# 2010 PM10 Maintenance Plan and Redesignation Request for the Coso Junction Planning Area

May 17, 2010

Prepared by: Great Basin Unified Air Pollution Control District

2010 District Governing Board: Tom Sweeney, Alpine County, Chairman Linda Arcularius, Inyo County, Vice-Chairman Richard Cervantes, Inyo County Byng Hunt, Mono County D. “Hap” Hazard, Mono County Neil McCarroll, Town of Mammoth Lakes Henry “Skip” Veatch, Alpine County

Authors: Duane Ono, Deputy Air Pollution Control Officer Ken Richmond, ENVIRON International Corp.

Great Basin Unified Air Pollution Control District Theodore Schade, Air Po llution Control Officer 157 Short Street Bishop, California 93514 Tel: (760) 872-821, Fa x: (760) 872-6109 Website: www.gbuapcd.orgThe authors gratefully acknowle dge the excellent support from Mike Slates for providing maps, Phill Kiddoo and Chris Howard for an alyzing the PM10 and meteorological data, Dan Johnson for data collection and photo do cumentation at Coso Junction, and Jonathan Becknell for updating the emissions inventory for perm itted facilities.2010 Coso Junction PM10 Maintenance Plan

i PM10 Maintenance Plan and Redesignation Request for the Coso Junction PM10 Planning Area

EXECUTIVE SUMMARY

This document is a revision to the 2004 PM10 St ate Implementation Plan (SIP) for the Coso Junction PM10 Planning Area. It includes 1) a request to redesignate the area from nonattainment for the National Ambient Air Quality Standard for PM10 (federal standard) to attainment based on monitoring data and a modeli ng analysis, and 2) a maintenance plan that contains requirements to ensure the federal PM10 standard will not be violated in the future. As required to redesignate the area to attainment , the enclosed monito ring data and modeling analysis show the Coso Junction Planning Area (CJPA) had less than or equal to 1.0 average annual exceedances of the federal PM10 standard (150 μ g/m 3 for a 24-hour average) during the 3-year period from January 2007 through December 2009.

The 2004 State Implementation Plan for the Coso Junction Planning Area examined the PM10 problem during the period from 1985 to 2003. Du ring that period, 15 violations of the federal 24-hour PM10 standard were monitored at the Coso Junction rest area on Highway US 395. Thirteen of those violations were found to have been caused by windblown dust from the dry lake bed of Owens Lake that is 14 miles outsid e (to the north) of the Coso Junction Planning Area. In November 2004, the District adopted a SIP for the CJPA to explain how the area would be brought into attainment. Since PM10 violati ons at Coso Junction were primarily caused by windblown dust from Owens Lake, the Coso J unction attainment demo nstration relied on implementing dust controls outside of the pl anning area. Under the 2003 Owens Valley PM10 SIP, windblown dust from 29.8 square miles of the dry lake bed at Owens Lake were required to be controlled by December 2006. A dispersion mode ling analysis showed these dust mitigation efforts would be adequate to bring the Coso Junction Planning Area into attainment.

A review of daily ambient monitoring data from Coso Junction showed three monitored exceedances of the federal 24-hour PM10 standard (150 micrograms per cubic meter, μ g/m 3 ) during the 3-year period from January 2007 through December 2009. The federal 24-hour PM10 standard allows no more than an average of 1.0 expected exceedances per year over a 3-year period. Since daily PM10 monitor data show ed the monitor site had an average of 1.0 exceedances per year, PM10 levels near the monitor site can be considered to be in attainment with the federal standard.

A closer examination of the three exceedances found that two exceedances in 2007 (6/5/2007, 217 μ g/m 3 ; 12/6/2007, 283 μ g/m 3 ) were caused by windblown dust from an unpaved truck parking area west of the PM10 monitor site. Th e owner of the unpaved pa rking area was notified and the area was graveled in 2008 and surfaced w ith asphalt in 2009 to control fugitive dust. The third monitored exceedance (12/22/2009, 168 μ g/m 3 ) was caused by windblown dust from Owens Lake. During that event, dust source ar eas at Owens Lake that were not previously identified in the 2003 Owens Valley SIP contri buted to the exceedance at Coso Junction. A revision to the Owens Valley SIP in 2008 included th e majority of these dust source areas as part of an additional 9.8 square miles of the lake be d that was controlled using shallow flooding in2010 Coso Junction PM10 Maintenance Plan

ii April 2010. Another 3.5 square miles of the lake bed are expected to be controlled by October 2010. Therefore, dust control measures were impl emented to mitigate the causes of dust for all three PM10 exceedances at Coso Junction that took place during the 3-year attainment demonstration period.

Although daily PM10 monitor data collected at the Coso Junction rest area showed the area could be considered to be in attainment with the federal standard, highe r PM10 levels are likely to have occurred at locations closer to Owens Lake, since this is the primary source of windblown dust that caused Coso Junction to be de signated nonattainment. The monitor site at the Coso Junction rest area is about 18 miles south of Owens Lake, while the northern boundary of the CJPA is closer at 14 miles from Owens Lake. To determine if windblown dust from Owens Lake caused PM10 violations at the norther n boundary or at other locations in the CJPA, a dispersion model was run to analyze windblown dust impacts for the 3-year period from July 2006 through June 2009.

To evaluate attainment through a modeling anal ysis, the fourth highest value over a 3-year period must be below 150 μ g/m 3 at all locations. The District used the CALPUFF dispersion model, which is a guideline model recommended by the United States Environmental Protection Agency (US EPA) for long-range transport a nd situations where complex winds influence dispersion. As expected, the CA LPUFF model showed the highest PM10 concentrations were at the northern boundary of the CJPA. The highest s ite had two days with modeled impacts above 150 μ g/m 3 and a third high concentration of 150 μ g/m 3 . Since 150 μ g/m 3 is not an exceedance of the PM10 standard there were only two modeled ex ceedances at the highest receptor site in the CJPA. The fourth highest modeled value at the same site for the 3-year period was 137 μ g/m 3

. Therefore, the CALPUFF model analysis demonstrated it is reasonable to be lieve that attainment of the standard was achieved at all locations in the planning area.

As a result of our evaluation of monitoring data and a CALPUFF modeling analysis, the District recommends through the adoption of this SIP re vision that the Californi a Air Resources Board request the US EPA redesignate the Coso J unction Planning Area from nonattainment to attainment for the federal PM10 standard.

To ensure compliance with the federal PM10 standard is maintained in future years, the District evaluated future activities that could affect PM10 levels in the planning area and the adequacy of existing rules, policies and emi ssion control requirements to control emissions from those sources and activities. District staff found that existing rules for fugitive dust and new source review were adequate to contro l potential new sources within th e Coso Junction Planning Area. For PM10 sources outside the planning area, th e major concern is for windblown dust from Owens Lake. District staff believes the contro l strategy and contingency requirements in the 2008 Owens Valley PM10 SIP are adequate to prot ect air quality in the Coso Junction area. Therefore, no additional contingency measures w ill be needed to ensure future compliance with the federal PM10 standard in the Coso Junction Planning Area.2010 Coso Junction PM10 Maintenance Plan

iii PM10 Maintenance Plan and Redesignation Request for the Coso Junction PM10 Planning Area

Table of Contents

Page Executive Summary i
Table of Contents iii Glossary v

Sections
1 Planning Area 1

2 Clean Air Act Regulatory History 1

3 Air Quality 4

4 Attainment Emissions Inventory 9

4.1 Stationary Source Emissions 9
4.2 Area Source Emissions 9
4.3 Mobile Source Emissions 10
4.4 Emissions Growth Forecast 10
4.5 Wind Erosion from Sources Other than Owens Lake 11
5 Control Strategy 11

5.1 Contingency Measures 12 5.2 Miscellaneous Sources and Model Background 15
6 Air Quality Modeling and A ttainment Demonstration 16

6.1 Modeling Techniques 16
6.2 Model Results 18
7 Transportation Conformity 22

8 General Conformity 22

9 Request to Redesignate Coso Junction to Attainment 22

10 Request to Approve Coso J unction PM10 Maintenance Plan 23

11 References 242010 Coso Junction PM10 Maintenance Plan

iv PM10 Maintenance Plan and Redesignation Request for the Coso Junction PM10 Planning Area

Table of Contents

Appendices

A PM10 Air Quality Data for Coso Junction, CA (1985 – 2009)
B PM10 Concentrations and Hourly Me teorological Data for Exceedance Days

C Board Order #080128-01 Requiring the City of Los Angeles to Undertake Measures to Control PM10 Emissions from the Dried Bed of Owens Lake D Dispersion Modeling Results for Coso Junction PM10 Planning Area

Figures Page

1 Coso Junction PM10 Planning Area map 2
2 Former Searles Valley PM10 Planning Area map 3

3 PM10 monitors in and near th e Coso Junction Planning Area 5

4 Emissions trend for Owens Lake emission reductions 13
5 Photo of truck parking area west of Coso Junction PM10 monitor site 15
6 CALPUFF modeling domain 17

7 4 th highest PM10 model concentration from July 2006 through June 2009 20
8 Map of 24-hour average PM10 pred ictions for the design day 21

Tables

1 Summary of PM10 exceedances in the Coso Junction Planning Area 6

2 Exceedances associated with wi ndblown dust from Owens Lake 7

3 Annual PM10 Concentrations in the Coso Junction Planning Area 8
4 PM10 emissions inventory for the Coso Junction Planning Area (2009-2025) 10
5 Existing District Rules and Regulat ions for control sources of PM10 14
6 Summary of maximum PM 10 model predictions 192010 Coso Junction PM10 Maintenance Plan

v GLOSSARY

CALPUFF A USEPA recommended air quality model for long-range transport and situations where complex winds influence dispersion.

CARB California Air Resources Board

CFR Code of Federal Regulations

CH&SC California Health and Safety Code

CJPA Coso Junction Planning Area

CoGa Coso Gate model receptor site

CoJu Coso Junction model receptor site

District Great Basin Unified Air Pollution Control District

Dust ID Program Owens Lake Dust Identification Program

Federal Standard National Ambient Air Quality Standard (PM10 = 150 μg/m 3 for a 24-hour average)

GBUAPCD Great Basin Unified Ai r Pollution Control District

PM10 particulate matter less than 10 microns

PSD Prevention of Significant Deterioration

SIP State Implementation Plan

US EPA United States Environmental Protection Agency

km kilometers

m/s meters per second

mph miles per hour

μg/m 3 micrograms per cubic meter2010 Coso Junction PM10 Maintenance Plan

vi BLANK PAGE2010 Coso Junction PM10 Maintenance Plan

1 PM10 Maintenance Plan and Redesignation Request for the Coso Junction PM10 Planning Area

1 Planning Area

The Coso Junction PM10 Planning Area (CJPA) is located in Eastern Calif ornia in the southern portion of Inyo County (Figure 1). It is an arid desert area that receives less than 5 inches of rain per year. The area is rural in nature and sparse ly populated. The principle PM10 monitor site is located at the Coso Junction rest area in the Ro se Valley. This valley is flanked by the Sierra Nevada and Coso mountain ranges. The China Lake Naval Air Weapons Station, which covers most of the CJPA, is generally restricted from public access.

Air pollution in the Coso Junction Planning Area is dominated by windblown dust transported from Owens Lake, which is located outside th e planning area. Air pollution from District permitted facilities within the CJPA boundaries has generally not had a significant impact on PM10 concentrations in the planning area. Thes e sources include the Coso geothermal power operations, military operations at the China La ke Naval Air Weapons Station, and volcanic cinder and pumice mining operations. Although gene rally not a problem in the planning area, high PM10 readings were documented in 1990 due to windblown dust from abandoned agricultural land, in 200 2 from a wildfire, and in 1990 fr om windblown dust from an unpaved truck parking area. None of thes e types of events are expected to recur at Coso Junction. The agricultural land just north of the monitor site was stabili zed by natural vegetation cover in 1991 after the land was fallowed. Since that time no agricultural activities have taken place in the CJPA. Dust from the unpaved truck parking area, located adjacent to the PM10 monitor site was mitigated by covering it with gravel in 2008 and then asphalt pavement in 2009.

2 Clean Air Act Regulatory History

The Coso Junction Planning Area was initially designated as a PM10 nonattainment area in 1987 along with the Indian Wells Valley and Trona. Together they comprised the Searles Valley PM10 nonattainment area as shown in Figure 2. The Great Basin Unified Air Pollution Control District adopted a State Implementation Plan (S IP) for the Coso Junction portion of the Searles Valley PM10 nonattainment area in November 1991 (GBUAPCD, 1991). This was followed by air quality plans for the Indian Wells Valley and Trona, which were regulated by the Kern County Air Pollution Control Distri ct and the Mojave Desert Air Quality Management District (formerly San Bernardino County Ai r Pollution Control District).

In August 2002, the United States Environmenta l Protection Agency (US EPA) redesignated the Searles Valley into three separate PM10 nonattai nment areas. Under this regulatory action, Coso Junction and the Indian Wells Va lley were classified as moderate PM10 nonattainment areas, and a finding of attainment was made for Trona. (Federal Register, 2002a, 2002b) In 2003, Indian Wells Valley was reclassified to attainme nt with US EPA’s approval of the Moderate Area SIP and Maintenance SIP. (Federal Re gister, 2003a and 2003b) In November 2004, the Great Basin Unified Air Pollution Control District adopt ed a SIP revision for the Coso Junction PM10 Planning Area that forecast compliance with the federal PM10 standard in 2010.2010 Coso Junction PM10 Maintenance Plan

2 Figure 1. The Coso Junction Planning Area is located in the southern portion of Inyo County, CA. Much of the planning area is covered by the China Lake Naval Air Weapons Station, which has restricted access for the general public. Most of the PM10 standard exceedances monitored at Coso Junction were caused by windblown dust from the exposed lake bed at Owens Lake.2010 Coso Junction PM10 Maintenance Plan

3 Figure 2. The Searles Valley PM10 Nonattainmen t Area was reclassified into three separate planning areas in 2002. Indian Wells Valley and Trona were classified attainment for the federal PM10 standard in 2002 and 2003.

The Coso Junction attainment demonstration wa s based on controlling dust from Owens Lake, which was scheduled to implement dust control m easures on 29.8 square miles of the lake bed by December 31, 2006. The 2004 Coso Junction SI P included a CALPU FF dispersion model analysis that indicated that afte r dust controls were implemente d at Owens Lake at the end of 2006, the Coso Junction Area would be in attainment. However, an additional 3 years of data collection and monitoring were needed to demonstr ate the CJPA had attained the PM10 standard.

This document is intended to provide the air quality monitoring data and modeling analysis to demonstrate the area has attained the PM10 st andard. In addition, it includes regulatory requirements to ensure the CJPA will maintain co mpliance with the federal PM10 standard in the future.2010 Coso Junction PM10 Maintenance Plan

4 3 Air Quality

Twenty-two exceedances of the federal 24-hour PM10 standard were monitored at Coso Junction in the 24 years from 1985 to 2009. Eighteen out of 22 of these exceedances were caused by dust from Owens Lake. High northerly winds and hi gh PM10 concentrations near Owens Lake are good indicators for windblown dust to be transporte d from the exposed lake bed at Owens Lake to the CJPA.

To document the Owens Lake dust impact at Coso Junction and other downwind sites, a specialpurpose monitoring network was operated from 1993 to 1996. The monitoring network shown in Figure 3 measured Owens Lake dust impacts at five downwind sites and found exceedances of the standard as far as 50 miles from Owens Lake . PM10 monitors at Coso Junction, Navy I, and Pearsonville are within the CJPA boundaries. Si tes north of Coso Junction are in the Owens Valley PM10 planning area and the monitor sites in Ridgecrest and Inyokern are in the Indian Wells PM10 planning area.

Table 1 shows a summary of the PM10 exceedances monitored in the CJPA and the levels measured at other sites in the network. Ta ble 2 shows PM10 concentrations, wind speed and directions in the Owens Lake area for these ex ceedance days. As previously mentioned, 18 of the 22 exceedances in the CJPA were caused by dus t from Owens Lake. The exceptions to this are four events measured at Coso Junc tion on 4/23/90, 7/25/02, 6/5/07, and 12/6/07.

• The event on 4/23/90 was caused by windblow n dust from abandoned agricultural land located upwind from the monitor site. In 1991, this agricultural field naturally revegetated after heavy March rains. Since that time, the field has remained covered with volunteer vegetation and has not been observe d as a dust source area. (GBUAPCD, 1991)

• The event on 7/25/02 was caused by smoke from the McNally wildfire in the Sierra about 20 miles west of the planning area. About 150,000 acres of mixed conifer, heavy brush and grass burned from July 21 to Augus t 29, 2002. (Wilderness Society, 2003)

• Two events on 6/5/07 and 12/6/07 were cau sed by windblown dust from an unpaved truck parking area west of the PM10 monitor site. The truck stop owner was notified and the parking area was surfaced with gravel in 2008 and recycled asphalt in 2009.

Table 3 shows the number of monitored exceed ances per year, and the expected number of exceedances per year based on the monitoring fr equency. Prior to 2006, samples were normally collected on a once every sixth-day, or once ev ery third-day schedule. In 2006, daily PM10 monitoring was initiated at Coso Junction. Tabl e 3 also includes the 3-year annual average PM10 concentrations for Coso Junction, which in 2009 was 19 μ g/m 3 . However, it should be noted that the US EPA revoked the annual PM10 standard in 2006, which at the time was set at 50 μ g/m 3 . A complete list of PM10 monitor data fo r Coso Junction and other nearby sites is included in Appendix A, and hourly data for th e 22 exceedances is summarized in Appendix B.2010 Coso Junction PM10 Maintenance Plan

5 Figure 3. PM10 monitor locations in and near the Coso Junction Planning Area.2010 Coso Junction PM10 Maintenance Plan

6 Table 1. Summary of PM10 exceedances monitored over 150 μg/m 3 in the Coso Junction Planning Area and concentrations at other sites on the same day. See Table 2 for causes of exceedances in the CJPA for the dates shown below and Appendix B for hourly meteorological data for these events.

24-Hour Average PM-10 Concentrations ( μ g/m 3 ) Coso Junction Planning Area Indian Wells Valley Owens Valley Planning Area

Exceedance Date Coso Junction Navy Pearsonville Ridgecrest Inyokern Keeler Olancha Lone Pine Dirty Socks Flat Rock Shell Cut

4/25/1985 307 92 4/2/1986 1175 95 6/7/1986 157 44 1/15/1987 196 100 25 2/3/1989 227 101 1861 126 4/23/1990 866 94 200
10/26/1993 254 131 16 59 112 346
12/23/1993 188 50 18 9 412 185 58

1/5/1994 388 239 75 199 365 76 4/8/1995 692 392 235 158 128 107 4/9/1995 567 331 2252 52 4/21/1995 337 268 51 119 16 4/27/1996 50 18 176 92 81 65 657 28 5/23/1996 309 132 31 79 259 42 34 3/6/1998 91 246 305 33 42 3/18/1998 409 49 46 228
7/25/2002 175 36 87 71 64 75 100 90 2/2/2003 484 162 484 1062 116 10933 395 9162
12/28/2006 296 2101 428 126 104 735 94

6/5/2007 217 35 159 55 71 68 508 182
12/6/2007 283 13 38 15 29 10 16
12/22/2009 168 236 76 42 17 217 342010 Coso Junction PM10 Maintenance Plan

7 Table 2. Over the last 25 years, violations of the federal PM10 standard in the Coso Junction Planning Area were primarily caused by dust from the Owens Lake area. See Table 1 for PM10 concentrations on the dates shown below and Appendix B for hourly meteorological data for these events.

Exceedance Date Maximum Hourly Wind Primary Cause of Exceedance Max Speed MPH @ 10 m Direction of Max Wind Degrees 4/25/1985 30.0 335 N wind all day, Owens Lake Dust, Coso Met
4/2/1986 37.5 350 N wind all day, Owens Lake Dust

6/7/1986 27.5 315 Variable winds during day, Owens Lake Dust 1/15/1987 40.0 35 N wind all day, Owens Lake Dust

2/3/1989 38.0 285 Variable winds during day, Owens Lake Dust 4/23/1990 26.0 272 Abandoned Ag Land Dust
10/26/1993 29.3 18 N wind all day, Owens Lake Dust
12/23/1993 25.7 35 N wind all day, Owens Lake Dust

1/5/1994 31.0 22 Variable winds during day, Owens Lake Dust 4/8/1995 23.2 316 Coso Junction Met, Owens Lake Dust

4/9/1995 35.9 358 Coso Junction Met, Owens Lake Dust
4/21/1995 29.2 7 N wind all day, Owens Lake Dust
4/27/1996 26.0 38 N wind all day, Owens Lake Dust
5/23/1996 30.7 5 N wind all day, Owens Lake Dust

3/6/1998 34.9 354 Variable winds during day, Owens Lake Dust

3/18/1998 12.0 48 Variable winds during day, Owens Lake Dust 7/25/2002 17.6 163 McNally Fire smoke
2/2/2003 36.2 3 N wind all day, Owens Lake Dust
12/28/2006 46.8 337 N wind all day, Owens Lake Dust

6/5/2007 36.2 264 W wind, Coso Junction Parking Area Dust
12/6/2007 42.6 252 W wind, Coso Junction Parking Area Dust
12/22/2009 39.1 1 N wind, Regional and Owens Lake Dust2010 Coso Junction PM10 Maintenance Plan

8 Table 3. The expected number of exceedances per year has decreased since dust control measures were implemented on 29.8 square miles of the Owens Lake bed in December 2006.

PM10 Concentration (μg/m3) Number of Exceeds Expected Number of Exceedances Per Year Number Sample

Days Annual Average 3-Year Average Peak 24-Hour Year 1985 Invalid 307 1 49 1986 51.51 1175 2 12 58 1987 33.62 196 1 6 59 1988 22.12 35.75 92 0 0 59 1989 27.50 27.74 227 1 6 61 1990 29.37 26.33 866 1 6 60 1991 18.80 25.22 93 0 0 60 1992 Invalid 38 0 36 1993 28.78 254 2 12 59 1994 16.69 388 1 6 61 1995 32.28 25.92 692 2 12 58 1996 Invalid 309 1 51 1997 Invalid 92 0 54 1998 23.31 409 1 6 59 1999 14.84 46 0 0 114
2000 15.02 17.72 74 0 0 110
2001 11.88 13.91 100 0 0 122
2002 18.04 14.98 175 1 3 115
2003 20.54 16.82 484 1 3 121
2004 14.89 17.82 66 0 0 121
2005 18.24 17.89 97 0 0 119
2006 20.72 17.95 296 1 1 273 2007 19.91 19.62 283 2 2 363 2008 18.63 19.75 137 0 0 366 2009 18.59 19.04 168 1 1 3622010 Coso Junction PM10 Maintenance Plan

9 More information on the Coso Junction PM10 monito r site is included in the District’s annual Ambient Air Monitoring Network Plan, which was approved by the US EPA. (GBUAPCD, 2009a) As a commitment in the maintenance plan for the CJPA the District is authorized to continue daily PM10 monitoring at the Coso J unction rest area to ensure new and existing sources of PM10 are identified and cont rolled, if necessary. (CH&SC §40001)

4 Attainment Emissions Inventory

The attainment emissions inventory for the CJ PA is based on estimated daily PM10 emissions for 2008. Emission estimates for 2008 are typical of emissions in the CJPA over the 3-year period (2007-09) when PM10 compliance was determined from monitoring and modeling evaluations. PM10 emissions generated in the CJPA are primarily from permitted facilities on the China Lake Naval Air Weapons Station proper ty, which is generally restricted from public access. Table 4 shows the daily PM10 emissions inventory for permitted facilities in the CJPA and for area and mobile sources. Total PM10 emissions are estimated at 1,478 pounds per day. In comparison, total daily PM10 emissions genera ted in the CJPA are less than 0.1% of the emissions caused by windblown dust from Owens Lake, which is the primary cause of PM10 violations at Coso Junction. PM10 emissions from Owens Lake were estimated at 1.55 million pounds for the CJPA design day (January 5, 2007).

4.1 Stationary Source Emissions The point source emission estimates shown in Table 4 were developed from information contained in current District and federal Title V permit files. Unpaved road and haul road emissions for permitted sources are included in the daily emissions for each facility. Emissions were based on 10-hour workdays fo r the pumice and rock plants.

4.2 Area Source Emissions Unpaved road dust emissions in the area source cat egory are estimated for non-permitted facility related traffic. An estimate of PM10 emissions from reentrained road dust from unpaved roads is based on the method found in US EPA’s Compilation of Air Pollution Emission Factors, AP-42 (USEPA, 2006).

ܧ ൌ ௞ ൫ ௦ ଵଶ ൗ ൯ ೌ ൫ ௌ ଷ଴ ൗ ൯ ೏ ൫ ெ ଴.ହ ൗ ൯ ೎ െ ܥ Eq. 1

Where: E = PM10 emissions in pound per vehicle mile traveled

s = silt content of road surface material (5%) S

= mean vehicle speed (30 miles per hour) M = surface material moistu re content (assume 0.3%) C

= emission factor for 1980’s vehicle flee t exhaust, brake wear and tire wear (0.00047 for PM10).

For PM10 from public unpaved roads: k = 1.8, a = 1, d = 0.5 and c = 0.2.2010 Coso Junction PM10 Maintenance Plan

10 Table 4. Daily PM10 emissions inventory for the Coso Junction Planning Area for 2008 through 2025. For the purpose of the maintenance plan, no significant growth is expected in the emissions inventory through the year 2025.

Equation 1 yields an emission rate of 0.83 pounds of PM10 per vehicle mile traveled. Assuming an average of 2 vehicle trips per day on 50 miles of unpaved roads in the public portion of the CJPA, yields 100 vehicle-miles per day a nd 83 pounds of PM10 per day. (CARB, 2010a)

PM10 from paved road dust is based on CARB ’s emission estimates for Inyo County in 2008 (0.99 tons of PM10 per day) and pro-rated for the proportion of traffic in the CJPA (5.1%), which yields 101 pounds per day. (CARB, 2010b)

Based on population growth in Inyo County, area s ource emissions are not expected to change significantly in future years.

4.3 Mobile Source Emissions PM10 from on-road motor vehicle emissions (exc ludes re-entrained road dust) is based on CARB’s emission estimates for Inyo County in 2008 (0.12 tons of PM10 pe r day) and pro-rated for the proportion of traffic in the CJPA (5.1 %), which yields 12 pounds per day. (CARB, 2010) The mobile source emissions are not exp ected to change in future years.

4.4 Emissions Growth Forecast Due to the sparse population, lack of population growth, and the expectat ion that industrial operations in the planning area will not change significantly, the emission s inventory forecast will remain stable for all future years. The 2000 US census shows 102 people living in the Coso Junction Planning area in the communities of Pearsonville and Homewood Canyon. This is about 0.5% of the total populati on of Inyo County. According to the US Census Bureau, Inyo County’s population declined from 18,281 in 1990 to 17,945 in 2000. Population continued to Daily PM10 Emissions for 2008 through 2025 Stationary Sources Pounds/day
California Lightweight Pumice 167 China Lake Naval Air Weapons Station 84
Coso Operating Company 953 Halliburton Services 20
Twin Mountain Rock 58

Area Sources Unpaved Roads 83 Paved Roads 101

Mobile Sources
On

‐ Road Motor Vehicles 12

Total PM10 (pounds per day) 1,4782010 Coso Junction PM10 Maintenance Plan

11 decline to 17,136 in 2008. Over those 18 year s, Inyo County’s populatio n decreased by 4.5%. (US Census Bureau, 2010)

For the purpose of the emissions forecast for the maintenance plan, the daily PM10 emissions inventory will be the same as shown in Table 4 for the next 17 years through the year 2025.

4.5 Wind Erosion from Sources Other than Owens Lake Undisturbed open areas in the CJPA are genera lly invulnerable to signi ficant wind erosion. Ambient monitors show low PM10 concentrations (23 μ g/m 3 ) on windy days when winds are not from the direction of Owens Lake or other know n windblown dust source ar eas (see section 5.2). Two known windblown dust source areas in the CJPA, however were found to be significant.

In 1990 and 2007, three exceedances of the federa l PM10 standard were monitored at Coso Junction, which were caused by windblown dust fr om a fallow agricultural field and an unpaved truck parking area (see Table 2)

. As noted in the air quality di scussion, these areas are no longer a dust problem since the agricultural field is protected by volunteer vegetation cover and the truck parking area is now paved. Since these areas are no longer a significant source of dust, they are not included in the daily PM10 emissi ons in Table 4 for the years 2008 through 2025. However, PM10 emissions from these source areas can be estimated for each of the event days in 1990 and 2007.

A wind tunnel-based emissions algorithm was developed for the 1998 Owens Valley PM10 SIP, which can be used to estimate PM10 emissions from the agricultural field , public unpaved roadways and the unpaved truck parking area. Th e Owens Lake emissions equation for the fall period (equation 2) provides a good estimate for wind erosion in the CJPA since the surfaces can be considered to be disturbed, but they lack the efflorescent salts that characterize the lake bed surface at Owens Lake in the spring. (E = 0 in equation 2 for u < 7.6 m/s) (GBUAPCD, 1998)

ܧ ൌ 1.34 ൈ 10 ିହ ݁ ሺ଴.ଶହൈ௨ሻ Eq. 2

Where: E = PM10 emissions in grams per square meter per second

u = Hourly average wind speed at 10 m in meters per second (for u > 7.6 m/s)

Appendix B includes meteorological data for these three wind events. The agricultural field covered 314.5 acres on 4/23/1990, and the PM10 em issions on that day are estimated at 12,566 pounds. Wind erosion from the unpaved truck park ing area (4.7 acres) is estimated at 551 pounds on 6/5/2007 and 763 pounds on 12/6/2007. Wind er osion from unpaved roadways in the CJPA (46.8 acres) is estimated at 5,489 pounds on 6/5/2007 and 7,611 pounds on 12/6/2007.

5 Control Strategy

As discussed in the Air Quality section of th is document, PM10 exceedances in the CJPA are primarily due to the transpor t of windblown dust from the Owens Lake area. Therefore, achieving emission reductions at Owens Lake is the primary control strategy for reaching attainment in the CJPA. The US EPA classifi ed the southern Owens Valley as a serious PM102010 Coso Junction PM10 Maintenance Plan

12 nonattainment area in 1993 and required a SIP be developed to achieve compliance with the federal standard. A SIP was adopted in 1998 an d approved by the US EPA for the Owens Valley with an interim control strategy that required dust controls on 16.5 square miles of the lakebed. Under the Owens Valley SIP, the City of Los Angeles is responsible for mitigating the dust generated from Owens Lake in orde r to bring the area into attainment with the federal standard. (GBUAPCD, 1998) The Owens Valley SIP was revi sed in 2003 to expand dust controls to 29.8 square miles of the lake bed by Decemb er 31, 2006. (GBUAPCD, 2003) The City of Los Angeles successfully implemented these control measures by the required deadline. Another revision to the Owens Valley SIP in 2008 expanded control requirements to a total of 43.1 square miles of the Owens Lake bed. The Board Order to implement control measures in the 2008 SIP is included as Appendix C of this document. The City of Los Angeles is expected to have dust control measures implemented on 39.6 square mile s of the lakebed by April 1, 2010, and then to expand the control area to 43.1 square miles by October 1, 2010. (GBUAPCD, 2008; GBUAPCD, 2009b)

Figure 4 shows the annual PM10 emissions trend for the Owens Valley planning area. The blue line represents total PM10 emissions from all sources in the planning area, and the red line represents the windblown dust emissions from th e Owens Lake bed. The dashed lines represent emission forecasts for Owens Lake based on the implementation of additional control measures on the lake bed and in the Keeler Dunes. Ac tual PM10 emissions from the Owens Lake bed have been reduced by 90% since 2000 when the City of Los Angeles initiated efforts to control windblown dust at Owens Lake. Windblown dust emissions were estimated using hourly PM10 emission measurements collected through the Owens Lake Dust Identification Program. Hourly data on windblown dust was collected from 200 0 through 2008 using the methodology described in the Owens Valley PM10 SIP. (GBUAPCD, 2 008) The decrease in windblown dust emissions from Owens Lake after 2006 is reflected in the reduction in Owens Lake-caused PM10 exceedances monitored at Coso Junction in 2007, 2008 and 2009 (Table 3). The additional 2008 Owens Valley SIP control measures, which will be implemented in 2010 should result in even lower PM10 levels at Coso Junction than those observed during this 3-year period.

Other sources of PM10 that caused exceedances of the federal standard at Coso Junction included; a wildfire and windblow n dust from agricultural operation and from an unpaved truck parking area. These events were discussed in th e Air Quality section of this document. Current District rules are ade quate to prevent agricultural operati ons, prescribed burning, and windblown dust from disturbed surface areas from causing exceed ances of the standard in the future. Table 5 shows the current District rules that limit PM10 emissions in the planning area.

5.1 Contingency Measures The Owens Valley SIP also include s contingency measures (referre d to as Supplemental Control Requirements in the Owens Valley SIP) that requ ire the City of Los A ngeles to implement dust control measures on any new windblown dust area s on the lakebed and to improve dust control measures in areas where it is necessary to pr event exceedances of the PM10 standard at any location on the shoreline of Owens Lake (see Appendix C, Board Order #080128-01 Requiring the City of Los Angeles to Undertake Measures to Control PM10 Emissions from the Dried Bed of Owens Lake ). The District will rely on all the PM 10 control measures and the Supplemental Control Requirements in the Owens Valley SIP, a nd existing District rules to ensure compliance2010 Coso Junction PM10 Maintenance Plan

13 Figure 4. Since 2000, actual PM10 emissions from the exposed lakebed at Owens Lake have decreased by 90% as a result of dust control measures implemented by the City of Los Angeles. PM10 emissions will decrease in 2011 after additi onal dust controls are implemented on 13.3 square miles of the lake bed. This will bring the total to 43.1 square miles of dust control areas.

is maintained in the CJPA. The Board Order in Appendix C includes all the Owens Lake control measures and the Supplemental Control Requirements, which the District will rely on to prevent Owens Lake dust from causing future vi olations in the CJPA. (GBUAPCD, 2008)

The District is authorized to continue daily ambient PM10 monitoring at Coso Junction (CH&SC § 40001). If an exceedance of the federal PM10 standard is monitored the District will investigate the cause of the exceedance within 60 days following the end of the calendar quarter during which the event occurred. Exceedances found to be caused by dust from Owens Lake will be investigated to determine if the require d control measures were properly implemented in accordance with Board Order #080128-01. Exceedan ces found to be caused by dust from local sources that are subject to current District regulations will be addressed and corrected. Exceedances found to be caused by Exceptional Events, such as w ildfires or earthquakes will be flagged in accordance with US EPA policy (Federal Register, 2007).

To prevent new facilities from causing an air poll ution problem, any new facilities in the CJPA that may emit air pollution will be subject to th e District’s new source review rules (209-A, 216 and 216-A). Facilities that qualify as a major source under the US EPA federal permitting guidelines will also be subject to federal PSD (Prevention of Significant Deterioration) permitting requirements (40 CFR 51.166 and 52.21).2010 Coso Junction PM10 Maintenance Plan

14 Table 5. Existing District rules and regulations to control sources of PM10.

District

Rule Description

209-A Requires new sources with PM10 emissions greater than 250 pounds per day of total suspended particulates, or facility modificati ons of greater than 15 tons per year of PM10 to apply Best Available Control Technology to control PM emissions.

216 Requires the Air Pollution Control Officer to evaluate air pollution impacts before issuing an Authority to Construct or Permit to Operate for a new facility.

216-A Requires permits for any new secondary source of air pollution including buildings, commercial parking and housing developments.

400 Limits visible emissions from any source, except those exempted under Rule 405, to less than Ringelmann 1 or 20% opacity.

401 Requires reasonable precautions be taken to prevent visible particulate emissions from crossing the property boundary.

402 Prohibits sources of air pollution from causing a nuisance to the public or endangering public health and safety.

408 Limits agricultural burning operations to designated burn days and requires a burn permit.

409 Limits range improvement burning to designa ted burn days and requires a burn plan be approved by the Air Pollution Control Officer.

410 Limits forest management burning to designated burn days and requires a burn plan be approved by the Air Pollution Control Officer.

411 Limits wildland management burning to designated burn days and requires a burn plan be approved by the Air Pollution Control Officer.

502 Requires conservation management plans to reduce fugitive dust emissions from agricultural operations greater than 10 acres in Inyo, Mono and Alpine Counties

Reg. XII Requires that federal actions and federa lly funded transportation-related projects conform to SIP rules and that they do not interfere with efforts to attain federal air quality standards.

Reg. XIII Requires that federal actions and federally funded projects conform to SIP rules and that they do not interfere with efforts to attain federal air quality standards. Federal actions that have the potential to emit more than 100 tons per year of PM10 in the CJPA will be required to complete a conformity determination.2010 Coso Junction PM10 Maintenance Plan

15 Figure 5. Windblown dust from this truck parkin g area located west of the PM10 monitor site at the Coso Junction rest area caused two exceedances of the PM10 standard in 2007. The parking area was graveled in 2008 to control dust. In 2009, most of it was paved and used as a staging area for a highway construction project. The PM10 monitor site is the structure with the railing on top in the center of the photo. Coso Junction wind measurements are taken at a 10 m height on the tower to the left (north) of the PM10 monitor. (View looking to the northeast, February 24, 2010)

5.2 Miscellaneous Sources and Model Background To determine the PM10 contribution from miscella neous sources other than Owens Lake on days with Owens Lake dust events, the District re viewed the hourly PM10 data from the Coso Junction monitor site. By looking at hours with high winds (>7 m/s, 16 mph) and screening out wind directions from Owens Lake and the unpave d parking area located to the west of the monitor, the average PM10 concentration at Coso Junction was determined to be 23 μ g/m 3 on windy days. This is close to the av erage background concentration of 20 μ g/m 3 that was determined for sites in the Owens Valley Planning Area. If the unpaved parking area had been included in the wind direction screening, the average PM10 concentration for high wind hours would have been 40 μ g/m 3 . However, since this source has already been ade quately controlled by gravel and asphalt pavement it will not be tr eated in the model atta inment demonstration. Figure 5 shows a photo taken on February 24, 2010 of the paved truck parking area located west of the Coso Junction PM10 monitor site. To account for sources ot her than windblown dust from Owens Lake in the attainment dem onstration a background concentration of 20 μ g/m 3 was added to all 24-hour model predictions.2010 Coso Junction PM10 Maintenance Plan

16 6 Air Quality Modeling and Attainment Demonstration

Since 18 of the 22 PM10 violations monitored at Coso Junction were found to have been caused by windblown dust from the Owens Lake bed, the Owens Valley PM10 model was used to model the attainment demonstration for the Coso Junction PM10 redesignation request and maintenance plan. It should be noted the four non-Owens Lake-caused exceedances, were caused by: windblown dust from a fallow agricultu ral field, which is now stabilized with volunteer vegetation; an unpaved tr uck parking area, which has si nce been paved and graveled; and a wildfire in 2002. The air quality modeling study was not intended to simulate these types of non-recurrent events.

Dispersion modeling was performed to estimate PM10 concentrations during high wind events along the southern boundary of the Owens Valley PM10 Planning Area, which is the northern boundary of the CJPA. Dust source areas at Owe ns Lake were simulated using the methods described in the Owens Valley PM10 Planni ng Area 2003 and 2008 State Implementation Plan revisions (GBUAPCD, 2003; GBUAPCD, 2008). Based on the sand flux and meteorological data collected during July 2006 to June 2009, the simulations suggest PM10 concentrations from dust source areas on Owens Lake wi ll not cause violations of the federal PM10 standard in the neighboring Coso Junction PM10 planning area.

6.1 Modeling Techniques Dispersion model simulations were performed with the regulato ry version 5.8 of the CALPUFF modeling system following the techniques of the Owens Lake Dust ID Program summarized in the 2003 and 2008 Owen Valley SIPs. The data colle cted by the Owens Lake Dust ID Program include surface meteorological data (at 10 m hei ght), upper air meteorological soundings, source area delineations, and horizontal sand flux observa tions. Sand flux measurements are used as the basis for PM 10 emission rates from windblown sources on Owens dry lakebed. Full details on the modeling protocol for this study can be found in Distri ct Board Order #080128-01, Attachment C, Section 6.0 (incl uded as Appendix C of this document). Some of the features of the Coso Junction CALPUFF model simulation were:

• Model simulation period was from July 2006 to June 2009 using the last three years of data available from the Owens Lake Dust ID Program.

• The Owens Valley study domain was extende d to the south to include the common boundary of the southern Owens Valley a nd northern Coso Junction PM10 planning areas. The revised modeling domain is depict ed in Figure 6. The re vised study domain is 36 km-by-67 km versus the Owens Valley domain of 34 km-by-48 km.

• The same vertical and horizontal mesh si zes are used in both modeling analyses.

• Data collected at two additional surface meteor ological stations in the southern portions of the current domain were used to construc t the wind fields for the simulations. Data from the Coso Junction (CoJu) and Coso Ga te (CoGa) sites shown in Figure 6 were prepared using the same methods as desc ribed in the Owens Valley PM10 SIP.2010 Coso Junction PM10 Maintenance Plan

17 400 405 410 415 420 425 430 UTM East-West (km) 3990 3995 4000 4005 4010 4015 4020 4025 4030 4035 4040 4045 4050 4055UTM North-South (km) Keel Lone

Sock

Olan Atow Delt

Flat

Scut Cott Mill

CoJu CoGa Btow

Stan Lizt 

### Figure 1. Dispersion Modeling Domain Monitoring Stations Shown on 1-km Mesh Size Land Use and Terrain Terrain Contours in Meters, USGS Land Use

10 20 30 40 50 60 70 80 90 100 USGS Land Use

NAA Boundary Mixed urban Agriculture Range Forest Water Wetland Salt Flat/Sand/Barre n Snow

Tundra/Bare

Met. Site

TEOM Figure 6. The dispersion modeling domain for the Owens Valley and Coso Junction Planning Areas was 36 km by 67 km.2010 Coso Junction PM10 Maintenance Plan

18 • To assess attainment, PM10 concentration pr edictions were obtai ned at 90 receptors placed along the southern Owens Valley PM10 Planning Area boundary. The receptor interval shown in Figure 6 is 300-600 m. A r eceptor was also placed at the Coso Junction site where current and historical PM10 obs ervations are/have been collected.

• Area source PM10 emission fluxes were calculat ed using hourly Sensit sand motion data and seasonal proportionality constants (K-f actors) for July 2006 to June 2009. The procedures used to derive the seasonal 75 th percentile K-factors ar e described in the 2003 and 2008 Owens Valley PM10 SIPs.

• Twelve different area source c onfigurations were available from the Owens Lake Dust ID Program based on source delineations for the three-year period.

• No additional controls were assumed for the Owens Lake sources. Sources were characterized as observed duri ng the simulation period withou t the effects of controls planned for many of these areas.

• As in the 2003 and 2008 Owens Valley SIP at tainment demonstrations, the current simulations only include wi ndblown emissions from sources on the lakebed and the Keeler Dunes. As discussed in the previous section, in order to account for background and miscellaneous sources, model predictions were added to a background concentration of 20 μg/m 3 . This same background concentration is also included in the modeling protocol for the Owens Valley SIP (GBUAPCD, 2003; GBUAPCD, 2008).

• Attainment for the 24-hour PM10 NAAQS was assessed using the fourth highest daily prediction at the same receptor during the three-year simulation.

Appendix D of this document provides a summary of the model results. It also includes an evaluation of model performance comparing predic tions and observations for 10 monitor sites in the Owens Valley and Coso Junction planning ar eas. The model performance results suggest model predictions as a whole are relatively unbiased, but scattered, and that the predicted frequency distributions are generally within a factor-of-two of the observed distribution.

6.2 Model Results Table 6 summarizes the results for the CALPUFF simulations of Owens Lake dust events during July 2006 through June 2009, conservatively as suming no future controls would reduce emissions. Figure 7 shows predicted 24-hour design concentrations at th e common planning area boundary. The design concentration is the 4 th highest 24-hour predicti on in the three-year simulation. If the design concentrati on is under the federal standard of 150 μ g/m 3 , then that location is in attainment with the standard. The modeling results show the highest design concentration including background at the boundary of the CJPA is 137 μ g/m 3

.2010 Coso Junction PM10 Maintenance Plan

19 Table 6. Summary of maximum PM10 model predictions in the Coso Junction Planning Area for the period from July 2006 through June 2009. The design concentration is the 4 th highest 24-hour prediction in the three-year simulation at the same location, in this case it is 137 μg/m 3

.

Summary of Maximum PM10 Predictions July 2006 to June 2009

Statistic Period PM10 (μg/m 3 )
Max 24-hour 3q06-2q09 225.5

2 nd 24-hour 3q06-2q09 164.2 3 rd 24-hour 3q06-2q09 150.5 4 th 24-hour 3q06-2q09 136.6

Average 3q06-2q07 20.6
Average 3q07-2q08 21.1 Average 3q08-2q09 21.7 Average 2007 20.4 Average 2008 21.2

As would be expected, the highe st 24-hour PM10 concentration o ccurred at the boundary of the Owens Valley and Coso Junction planning areas near the valley floor and along the west side of the valley. The model showed PM10 concentrations decreasing at distances further from Owens Lake. The added distance to the southern boundary of the Owens Valley Planning Area and associated greater dilution of dust source plum es, produces much lower predictions than for receptors placed along the Owens Lake shoreline. Figure 8 shows that 24-hour average PM10 concentrations for the model design day for Co so Junction (January 5, 2007) decreased at locations further from Owens Lake.

The dust sources on the Owens Lake bed were simulated as ground level area sources located inside the historical shoreline. The CALPUF F modeling system assu mes passive, non-buoyant ground based sources remain ground based as they travel downwind and concentrations within individual dust plumes always decrease with downwind distance. Sta gnation and re-circulation of dust source plumes that might result in pock ets of higher concentrations at fixed downwind receptor locations generally do not occur concurrently with the regional high wind events that are necessary to produce emissions on the lakebed. When only emissi ons from lakebed sources are considered, attainment of the PM10 standard at the northern boundary of the CJPA is sufficient to demonstrate attainment within the entire planning area.2010 Coso Junction PM10 Maintenance Plan

20 400 405 410 415 420 425 430 UTM East-West (km) 3990 3995 4000 4005 4010 4015 4020 4025 4030 4035 4040 4045 4050 4055UTM North-South (km) Keel Lone

Sock

Olan Atow Delt

Flat

Scut Cott Mill

CoJu CoGa Btow

Stan Lizt

39
46

61 116 115 80 116 79 83 86 93 87 83

79 66 67

65 59 57 56 56 47 

### Fi g ure 6. Predicted 4th Hi g hest 24-hour PM10 ( μg /m3) Receptors at Southern Limit of Owens Valley PM10 Planning Area July 2006 to June 2009, Every 4th Prediction Plotted

Hi-4th Highest = 136.6 μg/m3

CoJu 4th Hi = 57.8 μg/m3 Figure 7. The predicted 4 th highest 24-hour PM10 concentration over 3 years for receptors on the northern boundary of the CJPA are shown on the map below. Every 4 th receptor concentration is plotted on the map. The 3-year modeling period is from July 2006 through June 2009.2010 Coso Junction PM10 Maintenance Plan

21 Figure 8. This isopleth map shows model concentrations for the 4 th highest day in the CJPA over the 3-year modeling period (January 5, 2007). Modeled 24-hour average PM10 concentrations are below the federal standard of 150 μg/m 3 at all locations in the CJPA.2010 Coso Junction PM10 Maintenance Plan

22 It should be noted the current analysis used estimates of wi ndblown emissions during July 2006 through June 2009—future emissions will be substantially lower. The model simulations for the attainment demonstration did not account for cont rols currently planned on many of these source areas that will be implemented in the future. If planned controls, such as the 13.3 square miles that will be completed in October 2010 were co nsidered in the modeling analysis, predicted concentrations would be much lower th an suggested by the current simulations.

7 Transportation Conformity

Transportation conformity requirements contained in District Regulation X II require that federal actions and federally funded transportation projec ts conform to SIP rules and that they do not interfere with efforts to attain federal air quality stands. Tr ansportation sources were not found to contribute to the nonattainment problem at Coso Junction and PM10 from paved roads. Estimated at 113 pounds per day, paved road emi ssions comprise less than 10% of the daily PM10 emissions in the CJPA (see Table 4), and less than 1/100 th of a percent of the Owens Lake dust emissions on the design day (1.55 million pounds on January 5, 2007). Due to their benign role in the PM10 problem in the CJPA, transporta tion-related projects such as road construction will be exempt from Transportation Conform ity determination requirements under District Regulation XII.

8 General Conformity

General conformity requirements contained in District Regulation XIII require that federal actions and federally funded projects conform to SIP rules and that they do not interfere with efforts to attain federal air quality standards. A conformity determination is currently required for any federally funded (non-transportation) proj ect or action that takes place in a moderate PM10 nonattainment area, including the CJPA that has the potential to exceed a de minimis PM10 emissions threshold of 100 tons per year. In order to maintain the stringency of control requirements in the CJPA under a maintenance pl an, the District will re tain the 100 tons of PM10 per year de minimis emissions threshold for triggering a conformity determination as currently required under District Regulation XIII.

9 Request to Redesignate Co so Junction to Attainment

Through this document the District demonstrated that, over the 3-year period from January 2007 through December 2009, the Coso Junction area atta ined the federal 24-hour standard for PM10. Daily PM10 monitoring data collected at Coso Ju nction over the last 3 years has not shown more than 1.0 exceedances of the PM10 st andard per year as required to demonstrate attainment of the federal standard. In addition, a dispersion modeling analysis wa s performed for a 3-year period to demonstrate no more than 1.0 exceedances of the PM10 standard could be expected at any location in the Coso Junction Planning Area. The District believes the Coso Junction PM10 Planning Area has attained the federal PM10 sta ndard and requests the California Air Resources Board recommend to the US Environmental Prot ection Agency that the area be redesignated from nonattainment to attainment with the federal PM10 standard.2010 Coso Junction PM10 Maintenance Plan

23 10 Request to Approve Coso Junction PM10 Maintenance Plan

To ensure that compliance with the federal PM10 standard is maintained in future years, the District evaluated future activities that could affect PM10 levels in the planning area and the adequacy of existing rules, polic ies and emission control requiremen ts to control emissions from those sources and activities. Di strict staff found that existing rules for fugitive dust, new source review and General Conformity were adequate to control potential new s ources within the Coso Junction Planning Area.

Emissions from PM10 sources in the CJPA decreased over the last 18 years due to a drop in local population and the closing of one of the permitted facilities. Emission sources in the CJPA are not expected to increase in the future, but it is mo re likely that they will either remain steady or decline. However, if new facilities are constr ucted in the CJPA, District regulations for new source review (Rule 209-A, 216, and 216-A) and federal PSD regulati ons (40 CFR 51.166 and 52.21) will prevent PM10 emissions from new faci lities from causing or contributing to exceedances of the PM10 standard.

The major concern for maintaining PM10 complia nce in the CJPA is for windblown dust from Owens Lake. Since 13.5 square miles of add itional control measures are expected to be implemented at Owens Lake by October 1, 2010, PM 10 air quality is expected to continue to improve in the CJPA as emissions from Owens Lake decline. District st aff believes the control strategy and contingency requirements in the 2008 Owens Valley PM10 SIP are adequate to protect air quality in the Coso Junction area. Therefore, no additional contingency measures will be needed to ensure future compliance with the federal PM10 standard in the CJPA.

Furthermore, as a commitment in the Coso J unction PM10 Maintenance Plan, the District will continue daily monitoring of PM10 at the Coso J unction rest area to help ensure new sources of PM10 are identified and controlled if necessary. If an exceedance of the federal PM10 standard is monitored the District will in vestigate the cause of the exceedance within 60 days from the end of the calendar quarter in which the event o ccurred. Exceedances found to be caused by dust from Owens Lake will be investigated to determine if the required control measures were properly implemented in accordance with Bo ard Order #080128-01. Exceedances found to be caused by dust from local sources that are subj ect to current District regulations will be addressed and corrected. Exceedances found to be caused by Exceptional Events, such as wildfires or earthquakes will be flagged in acco rdance with US EPA policy (Federal Register, 2007).

The District requests that this document be a pproved by the California Air Resources Board as the PM10 Maintenance Plan for the Coso Junc tion Planning Area and submitted to the US Environmental Protection Agency for their consideration and approval.2010 Coso Junction PM10 Maintenance Plan

24 11 References

CARB, 2010a. Comments on CJPA PM10 Emissions Inventory, California Air Resources Board, May 4, 2010.

CARB, 2010b. Emissions Inventory Data, Califor nia Air Resources Board, website accessed February 11, 2010, http://www.arb.ca.gov/ei/emissiondata.htm

. Federal Register, 2002a. Clean Air Act Redesignation and R eclassification, Searles Valley Nonattainment Area; Designation of Coso Junction, Indian Wells Valley, and Trona Nonattainment Areas; California; Determination of Attainment of the PM-10 Standards for the Coso Junction Area Particulate Matter of 10 microns or less (PM-10), Federal Register , August 6, 2002, Vol. 67, no. 151, pp 50805-50808.

Federal Register, 2002b. Clean Air Act Redesi gnation and Reclassification, Searles Valley Nonattainment Area; Correction, Federal Register , September 19, 2002, Vol. 67, no. 182, pp 59005-59006.

Federal Register, 2003a. Approval and Promulga tion of Implementation Plans and Designation of Areas; California – Indian Wells Valley PM-10 Nonattainment Ar ea, Federal Register , May 7, 2003, vol. 68, no. 88, pp. 24368-24370.

Federal Register, 2003b. Correct ion of Areas for Air Quality Planning Purposes; California-- PM-10 Nonattainment Area, Federal Register , June 23, 2003, vol. 68, no. 120, pp. 37090-37091.

Federal Register, 2007. Treatment of Data Influenced by Excep tional Events, Federal Register

, March 22, 2007, vol. 72, no. 55, pp 13560-13581.

GBUAPCD, 1991. Great Basin Unified Air Pollution Control District, PM10 State Implementation Plan for the Searles Valley Planning Area , GBUAPCD, Bishop, California, November 1991.

GBUAPCD, 1998. Great Basin Unified Air Pollution Control District, Owens Valley PM 10 Planning Area Demonstration of Attainment State Implementation Plan , GBUAPCD, Bishop, California, November 16, 1998.

GBUAPCD, 2003. Great Basin Unified Air Pollution Control District, Owens Valley PM 10 Planning Area Demonstration of Attainment State Implementation Plan 2003 Revision , GBUAPCD, Bishop, California, November 13, 2003.

GBUAPCD, 2008. Great Basin Unified Air Pollution Control District, 2008 Owens Valley PM 10 Planning Area Demonstration of Attainment State Implementation Plan , GBUAPCD, Bishop, California, January 28, 2008.

GBUAPCD, 2009a. Great Basin Unified Air Pollution Control District, Ambient Air Monitoring Network Plan , GBUAPCD, Bishop, CA, March 27, 2009.2010 Coso Junction PM10 Maintenance Plan

25 GBUAPCD, 2009b. Great Basin Unified Air Pollution Control District, Findings and Order Granting Regular Variance from Requirements Set Forth in Governing Board Order 080128-0, Docket No. GB09-06, Bishop, California, September 25, 2009.

US Census Bureau, 2010. U.S. Census Bureau, State and County QuickFacts, accessed February 11, 2010, http://quickfacts.census.gov/qfd/states/06/06027.html

. USEPA, 2006. United States Environmental Protection Agency, Compilation of Air Pollution Emission Factors AP-42 (Fifth Edition), USEPA, Research Triangle Park, North Carolina, updated at http://www.epa.gov/ttn/chief/ap42/index.html

. Wilderness Society, 2003. Wilderness Society, Summary of the McNally Fire, California: July 21- August 29, 2002 , Science & Policy Brief , Wilderness Society, Ecology and Economics Research Department, Washington, DC, No. 10, March 2003.2010 Coso Junction PM10 Maintenance Plan

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