Data & Sampling Results

Worker breathing zone data (area samples and personal monitoring) indicate that gas and vapor concentrations are orders of magnitude lower than concentrations found in tank headspaces, consistent with the dispersion modeling results. Chemicals that have been detected in the worker breathing zones are well below occupational exposure limits.

Thousands of data points have been collected on each chemical and in each tank farm using state-of-the-art gas chromatography-mass spectroscopy equipment. All these data points for the last 35 years are presented in the sets below.

The samples taken are measured for many chemicals including current COPCs and beyond. If any chemical measured in the tank (headspace) are measured above 10% of OEL, they are placed on the COPC list.

These detailed analyses are performed over months after sampling due to the complexity of the analytical techniques.


Non-personal sampling data

The following graphs display headspace vapor concentrations for chemicals of potential concern (COPCs) in parts per million (ppm) and compared to the appropriate occupational exposure limit (OEL) for data collected during the specified time period. (Note: personal sampling/medical data is not included in this section to respect individual privacy.)


How to read the data sets

The sampling results from the headspace are the concentrations of chemicals in the air inside of the underground tanks.

The sampling results from the source are from passive breather filters in single-shell tanks which are protected through establishment of the Vapor Control Zones. “Source-ENV” samples are taken for environmental information and give additional data for vapor hazard monitoring.

The sampling results from the area are in the work zone. No samples have detected any chemicals above 10% of the Occupational Exposure Limit (OEL) in the area. The samples that reflect high Reportable Detection Limits (RDLs) have been analyzed numerous times to ensure confidence that chemicals are below the OEL.