Appendix 1 Emissions Inventory Support MemorandumMarine Tank Vessel Loading Operations1 MEMORANDUM

TO: Anne Pope, EPA

FROM: Darcy Wilson, ERG

DATE: July 23, 2010

SUBJECT: Emissions Data Used in Residual Risk Modeling for Marine Vessel Loading Operations

The purpose of this memorandum is to provide information on the RTR database used in estimating residual risk for the Marine Vesse l Loading Operations Maximum Achievable Control Technology (MACT) source category.

BACKGROUND

Section 112 of the Clean Air Act (CAA) establ ishes a two-stage regu latory process to address emissions of hazardous air pollutants ( HAPs) from stationary sources. In the first stage, section 112(d) requires the Environmental Protecti on Agency (EPA) to develop technology-based standards for categories of industrial sour ces. In the second stage, known as the residual risk stage, section 112( f)(2) requires EPA to a ssess the health and

environmental risks that remain after sour ces come into compliance with MACT. If

additional risk reductions are ne cessary to protect public health with an ample margin of safety or to prevent adverse environmenta l effects, EPA must develop standards to address these remaining risks. As part of this second stage, data were gathered to assess

the residual risks from the Marine Vessel Loading Operations MACT source category.

EMISSIONS DATA USED IN RESIDUAL RISK MODELING

The 2002 National Emissions Inventory (NEI) data served as the star ting point for this assessment. Using the process MACT code, 1 a subset of the NEI was developed that contained facility, process, and emissions da ta for each facility in the Marine Vessel Loading Operations source category (MACT code 0603). The 2002 NEI data for Marine Vessel Loading Operations we re released through an Advanced Notice of Proposed Rulemaking (ANPRM) in March of 2007, wher e NEI revisions for facilities in the MACT source category were solicited from State and local agencies, industry representatives, and EPA. The revisions that were provided to EPA were incorporated into the NEI prior to th e initial NATA modeling.

Risks associated with facilities covered by the Marine Vessel Loading Operations MACT

standard were modeled in the initial 2005 NAT A risk assessment in June of 2009. EPA reviewed the results of this analysis, and pe rformed an in-depth review of the NEI data

1 Assigning data with MACT codes allows EPA to determine reductions attributable to the MACT program. The NEI associates MACT codes corresp onding to MACT source categories with stationary major and area source data.2 set for the source category. The NEI was revi ewed to identify additional processes with Marine Vessel Loading Operation Source Clas sification Codes (SCCs), and the NEI data were compared with data in the EPA’s Toxic Release Inventory (TRI). MACT code and

emission revisions were made as a result of thes e analyses. For facilities in the NEI that have Marine Vessel Loading Operations but do not have HAP emission estimates (only volatile organic compound (VOC) estimates, EP A applied speciation profiles to develop surrogate HAP emission estimates. EPA also id entified two facilities that are not subject to the Marine Vessel Loading Operations NESHAP.

EPA evaluated the facility-wide risks for Ma rine Vessel Loading Operations using the

2005 NEI data and risk assessment results th at were released in the 2005 NATA Risk Preview with State and local agencies in June of 2010. Revisions were made to the emission estimates for one facility. Two fac ilities were removed from the category—one was not subject to the NESHAP, and the other has ceased marine vessel loading operations. These revisions were included in the risk analyses, and will be reflected in the

final NATA risk assessment.