AIR POLLUTION CONTROL DISTRICT

DRAFT STAFF REPORT

Rule 400.3, Internal Combustion Engines

Rule 400.4 Emissions of Oxides of Nitrogen from Wallboard Kilns

Reasonably Available Control Technology

October 22, 2013

I BACKGROUND

In response to a finding by the United States Environmental Protection Agency (US 

EPA), that Imperial County failed to attain the 1997 8-hour Ozone National Ambient Air 

Quality Standard (NAAQS) of 0.08 parts per million (ppm), US EPA reclassified Imperial 

County to a “Moderate” non-attainment area on February 13, 2008. “Moderate” nonattainment areas are required, under the Clean Air Act (CAA), to develop and implement 

a State Implementation Plan (SIP) to reduce ozone-forming emissions of nitrogen oxides 

(NOx) and Volatile Organic Compounds (VOC). Of the many components of a federally 

mandated SIP, a Reasonable Available Control Technology (RACT) SIP is required to 

assure that major sources of ozone precursor emissions are controlled to a 

“reasonable” extent.1 

The Imperial County Air Pollution Control District (ICAPCD) submitted the approved 

RACT SIP along with the 2009 1997 8-Hour Ozone Modified Air Quality Management 

Plan (Modified SIP), demonstrating that Imperial County met the 1997 8-hour Ozone 

Standard, to US EPA for review and approval on December 21, 2010. Commitments 

identified under the submitted RACT SIP include the proposed adoption and/or revision 

of three rules that would address NOx emissions from new and existing sources 

throughout Imperial County. Adopting and implementing these identified Rules would 

only serve to assure compliance with the US EPA requirement that Imperial County is 

controlling, to a “reasonable” extent, ozone precursor emissions. The newly proposed 

Rule 400.3, Internal Combustion Engines (IC Engines) and Rule 400.4 Emission of 

Oxides of Nitrogen from Wallboard Kilns (Wallboard Kiln) are being developed to address 

the implementation of federal RACT on both IC Engines and Wallboard Kiln sources. The 

emission limitations of NOx for both newly proposed Rules are considered by the US 

EPA to constitute RACT.

The purpose of the newly proposed Rule 400.3 is to limit NOx and carbon monoxide (CO) 

emissions from stationary and portable IC Engines. IC Engines are used to power 

pumps, natural gas compressors, electrical generators, etc. There are a wide variety of 

IC engine designs and fuels. Engines are either two or four stroke and are classified as 

1 The EPA defines RACT as the lowest emission limitation that a particular source is capable of meeting by the application of 

control technology that is reasonably available considering technological and economic feasibility (44 FR 53762; September 17, 

1979) 

 

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 1 of 13
AIR POLLUTION CONTROL DISTRICT

either Rich Burn or Lean Burn, and are spark ignited or compression ignited. Typical 

fuels used in IC engines include natural gas, propane, butane, liquefied petroleum gas, 

gasoline, diesel fuel, or a combination of these fuels. As written the rule will require 

certain operators to modify their equipment or operation to achieve the proposed RACT 

NOx standards. Essentially, Rule 400.3 applies RACT to IC Engines greater than 50 

brake horsepower (bhp) which is consistent with state Air Toxic Control Measure (ATCM) 

requirements and Rule 202 Exemptions. Rule 400.3 establishes NOx and CO emission

limits that apply to Rich Burn Engines, Lean Burn Engines and diesel engines. The Rich 

Burn NOx limit is 90 parts per million per volume (ppmv) and the CO limit is 2500 ppmv. 

The Lean Burn NOx limit is 150 ppmv and the CO limit is 2500 ppmv. For engines 

utilizing diesel the limit is 600 ppmv for NOx and 2500 ppmv for CO. Finally, the rule 

allows additional compliance time for those existing IC engines that will be required to

retrofit their IC engines to meet the standard. 

The proposed rule was written after reviewing similar rules now in effect in other 

California counties, specifically Placer County and Mojave Desert. Like other rules, the

Imperial County Rule 400.3 applies to all sources operating IC engines. 

On October 18, 2007 the California Air Resources Board (CARB) adopted an Air Toxics 

Control Measure (ATCM) that included suggested control limits on particulate emissions 

for stationary diesel engines and requires compliance with NMHC+NOx standards (Title 

13, CCR, section 2423). The ATCM requires that all new and in use diesel stationary IC 

engines comply with the minimum Tier 1 standards. Because the Tier 1 NOx limits are 

more stringent than the RACT NOx limits contained in this rule, the NOx limits of Rule 

400.3 will be subsumed under the Tier 1 requirements of the ATCM. Compliance with 

these limits is assumed since the worst case NOx limits contained in the ATCM are 

more stringent than Rule 400.3 NOx limits. 

A District’s permitting database survey revealed that currently, there are no major 

sources of IC engines within Imperial County. The purpose of the proposed Rule 400.3 

is to fulfill previous commitments found in the District’s RACT SIP and to enhance 

enforceability of NOx and CO limits by adopting specific guidelines for testing, 

recordkeeping and reporting requirements.

The purpose of the newly proposed Rule 400.4 is to limit NOx emissions from stationary 

devices operated at wallboard production facilities. In 1973 there were only 108 

wallboard production facilities identified in the United States, and only one such facility is 

located in Imperial County. The United States Gypsum Company (USG) employs a 

fundamentally simple gypsum process which includes quarrying, calcinating and either 

size reduction and/or size separation operations. The equipment utilized by USG is 

considered standardized throughout the industry.

Rule 400.4 will require operators to modify their equipment or operations to achieve the 

proposed RACT NOx standards.

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 2 of 13
AIR POLLUTION CONTROL DISTRICT

The operational process in creating prefabricated board (wallboard) includes the use of 

crushed gypsum (calcium sulfate). Because of the process heat necessary to bake and 

dry the crushed calcium sulfate, Rule 400.4 limits the emissions of NOx to 30 parts per 

million by volume (ppmv) or 0.036 pounds (lbs) per million British Thermal Units (BTU) of 

heat input when operated on gaseous fuels, 40 ppmv or 0.052 lbs per million BTU of heat 

input when operated on liquid fuels and if a combination of gas and liquid fuels is used the 

heat input weight average of 0.036 and 0.052. 

II REQUIRED ELEMENTS/FINDINGS

Before adopting, amending or appealing any rule or regulation the Governing Board of 

the ICAPCD is required to make specific findings of necessity, authority, clarity, 

consistency, nonduplication, and reference (Health & Safety Code §40727). The 

ICAPCD is also required to hold a public meeting after the rule or regulation has been 

properly noticed (Health & Safety Code §40725). Relevant information supporting each 

of these findings and the propriety of the notice for the public hearing is presented 

below.

FINDING DEFINITION REFERENCE

Authority The ICAPCD has authority to adopt, 

amend, or repeal the rule by a 

provision of law or a state or federal 

regulation.

California Health and Safety Code, 

Section 40702 and Section 41010; 

1990 Federal Clean Air Act, Section 

110(a)(2)(H) and Section 182(d).

Necessity The proposed rule is needed to 

address US EPA’s RACT 

requirements for 8 hour Ozone SIP 

approval.

It is necessary for the ICAPCD to 

adopt this rule in order to fulfill the 

requirements of the Federal Clean Air 

Act Amendments of 1990.

Clarity Internal combustion engines rated 

greater than 50 horsepower will be 

affected by the proposed rule. The 

rule is written or displayed so that its 

meaning can be easily understood 

by the persons directly affected by it.

There is no indication at this time that 

the rule is not written in such a manner 

that the person affected by the rule 

can easily understand it.

Consistency The rule is in harmony with, and not 

in conflict with or contradictory to, 

existing statutes, court decisions, or 

state or federal regulations.

The ICAPCD has found that the rule is 

consistent with existing state and 

federal guidelines. 

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 3 of 13
AIR POLLUTION CONTROL DISTRICT

NonduplicationThe rule does not impose the same 

requirements as an existing state or 

federal regulation because 

suggested RACT requirements are 

not a regulation. 

The ICAPCD has found that the rule is 

consistent with existing state and 

federal regulations. Suggested RACT 

requirements must be adopted as a 

District rule and included in the SIP in 

order to be enforceable. 

Reference Any statute, court decision, or other 

provision of law that the ICAPCD 

implements, interprets, or makes 

specific by adopting, amending, or 

repealing the rule.

This rule is being proposed because of 

the requirements of the Federal Clean 

Air Act Amendments of 1990.

III PROPOSED RULE 400.3 – SUMMARY

The following is a general discussion of the proposed Rule 400.3 Internal Combustion 

Engines 

Section (A) - Applicability: This section states that the purpose is to limit the 

emission of NOx from Internal Combustion Engines. Specifically, to 

any Internal Combustion Engine rated greater than 50 bhp. Engines 

powered by any gaseous fuel or liquid fuel (including liquefied 

petroleum gas, gasoline or diesel fuel) are included. In order to avoid

duplication of requirements, all engines that are subject to the 

provisions of Rule 400.3 are not subject to Rule 400 requirements. 

Section (B) - Definitions: This section defines 5 new terms used in the rule. Other 

terms applicable to this rule but not included in this rule are found in 

Rule 101, Definitions.

Section (C) - Requirements: NOx emission limits are specified for Rich Burn Engines, 

Lean Burn Engines and diesel engines. The Rich Burn NOx limit is 90

ppmv at 15% oxygen on a dry basis and 2500 ppmv for CO. The LeanBurn limit is 150 ppmv at 15% oxygen on a dry basis and 2500 ppmv for 

CO. The Diesel Engine NOx limit is 600 ppmv at 15% oxygen on a dry 

basis and 2500 ppmv for CO. 

Section (D) - Exemptions: this section exempts engines used to preserve or protect 

property, human life, or public health during a disaster or a state of 

emergency; engines operated at agricultural sources that are located 

within facilities that are not classified as major agricultural sources; gas 

turbine engines; emergency stand-by engines operated less than 100 

hours per calendar year for the purpose of testing and maintenance

are exempted from compliance with the limits in this rule. In addition, 

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 4 of 13
AIR POLLUTION CONTROL DISTRICT

this rule has an exemption for existing Internal Combustion Engines to 

be permanently replaced with electric motors or removed from service 

by April 22, 2014. While not specified in this section, any engine(s) 

rated by the manufacturer less than or equal to 50 bhp, if they are 

maintained to manufacturer’s specifications, are exempted. 

Section (E) - Recordkeeping Requirements: Recordkeeping includes a list of 

specific records that are to be maintained on-site for each month or 

any part of a month that the device is operated. These records are 

required to demonstrate compliance with the rule limits or to 

demonstrate that the engines are maintained according to 

manufacturer’s recommendations. Any facility claiming an exemption 

status must keep records to document the claimed exempt status. An 

owner or operator of an engine(s) subject to this rule shall install a nonresettable totalizing fuel meter or non-resettable engine operating 

hour’s meter. 

Section (F) - Test Methods: Compliance with the requirements of Section C shall be 

determined in accordance with the test methods approved by U.S. 

EPA and/or CARB.

Section (G) - Compliance Testing: The owner or operator of any Internal 

Combustion Engine(s) with a bhp rating of 500 or greater shall 

demonstrate compliance through emission compliance testing not less 

than once every 36 months. All emission rates shall be based on an 

hourly average. Compliance testing may be extended to not less than 

every 60 months for combustion engine(s) which operate less than 500 

hours per 12 month periods (as demonstrated by operational logs) and

which emit less than 5 tons of NOx per 12 month period. This period 

may be extended if a source can prove that the engine(s) has not been 

operated during the calendar year. Also, the frequency of testing may 

be extended to not less than every 60 months for those engines 

operating more than 500 hours per year which demonstrate 

compliance with the limits on this rule by using a portable NOx 

analyzer during each quarter of operation. 

Section (H) - Records Retention: The owner or operator of any Internal Combustion

Engine(s) subject to this rule shall maintain all records required by this 

rule for a minimum of two calendar years. Title V facilities shall 

maintain these records for five calendar years. These records shall be 

maintained on the premises and made available to the ICAPCD upon 

request.

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 5 of 13
AIR POLLUTION CONTROL DISTRICT

Section (I) - Compliance Schedule: According to 40 CFR, Section 51.912(a)(3), the 

APCD can allow up to 30 months after the SIP due date for source 

compliance with this rule. Therefore, in order to provide a period of 

time to make the necessary upgrades or modifications to emission 

units not in compliance with this rule, Rule 400.2 allows for an 

alternative compliance schedule. Emission units not in compliance 

with the thresholds in Section C shall demonstrate full compliance with 

all applicable standards and requirements of this rule no later than one 

year after adoption of this rule. On or before six months after adoption 

of this rule, an owner or operator of an IC engine not in compliance 

with this rule shall submit for approval by the Air Pollution Control 

Officer (APCO), an Authority to Construct (ATC)/Permit to Operate 

(PTO) application amendment.

IV CONTROL TECHNOLOGY

The choice of a control technology is to be determined by the owner or operator of the 

affected facility. Different control technologies achieve different emission reductions 

represented by a percentage basis. If an IC engine is properly sized and maintained or 

is already equipped with emission controls, a smaller emission reduction may be 

necessary to achieve the NOx emission limits. In which case a number of less 

expensive control technologies such as air-fuel adjustment or timing retard may be 

sufficient to comply with the NOx emission limitations. In some cases no additional 

controls will be necessary.

Air-Fuel Adjustment. In a Rich Burn Engine, adjusting the air-fuel (A/F) ratio to a richer 

fuel mixture decreases the amount of oxygen available for NOx formation. Changing 

the A/F ratio can reduce NOx by 10% to 40%. Diesel and dual-fuel engines can 

achieve about 14% NOx reduction.

Alternative Fuels. Converting from distillate fuel to methanol would reduce NOx 

emissions by about 50%.

Electrification. Replacing IC engines with electric motors can reduce NOx emissions by 

100% at the source. However, the generation of electricity produces some NOx at the 

electric utility so that the overall effective NOx reduction is about 90%. This alternative 

is not always cost-effective. Factors determining feasibility and cost-effectiveness 

include access and distance to a power supply, cost of interconnection, and hours of 

operation per year. 

Emulsion. Water/fuel oil emulsion can reduce NOx emissions by reducing peak 

combustion temperature. One problem with this method is that water separating from 

the emulsion could cause pump and valve corrosion and rapid wear of piston rings and 

cylinder liners. This technology is still being developed and tested.

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 6 of 13
AIR POLLUTION CONTROL DISTRICT

Exhaust Gas Recirculation (EGR). Exhaust gas recirculation reduces NOx emissions 

by reducing the peak combustion temperature. This technology is found on nearly all 

modern automobiles. The presence of exhaust gas in the combustion zone acts as a 

heat sink and reduces the amount of oxygen available to produce NOx. With 25 

percent recirculation, an average NOx reduction of 36 percent can be achieved. This 

control technology works well for spark-ignited engines, but is not well suited for diesel 

engines.

Low-Emission (L-E) Combustion. Low-emission combustion designs incorporate a precombustion chamber which ignites a fuel-rich mixture that propagates to the main 

combustion chamber. The high exit velocity from the pre-combustion chamber 

promotes mixing and complete combustion of the lean A/F mixture in the main chamber, 

effectively lowering combustion temperatures and decreasing NOx emission levels. L-E 

combustion is available on new engines or as a retrofit kit for some older engines. This 

technology can be used on rich or lean-burn spark-ignited engines and on dual-fuel fired 

engines with a NOx reduction of approximately 87%. 

Non-Selective Catalytic Reduction (NSCR). NSCR is an emission control technology 

that can be used on spark-ignited rich-burn IC engines. This technology is also found 

on nearly all modern automobiles. Unburned hydrocarbons and CO in the exhaust 

gases react with nitrogen monoxide (NO) and nitrogen dioxide (NO2) over a catalyst to 

produce inert nitrogen gas and water. Installed in the exhaust stream, the system may 

also require automatic control of the fuel/air ratio to maintain a slightly fuel-rich mixture 

and to prevent catalyst blinding or fires in the catalyst bed. NSCR would reduce NOx 

emissions by about 90%.

Pre-stratified charge (PSC). A PSC fuel system for rich or lean-burn IC engines would 

reduce NOx emissions by about 87%. This control method uses recirculated exhaust 

gases and air injection into the intake manifold. It requires a modified long-duration 

high-energy spark ignition system because of the leaner fuel-air mixture in the 

combustion chamber.

Selective Catalytic Reduction (SCR). SCR is an emission control technology that can 

be used on spark-ignited lean-burn or compression-ignited (diesel) IC engines. A 

reducing agent (e.g., anhydrous ammonia) is added to the exhaust gas to reduce NO 

and NO2 to inert nitrogen gas and water in an oxidizing atmosphere. SCR can reduce 

NOx emissions by 80 – 90%. However, this control technology is cost-intensive and 

has the added hazardous waste management responsibilities associated with 

anhydrous ammonia.

Timing Retard. Retarding the spark timing in spark-ignited engines or the fuel injection 

timing in diesel or dual-fuel engines would reduce NOx formation by reducing peak 

cylinder temperatures. This is another control technique found in modern automobiles. 

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 7 of 13
AIR POLLUTION CONTROL DISTRICT

A six degrees timing retard reduces NOx an average of 25%, while hydrocarbons and 

CO emissions generally remain the same. However, the exhaust temperature 

increases thereby reducing engine efficiency and increasing fuel consumption about 5 

%.

Turbocharger/Aftercooler. A turbocharger uses energy from the exhaust stream to turn 

a compressor and increase the intake air pressure. Thus, a larger mass of air and fuel 

can be injected into the cylinder resulting in higher power output. Since the 

turbocharger increases the temperature of the air it compresses, a heat exchanger 

(aftercooler or intercooler) is usually used to lower the temperature of the intake air. 

Although the concentration of NOx increases, the increase in energy efficiency results in 

lower NOx emissions per unit of power output. This control method can achieve an 

average 25% reduction in NOx emissions, with an average 5% decrease in fuel 

consumption.

V PROPOSED RULE 400.4 – SUMMARY

The following is a general discussion of the proposed Rule 400.4 Emissions of Oxides 

of Nitrogen from Wallboard Kilns

Section (A) - Applicability: This section identifies the purpose and to whom the rule 

applies. The intent of the rule is to limit oxides of nitrogen (NOx) from 

kilns operated at new or existing wallboard facilities with a heat input 

rating of 5 million Btu’s per hour or more. Kilns subject to the 

requirements of this rule are exempt from the provisions of Rule 400

Section (B) - Definitions: This section defines “Wallboard Kiln” as a device for 

drying. This section also clarifies that any definition not found within 

Rule 400.4 can be found within Rule 101, Definitions.

Section (C) - Requirements: NOx emissions limits are specified in parts per million 

by volume or in pounds per million Btu of heat input. This section 

identifies the conditions for the limits as dry stack-gas and a hourly 

average of 3% volume stack-gas oxygen.

Section (D) - Exemptions: This section identifies exemptions applicable to kilns used 

at wallboard production facilities as during startup, shutdown or during 

a change in load. This section also limits the number of hours allowed 

when the combustion process is being brought up to operating levels. 

Kilns of more than 40 MM Btu per hour may not exceed 12 hours and 

kilns of equal to or less than 40 MM Btu per hour cannot exceed 6 

hours. Finally, this section allows for the permit to operate to dictate 

the number of hours not to be exceeded when bringing the combustion 

process up to operating levels.

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 8 of 13
AIR POLLUTION CONTROL DISTRICT

Section (E) - Monitoring and Recordkeeping Requirements: This section requires 

owners or operators to maintain operational logs of startups, 

shutdowns and fuel changes. In addition, owners and operators are 

required to keep a log of the type and quantity of each fuel used. This 

section further explains that compliance using CEMS data is to be 

based on an averaging period of one clock hour.

Section (F) - Test Methods: This section identifies the methods necessary to 

demonstrate compliance with emission limits. The section identifies 

US EPA and CARB test methods. This section also explains that other 

test methods approved by US EPA may be used.

Section (G) - Source Test Requirements: This section explains the levels of 

performance for source testing and the frequency required for source 

testing when demonstrating compliance. Source testing is required 

once every 12 months however there are provisions, of no less than 36 

months, for those kilns that operate less than 100 hours and that emit 

less than 5 tons of NOx per a 12 month period. Performance levels 

include 80% of the power rating or the highest achievable continuous 

power rating and the operational characteristics recommended by the 

manufacturer. For a compliance determination an average of three 

test runs are required and the submittal of a source test plan no less 

than 30 days prior to the actual source test. Notification of the actual 

date of the source test at least 7 days prior to the source test and with 

the final source test result submitted to the APCO within 60 days of the 

source test.

Section (H) - Records Retention: This section requires the retention of records for a 

minimum of two calendar years. Title V facilities are required to 

maintain records 5 calendar years. All records are required to be 

maintained on site and made available to the ICAPCD upon request.

VI CONTROL TECHNOLOGY

As mentioned above “calcination” is used for drying or aging crushed gypsum. The 

operational process and equipment is per industry standards and typically requires a 

continuously operating rotary or pot kiln and some silos. Kilns are direct fired with 

typical heat supplied through coal, natural gas or fuel oil. USG, the only wallboard 

facility in Imperial County uses natural gas. NOx control approaches are typically 

categorized as process modifications, combustion control approaches and NOx 

reduction controls. 

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 9 of 13
AIR POLLUTION CONTROL DISTRICT

Low-NOx burner systems which rely on staged combustion of air are available for all 

kiln types. Depending on the baseline emissions of a kiln, publications have reported 

NOx reduction rates of 23 to 47 percent. Staged combustion of fuel includes the use of 

preheaters/precalciners and mid-kiln firing. Industry publications reported results from 

tests conducted using mid-kiln firing. These tests demonstrated NOx reductions 

ranging from 28 to over 50 percent.

Control technology that removes or destroys NOx formed in the combustion process 

includes Selective Catalytic Reduction (SCR) and Selective Noncatalytic Reduction 

(SNCR). However, it is the owner or operator which will ultimately determine the most 

appropriated control technology for the facility, if necessary.

Selective Catalytic Reduction (SCR): SCR uses ammonia in the presence of a catalyst 

to selectively reduce NOx emissions from exhaust gases.

Selective Noncatalytic Reduction (SNCR): SNCR uses ammonia or urea without using 

any catalyst to reduce NOx in exhaust gases. NOx emission reductions have been 

recorded at 30 to 70 percent. Unlike SCR technology this approach avoids catalyst 

fouling but does require injection of reagents into the kiln at a temperature between 870 

to 1090°C (1600 to 2000°F). At these temperatures urea decomposes to produce 

ammonia which is responsible for NOx reduction.

VII ENVIRONMENTAL IMPACTS 

Rules 400.3 Internal Combustion Engine(s) and Rule 400.4 Emissions of Oxides of 

Nitrogen from Wallboard Kilns require that identified sources meet specific emission 

limits by controlling the emissions sources using technology or modifying the 

operational process. Analysis demonstrates that the control of NOx emissions from the 

implementation of Rule 400.3 and 400.4 was found not to have any significant 

environmental impacts which cannot be mitigated to a less than significant level.

VIII EMISSIONS REDUCTIONS FOR RULES 400.3 and 400.4

On October 18, 2007 the CARB adopted an ATCM that included suggested control 

limits on particulate emissions for stationary diesel engines and requires compliance 

with NMHC+NOx standards found in Title 13, CCR, section 2423. The ATCM requires 

compliance of all in use IC engines to a minimum Tier 1 standard. All Tier Zero diesel 

engines were required to be retrofitted to minimum Tier 1 standard by June 30, 2011. 

The Tier 1 NOx limits are more stringent than the RACT NOx limits in this rule; 

therefore, the NOx limits of Rule 400.3 will be subsumed under the Tier 1 requirements 

of the ATCM. Because the worst case NOx limits contained in the ATCM are more 

stringent than Rule 400.3 NOx limits compliance with Rule 400.3 limits is assumed. 

Since ATCM noncompliant engines were required to retrofit to Tier 1 standards in 2011, 

no further NOx emissions reductions are committed for the adoption of rule 400.3. 

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 10 of 13
AIR POLLUTION CONTROL DISTRICT

As mentioned above, only one wallboard facility is located in Imperial County. USG has 

installed low-NOx burner technology on its kilns since 2009. Therefore, no additional 

NOx emissions reductions are committed for the adoption of rule 400.4

IX COSTS AND COST EFFECTIVENESS

According to CARB’s ATCM for stationary diesel engines, all diesel engines are 

required to meet minimum Tier 1 NOx standards. The ICAPCD’s evaluation indicates 

that Tier 1 engine standards are sufficient to comply with Rule 400.3 standards. Since 

the Tier Zero engines identified in the District’s permitting database survey are already 

required to be retrofitted in order to comply with the ATCM standards regardless of cost 

or cost effectiveness, a cost effectiveness analysis for Rule 400.3 is not considered 

necessary. Furthermore, the ICAPCD’s survey did not identify any Rich-Burn or Lean 

Burn engines that may be out of compliance with Rule 400.3 limits thus a cost 

effectiveness evaluation for these types of engines is not necessary.

X RULE DEVELOPMENT PROCESS

In October of 2008, the ICAPCD held a meeting with U.S. EPA and CARB 

representatives via teleconference, to discuss the potential of the development of NOx 

rules to comply with RACT requirements. The ICAPCD agreed to initiate development 

of three NOx rules: 1) Stationary Gas Turbines and 2) Boilers, Process Heaters, and 

Steam Generators and 3) Internal Combustion Engines. Of the three identified rules 

only the Internal Combustion Engine rule had not been proposed for adoption. Both the 

Stationary Gas Turbine rule and the Boiler rule were adopted February 23, 2010. 

During the interim and during new discussions with US EPA NOx evaluations identified 

the need to develop a specific rule addressing kilns. Thus, the ICAPCD agreed to 

develop a rule specific to kilns for wallboard fabrication.

During the third quarter of 2012, October through December, ICAPCD prepared and 

released proposed draft versions of Rules 400.3 and Rule 400.4 to major local sources, 

soliciting comments prior to any formal hearing process. 

The ICAPCD conducted a public workshop on September 18, 2013 soliciting comments 

on Rule 400.3. The workshop was held at the ICAPCD office in El Centro. Comments 

provided by the public during the workshops were incorporated into the proposed rule 

as appropriate. A meeting was held with USG to solicit comments on the proposed 

Rule 400.4. No formal comments have been submitted by USG. 

Public notices of the proposed adoption of these rules were published in local 

newspaper on September 18, 2013. The notice and draft rules were made available on 

the ICAPCD’s website at www.co.imperial.ca.us Advisory notices were mailed to the 

permitted sources that had engines, including exempt and non-exempt.

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 11 of 13
AIR POLLUTION CONTROL DISTRICT

XI RECOMMENDATIONS:

 APCD ADVISORY BOARD:

The Air Pollution Control District Advisory Board is scheduled to meet on October 10, 

2013 to discuss the newly proposed Rules 400.3 and 400.4. Once the final 

recommendation is made by the Air Pollution Control District Advisory Board this 

section of the Draft Staff Report will be updated and the final recommendation will be 

announced during the scheduled Public Hearing on October 22, 2013.

 STAFF:

ICAPCD staff recommends adoption of the attached Rule 400.3 and 400.4. Adoption of 

both rules 400.3 and 400.4 will allow the ICAPCD to meet commitments identified in the 

Imperial County RACT SIP certifying that RACT requirements for NOx regulations are 

not deficient. Failure to adopt the NOx Rule 400.3 and Rule 400.4 will hinder the 

approval process in place for the Imperial County 2009 Modified Ozone SIP. 

XII DECLARATION OF FINDINGS

The Imperial County Air Pollution Control District Board hereby finds as follows: 

The adoption of the proposed new Rule 400.3 and Rule 400.4 for the Imperial County, 

is considered a project within the meaning of Section §21065 of the California 

Environmental Quality Act (CEQA).

The ICAPCD is a regulatory agency and the public agency with the principle 

responsibility for carrying out the project.

Clean air is a valuable and essential natural resource.

Proposed new NOx Rule 400.3 and Rule 400.4 will serve to reduce the amount of NOx 

introduced into the ambient air.

Proposed new Rule 400.3 and Rule 400.4 will serve to enhance and protect the 

environment by controlling air pollutant sources of NOx.

There has been no evidence presented to suggest that the implementation of the 

proposed new NOx Rule 400.3 and Rule 400.4 will have an adverse effect on the 

environment.

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 12 of 13
AIR POLLUTION CONTROL DISTRICT

There has been no evidence presented to suggest that the implementation of the 

proposed new Rule 400.3 and Rule 400.4 will lead to or result in cumulative adverse 

impacts. 

Health and Safety Code §40702 provides the authority to the ICACPD to enact the NOx 

Rule 400.3 and Rule 400.4. 

The requirements of the new NOx Rule 400.3 and NOx Rule 400.4 are clear and 

capable of being understood by those persons directly affected by it.

The new Rule 400.3 and Rule 400.4 do not conflict with or contradict any existing 

statute, court decision, or state or federal regulation.

The requirements of the new NOx Rule 400.3 and new NOx Rule 400.4 are not 

duplicative of any existing state or federal regulation.

Per the California Health and Safety Code section §40728.5 (d), a socioeconomic 

impact is exempt as the Imperial County has a population of less than 500,000 people.

XIII REFERENCES

California Air Resources Board "Determination of Reasonably Available Control 

Technology and Best Available Retrofit Control Technology for Stationary Spark-Ignited 

IC Engines”

San Joaquin Valley SJAPCD Rule 4701 Survey, September 1993.

October 22, 2013 Public Hearing Newly Proposed NOx Rules Page 13 of 13