Benzene Fenceline Monitoring Program

How the Program Works

Shell Norco implements the Benzene Fenceline Monitoring Program by utilizing passive absorption sampling, a process 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.

Public Communications

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 biweekly sampling period and can be found in the database below.