MEMORANDUM

DATE: August 12, 2010 

SUBJECT: Update Emissions Data Used in Residual Risk Modeling for the Marine Tank 

Vessel Loading Operations Source Category 

 EPA Contract No.: EP-D-06-118; EPA Project No.: 4-15 

 RTI Project No.: 0210426.004.015 

FROM: Karen Schaffner, RTI International 

TO: Stephen Shedd and Mary Tom Kissell, EPA 

 The purpose of this memorandum is to provide a update of emission data1 used in 

estimating residual risk for the Marine Tank Vessel Loading Operations (MTVLO) source 

category for the October 2008 RTR proposal (73 FR 60432; October 10, 2008). 

I. BACKGROUND 

Section 112 of the Clean Air Act (CAA) establishes a two-stage regulatory process to 

address emissions of hazardous air pollutants (HAPs) from stationary sources. In the first stage, 

section 112(d) (2) requires the Environmental Protection Agency (EPA) to develop technologybased standards for categories of industrial sources. In the second stage of the regulatory 

process, EPA is required under section 112(f)(2) to assess the health and environmental risks that 

remain after sources come into compliance with MACT.

As part of this second stage in the regulatory process, EPA is evaluating the risks 

remaining after implementation of the MTVLO MACT. In the current risk assessment analysis, 

data from the 2005 NEI/NATA database for MTVLO were used.

II. Emissions Estimate for the MTVLO Source Category 

The estimate of the number of facilities and the HAP emissions from the MTVLO source 

category have changed over time due to changes in the industry and the addition or closing of 

MTVLO at facilities. For example, in 1995 when the MTVLO MACT was promulgated, there 

were approximately 1,500 facilities that conducted MTVLO, and an analysis for calendar year 

(CY) 2000 showed that there were approximately 800 facilities that conducted MTVLO. The 

progression over time of facilities and the emissions data for the MTVLO source category are 

described below. The discussions include the MACT development (proposal and then 

promulgation in 1995), an analysis conducted for CY2000, the 2002 NEI dataset, and the current 

2005 NEI/NATA data set. 

 

1 Emissions Data Used in Residual Risk Modeling for the Marine Vessel Loading Source Category. K. Schaffner, 

RTI to D. Markwordt and M. Kissell, EPA. June 10, 2008, Attachment to docket item EPA-HQ-OAR-2008-0026.1. 
2 

A. MACT Development for MTVLO 

Table 1 presents a summary of the estimates used during the development of the MACT 

rule. The Waterborne Commerce Statistics Center (WCSC) database for the U.S. was used as 

the basis of the impacts analysis in the development of the MACT for MTVLO. The WCSC 

database contains detailed information on the types and quantities of commodities loaded and 

unloaded at U.S. ports, harbors, waterways, and canals. The analysis at proposal and 

promulgation of the MACT included all facilities in the source category. 

Table 1. Data for MACT Development for MTVLO

No. of facilities 

Uncontrolled HAP 

emissions, Mg 

Controlled HAP 

emissions, Mg 

Average emissions per 

facility, Mg/facility 

Full MTVLO source 

category (area sources and 

major sources) 

1500 8,000 1,400 0.97 Mg/fac 

Valdez Marine Terminal 1 5,021 100 NA 

Major sources (required to 

install MACT controls) 50 1,600 50 1.0 Mg/fac 

Other sources (both Area, 

and Major sources subject 

to MACT) 

1449 1,400 1,400 NA 

All Major Sources with 

MTVLO 300 Not calculated 

Number of Facilities. For the source category, we estimated that there were 

approximately 1,500 facilities conducting MTVLO (including petroleum refineries) and the HAP 

emissions were 1,400 Mg. At proposal of the MTVLO MACT,, we estimated that 300 to 360 

major source facilities were subject to the proposed MACT.2, 3 At promulgation of the MTVLO 

MACT rule, we estimated that approximately 50 major source facilities would need to install 

controls but did not publish an estimate of all the major sources that would be subject to the final 

rule. Between proposal and promulgation of the MTVLO MACT, we revised the rule to exclude 

MTVLO at refineries since they are covered by the refinery rule (there were approximately 130 

refineries at promulgation of the petroleum refinery rule at 40 CFR subpart CC, and 150 

petroleum refineries today). Thus at promulgation of the MTVLO rule, the number of subject 

facilities (i.e., major sources) could be somewhat less than 300 to 360, however, to ensure that 

we don’t underestimate emissions, for this analysis we will assume that approximately 300 major 

source facilities in the MTVLO source category, consistent with the MACT development. 

 Uncontrolled Emissions Estimates at MACT Promulgation. The uncontrolled emission 

estimates for marine vessel loading operations derived from the WCSC data base showed 

 

2

 59 FR 25004; May 13, 1994. 

3

 Calculation of a MACT Floor for Title III Rulemaking for Marine Vessel Loading Operations. T. Campbell, 

MRI, to D. Markwordt, U.S, EPA. September 30, 1993. 
3 

approximately 8,000 Mg of HAP prior to implementation of the MACT.4 (The uncontrolled 

emissions from the Valdez terminal in Alaska accounted for 5,000 Mg of these HAP.) 

• 1,600 Mg of HAP were emitted from approximately 50 terminals, and 

• 1,400 Mg of HAP from the remaining terminals. 

Emissions Estimates Following Implementation of MACT. We estimated that 1,600 Mg 

of HAP are emitted from approximately 50 terminals required to install controls under the 

MTVLO MACT. Following implementation of MACT (ignoring the Valdez terminal5), the 

WCSC emissions for marine vessel loading operations was estimated to be 1,400 Mg of HAP. 

The average HAP emissions per facility was estimated to be 0.97 Mg HAP from MTVLO (i.e., 

1,400 Mg divided by 1,500 facilities is 0.97 Mg/facility). The 1,400 Mg of HAP was estimated 

as follows: 

• 50 Mg of emissions from MACT controlled terminals: 1,600 Mg of HAP was 

reduced by 97 percent MACT requirement to 50 Mg of emissions, i.e., 1,600 x (1-

0.97), and 

• 1,400 Mg of HAP emitted from the remaining terminals. 

B. Calendar Year 2000 

For calendar year (CY) 2000, we conducted an analysis to determine the number of 

facilities and the HAP emissions from the MTVLO source category. The WCSC database was 

also used for the CY2000 analysis. The analysis in 2000 included all facilities in the source 

category. For CY2000, there were approximately 800 facilities and the HAP emissions were 900 

Mg, as shown in Table 2. 

Table 2. Data for CY2000 MTVLO

No. of 

facilities 

Uncontrolled HAP 

emissions, Mg 

Controlled HAP 

emissions, Mg 

Average emissions 

per facility, 

Mg/facility 

Full MTVLO source category 800 2,400 900 1.1 Mg/fac 

Major sources (required to 

install MACT controls) 50 1,520 58 1.2 Mg/fac 

Other sources (both Area, and 

Major sources subject to 

MACT) 

750 845 845 NA 

All Major sources 300 Not calculated Not calculated Not calculated 

 

4

 Technical Support Document for Proposed Standards: VOC/HAP Emissions from Marine Vessel Loading 

Operations. U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA450/3-92/011a. May 1992. 

5

 Emissions from the VMT were estimated to be approximately 100 Mg, i.e., 5,000 Mg uncontrolled emissions 

reduced by 98 percent, is 100 Mg. 
4 

Number of Facilities. Under this analysis, we estimated for CY 2000 that there are 

approximately 800 terminals in the marine vessel loading source category. Approximately 50 

terminals (major sources) are required to control MTVLO emissions under the MACT 

requirements. This estimate was based on several assumptions, including all terminals are 

collocated at major sources, the terminals are contiguous if collocated, and the terminals are bulk 

loading and thus included in the source category. Transportation of sealed containers are also 

likely included in the estimate of 800 terminals, however this activity should not be part of the 

source category (and would not result in emissions). 

Emissions Estimates for CY2000. Under this analysis, we estimated from WCSC 

database for calendar year 2000 that there are 1,500 Mg of uncontrolled HAP emitted from 

approximately 50 terminals would need to install controls under the MACT.6, 7 There are 

another 850 Mg of HAP that are emitted from the remaining terminals. The total uncontrolled 

HAP emissions were estimated to be 2,400 Mg for the source category. On a controlled basis, 

considering application of MACT control requirements, the total emissions from the source 

category were estimated to be 900 Mg of HAP for the 800 terminals. The average HAP 

emissions per facility is 1.1 Mg HAP (i.e., 900 Mg of HAP divided by 800 facilities is 1.1 

Mg/facility). 

• 50 Mg of emissions from MACT controlled terminals: 1,500 Mg of HAP was 

reduced by 97 percent MACT requirement to 50 Mg of emissions, i.e., 1,500 x (1-

0.97), and 

• 850 Mg of HAP emitted from the remaining terminals. 

C. NEI Emissions Dataset for 2002 

For the October 2008 RTR proposal, we used the most recent data from EPA’s NEI (year 

2002). The analysis based on the 2002 NEI included a subset of facilities in the MTVLO source 

category. There were 135 facilities and the MTVLO HAP emissions from the 2002 NEI were 

230 Mg, as shown in Table 3. 

 

6

 Assessing Residual Risk for Marine Vessel Loading Operations. Memorandum from B. Riddle, Alpha-Gamma 

Technologies, Inc., to D. Markwordt, EPA/ESD. October 10, 2002. 

7

 Calendar Year 2000 HAP Emissions Estimates from Marine Vessel Loading. From B. Riddle, Alpha-Gamma 

Technologies, Inc. Table 2-3, Estimated HAP Emissions from Marine Vessel Loading Prior to the NESHAP, and 

Table 2-4, Estimated HAP Emissions from Marine Vessel Loading after Compliance with the NESHAP. 
5 

Table 3. Data for 2002 NEI Dataset 

No. of facilities Reported MTVLO 

HAP emissions, Mg

Average emissions per 

facility, Mg/facility 

2002 NEI data set

135 230 1.7 Mg/fac 

Major sources in 2002 NEI (based on NEI 

identification as subject to MACT or current 

total facility emissions) 129 226 1.8 Mg/fac 

Area sources in 2002 NEI

6 3.6 0.60 Mg/fac 

Number of Facilities. The 2002 NEI HAP emissions data were used as the basis of the 

Residual Risk analysis for the initial October 2008 RTR proposal. The 2002 NEI database 

contained 135 facilities emitting 230 Mg (250 ton/yr) HAP.8 (The 230 Mg includes the 

emissions from the Valdez, Alaska terminal with 5.5 Mg of emissions following controls.) The 

average HAP emissions per facility in the 2002 NEI dataset was 1.7 Mg HAP for MTVLO (i.e., 

230 Mg divided by 135 facilities is 1.7 Mg/facility). There were 129 facilities identified as major 

sources in the dataset, with emissions of 226 Mg (the average HAP emissions per facility is 1.7 

Mg/facility, i.e., 226 Mg divided by 129 facilities is 1.7 Mg/facility), and there were 6 facilities 

that were identified as area sources of HAP and emissions are 3.6 Mg (the average HAP 

emissions per facility is 0.60 Mg/facility, i.e., 3.6 Mg divided by 6 facilities is 0.60 Mg/facility). 

D. NEI/NATA Emissions Dataset for 2005 

Currently, we are using the most recent data from the NEI/NATA (year 2005). The 

analysis based on the 2005 NEI/NATA includes a subset of facilities in the MTVLO source 

category. The MTVLO HAP emissions from the 2005 NEI were 450 Mg and there are 223 

facilities in dataset, as shown in Table 4. 

Table 4. Data for 2005 NEI/NATA Dataset 

Facilities with MTVLO No. of facilities Reported MTVLO 

HAP emissions, Mg

Average emissions per 

facility, Mg/facility 

2005 NEI data set 223 450 2.0 Mg/fac 

Major sources in 2005 NEI (based on 

NEI identification as subject to MACT or 

current total facility emissions) 

152 380 2.5 Mg/fac 

Area sources in 2005 NEI 71 64 0.90 Mg/fac 

Number of Facilities. The 2005 NEI/NATA database contains 223 facilities with 

MTVLO. The HAP emissions for MTVLO at these facilities are 450 Mg (490 ton) HAP.9 The 

 

8

 NPRM Dataset for Marine Vessel Loading. For October 10, 2008, Proposal of Marine Vessel Loading Risk and 

Technology Review. Docket item No. EPA-HQ-OAR-2008-0008-0019. 

9

 NPRM Dataset for Marine Vessel Loading. For 2010 Re-Proposal of Marine Vessel Loading Risk and 

Technology Review. 
6 

average HAP emissions per facility in the 2005 NEI/NATA dataset was 2.0 Mg HAP for 

MTVLO (i.e., 450 Mg divided by 223 facilities is 2.0 Mg/facility). There are 152 facilities 

identified as major sources in the dataset, with emissions of 380 Mg HAP (420 ton), and there 

are 71 facilities that are identified as area sources of HAP and emissions are 64 Mg (70 ton). 

E. Current Estimates for Major Source Facilities and Emissions 

The data analyses conducted over time for the MTVLO source category have shown that 

the number of facilities in the U.S. with MTVLO has declined over time. The data analysis in 

1995 showed that there were approximately 1,500 facilities with MTVLO and by 2000, the 

number of facilities had declined to 800 facilities. The average HAP emissions per facility value 

for the full source category data is typically 1 Mg/facility, with 0.97 Mg/facility in 1995 and 1.1 

Mg/facility in 2000. 

Unfortunately, we do not have data on a consistent basis over time to determine the major 

source facilities subject to this MACT standard. The datasets based on the WCSC included all 

facilities in the source category. The later datasets from the EPA NEI and NEI/NATA contain 

approximately half of the facilities in the source category but not all. Currently, we believe there 

are 300 major source facilities with MTVLO subject to this MACT, based on information from 

MACT development (see section II.A). Of those, we identified 152 facilities in the most recent 

NEI. Thus we applied a ratio of 300/152 to emissions shown in Table 5 to estimate total major 

source emissions. The emissions estimate for major source facilities is 760 Mg (840 ton). 

Table 5. Current Estimates for Major Source Facilities and Emissions Subject to MTVLO 

MACT 

Facilities with MTVLO No. of facilities MTVLO HAP 

emissions, Mg 

Average emissions per facility 

in NEI, Mg/facility 

Major Sources (Subject to MTVLO MACT) 

Major sources in 2005 NEI (based on 

NEI identification as subject to MACT 

or current total facility emissions) 

152 380 2.5 Mg/fac 

Estimate for Total Major Sources 300 760 NA