How to Perform a Method 9 Reading

Performing a VEO reading

After reviewing documentation, gathering equipment, and completing required field procedures, the observer is ready to read the visible emissions. This section covers the steps taken to complete a VEO reading. Filling out the VEO form is an integral part of the process and is covered in this section and the next.

Double-check field conditions and correct any issues. A reading may need to be postponed if conditions are not acceptable. Ensure the procedure has your full attention — do not text, talk on the phone, or perform other tasks while performing Method 9 observations.

The process

• Method 9 readings consist of observations at 15-second intervals over a period of six (6) minutes. A reading consists of 24 observations. Method 9 requires 24 consecutive observations. More than 24 observations may be required to meet the 24 sequential observations requirement if a reading is missed or another issue occurs.
• Observations are recorded to the nearest 5%.
• The resulting 24 observations are averaged to determine the opacity value.
• Method 9 prescribes that the observer shall not look continuously at the plume — observations are made by glancing at the plume at 15-second intervals.
• Use the comments field to document changes to the opacity or missed readings.

Recording the observations and determining the opacity