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(Adopted October 7, 2005) 

RULE 3503 EMISSIONS INVENTORY AND HEALTH RISK ASSESSMENT 

FOR RAILYARDS 

(a) Purpose 

The purpose of this rule is to determine criteria pollutant and toxic emissions from 

railyards to conduct health risk assessments estimating the cancer risk, chronic 

hazard index, and acute hazard index caused by emissions at railyards, and to 

notify the public regarding such health risks. 

(b) Applicability 

This rule shall apply to specified railyards in the District operated by Class I 

freight railroads and switching and terminal railroads in the District, subject to 

designation of additional railyards pursuant to subdivision (i). This rule is 

applicable to the following railroads and railyards: 

(1) Burlington Northern and Santa Fe Railway Company at the following 

locations: 

(A) Commerce Diesel Maintenance Facility, 6300 Sheila Avenue, 

Commerce, CA 90040; 

(B) Commerce/Eastern Intermodal Facility, 2818 Eastern Avenue, 

Commerce, CA 90040; 

(C) La Mirada Yard, 14503 Macaw Street, La Mirada, CA 90638; 

(D) Los Angeles Intermodal Facility, 3770 Washington Boulevard, 

Commerce, CA 90023; 

(E) Pico Rivera Yard, 7427 Rosemead Boulevard, Pico Rivera, CA 

90660; 

(F) San Bernardino Yard, 1535 W 4th Street, San Bernardino, CA 

92411; and 

(G) Watson Yard, 1302 Lomita Boulevard, Wilmington, CA 90744. 

(2) A railyard operated by Los Angeles Junction Railway, 4433 Exchange 

Avenue, Los Angeles, CA 90058. 

(3) A railyard operated by Pacific Harbor Lines, 340 W. Water Street, 

Wilmington, CA 90744. 

(4) Union Pacific Railroad Company at the following locations: 

(A) Anaheim Yard, 200 S Adams Street, Anaheim, CA 92802; 
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(B) City of Industry Yard, 17525 Arenth Street, City of Industry, CA 

91748; 

(C) Colton Yard, 19100 Slover Avenue, Bloomington, CA 92316; 

(D) Commerce Intermodal Facility, 4341 E. Washington Boulevard, 

Commerce, CA 90023; 

(E) Dolores Yard, 2442 Carson Street, Carson, CA 90810; 

(F) Intermodal Container Transfer Facility (ICTF), 2401 Sepulveda 

Blvd, Long Beach, CA 90810; 

(G) Los Angeles Transportation Center Intermodal Facility , 750 

Lamar Street, Los Angeles, CA 90031; 

(H) Meade Yard, 2402 Anaheim Street, Wilmington, CA 90744; 

(I) Mira Loma Auto Distribution Facility, 4500 Etiwanda Avenue, 

Mira Loma, CA 91752; and 

(J) Montclair Yard, 10773 Central Place, Montclair, CA 91763. 

(c) Definitions 

(1) CLASS I FREIGHT RAILROAD means a Class I railroad, as classified 

by the Surface Transportation Board in 49 CFR Part 1201 Subpart A, that 

primarily transports freight rather than passengers. 

(2) CRITERIA POLLUTANT means air contaminants for which federal or 

state air quality standards have been established. 

(3) DEDICATED RAILYARD EQUIPMENT means stationary, mobile, and 

portable equipment within a railyard that is owned, leased, or contracted 

by the railroad and used exclusively at the railyard including, but not 

limited to, cranes, yard hostlers, forklifts, chassis lifters, locomotive 

switchers, fuel tanks, wastewater treatment equipment, stationary internal 

combustion engines, or boilers. 

(4) HEALTH RISK ASSESSMENT means a detailed comprehensive analysis 

prepared to evaluate and predict the dispersion of hazardous substances in 

the ambient air and the potential for exposure of human populations and to 

assess and quantify both the individual and population-wide health risks 

associated with those levels of exposure. 

(5) IMPACT AREA means any location outside the boundaries of a railyard 

at which a health risk assessment pursuant to this rule indicates a cancer 

risk of greater than or equal to one in one million (1 x 10-6), a total acute 
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or chronic hazard index of one (1.0) or greater, not to exceed an area 

extending no further than 50 kilometers downwind in any direction. 

(6) LOCOMOTIVE means, for the purpose of this rule, a self-propelled piece 

of on-track equipment designed for moving or propelling railroad cars that 

are designed to carry freight, passengers or other equipment, but which 

itself is not designed or intended to carry freight, passengers (other than 

those operating the locomotive) or other equipment. The following 

equipment is not a locomotive: designed for operation both on highways 

and rails; specialized railroad equipment for maintenance, construction, 

post accident recovery of equipment, or repairs and other similar 

equipment; and vehicles propelled by engines with rated horsepower of 

less than 750 kW (1006 hp). See 40 Code of Federal Regulations Parts 86 

and 89 for a further description of this equipment. 

(7) LOCOMOTIVE ENGINE means the propulsion engine or engines 

incorporated into a locomotive or intended for incorporation into a 

locomotive. 

(8) MAXIMUM INDIVIDUAL CANCER RISK (MICR) means the 

estimated probability of a potential maximally exposed individual 

contracting cancer as a result of exposure to toxic air contaminants over a 

period of 70 years for residential receptor locations and 40 years for 

worker receptor locations for the highest modeled cancer risks within a 

receptor grid, as calculated pursuant to the District’s Health Risk 

Assessment Guidance for Railyards and Intermodal Facilities (August 

2005), or the most recently approved District revision to the Guidance. 

The MICR calculations shall include multi-pathway consideration if 

applicable. 

(9) NEW RAILYARD means a railyard built, acquired, or established on or 

after October 7, 2005 for operation by Class I freight railroads or 

switching and terminal railroads in the District. 

(10) OPERATOR means the railroad responsible for operations of a particular 

railyard in the District. 

(11) PUBLIC NOTIFICATION LEVEL, for purposes of this rule is a MICR of 

ten in one million (10 x 10-6) or a total acute or chronic hazard index of 

one (1.0), for any target organ system at any receptor location. 

(12) RAILROAD means a commercial entity that operates locomotives to 

transport passengers or freight. 
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(13) RAILROAD OPERATIONS means those operations associated with 

railroads such as line-haul services, switching and terminal services; 

maintenance, service, and repair of locomotives and railcars; on-road, offroad, and stationary equipment associated with activities such as loading, 

unloading, moving and transfer of freight, track repair and maintenance 

operations; and other similar operations conducted by a railroad, or an 

entity contracted by a railroad. 

(14) RAILYARD means a source or grouping of sources or other air 

contaminant-emitting activities where railroad operations and associated 

railroad activities occur that are located on one or more contiguous 

properties within the Basin in actual physical contact, and if separated, 

separated solely by a public roadway or other public right-of-way, and are 

owned or operated by the same person (or by persons under common 

control). Such above-described groupings, if on noncontiguous properties, 

connected only by land carrying railroad tracks that are used solely for 

activities including locomotive fueling or maintenance, loading or 

unloading of freight, building or breaking down of trains, loading or 

unloading of freight from railcars, or staging of locomotives or railcars for 

these activities, shall be considered one railyard. If the above described 

groupings on noncontiguous properties connected only by land carrying 

railroad tracks are not used solely for the activities described previously, 

they shall not be considered one railyard. 

(15) SCHOOL means any public or private school, including juvenile detention 

facilities with classrooms, used for purposes of the education of more than 

12 children at the school, including in kindergarten and any of grades 1 to 

12, inclusive, but does not include any private school in which education 

is primarily conducted in private homes. The term includes any building 

or structure, playground, athletic field, or other area of school property, 

but does not include unimproved school property. 

(16) SWITCHING AND TERMINAL RAILROAD means a non-Class I 

railroad engaged primarily in switching or terminal services for other 

railroads. 

(17) TOTAL ACUTE HAZARD INDEX (HI) means the sum of the individual 

substance acute HIs for all toxic air contaminants affecting the same target 

organ system. 
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(18) TOTAL CHRONIC HAZARD INDEX (HI) means the sum of the 

individual substance chronic HIs for all toxic air contaminants affecting 

the same target organ system. 

(19) TOXIC AIR CONTAMINANT, for the purpose of this rule, means an air 

pollutant which may cause or contribute to an increase in mortality or 

serious illness, or which may pose a present or potential hazard to human 

health. Toxic air contaminants are those listed in Appendix A-1, 

excluding criteria pollutants, of the Office of Health Hazard Assessment’s 

The Air Toxics Hot Spots Program Guidance Manual for Preparation of 

Health Risk Assessments (October 2003), or the most recently approved 

OEHHA revision to the Guidance Manual. 

(20) TRANSIENT RAILYARD EQUIPMENT means emission sources within 

a railyard that are not exclusively used at the railyard, including, but not 

limited to, line haul locomotives, delivery trucks, or transport refrigeration 

units, regardless of ownership. 

(21) WEIGHTED TOXIC AIR CONTAMINANT, for the purpose of this rule, 

is calculated by multiplying the mass emission rate of a toxic air 

contaminant quantified in a railyard-wide criteria pollutant and toxic air 

contaminant emissions inventory by the applicable inhalation cancer 

potency value listed in Appendix L, Table 1, of the Office of 

Environmental Health Hazard Assessment’s (OEHHA) The Air Toxics Hot 

Spots Program Guidance Manual for Preparation of Health Risk 

Assessments, or the most recently approved OEHHA revision to the 

Guidance Manual or Appendix. 

(d) Emissions Inventory 

(1) On or before April 7, 2006, an operator of a railyard shall submit an 

Interim Railyard Emissions Inventory Report that includes the following 

information for all emission sources within the railyard: 

(A) Specific identification, as described in the California Air 

Resources Board’s Emissions Inventory Criteria and Guidelines 

(July 1997) for stationary sources and the District’s Railyard 

Emissions Inventory Methodology for mobile sources, or the most 

recently approved revisions to these documents, of all dedicated 

and transient railyard equipment used or operated in the railyard, 

including: 
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(i) all stationary sources, including, but not limited to, 

combustion equipment, processes, storage tanks, and 

fueling stations. 

(ii) all on-road and off-road mobile sources, including, but not 

limited to, trucks, motor vehicles, locomotives, yard 

hostlers, forklifts, cranes, side loaders, empty handlers, 

chassis stackers, chassis loaders, and chassis flippers; 

(B) If data for a time interval covering typical operations and 

equipment activity for the railyard over a period of 12 months or 

more is not available, description of the time interval over which 

information required under subparagraphs (d)(2)(A) and (d)(2)(B) 

will be provided, including an explanation of the basis for selecting 

the time interval that: 

(i) Covers a period of at least three months within the past two 

years, or a shorter time interval as approved by the 

Executive Officer, provided the shorter time interval can 

accurately characterize typical annual emissions; and 

(ii) Shows how the a time interval less than 12 months will be 

extrapolated to develop an annual emissions estimate that is 

representative of typical annual operations and equipment 

activity for the railyard; 

(C) Description of the source(s) of emission factors for all equipment 

to be used and emission control efficiencies, if applicable; 

(D) Description of the railyard, including detailed facility map, 

identifying entrance(s) and exit(s) of the railyard, loading and 

unloading areas, fueling areas, service and maintenance areas, 

classification yards, locomotive parking/idling areas, and any other 

areas within the railyard where emission sources or operations 

contributing to emissions occur; and 

(E) Universal Transverse Mercator (UTM) coordinates for railyard 

location and railyard boundary vertices. 

(2) On or before October 9, 2006 an operator of a railyard shall submit a 

railyard-wide criteria pollutant and toxic air contaminant emissions 

inventory to the Executive Officer that includes the following information 

for all emission sources within the railyard: 
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(A) For dedicated railyard equipment, including both mobile and 

stationary equipment: emissions of criteria pollutants and toxic air 

contaminants for the time interval described under subparagraph 

(d)(1)(B). Such emissions shall be based on fuel use or activity 

data specific to that emission source, or alternative methods 

proposed by the railroad and approved by the Executive Officer, 

and engine information that is specific to that emission source, 

including: engine type, model classification, model year, 

horsepower, fuel type, emission factor, load factor, throttle notch, 

time duration at each throttle notch, and any emissions control 

devices on the emission source; 

(B) For transient railyard equipment, including mobile, portable, and 

stationary equipment: emissions of criteria pollutants and toxic air 

contaminants for the time interval described under subparagraph 

(d)(1)(B). Such emissions shall be based on an average number of 

daily trips, the idling time, the duration of time the source is at the 

railyard, and emission factors that are representative of the fleet 

mix for each source category; 

(C) Documentation of emission factors used and emission control 

efficiency claimed, such as manufacturer certification data, source 

tests, or other data developed for or resulting from regulatory 

development processes. The Executive Officer may approve the 

use of an alternative source of data, provided the alternative is 

demonstrated to the Executive Officer’s satisfaction as accurately 

characterizing the emission rate for the applicable equipment; and 

(D) The sum of weighted toxic air contaminants. 

(3) Methodology 

(A) The emissions inventory for criteria and toxic pollutants shall be 

prepared for stationary sources by using the applicable emissions 

inventory methodology established by the California Air 

Resources Board's, Emissions Inventory Criteria and Guidelines 

(July 1997), or the most recently approved CARB revision to the 

Guidelines which addresses this emissions inventory, or any subset 

of these Guidelines as specified by the Executive Officer. 

(B) The emissions inventory for criteria and toxic pollutants shall be 

prepared for mobile sources according to the emissions inventory 
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methodology specified in the District’s Railyard Emissions 

Inventory Methodology, or the most recently approved District 

revision to this Methodology, which revisions will be published as 

needed by the Executive Officer. 

(C) Railyard operators may propose alternative emissions inventory 

methodologies for criteria and toxic pollutants for specific source 

categories, provided the alternative methodology can accurately 

estimate emissions subject to Executive Officer approval. 

(e) Health Risk Assessment 

(1) On or before January 8, 2007, an operator of a railyard shall submit a 

health risk assessment to the Executive Officer based on the railyard-wide 

toxic air contaminant emissions inventory prepared pursuant to 

subdivision (d) that includes the following information: 

(A) Railyard name, address, and contact person; 

(B) Facility plot plan (including a length scale) showing: 

(i) all stationary and mobile source locations (including their 

elevations above sea level); 

(ii) building dimensions; 

(iii) truck and train routes; 

(iv) truck and train idling activities; 

(v) cargo handling activities; 

(vi) other on- and off-road equipment activities; and 

(vii) Universal Transverse Mercator (UTM) coordinates for 

railyard location and railyard boundary vertices; 

(C) Air dispersion model(s) used and the rationale for selection, model 

parameters and adjustments, if applicable, emission rates used in 

the modeling; 

(D) Receptor grid information for the impact area, including fenceline 

receptors, as specified in the South Coast Air Quality Management 

District's most recent Health Risk Assessment Guidance for 

Railyards and Intermodal Facilities; 

(E) Meteorological data used and the rationale for selection; 

(F) Risk assessment, based on an exposure duration of 70 years for 

residents and schools and 40 years for workers, including 

appropriate multipathway factors; 
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(G) Exposure isopleths identifying all areas in the surrounding 

communities showing the impact area; and 

(H) In instances where the impact areas of two or more railyards 

operated by a single operator overlap and where the summed 

cancer risk for all of the overlapping impact areas is greater than 

ten in one million, as identified by health risk assessments 

submitted pursuant to paragraph (e)(1), the operator of the 

railyards shall report the aggregate risk in the areas of overlap as 

part of its submittal under paragraph (e)(1). 

(2) When preparing the health risk assessment, the operator of a railyard shall 

follow the policies and procedures of the South Coast Air Quality 

Management District's most recent Health Risk Assessment Guidance for 

Railyards and Intermodal Facilities. 

(f) Approval of the Health Risk Assessment 

(1) Within 120 days of submittal of the health risk assessment pursuant to 

subdivision (e), the Executive Officer will accept or reject the health risk 

assessment. The Executive Officer shall reject the health risk assessment 

unless the health risk assessment is: 

(A) complete and contains the information required under paragraph 

(e)(1); 

(B) accurate in representing the emission sources from all operations at 

the railyard; 

(C) conducted consistent with the policies and procedures specified 

under paragraphs (e)(2) and (e)(3); and 

(D) conducted using an emissions inventory that is consistent with 

methodologies specified in paragraph (d)(3). 

(2) The District will conduct a public meeting to address the evaluation of the 

health risk assessment prior to approving the health risk assessment. 

(3) If the Executive Officer rejects the health risk assessment, the operator of 

a railyard shall revise and resubmit within 90 days after being notified in 

writing of the decision. The revised submittal shall correct all deficiencies 

identified by the Executive Officer. 

(4) Within 90 days of the submittal of a revised health risk assessment, the 

Executive Officer will accept or reject the revised health risk assessment. 

The Executive Officer will modify the health risk assessment to correct 
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any deficiencies that the operator has not properly corrected and accept it 

as modified within 120 days of the rejection of the second submittal or 

failure to resubmit. 

(g) Updating Emissions Inventory and Health Risk Assessment 

(1) On or before March 1, 2008, and on March 1 every two years thereafter, 

the operator of a railyard shall submit an updated emissions inventory for 

criteria pollutants and toxic air contaminants emissions inventory, 

providing the information required and prepared using the methodology 

specified in subdivision (d), representing the previous calendar year. 

(2) On or before the September 1 following submittal of an updated emissions 

inventory under paragraph (g)(1), the operator of a railroad shall update 

and submit a new health risk assessment, providing the information 

required and prepared using the methodology specified in subdivision (e) 

and subject to the provisions specified in subdivision (f), if: 

(A) the sum of weighted toxic air contaminants calculated to comply 

with paragraph (g)(1) is greater than 1.1 times the sum of weighted 

toxic air contaminants from the emissions inventory submitted 

pursuant to paragraph (d)(2); or 

(B) the impact area shifts due to changes at the railyard, such as 

movement of equipment or operations from previously established 

locations. 

(3) The previous health risk assessment is in effect until the Executive Officer 

accepts the updated health risk assessment. 

(h) Public Notification Requirements 

(1) The operator of a railyard with an approved health risk assessment 

showing a risk that exceeds the Public Notification Level, shall notify the 

public within 60 days of the Executive Officer’s approval of the health 

risk assessment and every 12 months thereafter, unless the total railyardwide risk has been reduced to below the Public Notification Level. 

(2) The notification shall be provided in accordance with the most recently 

District approved “Public Notification Procedures for Phase I and II 

Facilities under the Air Toxics Hot Spots Information and Assessment 

Act.” 
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(3) As part of the public notification process, at minimum two public 

notification meetings shall be held within the impact area. Public 

notification meetings shall be held at locations proposed by railyard 

operators and subject to the approval of the Executive Officer, based upon 

a determination that the location is reasonably accessible to residents and 

workers in the impact area. 

(i) Additional Railyards 

(1) The Executive Officer may require the operator to submit an emissions 

inventory and health risk assessment for a Class I freight railyard or 

switching and terminal railyard not identified in subdivision (b), when, 

based upon investigation, the Executive Officer determines that emission 

levels from the railyard may cause exceedance of the public notification 

level. The operator shall follow the schedule contained in subdivisions (d) 

and (e) except the time limits shall begin on the date of receipt of notice 

from the Executive Officer to require an emissions inventory and health 

risk assessment, instead of from the date of adoption of this rule. 

(2) Unless a health risk assessment shows risk that is less than the Public 

Notification Level, the operator of a new railyard shall submit an 

emissions inventory and health risk assessment to the Executive Officer 

according to the following schedule: 

(A) Submit an Interim Railyard Emissions Inventory Report in 

accordance with the requirements of paragraph (d)(1) within 12 

months following commencement of operation of the new railyard; 

(B) Submit a railyard-wide criteria pollutant and toxic air contaminant 

emissions inventory to the Executive Officer in accordance with 

the requirements of paragraph (d)(2) on or before 18 months 

following commencement of operation of the new railyard; and 

(C) Submit a health risk assessment to the Executive Officer meeting 

the requirements of subdivision (e) based on the railyard-wide 

toxic air contaminant emissions inventory prepared pursuant to 

subparagraph (i)(2)(B) on or before 21 months following 

commencement of operation of the new railyard. 
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(j) Fees 

The Interim Railyard Emissions Inventory Report, emissions inventory, health 

risk assessment, as well as the annual updates to the emissions inventory and 

health risk assessment and fees incurred under paragraph (f)(4), if applicable, 

shall constitute plans for the purpose of fees assessed under Rule 306 – Plan Fees. 

(k) Penalties 

Failure to comply with any requirement of this rule, including failure to comply 

with requirements of the District’s Health Risk Assessment Guidance for 

Railyards and Intermodal Facilities is a violation of this rule and subject to 

penalties under Health and Safety Code Section 42400 et seq.