a clean test season.
1. Audit Your Permit Testing Calendar
Pull your Air Pollution Control Permit and identify every test requirement due in the upcoming year. Note the applicable regulation, the test method, the emission source, and any operating condition requirements that must be met during testing. This is the foundation — everything else on this list flows from knowing exactly what's due and when.
Key things to confirm:
Which emission points require testing and under which regulation (Part 60, Part 63, state permit)
Whether any rule changes or ICRs issued this year added new testing requirements
Deadlines for any initial compliance tests triggered by new or modified sources
2. Review Your RATA Frequency Status
If your facility operates under Part 75, your RATA result from this year determines whether you test semi-annually or annually next year. Review your relative accuracy result now to confirm your testing frequency for the upcoming year and factor it into your scheduling decisions before you close out the year.
3. Schedule Your Q1 Testing Now — Before the Holidays
Testing contractors book up quickly in January. Facilities that wait until the new year to start the conversation often find their preferred window is already gone. By planning ahead with Alliance, you gain a partner that helps coordinate your testing strategy—not just perform the test.
When you schedule with Alliance, we help you:
Reserve testing dates before peak-season availability becomes limited
Review your testing requirements to confirm the correct scope and regulatory obligations
Develop a testing schedule that aligns with your compliance deadlines and facility operations
Provide timely proposals and contract support to help avoid Q1 procurement delays
Coordinate testing logistics to minimize operational disruption and keep projects moving
The earlier planning starts, the more flexibility you have.
4. Confirm Notification Letter Readiness
Most stack tests require advance regulatory notification — 30 days for Part 60 and Part 61, 60 days for Part 63. These letters must be signed by the Designated Representative and the Responsible Official. Confirm before year-end that:
Your DR and Responsible Official are current and authorized
A signed notification letter template is ready to submit when the test window is confirmed
You know which agency (EPA, state, or local) the notification goes to for each applicable test
Getting this wrong delays your test date and can create compliance exposure if you miss a deadline.
5. Coordinate Unit Outage Schedules With Operations
Get the Q1 outage schedule from your operations team before the holidays. Stack testing requires planned downtime and specific operating conditions — normal or worst-case operations depending on the applicable method. Without this coordination in hand, you can't confirm test windows with your contractor or submit notification letters on time.
6. Review Your Gas Cylinder Inventory
Gas vendors typically shut down or operate on reduced schedules over the holidays. Before year-end, confirm:
You have sufficient calibration gas cylinders on hand to carry you through the holiday period and into early Q1
Reference gas cylinders needed for upcoming linearity checks and RATAs are ordered, NIST-traceable, and not approaching expiration
Cylinder concentrations still match your current span settings
Running out of reference gas during a test window is an avoidable problem that a year-end inventory check prevents.
7. Review Hourly Max Values and Span Settings
Pull the highest hourly values recorded for SO2, NOx, CO2, and flow rate over the past year. If any values are approaching your current span or range settings, you may need a different blend of calibration or linearity gas cylinders heading into the new year. Catching this in December gives you time to adjust before testing begins.
8. Verify CEMS Readiness for Test Season
Your CEMS needs to be in a clean, passing state before a stack testing contractor arrives on site. A year-end CEMS review should confirm:
No unresolved out-of-control periods in recent calibration history
Daily calibration drift is within acceptable limits
Monitoring plan and QA/QC plan reflect current equipment configuration
Data Acquisition System is generating and archiving QA files correctly
A CEMS that isn't ready when the tester arrives can delay the test, invalidate runs, or require retesting — all of which add cost and compliance risk.
One Vendor for Both Sides of the Test
Most facilities manage CEMS compliance and stack testing through separate vendors. Alliance Technical Group is the one exception. As the largest stack testing provider in the U.S. and a full-service CEMS solutions provider — including our StackVision DAS, CEMS hardware, regulatory services, and ongoing compliance support — Alliance can coordinate both sides of your year-end planning through a single point of contact.
That means your CEMS readiness review, reference gas inventory, DAS configuration, and stack test scheduling can all be handled by one team that already knows your system.
