Technical Support Document 

for 

EPA's IVotice of Proposed Rulemaking 

on Revisions to the 

California State Implementation Plan 

as submitted by the State of California, 

for the Imperial County Air Pollution Control District 

EPA's Analysis of 

Imperial County Air Pollution Control District's 

Regulation VIII - Fugitive Dust 

Rules 800-806 

United States Environmental Protection Agency, Region IX 

Air Division 

February 20 10 
I. Overview of Regulation VIII and EPA's Imperial County PMlo Actions 

A. Regulation VIII Adoption and Submittal Chronology 

I 1 Board adopted revised (Rule 800) and new (Rules 801-806) versions of 1 

Date 

1 the Regulation VIII fugitive dust rules. 

The California Air Resources Board (ARB) submitted the November 8, 

1 2005 version of Regulation VIII to EPA as a revision to the California 1 

Action 

Plan SIP).^ 

July 2 1,2006 EPA found ARB'S June 16, 2006 submittal of Regulation VIII complete.2 

November 8, 2005 ) The Imperial County Air Pollution Control District (ICAPCD) Governing 

EPA has not incorporated into the SIP previous versions of any of the Regulation VIII rules. 

B. Regulation VIII Summary 

ICAPCD's Regulation VIII consists of seven interrelated rules designed to limit emissions of 

inhalable coarse particulate matter (PMlo) from anthropogenic fugitive dust sources in Imperial 

County. 

Rule 800. General Requirements for Control of Fine Particulate Matter, provides definitions, a 

compliance schedule, exemptions and other requirements generally applicable to all seven rules. 

It also describes specific exemptions and requirements for the U.S. Department of Defense 

(DOD), U.S. Bureau of Land Management (BLM) and U.S. Border Patrol (BP). Appendices A 

and B describe methods for determining compliance with opacity and surface stabilization 

requirements in Rules 801 through 805. 

Rule 801, Construction and Earthmoving Activities, establishes a 20% opacity limit and control 

requirements for construction and earthmoving activities. Affected sources must submit a dust 

control plan and comply with other portions of Regulation VIII regarding bulk materials, carryout and track-out, and paved and unpaved roads. The rule exempts single family homes and 

waives the 20% opacity limit in winds over 25 mph under certain conditions. 

Rule 802, Bulk Materials, establishes a 20% opacity limit and control requirements for bulk 

material handling, storage, transport and hauling. 

Rule 803, Carry-Out and Track-Out, establishes control requirements for removing carry-out and 

track-out material transported onto paved roads from unpaved roads and areas. 

1 Letter from Michael Scheible, ARB, to Wayne Nastri, EPA, June 16, 2006. 

2 Letter from Deborah Jordan, EPA, to Catherine Witherspoon, ARB, July 2 1,2006. 

Imperial County APCD - Regulation VIII - 2 - 

TSD, 0211 0 
Rule 804, Open Areas, establishes a 20% opacity limit and requires land owners to prevent 

vehicular trespass and stabilize disturbed soil on certain open areas. Agricultural operations are 

exempt from the rule. 

Rule 805, Paved and Unpaved Roads, establishes a 20% opacity limit and control requirements 

for unpaved haul and access roads, canal roads, and traffic areas that meet certain size or traffic 

thresholds. Single family residences and agricultural operations are exempt from the rule. 

Rule 806. Conservation Management Practices, requires agricultural operation sites greater than 

40 acres to implement at least one conservation management practice (CMP) for each of these 

categories: land preparation and cultivation, harvest activities, unpaved roads and unpaved traffic 

areas. 

C. PMlo Background and Related EPA Actions Concerning PMlo and Imperial County 

PMlo contributes to effects that are harmful to human health and the environment, including 

premature mortality, aggravation of respiratory and cardiovascular disease, decreased lung 

function, visibility impairment, and damage to vegetation and ecosystems. The population in 

Imperial County may be particularly vulnerable to these health impacts, having a high percentage 

of low income (1 9.7% of families below the poverty level, versus 9.6% nationally) and minority 

populations (76.0% Hispanic or Latino, versus 15.1 % nationally), a low educational attainment 

rate (63.0% high school graduates or higher, versus 84.5% nationa~l~),~ and decreased access to 

health care (including West Imperial and Calexico Medically Underserved Areas and Health 

Professional Shortage Areas throughout ~m~erial),~ all ofwhich may impact a community's 

ability to avoid and/or cope with environmental impacts. The Clean Air Act (CAA) requires 

States to submit regulations that control PMlo emissions to protect health of both the general and 

sensitive populations. 

Upon enactment of the 1990 Clean Air Act (CAA) Amendments, Imperial County was classified 

as moderate nonattainment for the PMlo national ambient air quality standards (NAAQS) under 

CAA Sections 107(d)(4)(B) and 1 88(a). By November 15, 199 1, such areas were required to 

develop and submit SIP revisions providing for, among other things, implementation of 

reasonably available control measures (RACM). CAA Sections 188(a) and (c)(l) also required 

moderate PMlo nonattainment areas to attain the PMlo standards by December 3 1, 1994. 

On August 1 1, 2004, EPA reclassified Imperial County as serious nonattainment for PMlo. As a 

result, under CAA Section 189(b)(l)(B), all best available control measures (BACM) were 

required to be implemented in the area within four years of the effective date of the 

3 U.S. Census Bureau, factfinder.census.gov, 

http:/ifactfinder.census.gov/servletiACSSAFFFacts'? event=Search&geo id=& geoContext=& street=& county-i 

rnpcrial+countv& citvTown-imperial+county& state-04000US06& zip-& lang=en& sse=on&pctxt-fph&p~sl-0 

- L 0; 

4 U.S. Department of Health and Human Services, muafind.hrsa.gov 

Imperial County APCD - Regulation VIII -3- 

TSD, 02/10 
reclassification, i.e., by September 10, 2008. Under Section 188(c), serious PMlo nonattainment 

areas were required to attain the PMlo standard by December 3 1, 2001 unless granted an 

extension under Section 1 88(e).5 

On December 1 1,2007, EPA determined that Imperial County had not attained the 24-hour PMlo 

standard by December 3 1,2001. The State was required to submit by December 1 I, 2008, a SIP 

revision including RACM and BACM. Pursuant to CAA Section 189(d), the plan was also 

required to provide for expeditious attainment and an annual reduction in PMlo emissions of not 

less than 5% of the most recent inventory until attainment.6 

On August 1 1, 2009, ICAPCD's Board adopted the "2009 Imperial County State Implementation 

Plan for Particulate Matter Less Than 10 Microns in Aerodynamic Diameter, Final," August I 1, 

2009 (2009 PMlo SIP). The 2009 PMlo SIP has not been submitted to EPA by the State. 

11. EPA's Evaluation of Regulation VIII 

A. Evaluation Criteria 

EPA is primarily evaluating Regulation VIII against three criteria: 

Enforceability - Regulations must be clear regarding, for example, who must comply, by what 

date, the standard of compliance, the methods used to determine compliance, and the process and 

criteria for obtaining any variation from the normal mode of compliance.7 Guidance used to help 

evaluate enforceability includes the Bluebook and the Little ~luebook.~ 

SIP Relaxation - CAA Section 1 lO(1) states that EPA cannot approve SIP revisions that interfere 

with attainment of the NAAQS or any other applicable requirement of the Act. 

BACM - We have defined BACM to be, among other things, the maximum degree of emission 

reduction achievable from a source category which is determined on a case-by-case basis 

considering energy, economic, environmental impacts and other costs.9 We have outlined in our 

guidance a four step process for identifLing BACM: (1) develop a detailed emissions inventory 

5 69 FR 48792 (August 11,2004). 

6 72 FR 70222 (December 11,2007). 

7 "Review of State Implementations Plans and Revisions for Enforceability and Legal Sufficiency" (Enforceability 

Guidance), Craig Potter, EPA, September 23, 1987. See also General Preamble for the Implementation of Title I of 

the Clean Air Act Amendments of 1990. 57 FR 13498, 13502 and 13541 (April 16, 1992) (General Preamble) and 

CAA $5 l lO(a)(2) and 172(c)(6). littp:i!www.epa.~ovicom~liance~resources!policies:!civiIlcadstationarvi'review-enfrpt.pdi.. 

8 "Guidance Document for Correcting Common VOC and Other Rule Deficiencies," U.S. EPA Region IX, August 

2 1, 200 1 (the Little Bluebook), and "Issues Relating to VOC Regulation Cutpoints, Deficiencies, and Deviations," 

U.S. EPA, OAQPS, May 25, 1998 (The Bluebook). 

9 "State Implementation Plans for Serious PM-I0 Nonattainment Areas, and Attainment Date Waivers for PM-I0 

Nonattainment Areas Generally; Addendum to the General Preamble for the Implementation of Title I of the Clean 

Air Act Amendments of 1990," 59 FR 4 1998,420 1 0 (August 16, 1994) (Addendum). 

Imperial County APCD - Regulation VIll -4- 

TSD, 02/10 
of PMlo sources: (2) evaluate the impact of various sources on PMlo concentrations to determine 

which are significant: (3) identify potential BACM for significant source categories and evaluate 

their reasonableness considering technological feasibility, costs, energy and environmental 

impacts; and (4) provide for the implementation of BACM or provide a reasoned justification for 

rejecting any potential BACM. lo 

When a moderate area is reclassified to serious, the requirement to implement RACM in CAA 

Section 189(a)(l)(C) remains. However, EPA does not ordinarily conduct a separate evaluation 

to determine whether measures for significant sources in a serious area also meet the RACM 

requirements. This is because in our serious area guidance, we interpret the BACM requirement 

as generally subsuming the RACM requirement (i.e., if we determine that the measures are 

indeed the "best available," we have necessarily concluded that they are "reasonably 

available"). ' 

B. Evaluation of Imperial County PM Inventory for Sources Requiring BACM 

CAA Section 189(b)(l)(B) and EPA guidance require that serious PMlo nonattainment areas 

implement BACM for all significant source categories. A source category is presumed to 

contribute significantly to a violation of the PMloNAAQS if its PMlo impact exceeds 5 pg/m3.12 

In October 2005, ICAPCD produced an analysis of BACM to support adoption of Regulation 

VIII. It applied the 5 pg/m3 threshold to the available PMlo inventory and 2002-2004 ambient 

PMlo data, and determined a de minimis level for significant source categories as 4.9 tons per day 

of ~~10.'~ ICAPCD identified four activities exceeding this level that were thus defined as 

significant sources needing BACM: 

1. Windblown dust from open non-crop-farm areas; 

2. Entrained and windblown dust from unpaved roads; 

3. Windblown dust from non-pasture agricultural lands; and 

4. Tilling dust. I" 

In 2008 and 2009, to support its PMlo attainment plan, ICAPCD revised its analysis of significant 

sources of PMlo to reflect 2006-2008 ambient PMlo data and a 2005 base year inventory.15 The 

State sought to exclude exceedances caused by high winds for regulatory purposes under EPA's 

exceptional events rule.'' All remaining PMlo exceedances occurred during low winds, so 

10 59 FR 42010-42014. 

11 59 FR 42010,42013-42014. See also 57 FR 13498, 13540-13541. 

12 59 FR42011. 

13 "Draft Final Technical Memorandum: Regulation VIII BACM Analysis," October 2005 (2005 BACM Analyis), 

Pg 8. 

14 2005 BACM Analysis, Table 3-6, pg. 16. 

15 2009 PMlo SIP, section 3.2. 

16 40 CFR 50. la) and 50.14. See letter from James N. Goldstene, ARB, to Deborah Jordan, EPA, May 19,2009, 

requesting exclusion of September 2,2006, April 12,2007, and June 5,2007 Imperial County PM,o exceedances. 

Imperial County APCD - Regulation VIII 

TSD, 02/10 
ICAPCD adjusted the inventory to eliminate windblown dust" and better reflect emissions from 

Mexico and other factors, and calculated a new de minimis threshold of 2 - 2.9% of the dayspecific exceedances. ICAPCD identified only two activities exceeding this level that were 

defined as significant sources needing BACM: 

1. Entrained dust from unpaved roads; and 

2. Tilling dust from agricultural operations.I8 

On December 22,2009, we did not concur with the State's exceptional event requests for high 

winds in 2006 and 2007.19 As a result, we replicate Imperial's de minimis calculations below 

without excluding the high wind events. The following table lists the measured ambient PMlo 

concentrations during exceedances caused largely by local (i.e., not Mexican) sources. 

Depending on the specific monitor, 2-3% of Imperial County's annual inventory is calculated to 

result in a 5 pg/m3 contribution to the air quality exceedances. 

-- 

' Exceedance (Date, Monitor, Value) *' ' Percent Equaling 5 ug/m3 I ,- -- 

The following table lists anthropogenic source categories that meet or exceed this threshold and 

are therefore considered significant sources needing BACM. 

6/05/07, Niland, 162 tLg/m3 

6/05/07, Westmorland, 226 yg/m3 

I Emission Source 

, Category From ICAPCD Average Annual PMlo Inventory ~missions~' % of Total 

5 + 162 pg/m3 = 3% 

5 + 266 pg/m3 = 2% 

1 Open areas I 1 

Windblown Dust, Other ~~Pt~d60% 1 

(npaved roads 

17 2009 PMlo SIP, Table 3.6, pg. 3-8. 

18 2009 PMlo SIP, Table 3.7, pg. 3-9. 

19 Letter, with enclosure, from Laura Yoshii, EPA to James Goldstene, ARB, Re: exceptional events requests 

regarding exceedances of the PM-I0 NAAQS in Imperial County, CA, December 22,2009. 

20 Data for this column are from the 2009 PMlo SIP, Table 2.1, pg. 2-4. 

21 Emissions data are from the 2009 PMlo SIP, Table 3.3, pg. 3-4. 

Imperial County APCD - Regulation VIII 

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r~ntrained Unpaved Road Dust, CityICounty 1 25 tpd, 9% 

Entrained Unpaved Road Dust, Canal 

Windblown Dust, Unpaved CityICounty Road 8 tpd, 3% 

Windblown Dust, Unpaved Canal Road 

Windblown Dust, Unpaved Farm Road 

Agricultural lands 

Tilling 7 tpd, 2% 

Windblown Dust, Non-Pasture Agricultural Lands 11 tpd, 4% 

C. Summary of EPA Evaluation Criteria 

Enforceability - The recordkeeping, reporting and other rule provisions help ensure that 

Regulation VIII, for the most part, can be enforced. However, we have identified below several 

provisions in Regulation VIII that we believe do not meet the enforceability requirements of 

CAA Section 1 1 O(a). 

SIP Relaxation - There is no prior version of Regulation VIII in the SIP, so our action does not 

raise issues regarding SIP relaxation and CAA Section 1 lO(1). 

BACM - We have compared Regulation VIII with analogous requirements in the South Coast 

Air Quality Management District (SCAQMD), San Joaquin Valley Air Pollution Control District 

(SJVAPCD), Maricopa County Air Quality Department (MCAQD), Clark County Department of 

Air Quality and Environmental Management (CCDAQEM) and other areas. In doing so, we 

recognize that some variability exists among sources in different areas, and that technically and 

economically feasible controls in one area may not be feasible in another area. Based on our 

analysis, we believe that Regulation VIII is generally consistent with analogous requirements in 

other serious PMlo areas and includes many provisions consistent with CAA requirements for 

BACM and with established EPA policy and guidance. However, we identie several provisions 

below where the State has not adequately demonstrated BACM implementation. 

D. Rule Deficiencies 

The following deficiencies preclude EPA's full approval of Regulation VIII. Section 1I.D. 1 below 

identifies deficiencies related to sources for which BACM is required as discussed above in 

Section 1I.B. While, as indicated above, BACM is determined on a case-by-case basis, the 

identification of potential BACM for a significant source category in Imperial County necessarily 

involves a consideration of control measures adopted andlor implemented in other geographical 

areas for the same and similar source categories. Therefore, in the following discussions we 

reference rules, statutes and other requirements in such areas that inform the determination of 

BACM for Imperial County sources. 

Section II.D.2 identifies one deficiency related to bulk materials, a source category for which 

BACM is not currently required based on the information available to EPA to date. 

Imperial County APCD - Regulation VlII 

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1. BACM-Related Deficiencies 

Open Areas 

a. Recreational off-highway vehicle (oHv)~~ activity causes much of the PMlo emissions from 

open areas in Imperial County. Rule 804 regulates only a small portion of these emissions, 

including some emissions from OHV activity on State lands where Rule 804 is apparently not 

being implemented. The vast majority of the OHV emissions in Imperial County are 

addressed only by requirements in Rule 800 Section F.5 for dust control plans (DCPs) for 

sources under the control of BLM. While BLM is required to describe in the DCPs the dust 

control measures that it intends to implement, BLM is not required to implement any specific 

BACM-level controls for OHV use. 

ICAPCD must provide an analysis of potential BACM controls for OHV activity in open 

areas and on unpaved roads and paths that are exempt from the specific requirements and 

measures in Rules 804 and 805 and identify, adopt and submit any appropriate revisions to 

Rules 800, 804 and 805. Such analysis should address as its starting point measures in EPA's 

1992 RACM guidance at 57 FR 18070, 18072 (April 28, 1992) and analogous requirements 

in other areas such as Arizona Revised Statute $49-457.03, and Clark County Air Quality 

Regulations, Section 90. ICAPCD should evaluate the feasibility and impacts of additional 

restrictions in recreational OHV areas, such as closing some of the 250 square miles that are 

open to OHV use that are particularly likely to impact populations, and restricting OHV 

activity during summer months when there is virtually no rain to reform surface crusts. In 

addition, ICAPCD must implement Rules 804 and 805 on all State lands used by OHVs or 

demonstrate in its BACM analysis that an exemption for OHV activity on such lands is 

appropriate. See Section 1II.B. 1 below for further discussion. 

b. The term "disturbed surface area" is used in several Regulation VIII rules but is never 

defined. For example, Rule 804 applies to a source category for which BACM is required 

and relies on the undefined term to describe rule applicability in Rule 804 Section B. In order 

to ensure that these rules are enforceable at a BACM level, ICAPCD must define "disturbed 

surface area" as do, for example, SJVAPCD Rule 8010 and SCAQMD Rule 403. 

Unpaved Roads and Traffic Areas 

c. Rule 805 Section D.2 exempts agricultural roads and traffic areas from opacity and 

stabilization requirements applicable to non-agricultural operation sites. Farm roads and 

traffic areas are only required to implement a CMP from the menus for unpaved roads and 

traffic areas in Rule 806. In contrast, for example, SJVAPCD requires that CMPs be 

implemented to meet opacity and surface stabilization requirements at the following 

22 As used in this Technical Support Document, the term "off-highway vehicle" or OHV includes all vehicles 

subject to the exemption in Rule 800 Section E.6 for recreational use of public lands in Imperial County. 

Imperial County APCD - Regulation Vlll - 8 - 

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thresholds: unpaved farm roads with 2 75 VDT or > 25 average daily vehicle trips by three or 

more axle vehicles; unpaved traffic areas with 2 50 average daily vehicle trips (on an annual 

basis) or > 25 average daily vehicle trips (on an annual basis) by three or more axle vehicles. 

ICAPCD must remove the exemption in Rule 805 Section D.2 or demonstrate how BACM is 

met in Imperial County for farm roads and traffic areas that are subject to less stringent 

requirements than other roads and traffic areas in the County and farm roads and traffic areas 

in other areas. 

d. Rule 800 Section F.6.c exempts roads owned or operated by BP from Rule 805 requirements 

that are "inconsistent with BP authority and/or mission." It is not clear what this exemption 

is intended to address, or how it would be implemented and enforced, particularly because 

both BP and ICAPCD staff have informally informed EPA that BP does not own or operate 

any roads in Imperial County. ICAPCD must either remove this exemption or narrow the 

exemption to specific mission activities and demonstrate that the exemption is minimized 

and necessary consistent with BACM requirements. 

e. The CAA requires ICAPCD to implement BACM by 2008 (i.e., four years after 

reclassification to serious).23 Rule 805 Section E.7 allows the County until 20 15 to stabilize 

heavily-travelled unpaved non-farm roads. This schedule is inconsistent with the statutory 

requirement and ICAPCD has not provided adequate evidence that this schedule is as 

expeditious as practicable, based upon economic feasibility or any other appropriate 

consideration. In evaluating economic feasibility of a measure that depends on public 

funding, EPA considers past funding of similar activities and availability of funding sources 

to determine whether public agencies have made good faith efforts to expeditiously 

implement the available control measures. ICAPCD must expedite the schedule for 

implementation of this measure or demonstrate good faith efforts to increase funding and 

priority of road stabilization projects consistent with national guidance. See Section III.B.3 

below for further discussion. 

f. Rule 805 Section E.7's requirement to stabilize all non-exempt unpaved County roads is also 

not adequately enforceable as currently structured. If ICAPCD retains the same structure, it 

must revise Rule 805 Section E.7 to clarify that the County must: (a) implement (and not just 

submit) a stabilization plan; (b) stabilize different unpaved roads each year; and (c) maintain 

all stabilized roads. 

Agriculture (see also section 1I.D. I .c above) 

g. Rule 806 Section E lists CMPs intended to control emissions from agricultural land 

preparation and cultivation (which includes tilling), harvest activities, unpaved roads and 

traffic areas, but these CMPs are broadly defined and there is no other mechanism in the rule 

23 Since 2008 has passed, BACM is now required to be implemented as expeditiously as practicable. Delaney v. 

EPA, 898 F.2d 687 (9th Cir. 1990). 

Imperial County APCD - Regulation Vlll 

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to ensure specificity. 24 The absence of sufficiently defined requirements makes it difficult 

for regulated parties to understand and comply with the requirements, and makes it difficult 

for ICAPCD or others to verify compliance and to enforce the requirements if necessary. The 

lack of specificity similarly renders it difficult to assess whether the measures constitute 

BACM level controls. ICAPCD must revise Rule 806 to ensure that CMPs are enforceable 

and are implemented at a BACM level or demonstrate why such a rule revision is not 

necessary. 25 SJVAPCD Rule 4550, for example, relies on an application submittal and 

approval process to ensure sufficient specificity of the particular measures implemented at 

each source. Great Basin Unified Air Pollution Control District (GBUAPCD) Rule 502 also 

has an application submittal and approval process. Alternatively, there may be another 

mechanism to ensure adequate specificity such as by revising and clarifying ICAPCD's CMP 

application forms. 

h. Rule 806 Section E requires one CMP from the "land preparation and cultivation" category 

and one CMP from the "harvest" category, while SJVAPCD Rule 4550 requires an additional 

CMP from the "cropland-other" category. GBUAPCD Rule 502 also requires that one CMP 

each be selected from the "land preparation and cultivation," "harvest," and the "croplandother" categories. ICAPCD must similarly require an additional CMP for cropland, or 

demonstrate why that is not appropriate. 

i. Windblown dust from non-pasture agricultural lands is also a significant source of PMlo that 

requires BACM independent of agricultural tilling. The CMPs in Rule 806 Section E, 

however, mainly control emissions by reducing the number of vehicle passes across fields, 

and sources are not required to select BACM level practices for controlling windblown dust 

from active or fallow agricultural fields. ICAPCD must revise Rule 806 to require BACM 

level windblown dust controls. In general, EPA believes that the evaluation of BACM level 

24 For instance, one of the CMPs that is both in the land preparation and cultivation menu in Section E.l and the 

harvest menu in Section E.2 is "equipment changes/technological improvements" which is defined in Section C.15 

as "To modify the equipment such as tilling; increase equipment size; modify land planning and land leveling; match 

the equipment to row spacing; granting to new varieties or other technological improvements. It reduces the number 

of passes during an operation, thereby reducing soil disturbance." This definition is too broad to ensure 

enforceability. Moreover, because there is no mechanism to narrow the definition for a particular agricultural 

operation, a CMP may be implemented in a manner less stringent than a BACM level of control. In a similarly broad 

fashion, Section C.34 defines "speed limits," a CMP that is both in the unpaved roads menu in Section E.3 and the 

unpaved traffic areas menu in Section E.4, as "enforcement of speeds that reduce visible dust emissions. The dust 

emissions from unpaved roads are a function of speed, meaning reducing speed reduces dust." However, an 

appropriate speed limit or range of speed limits is not specified or otherwise ensured. 

25 Section 1I.B identifies tilling and unpaved farm roads as significant source categories for which BACM is 

required. These sources are addressed by the CMP menus in Rule 806 Sections E.1 (land preparation and 

cultivation) and E.3 (unpaved roads). The CMPs in Rule 806 Sections E.2 (harvesting) and E.4 (unpaved traffic 

area) must also be fully enforceable at a BACM level because the activities occur at the same facilities and are 

integrally related to other activities identified as significant (i.e., tilling and unpaved roads respectively). By 

analogy, where enforceable VOC reasonably available control technology (RACT) level controls are required for 

refineries, SIP rules generally impose leak detection and repair requirements on valves, flanges, threaded 

connections, and other related equipment even if emissions from any one of these taken individually might be much 

smaller than the major source threshold requiring RACT. 

Imperial County APCD - Regulation Vlll - 10- 

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controls for a particular source or activity should include consideration of U.S. Department of 

Agriculture (USDA) approved conservation systems and activities. Although these guidelines 

may not specifically be designed to minimize air pollution, they are intended to be feasible 

and effective techniques that will reduce windblown dust, and thus would be appropriate 

measures to consider for BACM for such sources or activities for PMlo. SCAQMD Rule 403 

provides an example of such controls. See Section III.B.4 below for further discussion. 

2. Non-BACM Deficiency 

Rule 802 Section D. 1 allows the Air Pollution Control Officer (APCO) to set aside controls that 

might be used instead of water to stabilize surfaces of bulk materials. This discretion allows 

ICAPCD to approve alternatives to the applicable SIP without following the SIP revision process 

described in CAA Section 1 10. Moreover, ICAPCD has not demonstrated why such discretion is 

needed for measures such as covering, enclosing or sheltering material piles. While we prefer 

removal of the exemption and APCO discretion, SJVAPCD Rule 803 1 remedies the 

enforceability issue by requiring EPA approval.26 

111. Additional Information 

A. Additional Recommendations for the Next Revision of Regulation VIII 

The following revisions are not currently the basis for rule disapproval, but are recommended for 

the next time the rules are amended. 

1. Rule 800 Sections C.36 and E.7 provide a broad exemption for DOD "tactical training" that 

may be difficult to enforce. We could not find a similar exemption in analogous SCAQMD 

and SJVAPCD rules and believe this exemption should be further defined and limited in Rule 

800. 

2. If Rule 800 Section F.5.e. remains after addressing the deficiency summarized in section 

1I.D. 1 .a above, we note that the term "off-road event and/or competitions" is undefined, 

making it unclear as to when dust control plan and recreation area management plan (RAMP) 

requirements must be implemented by BLM. The 2005 BACM Analysis states that 5-1 0 

events occur per year, suggesting uncertainty about the threshold and magnitude of these 

events." Depending on the response to the issues we raise in section 1I.D. 1 .a, it may be 

appropriate for the rule to identi@ regular annual events and incorporate a visitor count 

threshold. 

3. We recommend that ICAPCD add a 0% opacity at the fenceline standard to Rules 80 1, 802, 

804 and 805, in addition to the 20% opacity standard. SCAQMD, MCAQD, and 

26 See Little Bluebook, pg. 17. 

27 2005 BACM Analysis, pg. 19. 

Imperial County APCD - Regulat~on VllI 

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CCDAQEM employ some version of this standard to aid enforcement. 

4. Rule 802 Section D.4 exempts transport and hauling of bulk material within a worksite from 

the requirement to cover loads and clean haul beds. We recommend that ICAPCD remove 

these exemptions. SJVAPCD Rule 803 1, for example, requires onsite haul trucks to cover 

loads. 

5. Regardless of vehicle size and number of trips, Rule 803 Section D.2 waives all carry-out and 

track-out control requirements for operations that remain at a location no more than 10 days 

in a 90 day period. In theory, this could waive these basic controls for operations with 

thousands of truck trips. We recommend that ICAPCD revise this consistent with SJVAPCD 

Rule 8041, for example, which uses only vehicle trips per day to determine applicability. 

6. ICACPD should consider revising Rule 804 Section B to apply requirements to smaller 

sources. MCAQD Rule 3 10.01, for example, applies similar requirements to 0.1 acres with 

500 square feet (sq. ft.) of disturbed surface area compared to Rule 804's 0.5 acres in urban 

areas and 3.0 acres in rural areas with 1000 sq. ft. of disturbed surface area. 

7. ICAPCD should consider revising Rule 805 requirements for unpaved traffic areas in light of 

more stringent requirements in other areas, such as MCAQD Rule 3 10.0 1. Specifically, Rule 

805 Section E.5 exempts areas smaller than one acre and 75 ADT from control while Rule 

3 10.0 1 only exempts lots serving four or fewer residential units. Rule 3 10.0 1 also establishes 

track-out clean-up requirements, while Rule 805 does not. 

8. ICAPCD projects that the 199 miles of County roads exceeding Rule 805's 50 ADT 

threshold will be stabilized using gravel, a control measure estimated to be 60% effective. 

For the most highly traveled roads, we recommend that ICAPCD consider requiring paving, 

which is estimated to be 99% effective in reducing entrained dust emissions and provides a 

longer lasting stabilized surface preventing windblown emissions. See Section III.B.2 below. 

9. ICAPCD estimates that canal roads contribute the most unpaved road mileage and PMlo 

emissions, but projects that no canal roads meet Rule 805's applicability threshold and are 

subject to control requirements. To address this large source of emissions, ICAPCD could 

consider a lower trip threshold in Rule 805 Section E.4. See Section III.B.2 below. We also 

recommend that ICAPCD consider strengthening the clarity and enforceability of canal bank 

control options described in Rule 805 Section F.2. For example, "canal bank surface 

maintenance" is vague and may be difficult to enforce. 

10. We recommend further refinements to the unpaved road inventory. Specifically, ICAPCD's 

ADT and VMT estimates may come partly from a 1993 SIP. 28 However, the ICAPCD 

documentation does not describe how these estimates were derived, whether they were based 

28 2005 BACM Analysis, Appendix B. 

[rnperial County APCD - Regulation VIll 

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on traffic counts, or whether they remain valid many years later. See Section III.B.2 below. 

1 1. Rule 806 Section C.7 defines "Chemigation/Fertigation," while Section E. 1 and the CMP 

Plan refer to "Chemical/Fertigationm and "Chemical Fertigation," respectively. We 

recommend using consistent names to enhance rule clarity. 

12. Rule 806 Section D. 1 exempts agricultural sources that are below 40 acres. While SJVAPCD 

Rule 4550 exempts farms below I00 acres, Maricopa's BMP rule29 and SCAQMD Rule 403 

exempt farms below 10 acres. The 2009 PMlo SIP notes that "According to information 

obtained from USDA/NRCS, parcels of size 3 40 acres account for approximately 96.95% of 

the area of all agricultural parcels in Imperial County. Thus, if emissions per acre of 

agricultural parcel are equal for all parcels (regardless of size), then Rule 806 applies to - 

97% of total emissions from all agricultural parcels."30 We question the assumption that 

emissions per acre of agricultural parcel are equal for all parcels in light of variability in 

crops, management practices, soil type, and other factors. As a result, we recommend 

ICAPCD consider lowering the exemption in Rule 806 from 40 acres to 10 acres. 

13. Rule 806 Section E.3 includes CMPs that are not designed to stabilize unpaved farm roads 

and therefore only minimally control windblown dust (i.e., restricted access, speed limit, 

track-out control and wind barriers). Particularly since ICAPCD estimates 6.01 tpd of 

windblown emissions and only 1.35 tpd of entrained emissions from unpaved farm roads, we 

recommend that ICAPCD revise this section to allow only CMPs that stabilize unpaved roads 

(i.e., dust suppressants, gravel, paving and watering). See Section III.B.2 below. 

B. Additional Background on Selected Deficiencies and Recommendations 

This section provides additional information regarding some of the issues identified above. 

1. Emissions from OHV Activity 

ICAPCD estimates that windblown dust from dunes, grassland and other open areas account for 

60% of annual PMlo emissions,3' and estimates that up to 22 tpd 32 of windblown PMlo from 

these areas are emitted from over 250 square miles (164,000 acres)33 used by recreational OHV.~~ 

ICAPCD projects an additional 1.34 tpd of emissions from non-wind emissions partly from OHV 

29 Arizona Administrative Code Section R18-2-611, "Agricultural PM lo General Permit; Maricopa PMlo 

Nonattainment Area and Maricopa County Portion of Area A," 

30 2009 PMlo SIP, pg. 4-8. 

3 1 See last table in Section 1I.B above. 

32 2009 PMlo SIP, Table III.B.4, Appendix III.B, pg 1II.B-8; 22 tpd = 7.77 + 1.43 + 0.8 + I 1.0 + 1. I. 

33 2009 PMIo SIP, Table III.B.4, Appendix III.B, pg 1II.B-8. 

34 OHV activity indirectly increases PMlo emissions by disturbing vegetation and surface crusts, leaving the surface 

less stable and more vulnerable to emissions during subsequent winds. 

Imperial County APCD - Regulation VIlI - 13 - 

TSD. 02/10 
activity on BLM and U.S. Forest Service roads.35 Additional emissions from OHVs directly 

entraining dust in open areas (i.e., not on established roadslpaths) are not addressed in existing 

emission inventories for Imperial County. 

In 1992, EPA identified OHV limitations as a required RACM for moderate PMlo areas under 

CAA Section 189(a)(l)(C), and listed three example controls: confining operations to specific 

areas, requiring use permits, and banning OHV activity ICAPCD Rule 804 Section 

E.l requires all persons (defined at Rule 800 Section C.29 to include both public and private 

entities) who own or otherwise have jurisdiction over open areas to restrict OHV activity in 

Imperial County by requiring them to maintain a stabilized surface and to meet a 20% opacity 

limit. Rule 805 may also control some emissions from OHVs on unpaved roads. The 20% 

opacity limit in Rules 804 and 805 and the stabilization standards and methods found in Rule 800 

Appendices A and B are common PMlo controls and are generally consistent with other serious 

PMlo area fugitive dust rules. However, ICAPCD estimates that Rule 804 addresses only 1% of 

emissions from Imperial County's open land.37 

Most emissions from OHV activity in Imperial County occur on BLM lands that are exempted 

from Rule 804 and Rule 805 requirements by Rule 800 Section E.6. ICAPCD Rule 800 also 

requires BLM to submit and implement DCPs to limit PMlo from OHVs, although there are no 

requirements that they contain specific BACM for OHV activity. OHV activity also occurs in 

Ocotillo Wells State even though State lands are not exempted from Rule 804's opacity 

and stabilization requirements. 

BLM, DOD, U.S. Fish and Wildlife, Bureau of Reclamation, and California prohibit or limit, 

independent of Rule 804, OHV activity on substantial open areas under their control in Imperial 

StatelFederal agencies also charge a nominal fee for OHV areas, such as $50/year for 

an OHV day use annual pass.40 While these OHV restrictions include some features of the 1992 

RACM guidance, the State has not demonstrated that current RACM, much less BACM, is 

implemented for these sources. For example: 

a. None of the OHV restrictions on BLM lands (either through the DCPs or the restrictions to 

specific areas) are in regulatory form and submitted for inclusion in the SIP pursuant to CAA 

Sections 1 10 and 189. 

b. Despite the fees and other programs that may reduce OHV activity and hence PMlo 

35 2009 PMlo SIP, Table 111.2, Appendix III.A, pg. 1II.A-6. This accounts for direct PM,, emissions caused by 

OHV activity by entraining dust through contact between tires and unpaved surfaces. 

36 57 FR 18072, Appendix Cl (April 28, 1992). 

37 BACM Amendments to Regulation VIII, Fugitive Dust Rules, ICAPCD Staff Report, November 8, 2005, Table 

3, pg 6. 

38 2009 PMlo SIP, Table I11.B-I, Appendix III.B, pg 1lI.B-2 

39 2009 PMlo SIP, Table 1II.B-1, Appendix III.B, pg 1II.B-2. 

40 California State Parks, Off-Highway Motor Vehicle Recreation Passes and Fees Schedule, 2009, 

http://ohv.parks.ca.gov/?page-id=25760 

lmperial County APCD - Regulation Vlll 

TSD, 02/10 
emissions, there are still over 1.4 million users per year to the dunes area alone,41 and over 

250 square miles open to OHVs in Imperial County. No evidence was presented to suggest 

that fees and OHV restrictions on public land in Imperial County have been designed for 

and/or are effective in reducing PMlo emissions and impacts. 

c. ICAPCD has not provided an analysis of potential BACM controls for OHV activity. 

Previous ICAPCD BACM analysis for Regulation VIII in general relied largely on 

comparison to SJVAPCD 's analogous Regulation VIII.~~ However, SJVAPCD does not 

have large OHV open areas such as those in Imperial In addition, other areas 

currently regulate this specific source category. See Arizona Revised Statute 549-457.03 

which prohibits recreational OHVs on PMlo high pollution advisory days. This regulation 

was developed with the support of the local OHV industry. See also Clark County Air 

Quality Regulations, Section 90, which effectively restricts OHV activity on BLM and other 

open areas greater than 5,000 square feet within the Las Vegas PMlo nonattainrnent area. 

44 

d. Among other things, it seems reasonable to expect that ICAPCD's BACM analysis would 

evaluate the feasibility and impacts of additional restrictions in OHV areas, such as closing 

some of the 250 square miles that are particularly likely to impact populations, or restricting 

OHV activity during summer months when there is virtually no rain to reform surface crusts. 

2. Emissions from Unpaved Roads 

3. BACM Implementation for Unpaved Non-Farm Roads 

4 1 Imperial Sand Dunes Recreation Area Management Plan (RAMP), U.S. DOI, BLM, El Centro Field Office, May 

2003, pg. 5. 

42 ICAPCD Staff Report, BACM Amendments to Regulation VIII, Fugitive Dust Rules, November 8,2005. 

43 See http:!/ww.blin.~ov/ca~st/e~i!pro~~rr:~~'eation/ol~v.lit~nl 

44 PMlo State Implementation Plan for Clark County, Adopted by Clark County Board of Commissioners, June 19, 

2001, pg. 4-8 1, http://www.accessclarkcounty.com/depts/daqeaq/paminages/pmlOsip2OOl .aspx. 

2005 PMlo Emissions and 

Imperial County APCD - Regulation VIII 

TSD, 02/10 

Inventory assumed ADT level taken from Appendix B, 2005 BACM Analysis. Road mileage and estimated annual 

average emissions from 2009 PMlo SIP, Table 3.2, pg 3-3. Emission reductions from 2009 PMlo SIP, Table 4.1, pg. 

4-5 . 

Road Category 

Cnty <50 ADT 

Cnty >50 ADT 

, City Roads 

Canal Roads 

Federal Roads 

Farm Roads 

Total 

Un2aved Road Emissions Inventory Data 

Road 

Miles 

1155 

199 

7.5 

6 148 

139 

2263 

7648.5 

Rule 805 

Threshold 

(miles) 

exempt 

50 

5 0 

2 0 

5 0 

-- 

Inventory 

Assumed 

ART 

10 

70 

10 

5 

10 

-- 

Reg VIII 

Reduction 

(t~d) 

0 

8.73 

0 

0 

0 

1.11 

9.84 

Windblown 

Emissions 

(tpd) 

6.64 

1.14 

0.03 

16.32 

0.37 

6.01 

24.5 

Entrained 

Emissions 

ad) 

11.11 

13.4 

0.07 

29.57 

1.35 

1.35 

55.5 
As discussed in Section 1.C above, CAA Section 189(b)(l)(B) required BACM implementation 

in Imperial County by September 10,2008. Despite the September 10,2008 BACM 

implementation requirement, ICAPCD projects that the 199 miles of unpaved roads subject to 

Rule 805 will not be stabilized until 2015. This assumes that the County will gravel 19.9 miles 

of unpaved roadway each year for ten years beginning in 2006.~' 

We recognize that some control measures, such as paving a network of unpaved roads, may 

involve significant costs to public entities. EPA has explained that, where economic feasibility of 

control depends on public funding, we will consider past funding and the future availability of 

funding sources to determine if a good faith effort is being made to implement BACM 

expeditiously. For example, an existing unpaved road stabilization program should retain its 

existing level of funding and the state should provide evidence of ambitious efforts to increase 

future funding and increase the future priority of the unpaved road stabilization program for 

existing revenue streams.46 ICAPCD states that the County budget for paved road maintenance 

is $2 million per year 47 but does not explain whether this entire amount is to be allocated to the 

unpaved road stabilization program. Assuming that the entire amount is to be so allocated, 

ICAPCD does not explain the relationship between this budget and the schedule for stabilizing 

unpaved roads, does not explain how this budget was derived in light of various federal, state, 

and local (including local Measure D) funding sources for public works construction and 

maintenance, or otherwise provide the demonstration contemplated by the relevant EPA 

guidance. 

Using the per mile cost figures provided by the Imperial County Department of Public Works 

(ICDPW), and again assuming that the entire $2 million annual budget will be used for unpaved 

road stabilization, we estimate the costs of twenty miles of annual road stabilization in the table 

below. Since ICAPCD projects that gravelling will be used predominantly,48 it appears only 9% 

of the $2 million annual budget would be needed for roadway stabilization to comply with the 

ten year schedule in Rule 805 Section E.7. It is not obvious from the information provided in the 

submittal, therefore, why Rule 805 Section E.7 does not require a more expedited schedule. 

Estimated Unpaved Road Stabilization Annual Costs I 1 Control Measure I Costhile / 20 mile cost I % of ICDPW $2M Budget I 

/ Pave / $131,000 1 $2.62 M 1 131% / 

Cost factors taken from 2009 PMlo Plan, pg. 4-8,. 

& water 

Implementation schedule taken from 2009 PM,o Plan,, Table 1V.C-1, Appendix 1V.C. 

45 2009 PMlo SIP, Table 1V.C-I, Appendix 1V.C-1, pg. 1V.C-I. 

46 59 FR 42013. 

47 2009 PMlo SIP, pg. 4-8. We did not find citations for ICAPCD's $2 milIion/year budget estimate, such as funding 

documents or county budgets. 

48 2009 PMlo SIP, pg. 4-8, footnote 67. 

$2,980 

$8,950 

Imperial County APCD - Regulation Vlll 

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$59,600 

$179,000 

3% 

9% 
4. Agricultural Windblown Dust 

Rule 806 does not require BACM level controls for controlling windblown dust from active or 

fallow agricultural fields. In general, EPA believes that the evaluation of BACM level controls 

for a particular source or activity should include consideration of USDA approved conservation 

systems and activities. Although these guidelines may not specifically be designed to minimize 

air pollution, they are intended to be feasible and effective techniques that will reduce windblown 

dust, and thus would be appropriate measures to consider for BACM for such sources or 

activities for PMlo. USDA's National Agronomy Manual explains that controls for reducing 

wind erosion should be based on the following principles.49 

a. Establish and maintain adequate vegetation or other land cover. 

b. Reduce unsheltered distance along the wind erosion direction. 

c. Produce and maintain stable clods or aggregates on the land surface. 

d. Roughen the land with ridge and/or random roughness. 

For active agricultural fields, some CMPs in Rule 806, such as cover crops, are based on these 

principles and should help control windblown dust. Other CMPs in the rule, such as precision 

farming, mainly target entrained dust by reducing the number of vehicle passes across the field. 

While Imperial County farms may choose windblown dust control CMPs, they are not required to 

do so even though BACM for agricultural windblown dust emissions must be implemented in 

Imperial County as discussed in Section 1I.B above. We note SCAQMD requirements for active 

agricultural fields below. EPA would expect a meaningful BACM analysis to include a review of 

windblown dust requirements for active fields in SCAQMD and other areas. 

Rule 806 does not apply to fallow agricultural fields," and hence cannot provide BACM level 

controls for these fields. IID currently has a Fallowing Program which compensates volunteer 

farmers for fallowing. From July 2007 to June 2008, about 16,000 acres were in the 2007-2008 

IID Fallowing ~ro~ram." During approximately the same period, between about 27,000 and 

32,000 acres were fallow in Imperial County outside of IID's Fallowing program.j2 While IID's 

49 National Agronomy Manual, USDA NRCS, October 2002, pg. 502-1 7. The National Agronomy Manual also lists 

the following principle which does not seem to be applicable to Imperial sources: "Reshape the land to reduce 

erosion on knolls where converging windflow causes increased velocity and shear stress." 

50 The CMPs from which sources are required to select in order to reduce emissions from on-field sources are for 

reducing PMlo emissions from land preparation and cultivation (Rule 806 Section E.l) and for reducing PM,, 

emissions from harvest (Section E.2). If implemented in certain ways, some of the CMPs in these categories, such as 

cover crop, may also reduce emissions from fields that become fallow. However, there are no requirements in Rule 

806 to address emissions from fallow fields. 

5 1 IID's program started in 2003 and will continue until 2017. "Imperial lrrigation District Fallowing Program 

Status Report," February 19, 2008, on web page http://www.iid.com/Water/FallowingPrograms, direct link: 

http://www.iid.com/Media~Fallowing-Program-Summary-2003-2008-Presentation.pdf. See page 1 1 for acreage 

during the 2007-2008 Fallowing Program. 

52 See Imperial Irrigation District Water Department Monthly Crop Acreage Report, August 13, 2008, pgs. 13 and 

22, for data on fallow acreage outside of IID's program from August 2007 to August 2008. 1ID's Monthly Crop 

lmper~al County APCD - Regulation VIII - 17- 

TSD, 021 1 0 
Program requires some dust mitigation, we were unable to identify any requirements for 

controlling emissions from the fields that are outside IID's program. EPA would expect a 

meaningful BACM analysis to include a comparison of the requirements that are currently in 

place for mitigating emissions from fallow fields both within and outside of IID's program with 

requirements in other areas, including SCAQMD. 

SCAQMD, for comparison, enforces several requirements designed to reduce agricultural 

windblown dust from active and inactive fields. SCAQMD Rule 403 and the associated 

handbooks53 for the South Coast and Coachella air basins were developed with extensive input 

from NRCS and the agricultural community and mainly seem based on the principles in USDA's 

National Agronomy Manual. Among other things, SCAQMD Rule 403 and the associated 

handbooks require growers to: 

a. Cease certain soil preparation and maintenance activities when winds exceed 25 miles per 

hour. 

b. Implement one of four specific practices to reduce windblown dust from actively disturbed 

fields. Active conservation options include soil moisture monitoring (ensuring soil moisture 

to prevent visible dust emissions beyond 100 feet), irrigation systems (irrigating or bedding 

fields as soon as feasible after land leveling to prevent the field being left smooth and dry), 

minimum tillage and mulching. 

c. Implement three of nine specific practices to reduce windblown dust from inactive (fallow) 

fields. Inactive conservation options include cover crop, crop residue management, surface 

roughness, minimum tillage, cross wind stripcropping, field windbreaks, ridge roughness and 

wind barriers. 

IV. EPA's Proposed Action 

The submitted Regulation VIII rules strengthen the SIP and largely meet the relevant CAA 

Section 1 10 and part D requirements, but the deficiencies discussed above preclude full approval. 

EPA staff recommends a simultaneous limited approval pursuant to CAA Sections 1 10(k)(3) and 

30 1 (a) and limited disapproval pursuant to Sections 1 10(k)(3), 1 1 O(a) and 189(a)(l)(C) and 

(b)(l)(B) of the seven inter-related Regulation VIII rules. If finalized as proposed, the 

deficiencies identified in Section 1I.D. 1 of this Technical Support Document would trigger CAA 

Section 179 sanctions and a Section 1 10 federal implementation plan (FIP) obligation. The 

deficiency identified in Section II.D.2 would not trigger sanctions or a FIP obligation at this time 

because it does not appear associated with SIP revisions that are required by the CAA. 

Acreage Report, June 13, 2007. has similar data for June 2006 through June 2007. IID uses the term 'idle' if there is 

no crop on the field for less than a year, and codes a field as 'fallow' if it does not have a crop for over a year. 

53 The South Coast and Coachella Valley Agricultural Handbooks are relied on for certain compliance options 

within SCAQMD Rule 403. 

Imperial County APCD - Regulation VlII 

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