## Off

- Highway Vehicle (OHV) Area Best Available Control Measures (BACM) Assessment

P repared for: Imperial County Air Pollution Control District El Centro, CA

Prepared by:
ENVIRON International Corporation Los Angeles, California

Date:
October 2012

Project Number:
0 5

- 21191AContents ii ENVIRON 

## Contents

Page

1 History 1

2 Emissions from OHV

- related Open Areas 2

2.1 Windblown Emissions 2

2.2 Entrained OHV Emis sions 3

2.2.1 OR Event Entrained Emissions 3

2.3 Summary 4

3 Potential Control Measures 4

3.1 RACM Guidance Summary (April 28, 1992 57 FR 18072) 4

3.1.1 Restrict OHV Activity Locations 4

3.1.2 Require Use of Permits 4

3.1.3 Restrict OHV times (an activity ban on OHV

- approved lands) 5

3.2 Potential BACM and other measures 5

4 BACM Comparative Analysis 5

4.1 Restrict OHV Locations 6

4.2 Require Use of Permits 6

4.3 Restrict OHV times (an activity ban on lands on OHV Recreational Use Areas) 7

4.4 Potential BACM and other measures 7

5 Feasibility and Impact Analysis 8

List of Figures

Figure 1: Federal and State Lands in Imperial County (2009 PM 10 SIP) Figure 2: Maricopa Land Ownership Distribution Figure 3 Imperial Sand Dunes Recreation Area

List of Appendices

Appendix A: PM 10 Nonattainment Areas: Selected Comparisons

P: \ I \ Imperial \ 2012

- 2013 \ OHV BACM anal ysis 2012 \ 121003 OHV BACM Analysis

- Final.docxHistory 1 ENVIRON 

## Executive Summary

This report is the latest Best Available Control Mea sures (BACM) assessment for Off

- Highway Vehicle (OHV) areas

. It was prepared at the reque st of the Imperial County Air Pollution Control District (ICAPCD or District) in support of its proposed amendments to Regulation VIII

, F ugitive

D ust R ules (in particular, Rule 800 open area requirements)

. Open areas are non

- urban, non

agricultural undeve loped lands

. Regu lation 800 and the proposed OHV

- related open area amendments are described in Section II.B of the ICAPCD Staff Report for the BACM Amendments to Regulation VIII, Fugitive Dust Rules

. In general, the OHV

- related open area amendments include new or revised definitions, clarification of applicability, and revised OHV

related requirements (dust control plan contents, explicit list of certain BACM control measures, etc.) In this report , we present:

• The history of ICAPCD BACM assessments for open areas and recent regulatory actions. Those assessments are included, by reference, in this report.

• The emissions from open areas in Imperial County, with a focus on OHV areas and

activities. In thi s section, other serious PM 10 non

- attainment areas that have appreciable OHV activity (areas within Maricopa and Clark County counties) and OHV requirements are also described to facilitate the comparative analysis.

• Potential control measures (including Re asonably Available Control Measures (RACM) described in federal guidance and BACM measures in serious non

- attainment areas).

• BACM comparative analysis of OHV

- related measures in serious non

- attainment areas.

• Feasibility and impact analysis of proposed Rul e 800 OHV

- related amendments.

Based on this assessment, Rule 800 and the proposed Rule 800 amendments are at least as stringent as open area OHV requirements in other serious PM 10 non

- attainment areas.



## 1 History

On August 11, 2004 the United States Environmental Protection Agency (EPA) issued a finding that Imperial County failed to attain PM 10 National Ambient Air Quality Standard (NAAQS) by December 21, 1994. Therefore, under CAA Section 189(b)(1)(B), all Best Available Control Measures (BACM) wer e required to be impl emented by September 10, 2008 and a PM 10 attainment plan was required by December 2008.

On November 8, 2005, the Air District adopted its fugitive dust BACM rules in anticipation of its

PM 10 Attainment Plan to expedite emission reduc tions and document high wind events according to the EPA’s Exceptional Events Rule. The Regulation VIII rules impose stringent requirements to reduce the amount of PM 10 entrained in the ambient air as a result of emissions generated from anthropogenic fug itive dust sources, which include agriculture, construction,
recreational off

- highway vehicle s and unpaved roads. The 2005 BACM Technical Assessment was prepared and approved by ICAPCD. The rules were submitted to EPA on June 16, 2006

. ICAPCD and CARB al so submitted documentation for three high

- wind days in 2006 and 2007 demonstrating that the PM 10 exceedances were caused by exceptional events. O n AugustEmissions from OH V

- related Open Areas 2 ENVIRON 2009, ICAPCD adopted its 2009 Imperial County PM 10 State Implementation Plan (2009 PM 10 SIP) , which i ncluded an attainment demonstration based, in part, on the exclusion of the exceptional events. A revised BACM assessment was also included in the 2009 PM 10 SIP. On July 8, 2010

, EPA granted limited approval/disapproval to Regulation VIII based on reject ion of the 2006 and 2007 exceedences. The Air District filed a petition with the Ninth Circuit for review of EPA’s limited disapproval . A fter hearing oral arguments from the parties, the Ninth Circuit

ordered them to mediation.

The mediation was settled by all parties after multiple sessions. As part of the settlement, the Air District agreed to amend some of the Regulation VIII rules to further enhance BACM requirements. The District is proposing to revise rule 800 to include specific BACM requirement s to reduce fugitive dust emissions from OHV recreational areas.



## 2 Emissions from OHV

- related Open Areas

As detailed in the 2009 PM 10 SIP (c.f.., Appendix III.B.1, first sentence) , most of the areas in the District’s jurisdiction are open areas, of which 7 7% of the total land area is state/federally managed or owned (see Appendix A “PM 10 Nonattainment Areas: Selected Comparisons” of this report for a summary ) . The rest of the land is mainly agriculture (20%), urban areas (

~ 2%) and less than one percent is vacant, developable land. Figure 1 shows the Imperial County and federal/state lands. Both Imperial County and the Maricopa County serious PM 10 non

- attainment area (Maricopa nonattainment area) have appreciable OHV open areas and OHV regulations. (The Cla rk County serious non

- attainment area includes mostly the populated greater L a s Vegas area and has more limited OHV open areas). 1 Key differences between Imperial County

and the Maricopa nonattainment area , particularly open lands within those areas, are important
in the discussion of OHV

- related emissions and the control measure comparative analysis. Those differences will be referenced below; a more detailed discussion of those differences can
be found in Appendix A (PM 10 Nonattainment Areas: Selected C omparisons). This report considers 1) windblown emissions from lands where there has been OHV activity and 2)
entrained dust emissions from OHV travel.



### 2.1 Windblown Emissions
Windblown emissions from open areas are the largest emission inventory contributor in Imperial County. Based on the 2009 PM 10 SIP analysis of windblow n dust emissions from vacant lands (Appendix III.B) , all open areas produce 157 tons of windblown PM 1 0 per day (t ons/day ), which are mostly from the 1.9 million acres of state/federal lands

. State and federal OHV areas (the 164,000 acres where OHV activity is not restricted) produce 8.8 t ons/day of the total 157 tons/day . Analysis results demonstrate that private lands have negligible windblown dust emissions (see Appendix A and the 2009 PM 10 SIP Appendix III.B ). Figure III.B.6 of the 200 9

PM 10 SIP (Appendix III

- B

, also in Appendix A, Figure 7) shows spatial distribution of open area

1 As discussed in Appendix A in more detail, “ The Imperial Valley nonattainment area includes almost all of Imperial County, CA; thus, Imperial Valley and Imperial County are used interchangeably in this Report. The Maricopa nonattainment area includes only about 31% of Maricopa County. The Maricopa nonattainment area is heavily populated; only the central portion of the Imperial Valley nonattainment area is populated (and that lightly).” Similarly, the Clark County nonattainment area is only a small portion of Clark County as a whole.Emissions from OHV

- related Open Areas 3 ENVIRON windblown dust and OHV

- allowed areas. As noted directly above, less than 6% of the open

area windblown dust emissions come from federal/state areas that are open to OHVs. A t the request of EPA shortly before the 2009 PM10 SIP adoption hearing , a more conservative

estimate assuming greater levels of soil disturbance was prepared that showed an additional 0

to 12 t ons/day of windblown emissions could potentially be emitted based on differing assumptions about soil disturbance ; ICAPCD does not believe that there are appreciable additional emissions but included this analysis i n the final 2009 PM 10 SIP (Appendix III .B)

.



### 2.2 Entrained OHV Emissions
The motion of an OHV over an open area can entrain dust from the ground into the air

– these emissions are a function of the weight and speed of the OHV, as well as other parameters

. Due to the small user population within day

- trip driving range, no activity data are available. However, an estimate of these emissions can be made based on Maricopa nonattainment area

emissions (see Appendix A of this report for details on the methodology and results) . The Maricopa non

- attainment area OHV entrained emissions are 6.02 tons/day ; the population ratio of Imperial County to Maricopa is 175,000:4,297,000. The population ratio of Maricopa to Imperial County is a reasonable metric since the activity in both locations is driven by the

num ber of riders. In t he Arizon a Trails 2010 Report 2

, Maricopa records that 1,027,000 or 22% of its population has general riders of which 511,000 or 10.7% of them are self

- described core riders. The core Maricopa riders are almost three times the whole Imp erial County population. Using the population to emission ratio, Imperial County’s OHV emissions would be < 0.25 tons/day based on an annual average day. Based on the socioeconomic distribution in the population, actual emissions are expected to be lower. 3 It is reasonable to expect near

- zero emissions on wind event days and the hottest days because the number of these riders would be negligible.



### 2.2.1 OR Event Entrained Emissions

Off

- road (OR) events differ from OHV events because they can attract riders fro m outside of Imperial County . Large OR events only occur on state and/or BLM

- approved OHV areas. In addition, large OR events must receive a permit from the land manager and abide by several regulations and requirements, including those related to Rule 800.

For state lands, specif ic OHV areas (such as Ocotillo Wells SRVA) make up 28% of the state

lands in Imperial County . Generally, these areas have low OHV speed events (geocaching, church groups, etc.) of small groups of 20

- 100 people ; however, some holidays can draw more
than 25 0 attendees. These OR events generally occur on the weekends or holidays and are typically rescheduled if the conditions are either too hot and/or windy.

For federal lands under the jurisdiction of t he Bureau of Land Management (BLM) , specific
OHV

- allowe d areas are approximately 11% of those land s (OHV ban on over 90% of BLM

managed lands). Large

- scale OHV events occur five to ten times per year ; the largest events

2 http://azstateparks.com/publications/download s/2009_Trails_2010_Final_c.pdf

. 3 From the US Census ( http://quickfacts.census.gov/qfd/states/00000.html ) for 2006

- 2010: Imperial County median household income ($36,685) compared to Maric opa County ($55,054). Unemployment rate in Imperial County was 21.4% compared to 13.9% in Maricopa.Potential Control Measures 4 ENVIRON are in the Imperial Dune area on large sand dunes east (and generally downwind) of populate d

areas

. Such large OR events are not held in high wind and/or high heat conditions because of safety

, including low visibility and heat

- related illnesses

, and other concerns. Such large

- scale OR events have not occurred during any documented exceptional event and thus, direct OR

entrained dust emissions have not contributed to any exceedance.



### 2.3 Summary
Relying on the exceptional events determinations by ICAPCD and CARB, the 2009 PM 10 SIP concluded that windblown dust, including from open areas, was not a s ignificant source. Based on EPA’s rejection of those event determinations

, EPA does consider open area windblown dust emissions to be significant. Regardless, the 2008 PM 10 SIP calculated that of the 157 tons/day of annual average emissions from open area s, approximately 9 tons/day of emissions come from areas where OHV activity and OR events are allowed . ( D ifferent soil disturbance assumptions could yield from 0 tons/day to 12 tons/day of additional windblown emissions.)

Large

- scale OR events are expecte d to have zero or negligible entrained dust emissions on potential exceedence days because those OR events are not held during days when potential

exceedence

- day conditions occur.

Other (non

- event) OHV entrained dust emissions are estimated to be de mini mis (<0.25 tons/day or less than 0.1% of the annual average inventory). These emissions are expected to be near zero on potential exceedence days because of the conditions associated with those days (i.e., high winds resulting in low visibility and high te mperatures).



## 3 Potential Control Measures

3.1 RACM Guidance Summary (April 28, 1992 57 FR 18072)
EPA issued Reasonably Available Control Measure (RACM) guidance in 1992 (April 28, 1992 FR 18072, Appendix C1). The three RACM listed in the Guidance were: 1) conf ine operations to specific areas; 2) require use permits; and 3) ban OHV activity (for specific locations/times).



### 3.1.1 Restrict OHV Activity Locations

BLM restricts OHV activity to four areas (Imperial Sand Dunes, Plaster City, Superstition Mountains, Arroyo Salado) of the BLM land . Only 136,000 acres ( or 11% of the total 1.26 million

acres ) of BLM land are currently open to OHV activity . More restrictions are applied to State parks, which are 100,000 acres. The S tate (Department of Parks and Recreation) restrict s OHV activity to two areas, Ocotillo Wells SVRA and Heber Dunes SVRA ; only 28,000 acres ( or 28%
of 100,000 acres of state lands in Imperial County) are open to OHVs. Thus, OHV activity is restricted to 164,000 acres. Thus, only ~9% of state/fede ral lands (164,000 acres out of 1,360,000 acres) allow OHV activities. As noted in Section 4 below, both Maricopa and Clark
counties also restrict OHV activities to certain areas.



### 3.1.2 Require Use of Permits
OHV p ermits are required by the State of California and large scale OR events require special approvals by state/federal authorities. From www.dmv.ca.gov/vr/ohvredgreen.htm :BACM Comparative Analysis 5 ENVIRON California Air Resources Board (ARB) established regulations to limit the use of Off

- Highway Vehicles (OHVs) that do not meet emission standards applicable for California OHV riding areas. After the regulations were established, ARB and DMV worked together to develop criteria for identifying non

- complying OHVs. OHVs are registered by the Department of Motor Vehicles (DMV). A red or green sticker is issued depending upon certain criteria.

Green stickers are issued for all California OHVs year model 2002 and older, including those that were previously issued a red sticker, and to 2003 and newer complying vehicles. Green stickers are issued to OHVs for year round use at all California OHV riding areas.

Red stickers are issued to 2003 year model and newer OHVs that are not certified to California OHV emission standards. If your OHV has a "3" or "C" in the eighth position of the vehicle identification number (VIN) then your vehicle will be issued a red sticker. Red stickers are issued to OHVs that can use Califor nia OHV riding areas for seasonal use only.

BLM 4 requires Special Recreation Permit (SRP s ) for competitive use and organized group activity and event use to “ manage visitor use [and] protect natural and cultural resources.”
These are discussed in more detail in Section 4.2.



### 3.1.3 Restrict OHV times (an activity ban on OHV

- approved lands)

Permit restrictions on times when areas where OHV activity is allowed would only affect
entrained dust

- related emissions because the area is alre ady disturbed . As noted in Section 2 above, entrained e missions from other OHV activities on these lands is de minimis and OR events do not occur during exceedence conditions ; thus, entrained dust

- related emissions are not significant contributors to high

- wind event PM levels and do not contribute to exceedences in Imperial County

.



### 3.2 Potential BACM and other measures

ICAPCD Rule 800 includes measures that minimize OHV

- related dust emissions (c.f. Rule 800 F.5)

. These requirements were based on Maricopa and Clark County regulations at the time of Regulation adoption (2005). These measures include dust control plans with stipulations, OHV area descriptions, and PM 10 control measures (including on unpaved roads, parking and open areas). Maricopa and Clark Co unties describe control measures (e.g., Clark County 90.1 in nonattainment area only and Maricopa AZ 49

- 457.03 that prohibits OHV activity on high pollution advisory days except for events with dust abatement measures) that are similar to
those in Rule 800 and proposed amendments to Rule 800 that would enhance dust control plan requirements and include explicit BACM as dust abatement measures

.


## 4 BACM Comparative Analysis

This section compares the OHV

- related control measures in ICAPCD Rule 800 and proposed

amendments to similar measures in other serious PM 10 nonattainment areas with appreciable OHV activity (e.g., Maricopa County and Clark County nonattainment areas). In comparing

4 From BLM web site (www.blm.gov/ca/st/en/prog/recreation/recpermit.html): Competitive Use means any organized, sanctioned, or structured use, event, or a ctivity on public land in which two or more contestants compete and either (1) participants register, enter, or complete an application for the event, or (2) a predetermined course or area is designated. ” “ Organized group/event permits are for noncommercial and noncompetitive group activities
and recreation events.”BACM Comparative Analysis 6 ENVIRON control measures among the serious PM 10 nonattainment areas with appreciable OHV activity, it is important to remember the key differences among these areas ( see Appendix A and Figures
1 and 2 ).



### 4.1 Restrict OHV Locations

Maricopa Rule 9

- 500.27 states the following in regards to OHV activity: “city or town shall adopt, implement and enforce an ordinance that prohibits the operation of any vehicle, including an off highway vehicle, an all

- terrain vehicle or an off

- road recre ational motor vehicle, on a unpaved surface that is not public or private road, street or lawful easement and that is closed by the landowner by the rule or regulation of a federal agency, this state, a county of municipality”. Note that OHV activity can occur on lands under state or federal agency jurisdiction. Clark County, S ection 90 states that OHV are prohibited, by fencing or other barriers, in non

attainment areas unless control measures are used to establish a stabilized surface afterwards.
Clark C ounty has essentially banned OHV activity, but only in non

- attainment areas near Las Vegas (and not in OHV areas outside the non

- attainment area) . Both Maricopa and Imperial County, through federal and state land managers, have restricted OHV activity to specific

locations. Even within Imperial County recreational areas, OHVs are restricted to certain locations, such as Imperial Sand Dunes (see Figure 3). Proposed amended Rule 800 would add specific requirements for any new recreational OHV areas to inco rporate mitigation measures and demonstrate that any new emissions will not create new violations or delay
attainment of the federal PM 10 standard.

Further restriction of OHV areas would not be effective. OHV areas are established to minimize OHV activity in other areas, particularly where there are natural resources being protected.
BLM and State Parks officials believe that further limiting the size of OHV areas would have the effect of increasing illegal OHV activity on non

- travelled lands. Potential environmental effects include use in new areas and/or on private property, use in areas not managed for OHV recreation, trespass on closed areas and economic effects of job loss and business closure on Imperial County. T his would have the inadvertent effec t of increasing the potential for windblown dust emissions, rather than reducing them.



### 4.2 Require Use of Permits
Persons using OHVs in Imperial County are required to have a state permit. Similar permitting requirements are also in effect in Maricopa and Clark counties. BLM 5 requires Special Recreation Permits for competitive use and organized group activity and event use to “ manage visitor use [and] protect natural and cultural resources.” As noted at ww.blm.gov/ca/st/e n/prog/recreation/recpermit.html :

Objectives of the BLM recreation permitting system are to satisfy recreational demand within allowable use levels in an equitable, safe, and enjoyable manner while minimizing adverse resource impacts and user conflicts. In issuing recreation permits to re creational users of public

5 From BLM web site ( www.blm.gov/ca/st/en/prog/recreation/recpermit.html): Competitive Use means any organized, sanctioned, or structured use, event, or activity on public land in wh ich two or more contestants compete and either (1) participants register, enter, or complete an application for the event, or (2) a predetermined course or area is designated. ” “ Organized group/event permits are for noncommercial and noncompetitive group a ctivities
and recreation events.”BACM Comparative Analysis 7 ENVIRON lands, the BLM authorizes permittees use of the lands and/or related waters for permitted

purposes. This represents a privilege to use public lands and/or related waters which is subject to the terms and conditions of the permit s. Recreation permits are managed in a manner which is consistent with management objectives determined in resource management plans, recreation area management plans, or in their absence, through recreation management objectives resulting from analysis of resources and visitor use for each area.

From the BLM SRP Handbook 6 :

All SRP applications must include the following: a) the current Special Recreation Permit application typed or printed in ink and completely filled out, b) a map produced using Global

Po sitioning Systems with transferable compatible data to the BLM computer systems, c) operating/business plan or other information the BLM requests, d) advance payment of estimated fees (if cost recovery is required), and e) copies of other licenses and perm its from state, local, and/or federal agencies (if applicable).

ICAPCD requirements are discussed in Section 4.4 below.



### 4.3 Restrict OHV times (an activity ban on lands on OHV Recreational Use
Areas )
Comparative BACM analysis was also conducted on OHV activities during specific times. Maricopa County only allows OR events on pollution alert days if there is dust abatement for staging areas, parking areas and entrances. ICAPCD Rule 800 requires dust abatement during OR events regardless of air quality conditions. The proposed amendments to Rule 800 would make these abatement requirements more specific. ICAPCD is proposing amendments to Rule 800 (new F.5.g) that include restrictions on OR events during summer months, as well as clarify
OHV

- related def initions and unpaved road/traffic area requirements.

Maricopa County prohibits OHV activity on pollution advisory days, except for authorized OR

events with dust abatement measures , business, or government travel, and/or abated closed

course. Entrained du st e missions from OHV activities are de minimis in Imperial County, 0.25 tons/day (< 0.1% of inventory ); the Maricopa nonattainment area has 6 tpd of entrained OHV

related emissions , which is 4% of that area ’ s total inventory. Further activity

- related r est rictions would not result in any appreciable emission reduction on potential exceedence days, high wind days in particular.



### 4.4 Potential BACM and other measures
In addition to the requirements described above, ICAPCD Rule 800 includes measures that

minimiz e OHV

- related dust emissions (c.f. Rule 800 F.5). Many of t hese requirements were based on Maricopa and Clark County regulations at the time Regulation VIII was initially adopt ed in 2005. These measures include dust control plans with stipulations, OHV area descriptions, and PM 10 control measures (including on unpaved roads, parking and open areas).

Amendments to Rule 800 that clarify definitions and requirements (particularly for specif ic unpaved road/traffic area control measures) are proposed that meet EPA recommendations

.

6 www.blm.gov/pgdata/etc/medialib/blm/ca/pdf/caso/publications.Par.23962.File.dat/SpecialRe creationPermit.pdfFeasibility and Impact Analysis 8 ENVIRON Certain amendments to Rule 800 include additional requirements if new recreational OHV use areas are designated (c.f., Section F.7); these proposed requirements are not found in any other jurisdiction.

Maricopa’s rule effectiveness amendments pertained to Rule 310.01 and specifically to the 100,000+ vacant lots in Maricopa County. Rule 804 already applies to these lands. In addition, less than 1% of open lands are urban vacant areas in Imperial County (compared to 52% of Maricopa’s nonattainment area open lands that are private/developable vacant lands). Thus, increased rule effectiveness on these minimal areas would not appreciably affect emissions.



## 5 Feasibility and Impact Analysis

In the feasibility and impact analysis in ICAPCD’s 2005 BACM assessment (Chapter 5) and
ICAPCD’s 2009 PM 10 SIP (Chapter 5), the control effectiveness and costs/cost effectiveness of the 2005 Rule 800 were assessed. In this analysis, certain additional measures (such as further restricting OHV-permitted areas) were analyzed and determined to be ineffective and/or infeasible. OHV activity has been increasingly restricted on public lands; it is currently restricted to less than 9% of all federal/state land. Federal and state land managers believe that further restriction of the land approved as OHV recreational areas would be ineffective, and perhaps counter-effective, because activity would move to non-permitted areas that do not have dust control plans. This would potentially increase windblown emissions if those areas are significantly more disturbed as a result of this new activity.

The proposed amended Rule 800 contains additional changes to enhance BACM for open areas (see Staff Report for more details). The proposed amended Rule 800 clarifies and/or strengthens the requirements and does not interfere or lessen any existing BACM requirements. DPR, BLM and/or users of their lands will incur costs related to the preparation of new or revised Dust Control Plans (per Rule 800 Section F.5), meeting new requirements (if any) for large-scale off-road events and high-trafficked unpaved roads/parking areas, and any Rule 800 F.7.b determinations and related interagency consultation. At this time, such costs cannot be quantified, although it is expected that the cost-effectiveness and cost of such actions would be
consistent with those described in the 2005 BACM assessment for similar actions.ENVIRON 

## FiguresENVIRON Figure 1: Federal and State Managed Lands in Imperial County (2009 PM 10 SIP)

Figure 2: Maricopa Land Ownership distribution (Passive/Restricted areas are federal/state managed)ENVIRON 

### Figure 3: Imperial Sand Dunes Recreation Area (note restrictions on OHV activity, including outside the ISDRA, military bombing areas, wilderness areas, and vehicle closure areas)ENVIRONENVIRON 

## Appendix A

PM 10 

### Nonattainment Areas: Selected Comparisons

## PM 10 

## Nona ttainment Area s: Selected Comparisons

Prepared for: Imperial County Air Pollution Control District El Centro , California

Prepared by: ENVIRON International Corporation
Los Angeles, California

Date: September 2012

Project Number:
05

- 21191APM 10 Nona ttainment Areas: Selected Comparisons

Contents i 

## Contents

Page Executive Summary

1 Nonattainment Area Land and Population Comparison 1

2 Nonattainment Area Emission Comparison 3

List of Tables

Table 1: Land Area, Population and Population Density Comparison

Table 2: Major Open Areas

Table 3: Area and Emissions Related to Wind Erosion in Imperial County

List of Figures

Figure 1: Imperial County Figure 2: Maricopa County and Maricopa Nonattainment Area Figure 3: Imperial County Nonattainment Area Figure 4: Maricopa County and Nonattainment Area Figure 5: Maricopa and Imperial County Areas Figure 6: Federal and State Managed Lands in Imperial County Figure 7: Windblo wn Dust Emissions in Imperial County

List of Acronyms

ICAPC D Imperial County Air Pollution Control District

mi 2 square miles

PM Particulate Matter

PM 10 ; PM

- 10 Particulate Matter less than 10 microns in aerodynamic diameter

SIP State Implementation Plan

P: \ I \ Imperial \ 2012

- 2013 \ OHV BACM analysis 2012 \ App A Nonattainment area comparison final.docxPM 10 Nona ttainment Area s : Selected Comparisons

Executive Summary ES

- 1 

## Executive Summary

This R eport has been prepared to provide a comparison of the Imperial Valley serious PM 10

nona ttai nment area (Imperial Valley non attainment area) with the Maricopa Coun ty serious

PM 10 non attainment area (Maricopa non attainment area)

. These two non attainment areas differ in many ways, but this Report focusses on two of the main differences:

• Differences in the scope and character of the non

- attainment areas

• Differences in the contribution of open

- area windblown dust emissions to the

non

- attainment area emission inventory

The Imperial Valley non attainment area includes almost all of Imperial County, CA; thus, Imperial Valley and Imperial County are used interchangeably in this Report. The Maricopa

non attainment area includes only about 31% of Maricopa County. T he Maricopa nonattainment

area is heavily populated ; only the central por tion of the Imperial Valley non attainment area is populated (and that lightly). The Report notes that in comparison to the Maricopa nonattainment area, the I mperial Valley PM 10 serious non attainment area, which includes almost all of Imperial County, has :

• a 45% larger land area (4, 200 mi 2 vs. 2,880 mi 2 ) ;

• 96% less population (175,000 vs. 4,297,0 00) ; and

• an over 97% lower population density ( 42 people/ mi 2 vs. 1,492 people/mi 2 )

.

Federal and state managed lands cover almost 7 7 % of the land area in Imperial County.
Windblown dust from these remote desert areas accounts for 54% of the emissions on an annual average day. In contrast, only about 11% of the Maricopa non attainment area annual average day emissions come from “other” windblown sources , including private and public
vacant lands

. During the windiest mon t h of the year in Imperial County (April in this analysis),

these state and federal ly managed remote desert areas can account for over 7 2 % of the month’s average day emissions. The percentage would be even higher on the highest wind days. Unlike in Imper ial County, t he majority of these types of lands in Maricopa County are not even in the Maricopa nonattainment area ; emissions from those lands are not in the anthropogenic inventory for the Maricopa non

- attainment area and sources there are not subject

t o serious nonattainment area requirements.

These are two of the important differences between the I mperial Valley and Maricopa

non attainment areas that can be taken into consideration when evaluating inventories, best available control measures, exceptional eve nts, and other serious PM 10 non attainment area Clean Air Act requirements in these areas.PM 10 Nona ttainment Area s : Selected Comparisons

Nonattainment Area Land and Population Comparison 1 

## 1 Nona ttainment Area Land and Population Comparison

M ost of Imperial County falls within the Imperial Valley Planning Area (Imperial Valley) (40 CFR part 81) . Thus, Imperial Valley and Imperial County are used interchangeably in this Report. The Maricopa non

- attainment area includes only about 31% of Maricopa County.

Figure 1 shows Imperial County and its monitoring stations. 1 The county covers 4,597 mi 2 ; the land portion covers 4, 200 mi 2 . Almost 7 7 % of the county land area are state or federal ly managed lands ( 3,244 mi 2 ). Only the central area , which is extensively covered by agricultural lands (~ 870 mi 2 ), is populated , and that sparsely

.

Figure 2 show s the Maricopa non

- attainment area. 2 As noted above, the Maricopa nonattainment area only covers a portion of Maricopa County. Densely populated urban areas
cover much of the central area of the nonattainment area. Large remote areas of the county are

not included in the nonattainment area

.

Table 1 compares the land area, population, and population density of the two nonattainment

areas.

Table 1 : Land Area, Population and Population Density Comparison

Nonattainment Area Area (mi 2 ) Population Population Density Notes

Imperial Valley (essentially Imperial County) 4, 200 175,000 42 State

- a nd/or federal

- managed lands:
3,244 mi 2 (~ 77 % of land area)

Maricopa non

- attainment area (partial county) 2,88 0 4,297,000 1,4 92 Maricopa County (9,223 mi 2 ) : essentially 100% of the population in

the nonattainment area

Data Sources : 2009 Imperial County PM 10 SIP:

www.co.imperial.ca.us/airpollution/attainment%20plans/final%20ic%202009%20pm10%20sip%20document.pdf Maricopa Association of Governments 2012 Draft 5% Plan: www.azmag.gov/Projects/Project .asp?CMSID=1120

1 From 2009 Imperial County PM 10 SIP: Figure 2.1.

2 From March 2012 DRAFT Maricopa Association of Governments Five Percent Plan for PM

- 10 for the Maricopa

County Nonattainment Area: Figure 2

- 1PM 10 Nona ttainment Area s : Selected Comparisons

Nonattainment Area Land and Population Comparison 2 Table 2 compares the major land use categories subject to wind erosion.

Table 2: Major Open Land s (in mi 2 and % of Total Major)

Nonattainment Area Agricultur al

Areas Vacant (developable) Non

- Private Open Space Total of Major Open Lands

Imperial Valley (essentially Imperial County) 873 (21%) 63 (1%) 3

, 244 (78%) 4,180 (100%)

Maricopa non

- attainment area (partial county) 203 (14%) 739 (52%) 473 (33%) 1,416 (100%)

Maricopa County 463 (6%) 3,481 (45%) 3,709 (48%) 7,653 ( 100 %)

Data Sources: 2009 Imperial County PM 10 SIP:

www.co.imperial.ca.us/airpollution/attainment%20plans/final%20ic%202009%20pm10%20sip%20docume nt.pdf Maricopa Association of Governments 2012 Draft 5% Plan: www.azmag.gov/Projects/Project.asp?CMSID=1120 ; Appendix A , Table 1.5

- 2.

These metrics are relevant because they are related to emissions. Greater land area provides more locations for anthropogenic activity and/or open areas susceptible to producing windblown dust. Generally, the greater the population and population density, the greater the anthropogenic activity that can generate emissions (e.g., residential fuel combustion, vehicle miles travelled). In the case of the Maricopa nonattainment area, it was defined to include only the populated area of Maricopa County; the remote, sparsely populated areas of the county (~ 69% of the county) are not included in the nonattainment area. In contrast, all of Imperial County is essentially in the nonattainment area, including remote, sparsely populated areas of

the county that account for over 77 % of its land area.

Figures 3 and 4 show satellite photographs of Imperial Cou nty and the Maricopa County/Maricopa nonattainment area, respectively. These photographs pictorially present the land use and population metrics described above. The central populated area , which is predominantl y agricultural, occupies about 23% of Imperial County land area ( Figure 3 ). The Maricopa nonattainment area occupies about 31% of Maricopa County ( Figure 4 ). Figure 5 gives a relative comparison of the Maricopa nonattainment area and the populated portion of Imperial County. These area s encom pass the area of the majority of human activit y . However, the Imperial Valley nonattainment area ( Figure 3 ) also includes remote, sparsely populated areas that are excluded from the Maricopa non

- attainment area (but ar e within Maricopa County). A lmost all of the remote, non

- populated area within Imperial County is under state or federal management.PM 10 Nona ttainment Area s : Selected Comparisons

Nonattainment Area Emission Comparison 3 

## 2 Nona ttainment Area Emission Comparison

Federal and sta te managed lands cover about 77 % of the land area in Imperial County. Figure 6 shows federal and state managed lands in Imperial County. 3 Figure 7 shows the annual windblown dust emissions in Imperial County ; 4 the highest windblown emission s are from remote, non

- populated federal and s tate lands.

Table 3 compares the area and emissions from area sources subject to wind erosion.

Table 3 : Area and PM 10 Emissions Related to Wind Erosion in Imperial County

Agriculture Urban open

areas Other (remote

state and federal) Remaining inventory % Windblown

from remote state

and federal lands

Area (1000s of acres) 559 40 2076

-- --

Windblown emissions (average day

– tons/day) 11 <0.1 158 (94% of windblown dust) 125 54% (out of 294)

Windblown emissions (windiest month average day

– tons/day) 28 <0.0 4 0 6 125 72 % (out of 5 56 )

Data S ources: 2009 Imperial County PM 10 SIP:

www.co.imperial.ca.us/airpollution/attainment%20plans/final%20ic%202009%20pm10%20sip%20document. pdf

Windblown dust from these rem ote desert areas accounts for 54% of the emissions on an annual average day. In contrast , non

- agricultural windblown dust accounts for about 11% of the Maricopa non

- attainment area a nnual average day emissions 5 and a fair portion of these emissions come from private vacant (developable) land. During the windiest month (April, as identified in the Impe rial Valley windblown dust studies 6 ), windblown dust from these areas can
account for 7 2 % of that month’s average day emissions. It would be expected that on the windiest day s that this percentage would be even larger.

3 From 2009 Imperial County PM 10 SIP: Appendix III.B, Figure III.B.1.

4 From 2009 Imperial County PM 10 SIP: Appendix III.B, Figure III.B.6.

5 From March 2012 DRAFT Maricopa Association of Governments Five Percent Plan for PM

- 10 for the Maricopa

County Nonattainment Area: Table ES

- 1.

6 ENVIRON, 2004. Final Report

– Development of a Wind Blown Fugitive Dust Model and Inventory for Imperial

County , California. See also ENVIRON 2005 Technical Memorandum (2005 BACM Report Appendix A).PM 10 Nona ttainment Area s : Selected Comparisons



## FiguresPM 10 Nona ttainment Area s : Selected Comparisons



### Figure 1: Imperial County

(From Figure 2.1 of the 2009 Imperial County PM 10 

### SIP. Nonattainment area includes most of Imperial County.)

Figure 2: Maricopa County and Maricopa Nonattainment Area

(From Figure 2

- 1 of the March 2012 Draft Maricopa 5% PM

- 10 Plan) Niland

Westmorland Brawley

El Centro

C. Ethel

C. GrantPM 10 Nona ttainment Area s : Selected Comparisons



### Figure 6: Federal and State Managed Lands in Imperial County (2009 PM 10 

### SIP)

Figure 7: Windblown Dust Emissions in Imperia l County (2009 PM 10 

### SIP)