EC

/R Incorporated Providing Environmental Technical Support Since 1989

501 Eastowne Drive, Suite 325 y Chapel Hill, North Carolina 27514 

Telephone: (919) 484-0222 y Fax: (919) 484-0122 

 

MEMORANDUM 

DATE: February 15, 2010 

SUBJECT: MACT Floor Determination for Existing Stationary Non-Emergency CI RICE 

Less Than 100 HP and Existing Stationary Emergency CI RICE Located at Major 

Sources and GACT for Existing Stationary CI RICE Located at Area Sources 

FROM: Bradley Nelson and Tanya Parise, EC/R, Inc. 

 

TO: Melanie King, EPA OAQPS/SPPD/ESG 

1.0 PURPOSE 

The purpose of this memorandum is to document the analysis of the maximum 

achievable control technology (MACT) floor and MACT for existing stationary non-emergency 

compression ignition (CI) reciprocating internal combustion engines (RICE) less than 100 

horsepower (HP) and existing stationary emergency and black start CI engines located at major 

sources. The generally achievable control technology (GACT) for existing stationary CI RICE 

located at area sources of hazardous air pollutants (HAP) emissions that are subject to National 

Emission Standards for Hazardous Air Pollutants (NESHAP) is also presented in this 

memorandum. 

The analysis for existing stationary non-emergency CI engines greater than or equal to 

100 HP located at major sources of hazardous air pollutants (HAP) emissions is presented in a 

separate memorandum titled “MACT Floor Determination for Existing Stationary NonEmergency CI RICE Greater Than or Equal 100 HP Located at Major Sources,” which is 

available in the rulemaking docket (EPA-HQ-OAR-2008-0708). 

2.0 INTRODUCTION

The EPA has developed a regulation addressing toxic air emissions from the following 

existing stationary CI RICE engines: 1) engines that are located at area sources of HAP 

emissions; 2) engines that are less than or equal to 500 HP and are located at major sources of 

HAP emissions; and 3) non-emergency CI engines that are greater than 500 HP and are located 

at major sources of HAP emissions. The regulation was developed following criteria set forth 

under section 112 of the Clean Air Act (CAA). Section 112(d) of the CAA stipulates that EPA 

must promulgate emission standards that require the maximum degree of HAP reduction. 

According to 112(d)(3)(A) of the CAA, the emission standards for existing major sources must 

be no less stringent than the average emission limitation achieved by the best performing 12 

percent of existing sources for which the Administrator has emissions information. For existing 
2 

area sources, EPA has the option under 112(d)(5) of the CAA to promulgate emission standards 

or requirements GACT or management practices in order to reduce HAP emissions. The EPA 

has previously issued a similar regulation affecting existing and new stationary RICE greater 

than 500 HP at major sources, which was promulgated in 2004 and for new stationary RICE less 

than or equal to 500 HP at major sources, which was promulgated in 2008. 

Section 112 of the CAA outlines the statutory requirements for the EPA’s stationary 

source air toxics program. Section 112(k) of the CAA requires the development of standards for 

area sources which account for 90 percent of the emissions in urban areas of the 33 urban HAP 

listed in the Integrated Urban Air Toxics Strategy (UATS). These area source standards can 

require control levels which are equivalent to either MACT or GACT, as defined in the CAA 

under section 112(d)(2) and (3) and section 112(d)(5), respectively. 

Section 112 of the CAA allows the EPA to establish subcategories among a group of 

sources. A complete discussion of the subcategory selection is presented in a separate 

memorandum.1

 

3.0 MACT FLOOR AND MACT DETERMINATION 

Non-Emergency CI Engines <100 HP

 For stationary CI engines less than 100 HP, EPA determined that it is not feasible to 

prescribe or enforce an emission standard because the application of measuring methodologies to 

this subcategory of engines is not practicable due to technological and economic limitations. In 

order to measure the CO emissions from these engines in terms of volumetric concentration on a 

dry basis and corrected to 15 percent oxygen (O2), the following test methods are required: 

• EPA Method 1 or 1A for selection of sampling ports; 

• EPA Method 3, 3A, or 3B or ASTM Method D6522-00 (2005) for determining the O2

concentration; 

• EPA Method 4 for measuring the moisture content; and 

• EPA Method 10 or ASTM Method D6522-00 (2005) for measuring the carbon 

monoxide (CO) concentration. 

The test methods require the sample point to be a certain distance between the engine and 

the exhaust. Because engines below 100 HP often have exhaust pipes with very small diameters 

and lengths, stack testing using these methods could require a modification or extension of the 

exhaust pipe to accomplish the test. Furthermore, the cost of performing a stack test ranges from 

approximately $1,000-5,000 depending on the method used. Generally, 100 HP engines cost 

around $5,000-$7,000 and 50 HP engines cost approximately $4,000-$5,000, so the cost of 

performance testing could approach the cost of the engine itself. Given the cost of the testing 

itself, the physical adjustments necessary to accomplish the test, and the particular circumstances 

pertaining to engines below 100 HP, EPA believes that the application of measurement 

methodology to this class of engines is not practicable due to technological and economic 

 

1

 Memorandum from Bradley Nelson and Tanya Parise, EC/R Inc. to Melanie King, EPA OAQPS/SPPD/ESG, 

Subcategorization of Existing Stationary CI RICE (see EPA-HQ-OAR-2008-0708). 
3 

limitations. Therefore, work practices are the MACT floor for existing stationary nonemergency CI engines less than 100 HP. 

To determine the work practices, EPA reviewed information obtained from different 

manufacturers and operators of CI engines. The EPA has determined that the maximum 

achievable control, based on the work practices of the best controlled engines, is to maintain and 

replace the following stationary engine components: oil and oil filter, air cleaner, hoses, and 

belts. According to information received from manufacturers and operators of stationary 

engines, these parameters are the most appropriate to ensure proper operation for minimizing 

HAP emissions. Each of these work practices limit HAP emissions by allowing the engine to 

operate at peak efficiency. Changing the oil and oil filter reduces the wear on the pistons and 

cylinders and limits the amount on worn metals that may be introduced to the exhaust stream. 

Inspecting the air filter limits the introduction of oil mist and other contaminants to the 

combustion chamber. Inspecting the belts and hoses ensures that the engines cooling and 

electrical systems are operating, therefore eliminating the burning of oil and ensuring that the 

electrical systems are functioning as intended. 

Intervals for checking, inspecting and replacing the oil and oil filter, air cleaner, hoses, 

and belts vary with engine makes and models, application, location, and other factors, therefore 

making it difficult to define specific maintenance intervals that would be represent the operation 

of the best controlled engines. However, EPA must promulgate specific requirements pursuant 

to section 112(d) of the CAA and the information indicates that there are commonalities in 

maintenance interval frequencies for the best controlled engines. Based on the information 

provided, EPA believes that the work practices below are what the best controlled existing 

stationary non-emergency CI engines less than 100 HP are currently doing and for that reason 

the MACT floor for these engines is work practices as follows: 

• changing the oil and oil filter every 1,000 hours of operation or annually, whichever 

comes first; 

• inspecting the air cleaner every 1,000 hours of operation or annually, whichever 

comes first; and 

• inspecting all hoses and belts and replacing as necessary every 500 hours of operation 

or annually, whichever comes first. 

 As discussed above, current maintenance procedures vary from engine to engine based on 

a number of factors including engine design, fuel, operating characteristics, and so on. 

Maintaining the oil however, is, one of the most important activities operators can perform to 

minimize emissions and to ensure proper operation and performance. 

 In addition to following a set schedule for checking and replacing the oil, it is also 

common that the oil is monitored through an oil analysis program where the oil is periodically 

sampled to determine oil quality. Based on the oil sample that is extracted, an oil analysis can be 

performed that can indicate if it is time to replace the oil or if the existing oil has not reached 

condemning limits it can continue to be used. Based on the analysis a decision can be made 

whether to drain and replace the oil or if the oil change interval can be extended if the properties 

of the oil are within acceptable limits. Appropriate parameters and condemning limits that 
4 

would indicate oil degradation and the presence and quantity of contaminants varies. However, 

EPA has determined that the parameters that would most appropriately indicate the oil quality 

are the total base number (TBN), viscosity, and water content. The TBN is an indication of the 

alkalinity of the oil and the viscosity of the oil is a measure of how well the oil flows and these 

parameters are, along with water content, measures of the condition of the oil. If the following 

levels below as measured through an oil analysis program are exceeded, EPA has determined 

that an oil change must be performed: 

• TBN is less than 30 percent of the TBN of the oil when new; or 

• viscosity of the oil has changed by more than 20 percent from the viscosity of the oil 

when new; or 

• percent water content (by volume) is greater than 0.5. 

 No other regulatory options beyond the MACT floor were identified as appropriate for 

existing stationary non-emergency CI engines below 100 HP. Therefore, MACT for HAP 

emissions is equivalent to the MACT floor for these engines. 

Emergency CI Engines 

 For existing stationary CI emergency engines located at major sources, EPA determined 

it is not feasible to prescribe or enforce an emission standard because the application of 

measurement methodology to this class of engine is impracticable due to the technological and 

economic limitations. Emergency engines typically only operate during emergencies or during 

periods of routine testing and maintenance. EPA determined that application of the emissions 

measurement methodologies during either of these periods is not practicable. It is impracticable 

to test emissions from stationary CI emergency engines during periods of routine testing and 

maintenance using the test procedures specified in the rule because it would increase the required 

number of hours of operation of the engine beyond the routinely scheduled reliability testing and 

maintenance operation, thereby increasing emissions. While emergency engines have periods of 

operation for scheduled maintenance and reliability testing, those periods are usually several 

hours shorter than the number of hours that would be required to run the necessary emissions 

tests under subpart ZZZZ. CARB conducted a survey of stationary emergency diesel engines in 

20022 to determine the average number of hours that stationary emergency diesel engines 

operate. The average hours of operation for maintenance and testing were 22 hours per year, 

which is less than two hours per month. For the engines that CARB surveyed, 86 percent 

operated less than 30 hours/year for testing and maintenance. Thirty percent operated less than 

10 hours/year. National Fire Protection Association (NFPA) codes require that stationary diesel 

engines that are used for emergency purposes are run 30 minutes per week (27 hours per year) 

for maintenance and testing purposes. It is also impracticable to apply the testing methodologies 

required in this rule to test the stationary engines during periods of emergency operation because 

emergencies are unplanned events and and implementation of the procedures specified in subpart 

ZZZZ require advance planning before tests are conducted. In an emergency, the owner/operator 

 

2

 California Air Resources Board Staff Report: Initial Statement of Reasons for Proposed 

Rulemaking. Airborne Toxic Control Measure for Stationary Compression Ignition Engines. 

Stationary Source Division, Emissions Assessment Branch. September 2003. 
5 

does not have the advance planning time necessary to implement subpart ZZZZ. It is also 

impracticable to test stationary CI emergency engines at major sources because of the large 

population of these engines. EPA estimates that there are over 200,000 existing stationary CI 

emergency engines from 100-500 HP at major sources that are subject to this rulemaking. There 

are only approximately 300-400 testing firms and these stationary engines are not the only 

sources that are required to be tested, so if testing were required for these engines, it would take 

many years to test all of these engines. The cost for testing all of these engines would be in 

excess of $200 million and would clearly also be unreasonable. 

For these reasons, work practices are appropriate and justified for this group of stationary 

engines because the application of measurement methodology is not practicable due to 

technological and economic limitations. Consequently, work practices are the MACT floor for 

existing stationary emergency CI engines located at major sources. 

Again, in order to determine the work practices for stationary emergency engines at 

major sources, EPA reviewed information obtained from different manufacturers and operators 

of CI engines. For the same reasons as discussed above for existing stationary non-emergency 

engines less than 100 HP at major sources, EPA has determined that maximum achievable 

control, based on the work practices of the the best controlled emergency engines, is to maintain 

and replace the following stationary engine components: oil and oil filter, air cleaner, hoses, and 

belts. EPA discussed above the effect that maintaining these parameters have on HAP 

emissions. 

As stated, intervals for checking, inspecting and replacing these components vary from 

engine to engine and determining specific maintenance intervals that would be represent the 

operation of the best controlled emergency engines is challenging. However, EPA must 

promulgate specific requirements pursuant to section 112(d) of the CAA and the information 

indicates that there are commonalities in maintenance interval frequencies for the best controlled 

engines. Based on the information provided, EPA believes that the below maintenance practices 

are what the best controlled existing stationary emergency CI engines are currently doing and for 

that reason, the MACT floor for these engines is maintenance practices as follows: 

• changing the oil and oil filter every 500 hours of operation or annually, whichever 

comes first; 

• inspecting the air cleaner every 1,000 hours of operation or annually, whichever 

comes first; and 

• inspecting all hoses and belts and replacing as necessary every 500 hours of operation 

or annually, whichever comes first. 

The changing of oil and the oil filter for stationary emergency engines is more frequent on an 

hourly basis than for non-emergency engines because of the nature of operation of these engines, 

which is for standby and intermittent use, and thus requires less hourly use over the same period 

of time, and oil quality is reduced over time even during periods when the engine is not used. 

 Emergency CI engines also have the option to use an oil analysis program to indicate if it 

is time to replace the oil or if the existing oil has not reached condemning limits it can continue 
6 

to be used. The provisions of the oil analysis program are the same discussed above for nonemergency CI engines <100 HP. 

 No other regulatory options beyond the MACT floor were identified as appropriate for 

existing stationary emergency CI engines at major sources. Because these engines are typically 

used only a few number of hours per year, the costs of emission control are not warranted when 

compared to the emission reductions that would be achieved. The cost per ton estimates for 

stationary emergency CI engines can be found in the memorandum entitled “Cost per Ton of 

HAP Reduced for Existing Stationary CI RICE” in the rulemaking docket (EPA-HQ-OAR-2008-

0708). Therefore, MACT for HAP emissions is equivalent to the MACT floor for these engines. 

Black Start Engines

 Black start engines are used solely to start up combustion turbines. They operate for very 

short durations and have the same issues as emergency CI engines based on their unique and 

limited operation. According to information received during the public comment period, black 

start engines typically operate no more than 10 minutes at a time and only operate during 

emergencies or during periods of high demand (see for example EPA-HQ-OAR-2008-0708-0088 

and 0129). The short time of operation makes testing of black start engines using the required 

procedures impracticable. Therefore, work practices are the MACT floor for existing stationary 

black start engines located at major sources and are as follows: 

• changing the oil and oil filter every 500 hours of operation or annually, whichever 

comes first, with the option to use an oil analysis program as discussed above; 

• inspecting the air cleaner every 1,000 hours of operation or annually, whichever 

comes first; and 

• inspecting all hoses and belts and replacing as necessary every 500 hours of operation 

or annually, whichever comes first. 

As with stationary emergency CI engines, no other regulatory options beyond the MACT 

floor were identified as appropriate for existing stationary black start engines at major sources. 

The limited operating time also makes applying aftertreatment to black start engines not 

effective. In addition, these engines operate a few hours per year, making further regulation of 

these engines economically impractical. Therefore, MACT is equivalent to the MACT floor for 

these engines. 

4.0 GACT DETERMINATION 

Under CAA section 112(d)(5), EPA may elect to promulgate standards or requirements 

for area sources "which provide for the use of generally available control technologies or 

management practices by such sources to reduce emissions of hazardous air pollutants." 

Additional information on generally available control technologies (GACT) or management 

practices is found in the Senate report on the legislation (Senate report Number 101-228, 

December 20, 1989), which describes GACT as: 
7 

. . . methods, practices and techniques which are commercially available and appropriate 

for application by the sources in the category considering economic impacts and the technical 

capabilities of the firms to operate and maintain the emissions control systems. 

 

Determining what constitutes GACT involves considering the control technologies and 

management practices that are generally available to the area sources in the source category. 

EPA also considers the standards applicable to major sources in the same industrial sector to 

determine if the control technologies and management practices are transferable and generally 

available to area sources. In appropriate circumstances, EPA may also consider technologies and 

practices at area and major sources in similar categories to determine whether such technologies 

and practices could be considered generally available for the area source category at issue. 

Finally, as EPA has already noted, in determining GACT for a particular area source category, 

EPA considers the costs and economic impacts of available control technologies and 

management practices on that category. 

Emergency CI 

For existing stationary emergency CI engines located at area sources, EPA believes that it 

is appropriate to set GACT to be the same requirements as is required for emergency engines at 

major sources because the same issues that were discussed above for stationary emergency CI 

engines at major sources apply to emergency CI engines at area sources. There is no reason why 

the requirements for engines located at area sources pursuant to GACT should be different than 

those for engines located at major sources. The management practices are generally available 

and being located at an area source does not prevent the engine from being maintained 

appropriately and according to how engines at major sources are being maintained. Further, the 

management practices do not present an economic burden on area source engines and are for that 

reason also considered appropriate. Therefore, GACT for existing stationary emergency CI 

engines at area sources is the use of management practices as follows: 

• changing the oil and oil filter every 500 hours of operation or annually, whichever 

comes first, with an option to use an oil analysis program as discussed above; 

• inspecting the air cleaner every 1,000 hours of operation or annually, whichever 

comes first; and 

• inspecting all hoses and belts and replacing as necessary every 500 hours of operation 

or annually, whichever comes first. 

Black Start Engines

For existing stationary black start engines located at area sources, EPA believes that it is 

appropriate to set GACT to be the same requirements as is required for black start engines at 

major sources because the same issues that were discussed above for stationary black start 

engines at major sources apply to these engines at area sources. There is no reason why the 

requirements for area sources pursuant to GACT should be different than those for black start 

engines at major sources. Therefore, GACT for existing stationary emergency CI engines at area 

sources is the use of management practices as follows: 
8 

• changing the oil and oil filter every 500 hours of operation or annually, whichever 

comes first, with an option to use an oil analysis program as discussed above; 

• inspecting the air cleaner every 1,000 hours of operation or annually, whichever 

comes first; and 

• inspecting all hoses and belts and replacing as necessary every 500 hours of operation 

or annually, whichever comes first. 

Non-Emergency CI <100 HP

For existing stationary non-emergency CI engines less than 100 HP located at area 

sources, EPA believes that it is appropriate to set GACT to be the same requirements as is 

required for non-emergency CI engines less than 100 HP at major sources because the same 

issues that were discussed above for stationary non-emergency CI engines less than 100 HP at 

major sources apply to non-emergency CI engines less than 100 HP at area sources. There is no 

reason why the requirements for engines located at area sources pursuant to GACT should be 

different than the requirements for engines located at major sources. Therefore, GACT for 

existing stationary non-emergency CI engines less than 100 HP at area sources is the use of 

management practices as follows: 

• changing the oil and oil filter every 1,000 hours of operation or annually, whichever 

comes first, with an option to use an oil analysis program as discussed above; 

• inspecting the air cleaner every 1,000 hours of operation or annually, whichever 

comes first; and 

• inspecting all hoses and belts and replacing as necessary every 500 hours of operation 

or annually, whichever comes first. 

Non-Emergency CI 100≤HP≤300

For existing stationary non-emergency engines between 100 HP and 300 HP, EPA 

determined that management practices were appropriate for GACT. Although add-on controls 

are technically feasible for these engines located at area sources, control costs are high and EPA 

believes that it is possible to achieve reasonable controls using management practices. For 

example, capital costs associated with installing an oxidation catalyst on a 200 HP diesel engine 

are about $4,500 with annual costs of $1,500. Such costs are significant particularly when one 

considers that the cost per ton of this option is as high as $265,000 per ton of HAP reduced for 

some engines. EPA has estimated that there are over 64,000 existing stationary non-emergency 

engines between 100 HP and 300 HP located at area sources. The impacts of requiring add-on 

controls on these engines would be more than $320 million for equipment costs alone and total 

yearly costs would be more than $105 million, not including associated costs such as monitoring, 

testing, reporting, and recordkeeping that would be necessary in order to ensure compliance with 

an emission standard. For more information on the cost per ton of HAP reduced, please refer to 

the memorandum entitled “Cost per Ton of HAP Reduced for Existing Stationary CI RICE” in 

the rulemaking docket (EPA-HQ-OAR-2008-0708). 
9 

Furthermore, EPA is attempting to minimize the burden of the proposed rule, specifically 

on small businesses and individual owners and operators. EPA does not believe that 

management practices would be a substantial burden on owners and operators such as home 

owners and small entities. Additionally, the cumulative testing cost that would be associated 

with requiring existing non-emergency CI engines between 100 HP and 300 HP at area sources 

to meet a numerical emission limitation would be in the vicinity of $37 million. In addition, 

there would be other associated costs with demonstrating compliance with a numerical emission 

limit, such as notification and reporting requirements. Finalizing the same numerical emission 

limit consistent with the emission limit finalized for existing non-emergency CI engines between 

100 HP and 300 HP at major sources would have possibly resulted in some existing area source 

engines having to install aftertreatment. Purchasing, installing and operating add-on controls 

would lead to even further costs, increasing the total burden on these sources. For example, 

assuming that 35 percent of existing stationary non-emergency CI engines between 100 HP and 

300 HP located at area sources would have to install and operate aftertreatment controls in order 

to comply with a numerical emission limit, capital and annual costs would add an additional 

$100 million in capital costs and $37 million yearly for operation and maintenance of the control 

device. EPA believes these costs are excessive and not justified in comparison to the amount of 

pollutant that would be reduced with requiring a numerical emission limit as was done for the 

same engines at major sources. 

Consequently, GACT for existing stationary non-emergency CI engines between 100 HP 

and 300 HP at area sources is the use of management practices as follows: 

• changing the oil and oil filter every 1,000 hours of operation or annually, whichever 

comes first, with an option to use an oil analysis program as discussed above; 

• inspecting the air cleaner every 1,000 hours of operation or annually, whichever 

comes first; and 

• inspecting all hoses and belts and replacing as necessary every 500 hours of operation 

or annually, whichever comes first. 

Non-Emergency CI 300<HP≤500

For subcategories of existing stationary non-emergency CI engines greater than 300 HP, 

EPA believes that oxidation catalyst is readily available and feasible for all existing stationary 

non-emergency CI engines above 300 HP generally regardless of location. Further, EPA has 

determined that costs associated with implementing HAP-reducing technologies are reasonable 

and justified. In addition, it is estimated that the benefits per ton are between $330,000 (Pope, 

7%) and $790,000 (Laden, 7%) for PM2.5 for existing stationary CI engines at area sources. For 

more information on the benefits per ton of PM2.5 emission reductions, please refer to the 

Regulatory Impact Analysis for the final rule, available in the docket. The benefits per ton 

outweigh the costs. Further information on the specific add-on control costs and cost per ton 

estimates can be found in the memorandum “Cost per Ton of HAP Reduced for Existing 

Stationary CI RICE,” available from the docket (EPA-HQ-OAR-2008-0708). Therefore, EPA 

has determined that GACT should be based on the use of oxidation catalysts for existing 

stationary non-emergency CI engines greater than 300 HP and less than or equal to 500 HP that 

are located at area sources. For existing stationary non-emergency CI engines greater than 300 
10 

HP and less than or equal to 500 HP located at area sources, GACT for HAP emissions was 

therefore determined to be 49 parts per million by volume dry basis (ppmvd) at 15 percent O2 or 

the reduction of CO by 70 percent. 

In addition, in order to provide further reduction in metallic HAP emissions from nonemergency engines between 300 HP and 500 HP at area sources, EPA believes GACT should 

include the same requirements for further reduction in crankcase emissions as was required for 

such engines at major sources. The rationale for promulgating such requirements for such 

engines at major sources is found in the preamble and Response to Comments document for this 

rule and in the memorandum titled “MACT Floor Determination for Existing Stationary NonEmergency CI RICE Greater Than or Equal 100 HP Located at Major Sources,” which is 

available in the rulemaking docket (EPA-HQ-OAR-2008-0708). 

Therefore, GACT for non-emergency CI engines between 300 HP and 500 HP that are 

located at area sources includes the following requirement: 1) install a closed crankcase 

ventilation system that prevents crankcase emissions from being emitted to the atmosphere, or 2) 

install an open crankcase filtration emission control system that reduces the crankcase emissions 

by filtering the exhaust stream to remove oil mist, particulates, and metals. 

Non-Emergency CI >500 HP

For stationary non-emergency CI engines greater than 500 HP, EPA believes that 

oxidation catalyst technology is readily available and feasible for all existing stationary nonemergency CI engines above 500 HP generally regardless of location. Further, EPA has 

determined that costs associated with implementing HAP-reducing technologies are reasonable 

and justified. In addition, it is estimated that the benefits per ton are between $330,000 (Pope, 

7%) and $790,000 (Laden, 7%) for PM for existing stationary CI engines at area sources. The 

benefits per ton outweigh the costs. Further information on the monetized benefits and the 

specific add-on control costs and cost per ton estimates can be found in the memorandum “Cost 

per Ton of HAP Reduced for Existing Stationary CI RICE,” available from the docket as (EPAHQ-OAR-2008-0708). Therefore, EPA has determined that GACT should be based on the use 

of oxidation catalysts for existing stationary non-emergency CI engines greater than 500 HP that 

are located at area sources. Therefore, for existing stationary non-emergency CI engines greater 

than 500 HP located at area sources, GACT for HAP emissions is 23 ppmvd of CO at 15 percent 

O2 or the reduction of CO by 70 percent. 

Again, in order to provide further reduction in metallic HAP emissions from nonemergency engines greater than 500 HP, EPA believes GACT should include the same 

requirements for further reduction in crankcase emissions as was required for such engines at 

major sources. Therefore, GACT for non-emergency CI engines greater than 500 HP that are 

located at area sources includes the following: 1) install a closed crankcase ventilation system 

that prevents crankcase emissions from being emitted to the atmosphere, or 2) install an open 

crankcase filtration emission control system that reduces the crankcase emissions by filtering the 

exhaust stream to remove oil mist, particulates, and metals. 

CI Engines Located in Rural Areas of Alaska not accessible by FAHS
11 

For CI engines less than or equal to 300 HP located in remote areas of Alaska, EPA has 

determined that GACT is management practices. However, GACT for other existing stationary 

non-emergency CI engines greater than 300 HP located at area sources is based on the use of 

add-on controls and requires either compliance with a concentration or a percent reduction 

standard. Non-emergency CI engines greater than 300 HP that are located in area of Alaska not 

accessible by the Federal Air Highway System (FAHS), due to issues related to fuel availability 

and cost, location of sources, and colder weather conditions, to name a few, face unique 

challenges. Therefore, EPA believes it is not appropriate to set the same standards as for nonemergency CI engines greater than 300 HP at other area sources. Therefore, GACT for nonemergency CI engines greater than 300 HP that are located in area of Alaska not accessible by 

FAHS is management practices as follows: 

• changing the oil and oil filter every 1,000 hours of operation or annually, whichever 

comes first, with an option to use an oil analysis program as discussed above; 

• inspecting the air cleaner every 1,000 hours of operation or annually, whichever 

comes first; and 

• inspecting all hoses and belts and replacing as necessary every 500 hours of operation 

or annually, whichever comes first. 
12 

Appendix A 

Existing Stationary CI Engine Test Data Summary
13 

Test Date Engine Number 

Engine Size (HP) 

Test Method 

Used 

CO Concentration (ppmvd @ 15% O

Test Facility Average 

Run 

1 

Run 

2 

R

Santa Barbara County Air Pollution Control District 1/22/2009 East Crane 3 160 CARB 100 479.8 496.4 497.5 44Santa Barbara County Air Pollution Control District 1/22/2009 West Crane 1 160 CARB 100 222.9 221.3 217.5 22Santa Barbara County Air Pollution Control District 1/20/2009 East Crane 1 450 CARB 100 129.6 124.2 127.5 13Santa Barbara County Air Pollution Control District 1/21/2009 East Crane 2 450 CARB 100 154.4 140.3 160.2 16Precision Power 7/27/2005 Engine 1 550 EPA Method 10 45.6 46.6 45.0 4Precision Power 7/29/2005 Engine 2 550 EPA Method 10 90.9 93.5 90.4 8Precision Power 7/29/2005 Engine 2 550 EPA Method 10 57.7 56.6 58.8 5Precision Power 7/29/2005 Engine 2 550 EPA Method 10 41.6 42.5 41.0 4Precision Power 7/27/2005 Engine 2 550 EPA Method 10 23.5 23.7 23.7 Precision Power 7/28/2005 Engine 3 550 EPA Method 10 82.8 62.0 93.5 9Precision Power 7/28/2005 Engine 3 550 EPA Method 10 59.9 59.3 58.3 6Precision Power 7/28/2005 Engine 3 550 EPA Method 10 39.5 40.8 39.7 3Precision Power 7/28/2005 Engine 3 550 EPA Method 10 42.8 41.6 44.3 4Precision Power 7/26/2005 Engine 3 550 EPA Method 10 42.3 41.9 43.7 4Precision Power 7/26/2005 Engine 4 550 EPA Method 10 28.9 25.6 23.2 3CSU-Engines & Energy Conversion Laboratory 9/2/1999 Caterpillar 3508 1000 EPA Method 10 76.8 76.8 CSU-Engines & Energy Conversion Laboratory 9/1/1999 Caterpillar 3508 1000 EPA Method 10 44.1 44.1 CSU-Engines & Energy Conversion Laboratory 8/31/1999 Caterpillar 3508 1000 EPA Method 10 43.5 43.5 CSU-Engines & Energy Conversion Laboratory 8/31/1999 Caterpillar 3508 1000 EPA Method 10 41.6 41.6 CSU-Engines & Energy Conversion Laboratory 9/1/1999 Caterpillar 3508 1000 EPA Method 10 42.7 42.7 CSU-Engines & Energy Conversion Laboratory 8/31/1999 Caterpillar 3508 1000 EPA Method 10 45.2 45.2 CSU-Engines & Energy Conversion Laboratory 8/31/1999 Caterpillar 3508 1000 EPA Method 10 44.1 44.1 CSU-Engines & Energy Conversion Laboratory 9/1/1999 Caterpillar 3508 1000 EPA Method 10 41.6 41.6 CSU-Engines & Energy Conversion Laboratory 9/1/1999 Caterpillar 3508 1000 EPA Method 10 76.2 76.2 CSU-Engines & Energy Conversion Laboratory 8/31/1999 Caterpillar 3508 1000 EPA Method 10 39.8 39.8 Badami Development Facility 6/26/2003 Generator 2 1680 EPA Method 10 327.1 330.3 330.1 32Badami Development Facility 6/26/2003 Generator 2 1680 EPA Method 10 265.4 267.2 263.7 26Badami Development Facility 6/26/2003 Generator 2 1680 EPA Method 10 196.9 182 200 Badami Development Facility 6/25/2003 Generator 2 1680 EPA Method 10 77.7 77.8 74.9 8Northstar Development Project - BP 7/8/2004 Engine 6 3570 EPA Method 10 69.4 69.2 69.2 6Northstar Development Project - BP 7/8/2004 Engine 6 3570 EPA Method 10 54.9 55.8 54.2 5Northstar Development Project - BP 7/9/2004 Engine 6 3570 EPA Method 10 55.5 56.7 54.9 5Northstar Development Project - BP 7/9/2004 Engine 7 3570 EPA Method 10 142.9 142.9 Northstar Development Project - BP 7/9/2004 Engine 7 3570 EPA Method 10 131.1 126.5 132.1 13Northstar Development Project - BP 7/9/2004 Engine 7 3570 EPA Method 10 127.8 127.8