3. 30 .2016 Comparing the Emission Inventories for the San Joaquin Valley State Implementation Plans

Emission inventories are one of the fundamental building blocks in the development of a State Implementation Plan (SIP or Plan). Emission inventories provide the basis from
which the State builds an attainment demonstration ; therefore, substantial time and resources are expended to ensure the inventory reflect s the best information available
at the time the SIP is submitted to the U.S. Environmental Protection Agency (U.S.
EPA )

.

Developing and maintaining an accurate and comprehensive emission inve ntory is an iterative process . ARB and local air districts’ staffs continually review the methodologies and technical data behind the emission estimates and perform updates as necessary to reflect better understanding of the emission sources. Therefore, emission inventories submitted with subsequent SIPs are likely to present different estimates for some categories.

In California, responsibility for emission inventory development is split between ARB
and 35 a ir d istricts. The San Joaquin Valley Air Poll ution Control District (Di strict ) has responsibility for all point sources with in their jurisdiction

, some area sources , and
aircraft emissions . ARB has responsibility for the balance of the area sources, all on

road sources, and the balance of off

- road sources.

District s taff work with facility operators to develop point source inventories, which are reported annually to ARB. In most cases, these annual updates reflect actual emission estimates based on facility activity rates, changes in industrial pro cesses, and changes
in the number of operating facilities due to startups or closures. The District and ARB update area source emission estimates periodically, primarily as needed for SIP
revisions

. Methodology updates may include changes in estimation m ethod s , updated emission factors, and/or updated activity data. On

- road and off

- road models are also updated regularly, both as part of SIP development and in support of ARB’s own regulations

.

U.S. EPA regulations require that SIPs include a base year in ventory and forecasted inventories for milestone years. Forecasted inventories are a p rojection of the b ase year inventory that reflects expected growth trends in each sector and emission reductions due to adopted control measures. As with the base year inventory, forecasted inventories represent our best assessment of growth trends at the time. Subsequent inventory forecasts are likely to reflect differences due to changes in the growth trends, estimation methodology refinements and improvements, additi onal control measures, and sometimes corrections to the original base

- year emissions.

The f ollowing is a discussion of the various emission inventories under review by U.S.
EPA:3. 30 .2016 Current Emissions Inventory

The most current emission inventory was submitted to U.S. EPA as part of the San Joaquin Valley 2015 Plan for the 1997 PM2.5 Standard

. This inventory uses 2012 as the base year. The point source emissions reflect actual data reported by the facilities through 2012, and in most instances the fo recasted emissions (2013 and subsequent years) reflect growth assumptions that were reviewed and updated as recently as 2012. Areawide emission estimates reflect updates to several methodologies, and mobile source emissions were generated with updated vers ions of ARB’s o n

- r oad model (EMFAC2014) and various modular updates of the off

- road model. The inventory reflects control measures adopted as of May 201 4

.

2007 PM10 Maintenance Plan Inventory

The 200 7 PM10 Maintenance Plan inventory use d 2002 as the b ase year. The point
and areawide emission forecasts are based on projections of the 2002 inventory that reflect growth forecasts developed in 2001

. Areawide emission estimates are based on methodologies developed i n the late 1990s to early 2000s. Mobile source emission estimates for all the years were generated by EMFAC2007 and OFFROAD 2007
models. The inventory reflects control measures adopted as of June 2006

.

The most significant differences between the 2007 PM10 Plan and the current inventory

are as follows :

• ARB and District Rule updates

– T he current inventory accounts for several
District rules that were not included in the 2007 PM10 Plan. These include
District rules for open burning; boilers, steam generators and process heaters; dryers, dehydrators and ovens; internal combustion engines; confined animal operations; wine fermentation and storage; automotive coatings, and oil production wells. In addition, the current inv entory also reflects ARB rules impacting mobile source emissions (heavy

- duty truck reflash; idling regulation;

on

- road and off

- road Carl Moyer incentives; transportation refrigeration units, portable diesel engines, large spark ignition engine regulation, and ocean going
vessels ) and consumer products.

• Baseline corrections

– T he current inventory reflects baseline corrections to the Manufacturing and Industrial and Food and Agriculture categories tha t result in a reduction of 30 tons per day of NOx emissio ns.

• M anaged b urning and d isposal

-- The emission estimates for agricultural and prescribed burning in the 2007 Plan are based on projections made from the acreage burned in 2002 or earlier. T he current inventory reflect s emissions
based on the 20 12 agric ultural crop acreage burned resulting in a reduction of
9.4 tons of NOx compared to p revious projections. The new estimates also
reflect the reclassification of “Wildfire Use” as a natural source category

, further3. 30 .2016 reducing the emissions of NOx by 0.8 tons

. T he managed burning emissions for
2005 in the 2016 SIP inventory for PM10 are reduced from the PM10 plan inventory reflect ing actual estimates based on the agricultural crop and forest land acreage burned under the District’s Agricultural Burning Program.

• Off

- Road models update

– The current inventory reflects updates to ARB’s off

road source emissions using a newer suite of category

- specific models developed to support recent ARB regulations. These updates include locomotives, ocean

- going vessels, recreational boats, transportation refrigerat ion
units , construction equipment, oil drilling and workover equipment

, cargo handli ng equipment, and farm equipment.

2011 Ozone SIP Revision Inventory

The original 2007 Ozone SIP Plan was built on the same underlying elements (base year, growth assumptions, area source methodologies, mobile source model versions, and control measures) as the 2007 PM10 Maintenance Plan inventory discussed above.
The 2011 Ozone SIP Revision inventory is an update that incorporates corrections to the baseline, emission reductions from ARB and District rules that were not initially included, and adjustments to the on

- road and off

- road emissions due to impacts from
the econom ic recession that started in 2007.

The most significant differences between the 2011 Ozone SIP Revision and the current inventory are due to large decreases in the actual reported emission s for several point source categories ( cogeneration, oil and gas production, food and agriculture, glass manufacturing and composting) , compared to their projected emissions in the earlier plan . Other significant differences include:

• Managed b urning and d isposal

-- The emission estimates for agricultural and prescribe d burning in the 2007 Plan are based projections made from the acreage burned in 2002 or earlier. The current inventory reflects emissions based on the 2012 agricultural crop burned acreage, which has undergone significant reductions since the earlier pla n. The new estimates also reflect the reclassification of “Wildfire Use” as a natural source category.

• Off

- Road models update

– The current inventory reflects updates to ARB’s off

road source emissions using a newer suite of category

- specific models
deve loped to support recent ARB regulations. These updates include locomotives, ocean

- going vessels, recreational boats, transportation refrigeration
units , construction equipment, oil drilling and workover equipment , cargo handling equipment, and farm equipm ent.

• Farming Operations

– The livestock emission estimates for VOC only in the 2011 Ozone SIP Revision inventory was based on California Department of Food and Agriculture livestock population estimates from 2000. The current inventory3. 30 .2016 reflects populatio n estimates from the U.S. Department of Agriculture (USDA)
2012 Census of Agriculture and updated emission factors provided by the
District

. Additionally, the current inventory includes VOC emission estimates for silage, a category that was not inventorie d in the 2011 Ozone SIP Revision

.

2012 PM2.5 Plan Inventory

The 2012 PM2.5 SIP inventory represents the next major inventory update since the
2011 Ozone SIP Revision. In addition to the 2011 Ozone SIP R evision updates, it incorporates several other updates that are also reflected in the current inventory . It
uses 200 7 as the base year, so the point source inventory reflects actual emissions reported by the facilities throu gh that year. The inventory also incorporates a major revision of the growth p rofiles (conducted in 2011

- 2012) to reflect more recent
socioeconomic trends , including the impact of the 2007 recession. Several area source methodologies were updated to reflect recent activity data and /or revised emission
factors. The on

- road emissio n source estimates were generated using EMFAC2011 with activity data provided by the local transportation planning agencies, and the off

road mobile source estimates reflect updates to several categories. The inventory reflects control measures adopted as of June 2011.

Since the 2012 PM2.5 Plan inventory reflects many of the updates included in the current inventory, the differences between them are much smaller. All of the differences in point source emissions can be attributed to year

- to

- year fluctuati ons in source activity. The most significant differences include:

• Managed b urning and d isposal

-- The agricultural burning emissions in the 2012 Plan inventory were forecasted from the 2007 agricultural crop acreage burned under the District’s Agricultur al Burning Program acreage; however, in the current inventory they were estimated from the 2012 actual acreage.

• Off

- Road Models update. For the locomotive and recreational boat emissions categories the 2012 Plan inventory included preliminary adjustments for these two categories based on on

- going model development. The current inventory includes estimates from the final model updates.

• Farming operations

– The livestock emissions in the 2012 Plan inventory were
forecasted from an estimate based on cattle population estimates from the 2007 USDA Census of Agriculture. The current inventory reflects emissions based on livestock population estimates from the 2012 USDA Census

. For PM2.5, the

current inventory shows 2.11 tons decrease in 2017, mainly in two c ategories: Tilling Dust and Feedlot Cattle. For Agricultural Land Preparation and Harvest Operations, ARB updated the emission estimation methodology and the particle

size profile of particulate matter. For Livestock Husbandry, ARB updated the
emission est imation methodology with new cattle population and emission
factors.