Evaluation of Benzene FencelineMonitoring Program in USEPA’s Proposed Refinery Sector RuleBy: Ted Bowie, Kimberly Wahnee, David Phong, and Idania Zamora

Overview of Refinery Source Category

• 142 large (major sources) and 7 small (area source) petroleum refineries in the United States

• EPA: Refineries emit ~20,000 tons per year hazardous air pollutants (HAPs)

• Proposed rulemaking includes amendments to Maximum Achievable Control Technology (MACT) standards and New Source Performance Standards (NSPS)

– MACT 1 (1995) covers non-combustion or evaporative sources (e.g., equipment leaks, tanks, wastewater, miscellaneous process vents, cooling towers)

– MACT 2 (2002) covers combustion sources (e.g., catalytic cracking units, catalytic reforming units, and sulfur recovery units)

– NSPS J/Ja (2012) covers fuel gas combustion devices, FCCU, sulfur plants, delayed cokers, flares, and process heaters

Data source: USEPA

Overview of Proposed Rule

• Proposal signed by EPA on May 15, 2014

• Emission control requirements for storage tanks, flares, and coking units

• Monitoring of benzene concentrations at refinery fencelines

• Eliminate exemptions to emission limits during periods of startup, shutdown, and malfunction

• Technical corrections and clarifications to the Petroleum Refinery NSPSs

What Does EPA’s Residual Risk Analysis Show?

• Risk deemed to be “acceptable” under 112(f)

• Highest maximum individual risk (MIR) estimated at 60 in a million (actuals) and 100 in a million (allowables)– Highest MIR driven by naphthalene and benzene from equipment leaks

• Sector-wide population at risk greater than 1 in a million is predicted at 5,000,000– Cancer incidence of 0.3 cases/year driven by delayed cokers (DCU) and

PAHs

• Maximum chronic non-cancer HI of 0.9 due to emissions hydrogen cyanide from FCCU

• Maximum acute non-cancer HQ of 5 due to emissions of nickel from FCCU

• Proposed amendments estimated to lower population at risk to 4,000,000, and reduce incidence about 18%

Rationale for Benzene FencelineMonitoring Program

• Purpose: “Backstop” to detect under-counted emissions (particularly fugitives)

• Certain emissions sources (e.g., fugitive leaks) difficult to quantify with methods currently available

• Uncertainties in emissions estimates related to mischaracterization of emission sources:– Exclusion of nonroutine emissions

– Omission of sources that are unexpected, not measured, or not considered part of the affected source

– Improper characterization of sources for emission models and emission factors

Data source: USEPA

Fenceline Monitoring Requirements

Small (<750 acres)

12 monitors

30° interval

90

180

27

0

0

27

0

Medium (750-1,500

acres)

18 monitors

20° interval

Large(>1,500 acres)

24 monitors

15° interval

Fenceline Monitoring Requirements (cont)

• Passive diffusive tube monitors

• Annual average of 2-week samples, calculated as:

• Compare to action level of 9 μg/m3

• Calculate rolling annual average within 30 days of completion of each sampling episode– If exceedance, initiate root cause analysis

– Develop corrective action plan and take corrective action

• Recordkeeping and Reporting – Report fenceline data within 45 days of the end of semiannual

periods

– Site specific ambient monitoring plan

HFC = Maximum (MFCi –OSCi)

Data source: USEPA

Potential Issues with Benzene FencelineMonitoring Requirements

• Possible community misunderstanding

• Monitoring results largely dependent on configuration of benzene sources

• Alternative chemicals may be better surrogates of fugitives from some refineries

• Identification of background or offsite contributors difficult with passive sampling approach

• Monitoring provides little (if any) information regarding which sources to control

• Significant cost

• No offramp for refineries with low benzene concentrations

Public Relations

• Fenceline concentrations are not representative of chronic risks, but some members of the public may misunderstand the data

• Stated purpose of benzene monitoring is to detect un-reported emissions, but…– Some might attempt to equate

benzene concentrations to risks

– Data will be publically available

Is Benzene the Best Surrogate for Fugitives?

• Total VOCs might be a better surrogate– Not all facilities have large benzene emissions

– Larger emissions of VOCs easier to measure/detect

– Affordable, real-time instrumentation for measurement of total VOCs (e.g., PID) allows correlation with wind direction

Benzene Total VOCs

Average Fugitive Emissions (% of total) 64% 64%

Total Emissions (1,000 TPY) 1.2 99

Facility Counts 142 142

Identification of Background Difficult with Passive Sampling

Facility 1

Facility 2

Facility 3

Identification of Background Difficult with Passive Sampling (cont)

Facility 1

Facility 2

Facility 3

Identification of Offsite Contributors Difficult with Passive Sampling

Facility 1

Facility 2

Facility 3

Identification of Offsite Contributors Difficult with Passive Sampling (cont)

Facility 1

Facility 2

Facility 3

Configuration Determines Whether Monitoring Provides Information on Which Sources to Control

Significant Cost

Costs for Fenceline Monitoring

Model PlantCapital Costs (US$) Annualized Cost (US$)

In-House Analysis

Outsourced Analysis

In-House Analysis

Outsourced Analysis

Small 85,440 21,370 36,300 64,200

Medium 86,650 22,580 41,000 86,900

Large 88,270 23,960 45,900 109,700

• Does not include costs for:– Site specific monitoring plan

– Root cause analysis

– Corrective action plan and implementation

Strategies to Overcome Program Limitations

• Conduct dispersion modeling– Identify which sources are

driving benzene concentrations

– Identify benzene “hot spots”

• Perform meteorological data analysis– Determine if winds are consistent, or if diurnal or seasonal

variations are present

– Identify which monitors are upwind and downwind (if possible)

Strategies to Overcome Program Limitations (cont)

• Consider additional monitors– Offsite monitors can help tease

out background and offsite sources

– Onsite monitors can help identify larger fugitive sources (e.g., LDAR)

• Consider focused real-time monitoring – Determine if concentrations due to onsite or offsite sources

– Identify and correct problems quicker than with passive approach

– Options range from simplistic (e.g., PID) to more sophisticated (e.g., UV-DOAS)

Questions?

Ted Bowie, MS, PE, CIHENVIRON International Corporation

San Francisco, California

tbowie@environcorp.com