July 8, 2015

MEMORANDUM

SUBJECT: Technical Support Document: Approval and Promulgation of Implementation 

Plans; Texas; El Paso; Particulate Matter Contingency Measures

FROM: Jeff Riley, Environmental Scientist

Air Planning Section (6PD-L)

TO: FILE

I. Background

The Clean Air Act requires the Environmental Protection Agency (EPA) to establish national 

ambient air quality standards (NAAQS) for pollutants that cause or contribute to air pollution 

that is reasonably anticipated to endanger public health or welfare. States have developed a State 

Implementation Plan (SIP) that identifies how these standards will be attained and maintained. 

The State must submit revisions to the SIP to EPA for approval. EPA reviews and approves the 

revision if it conforms with the Federal Clean Air Act (CAA) and Federal regulations. Approval 

makes the revisions Federally enforceable. If the revision does not conform with the CAA and 

Federal regulations, EPA disapproves it. Disapproval may lead to further revisions by the State 

or development of a Federal Implementation Plan by EPA.

A. El Paso PM10 History

Under the 1990 CAA Amendments, the City of El Paso, Texas was designated nonattainment 

of the NAAQS for particulate matter (PM) with an aerodynamic diameter less than or equal to a 

nominal ten micrometers (PM10) and classified as a moderate PM10 nonattainment area under 

sections 107(d)(4)(B) and 188(a) of the CAA. The CAA required that states with moderate PM10

nonattainment areas submit SIPs to the EPA by November 15, 1991, detailing how the areas 

would attain the NAAQS by the December 31, 1994 deadline.

On November 5, 1991, the Texas Air Control Board (TACB), a predecessor agency of the 

Texas Commission on Environmental Quality (TCEQ) submitted the El Paso PM10 Attainment 

Demonstration SIP revision. The SIP revision added PM control measures into 30 Texas 

Administrative Code (TAC) Chapter 111, Control of Air Pollution from Visible Emissions and 

Particulate Matter. These control measures included prescribed burning, residential burning, and 

fugitive dust control measures. Specifically, the fugitive dust control measures added to 30 TAC 

Chapter 111, Subchapter A, Visible Emissions and Particulate Matter, Division 4, Materials 

Handling, Construction, Roads, Streets, Alleys, and Parking Lots, §111.147 consisted of the 

requirement that existing unpaved alleys within the city limits be paved at a rate of 15 miles per 

year, as well as setting frequencies for street sweeping in designated sections of the El Paso area.

In addition to these PM10 control measures, the November 5, 1991 SIP revision included a 

modeling demonstration, under CAA Section 179B, providing for timely attainment but for 

particulate emissions from Mexico. Section 179B allowed that moderate nonattainment areas 
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would not be reclassified as serious if the state could demonstrate that such areas would achieve 

attainment by the December 31, 1994 deadline if not for air quality impact contributions from 

emissions emanating from outside the United States. In response to the CAA Section179B 

provision, Texas demonstrated attainment of the PM10 NAAQS for the El Paso moderate 

nonattainment area through dispersion modeling of United States emissions alone. On January 

18, 1994 (59 FR 02532), EPA approved the El Paso PM10 SIP revision, and approved the 

attainment demonstration SIP as meeting the requirements of Section 179B, showing that the 

area would timely attain the PM10 standard but for emissions from Mexico. EPA also approved 

the three types of PM control measures added to 30 TAC Chapter 11 as contingency measures 

because they went beyond reasonably available control measures and were not relied upon to 

show attainment or reasonable further progress (RFP).

As part of its approval of the PM10 SIP revision, EPA also approved the included 

Memorandum of Understanding (MOU) dated November 5, 1991, between the City of El Paso 

and the State which outlines the responsibilities and regulatory requirements for both parties in 

implementing the El Paso area dust control methods. This MOU was replaced with a 

Memorandum of Agreement (MOA) with the City of El Paso on November 29, 2001, containing 

the same requirements. However, Texas has not submitted a formal request to EPA to replace the 

SIP-approved MOU with the MOA, so the MOU remains in the SIP.

On November 21, 2003, the El Paso Metropolitan Planning Organization submitted a letter 

requesting that the TCEQ develop a PM10 redesignation request and maintenance plan for the El 

Paso area. On December 28, 2009, the TCEQ requested information from the City to determine 

what efforts El Paso has taken to support a request for redesignation. In a response letter dated 

January 29, 2010, the City provided the following:

 the City has programs funded annually in both the City's capital improvement budget and 

in the Department of Transportation/Street Department operations budget in an effort to 

comply with environmental regulations;

 the City has committed to an alley paving program at a level in alignment with its own 

internal budgetary capacities, but not at the rate of 15 miles per year as required under 

§111.147;

 the City maintains an inventory of street and alley paving efforts to document the current 

status and projections for future paving activities; and

 the City's Air Quality Program conducts surveillance and investigations to ensure 

compliance with, and enforcement of, Chapter 111 rules.

B. Texas’ Submittals

On March 7, 2012, Texas submitted revisions to the El Paso SIP to remove the requirement 

to pave alleys at the rate of 15 miles per year, and replace it with the following requirements: 1) 

all new alleys must be paved; 2) unpaved alleys may not be used for residential garbage and 

recycling collection; and 3) recycled asphalt product (RAP) as defined in §111.145 and 

§111.147(1) may be used as an alternate means of Particulate Matter control for unpaved alleys. 

The SIP revisions also change the established street sweeping frequency requirement from four 

times per year to three times per year in the city limits and from six times per week to four times 

per week in the central business district. Revisions to the MOA between the TCEQ and the City 
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of El Paso to reflect the revised control measures and the respective responsibilities were also 

included as part of the SIP revision. The El Paso SIP revision would incorporate the State’s 

revisions to 30 TAC §111.147 into the PM SIP.

II. Evaluation

The State’s submittal is intended to provide the City with alternative methods of PM control, 

and demonstrate that the changes to §111.147 will not interfere with continued attainment of the 

PM10 NAAQS in order to comply with the anti-backsliding provisions in CAA Section 110(l). 

The revisions to §111.147(1)(E) and (2) would substitute the established alley paving and street 

sweeping measures with alternate control measures currently in place in the El Paso area that the 

State argues have resulted in PM10 emissions reductions equivalent to or greater than what would 

have been achieved if the City had continued to implement the prior version of §111.147(1)(E) 

and (2). These control measures include the use of RAP on existing unpaved alleys, city 

ordinances requiring developers to pave any new alleys they create, and reduced alley traffic.

Section 110(l) of the CAA states that EPA cannot approve a SIP revision if the revision 

would interfere with any applicable requirement concerning attainment and RFP, or any other 

applicable requirement of the CAA. Therefore, the EPA will approve a SIP revision that removes 

or modifies control measure(s) in the SIP only after the State has demonstrated that such removal 

or modification will not interfere (“noninterference”) with attainment of the NAAQS, Rate of 

Progress (ROP), RFP or any other applicable requirement of the CAA. Because the City 

implemented early the contingency measures for paving of alleys and street sweeping on an ongoing basis since 1991 even though never required by EPA to be implemented, Texas only must 

show that the status quo in air quality is preserved, and noninterference is demonstrated. Texas 

provided a qualitative analysis of the emission reductions coupled with evaluation of air quality 

data to show that the level of emissions provided for by the revised early implemented 

contingency measures would not interfere with attainment or RFP.

At the time of EPA’s approval of the paving of alleys as a contingency measure, there were 

an estimated 89 miles of unpaved alleys, and the projected 1994 emissions were to be reduced by 

0.5 percent. The State has documented in its submittal that the inventory of unpaved alleys in El 

Paso has significantly decreased from 66% of total alley miles in 1991, to 16% of total alley 

miles in 2010, with approximately 23 miles of unpaved alleys remaining. On December 3, 2014, 

the State provided subsequent data from the City indicating that between 2010 through 2014, the 

percentage of unpaved alleys has continued to decrease to 13% of the total inventory, with 

approximately 17 miles of unpaved alleys remaining. This represents an 81% reduction of the 

original inventory of unpaved alley miles in the City of El Paso, through early implemented 

contingency measures that were not relied upon to demonstrate attainment. A total of 72 alley 

miles have been paved and the estimated emissions reductions for 1994 have been met. Further 

progress has been made in part through the use of RAP as an alternate means of PM control for 

pre-existing unpaved alleys. The overall inventory of unpaved alleys in El Paso has continued to 

decrease, and thereby further reductions in PM10 levels have occurred well beyond those levels 

represented in the approved attainment demonstration.
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The City also established ordinances requiring developers to pave any new alleys, ensuring 

that the inventory of unpaved alleys will not increase. In addition, the City discontinued garbage 

collection in alleys in 1997, significantly reducing traffic in all alleys. The submitted SIP 

revision codifies this discontinuation by prohibiting garbage collection in alleys. Some 

commercial trash collection routes may still occur in paved alleys, and future growth may require 

trash receptacles to be located in paved alleys for newly developed residential areas, but traffic 

on unpaved alleys has been substantially reduced since 1991. Further, §111.147(2) maintains an 

existing requirement that sand applied to roads in El Paso for the specific purpose of snow or ice 

control must be removed as soon as such control is no longer necessary. The progress made by 

the City's alley and road paving programs, paving ordinances for new alleys, and discontinued 

garbage collection in alleys have reduced the overall amount of unpaved roadways, and therefore 

fugitive dust, in the El Paso area. These measures to reduce airborne PM10 have reduced the need 

to sweep streets at the frequencies originally specified under §111.147. The City has committed 

to include street and alley paving and sweeping in its annual budget for continued maintenance 

of the PM10 standard.

The State’s submittal also relied upon Federal Reference Method (FRM) PM10 ambient 

monitoring data reported by the Socorro monitoring site (AQS ID 481410057) for the years 2007 

through 2009 to demonstrate that the area monitored no exceedances of the PM10 24-hour 

NAAQS. The El Paso area continues to monitor attainment of the PM10 NAAQS based on data 

from the Socorro site and other network monitors through 2013. The level of the 1987 NAAQS 

for PM10 is 150 micrograms per cubic meter (μg/m3), and the NAAQS metric for the PM10

NAAQS is the 3-year average expected number of exceedances (ENE). The NAAQS is not to be 

exceeded more than once per year on average over a 3-year period. 

Concentrations flagged by States, Tribes, and local agencies as exception events (e.g., high 

winds, wildfires, volcanic eruptions, construction) and concurred by the associated EPA 

Regional Office are not included in these calculations. Data from quality assurance monitors, 

data from special purpose monitors operating less than 24 months, data identified as “nonregulatory”, data collected with non-reference/equivalent methods, and other data judged by 

EPA as not meeting 40 CFR 58 monitoring requirements are also not included in these 

calculations; such data are deemed to be not NAAQS comparable. The Average Estimated 

Exceedances values shown in Table 1 are computed for the latest 3-year period using Federal 

Reference Method or equivalent data reported by States, Tribes, and local agencies to EPA's Air 

Quality System (AQS). Only valid, NAAQS comparable Average Estimated Exceedance values 

are shown in this table.

Table 1: El Paso County PM10 Monitor Expected Number of Exceedances (ENE) 2007-2013

2007 2008 2009 2010 2011 2012 2013

Monitor 

Location & Site 

ID

ENE ENE ENE ENE ENE ENE ENE
5

10834 Ivanhoe 

(Ivanhoe Fire 

Station)

48-141-0029

0 0 0 0 0 0 0

301 Midway 

Dr. (Riverside 

High School)

48-14-0038

0 0 0 0 0 0 0

320 Old Hueco 

Tanks Rd. 

(Socorro)

48-141-0057

0 0 0 1 2 0 0

Data obtained from U.S. EPA Air Quality System, 7/9/2015

 

EPA believes the requirements that no further unpaved alleys be allowed and the reduced 

traffic on these alleys provides for continued reduction of PM emissions. With the current level 

of emission reductions, the area is meeting the PM10 standard. We expect that further reductions 

will continue into the future as the few remaining alleys are paved or treated with RAP. EPA 

agrees that RAP can be effective in suppressing dust. Moreover, these reductions are surplus to 

the 1991 attainment demonstration showing attainment but for emissions from Mexico because 

many additional alleys have been paved since the 1994 “but for” attainment date. Because the 

reductions that have been achieved in the El Paso area are well in excess of the reductions in the 

“but for” attainment demonstration, and because these reductions will be continued through early 

implemented contingency measures and the area is now meeting the standard, compliance with 

the anti-backsliding provisions in CAA Section 110(l) is demonstrated. The SIP revision will not 

interfere with the area’s ability to continue to attain or maintain the affected NAAQS or other 

CAA requirements.

IV. Conclusion

We have reviewed the El Paso PM10 contingency measure revision request and believe that 

approval of the submittal is warranted, consistent with the requirements of CAA Section 110(l).

EPA believes that the TCEQ has submitted sufficient information to support the SIP revision.

V. Recommended Agency Action

We are proposing to approve revisions to the Texas SIP that pertain to changes to the PM10

contingency measures in the City of El Paso. The State’s revisions submitted on March 7, 2012 

amend rule 30 TAC §111.147(1)(E) by removing the requirement to pave alleys at the rate of 15 

miles/year, and replacing it with the following requirements:

1) All new alleys must be paved;

2) Alleys may not be used for trash pickup; and

3) The use of recycled asphalt product as defined in §111.145 and §111.147(1) may be used 

as an alternate means of particulate matter control for alleys. 
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We also are approving 30 TAC §111.145 and §111.147(1) that define RAP, and 30 TAC § 

111.147(2) that changes the sweeping frequency requirement from 4x/year to 3x/year in the city 

limits and from 6x/week to 4x/week in the El Paso central business district. We have evaluated 

the State’s submittals and have determined that they meet the applicable requirements of the 

Clean Air Act and EPA regulations, and are consistent with EPA policy.