Benzene Fenceline Monitoring Program
The Shell Norco Manufacturing Complex conducts bi-weekly passive sampling along the facility property boundary for the target analyte of benzene. The passive samples are collected and analyzed in accordance with Methods 325A and 325B of Appendix A to 40 CFR Part 63.
These Methods call for passive absorption sampling in which clean absorbent tubes are deployed and collected every two-weeks and sent to a laboratory for concentration analysis. When used tubes are collected, a new set of tubes is immediately deployed to begin the next two-week sampling period.
From these sampling results, a period benzene concentration delta (Δc) is calculated using the minimum and maximum individual monitor results. An annual rolling average using 26 period ΔC’s is also calculated and compared against the action level of 9 µg/m3. Within 5 days of determining that the action level has been exceeded for any annual average Δc and no longer than 50 days after completion of the sampling period, Shell Norco will initiate a root cause analysis (RCA). Once corrective actions are implemented, if the next period following implementation is also above the action level, Shell Norco will develop a corrective action plan and submit to the USEPA within 60 days.
As part of this program, Shell Norco will post the individual sample result for each monitor, each biweekly annual average concentration difference value, as well as any corrective action plans submitted to the USEPA. The sample results will be posted within 30 days of the end of the bi-weekly sampling period.