CHAPTER 4 - AREA SOURCES EMISSIONS

1996 Emission Inventory for the Alamo Area Council of Governments Region  

 

Area Sources Emissions Chapter Contents

 

Gasoline Distribution

The gasoline distribution network for automobile gasoline in the United States is a complex system of retail and wholesale outlets. Gasoline distribution can include many sources of emissions. In this category, gasoline distribution emissions from vehicle refueling, tank truck unloading, tank breathing losses, tank trucks in transit, and other emissions are calculated. The emissions calculated in this section do not include marine vessel loading, gasoline bulk tanks, loading and unloading of railway tank cars, and pipeline emissions. In the AACOG region, there is no marine vessel loading. Gasoline bulk tanks emissions are included in the point source database.

In order to calculate VOC emissions from gasoline distribution, this section is divided into five sub-categories.

1. Trucks in Transit. These emissions are created by pressure in the truck tank, thermal effects, and leaking delivery trucks. This includes emissions from both loaded and empty trucks in the region.
2. Tank Breathing Losses. Emissions are emitted by the storage of fuel in underground storage tanks at gas stations.
3. Tank Truck Unloading. The transfer of fuel from the tank truck to the service station creates emissions in this category.
4. Vehicle Refueling. The displacement of vapors from the vehicle fuel tank produces emissions. Gasoline temperature, Reid Vapor Pressure (RVP), and dispensing rate affect emissions.
5. Other Losses. This group includes emissions from the spillage of fuel.

In this inventory, emissions from diesel fuels distribution will not be considered because the potential to emit emissions is extremely low (less then 0.01 tons a year).

Methodology

Emissions from Refueling Emissions, Service stations tank truck unloading, tank breathing losses, tank trucks in transit, and other emissions were calculated based on gasoline sales for each county. Gasoline sales tax for each county was obtained from the Texas Comptroller of Public Accounts for the State of Texas. Gasoline sales tax data is only available at the state level. Thus, to calculate the amount of gallons sold in Bexar county the following formula was used. The state gasoline sales tax is 20 cents per gallon, the sales tax is multiplied by 5 to convert it to dollars. In Texas, approximately 1 percent of on-road vehicles are exempt from paying gasoline sales tax. Thus, gasoline sales were increased by one percent to account for these exempt vehicles.

Sample Calculation

Bexar Population *(State Gasoline Sales Tax) * 5 * 1.01 = Gasoline Sales in Bexar
State Population

 1,358,865 *(1,909,335,627.44) * 5 * 1.01 = 684,974,617 Gal. sold in Bexar
19,128,261

The following table lists the population and amount of gasoline sold for every county in the AACOG region.

* Population figures are from the Texas Water Development Board's "Most Likely" scenario

Gasoline Sales per County AACOG region, 1996
County	Population*	Gallons Sold
Atascosa	33,749	17,012,145
Bandera	13,193	6,650,308
Bexar	1,358,865	684,974,617
Comal	68,360	34,458,805
Frio	14,641	7,380,213
Gillespie	19,302	9,729,723
Guadalupe	77,950	39,292,918
Karnes	13,729	6,920,494
Kendall	16113	8,122,217
Kerr	40,488	20,409,130
Medina	30,934	15,593,164
Wilson	25,007	12,605,491
Total	1,712,331	863,149,225

 

After gasoline sales per county were determined, EPA emission factors were used to calculate VOC emissions. Sample calculation for Tank Truck unloading emissions factor per 1000 gallon sold is:

Formula:	LL = 12.46 S P M
	T

Where:	LL =	Loading Loss in lb. Of VOC/1000 gal.
	S  =	Saturation Factor (1)
	P  =	True Vapor Pressure (4.5)
	M  =	Molecular Weight (6.7)
	T  =	Temperature (68° F + 460)
Therefore:	LL =	12.46 * 1 * 4.5 * 67 / (460 + 68)
	=	7.11 lb./1000 gal.

The results of the sample calculation above is entered in the table below as "Tank Truck Unloading", results for similar calculations are in this table. These emission factors are in pounds of VOC emitted per 1000 gallons of fuel handled.

VOC Emission Factors for Loading Loss Gasoline Distribution in AACOG, 1996.

Category	Emission Factor
Vehicle Refueling	11 lb. of VOC/1000 gal.
Tank Trucks in Transit	0.12 lb. of VOC/1000 gal.
Tank Truck Unloading	7.1 lb. of VOC/1000 gal.
Tank Breathing loss	1.0 lb. of VOC/1000 gal.
Other	0.7 lb. of VOC/1000 gal.

The seasonal adjustment factor was 1.039. The seasonal adjustment factor was calculated using Texas comptroller's gasoline sales tax by month for 1996 in Texas.

Average Ozone Monthly Gasoline Sales	= Seasonal Adjustment Factor
Average Monthly Gasoline Sales
826,851,654	= 1.039
795,556,511

The daily resolution of Gasoline Distribution was allocated according to the following table.

Daily Allocation of Gasoline Distribution.

Subcategory	Days per Week
Vehicle Refueling	7
Storage Tank Breathing	7
Trucks in Transit	6
Fuel Delivery to Outlets	6

Sample Calculation

Therefore, the calculation for Tank Truck unloading for Bexar County is:

(Gal. per year)*(lbs. of VOC per 1000 gal.)(Seas. Adj. Factor)	= VOC in TPD
(Activity days per year)*(1000 gal. sold)*(2000 lbs. per ton)

(684,974,617 * 7.11 * 1.039) / ( 312 * 1000 * 2000) = 8.11 Tons/Ozone Season Day

 

Spatial Allocation

Emissions were allocated based on the locations of gas stations in the 1995 Texas Workforce commission employment file. After careful examination, it was noticed that some of the gas station's employment and location were missing in the file. In other cases, total employment for a gas station chain was allocated to the head office. In these cases, the missing gas stations had to be geo-coded into the employment file. The total number of gas stations in Bexar, 232, where then allocated to the 4 km. air quality grid cells. Afterwards, the refueling emissions were applied based on the number of gasoline stations in each grid cell. Then the figures for tank truck unloading, trucks in transit, tank breathing losses, and other emissions were allocated to the 4 km. grids based on the location of gas stations. The same process was conducted in the other 11 counties of the AACOG region.

Notes:

U.S. Environmental Protection Agency, 1991. Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone. Volume 1. Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.

"Gasoline Marketing (Stage I and Stage II)", Emission Inventory Improvement Program, (Volume III, Chapter 11). TRC Environmental Corporation.

Office of the Comptroller of Texas, April. 1999. Texas Comptroller of Public Accounts Revenue Estimation. Austin, Texas.

 

Oil and Gas Well Production

The emissions inventory of the oil and gas producing industry begins at the wellhead. It includes the gathering, transmission and refining operations, and ends with the tank farms or wholesale storage operation.

The most accurate wellhead data would be from the Texas Railroad Commission's API Well Data File and the Well Status Report File. The Well Data File would site each individual well by latitude and longitude coordinates and assigns a specific well identification number. The Well Status Report would specify the daily production from each well (barrels for oil and MCF for gas wells) and enable the placement of production activity directly into the proper grid squares. There are now emission factors based upon equipment components (valves, connections, tanks, etc.) and a composite equipment structure of a representative well from each field could be modeled and the emissions from each well determined whether the well was in or out of production. These data files were not available for this inventory so a cruder methodology was employed.

Methodology

The Texas Natural Resources Conservation Commission (TNRCC) provided a paper copy of the Texas Railroad Commission's Oil Well Counts By County Report as of February 1997 which was used as the basis for determining the number of wells and their oil and gas production in 1996. These counts were multiplied by the emissions factors of 396 lbs. of VOC per operating oil well, and 35 lbs. of VOC per million cubic feet of gas produced by each operating gas well. Tanks located at the oil and gas well sites are calculated in the Leaking underground storage tanks (LUST) and above ground storage tank (AST) sections of the emissions inventory.

Sample Calculations

Atascosa County:

(1834 Producing oil wells)	*	(EPA Emission factor 396 lbs./well/year) / 2000	=	363.132 tons/year VOC emissions
(19,294,397 MCF gas produced/100000)	*	(EPA Emission Factor 35 lbs./ year) / 2000	=	3.377 tons/year VOC emissions

Seasonal Adjustment Factor = 1
Weekly adjustment Factor = 7 day week

Notes:

Texas Railroad Commission through the Texas Natural Resources Conservation Commission

Texas Natural Resources Conservation Commission

 

Small Stationary Source Fossil Fuel Use

Fuel Oil Consumption

This subcategory consists, in turn, of five subheadings that further define the groups consuming fuel oil products. These are Residential Distillate Consumption, Commercial/Institutional Distillate Consumption, Commercial/Institutional Residual Consumption, Industrial Distillate Consumption, and Industrial Distillate Consumption.

A. Residential Distillate Consumption

In the state of Texas, only distillate oil is consumed in residences and the quantity consumed is low. It is low for at least two reasons: the most important reason is that Texas is a major natural gas producer so natural gas is the fuel most often used for residential heating. Secondly, for the most part, winters are not severe in Texas and regardless of the type of fuel used, consumption is low as a consequence. The 1996 residential consumption of distillate fuel in Texas was less than 21,000 gallons (EIA, 1999). In addition, previous work done by Texas Air Control Board (TACB) indicates that the pollutant emissions of VOC, CO and NOx in this category are insignificant (Texas Air Control Board, 1992). Therefore, emissions were not calculated because of insignificant fuel usage.

B. Commercial Distillate Consumption

1. Introduction
   The total amount of distillate fuel oil consumed by commercial operations in Texas in 1996 is estimated to be 98,784,000 gallons (EIA, 1999).
2. Methodology
   It is first assumed that the commercial consumption of distillate fuel oil in each county is proportionate to the statewide consumption in the same manner as total county employment in the consuming industry to the industry's statewide employment. The SIC code of the commercial industry consuming distillate fuel oils is from SIC codes 50 to 87, and 89. Therefore, statewide commercial consumption of distillate fuel oil is divided by the statewide employment in the SIC codes industry and multiplied by the industry's employment in county to come up with the county's commercial consumption of distillate fuel oil. Numbers of employees by SIC code per county are available from the Texas Workforce Commission. The distillate fuel oil consumption is then multiplied by the emission factors of individual pollutant (VOC = 0.34 lb./1000 gal; CO = 5 lb./1000 gal; NOx = 20 lb./1000 gal) (EPA, 1999). The number of pounds is converted to tons per year by dividing by 2000. The tons per year are then seasonally adjusted to tons per day by multiplying a seasonal adjustment factor and divided by the annual activity day. The seasonal adjustment factor for VOC is 0.6 and its annual activity day is 312 (Assuming its weekly activity days is 6 so the annual activity day is 6 days * 52 weeks = 312 days per year). The seasonal adjustment factor for CO is 1.4 and its annual activity day is 312. The seasonal adjustment factor for NOx is uniform (1) and its annual activity day is 365 (Texas Air Control Board, 1992).
3. Sample Calculation
   Bexar County has 385,858 employees in commercial SIC code 50-87 and 89. The statewide employment in these SIC codes is 4,856,183 (U.S. Census Bureau, 1999a). The distillate fuel oil consumed for commercial use in Texas in 1996 is 98,784,000 gallons. In the following calculation, "O" is statewide consumption, "E" is statewide commercial employment; "e" is countywide commercial employment for Bexar County, and "o" is countywide consumption for Bexar County:

o = O * e / E = 98,784,000 * 385,858 / 4,856,183 =

7,849,085 (gal. of fuel oil consumed in Bexar Co., 1996)

VOC:	7,849,085 * 0.34 / 1000	= 2,668.689 (lbs. VOC/year)
	2,668.689 / 2000	= 1.33434 (ton/year)

Seasonally and weekly adjusted: 1.33434 * 0.6 / 312 =

0.00257 (ton/average ozone season day)

CO:	7,849,085 * 5 / 1000	= 39,245.43 (lbs.)
	39,245.43 / 2000	= 19.62271 (ton/year)

Seasonally and weekly adjusted: 19.62271 * 1.4 / 312 =

0.08805 (ton/day)

NOx:	7,849,085 * 20 / 1000	= 156,981.7 (lbs.)
	156,981.7 / 2000	= 78.49086 (ton/year)

Seasonally and weekly adjusted: 78.49086 / 365 =

0.21504 (ton/day)

 

C. Commercial Residual Consumption

Use of residual quality fuel by commercial operations in Texas is even smaller in numbers of barrels than is use of distillate. EIA (1999) estimates indicate that no commercial residual fuel oil was used statewide in 1996. Therefore, emissions were not calculated because of insignificant fuel usage.

D. Industrial Distillate Consumption

This was reported as point source emissions only. No emissions were calculated for area sources.

E. Industrial Residual Consumption

This was reported as point source emissions only. No emissions were calculated for area sources.

Coal Consumption

A. Residential Coal Consumption

No reported usage of coal for home heating in Texas (EIA, 1999). No emissions are calculated for area sources.

B. Commercial Coal Consumption

No reported commercial usage of coal in Texas (EIA, 1999). No emissions are calculated for area sources.

C. Industrial Coal Consumption

This was reported as point source emissions only. No emissions were calculated for area sources.

Natural Gas Consumption

A. Residential Natural Gas Consumption

1. Introduction
   There were 229 billion cubic feet of natural gas consumed in Texas during 1996 by residential users (EIA, 1999).

2. Methodology
   Assuming that the ratio of households using gas in a county to households using gas in the state stays the same from 1990 to 1996, the statewide natural gas usage in 1996 was multiplied by the ratio to yield the amount of natural gas usage for each county. The data of housing units using natural gas is available from the 1990 U.S. National Census. The amount of the natural gas usage for each county was multiplied by an emission factor (VOC = 5.5 lb./million cubic feet; CO = 40 lb./million cubic feet; NOx = 94 lb./million cubic feet) (EPA, 1999). Then the emission amount by pounds was converted to tons per year by dividing by 2000. Finally, the seasonal adjustment factor was applied to yield the emission amount of tons per day. The seasonal adjustment factor for VOC is 0.3 and its annual activity day is 365. The seasonal adjustment factor for CO is 1.7 and its annual activity day is 365. The seasonal adjustment factor for NOx is uniform (1) and its annual activity day is 365 (Texas Air Control Board, 1992).

3. Sample Calculation
   Atascosa County has 3181 housing units using natural gas and Texas has 3,059,752 housing units using natural gas in 1990 (U.S. Census Bureau, 1995). The statewide consumption of natural gas in 1996 by residential users is 229 billion cubic feet. If "G" is statewide consumption, "H" is statewide housing units using natural gas; "h" is countywide housing units using natural gas, and "g" is countywide consumption, then:

g = G * h / H = 22,900,000,000 * 3,181 / 3,059,752 = 23,805,956 (cubic feet)

VOC:	23,805,956 * 5.5 / 1,000,000	= 130.933 (lbs.)
	130.933 / 2000	= 0.06547 (ton/year)

Seasonally adjusted: 0.06547 * 0.3 / 365 =

0.00005 (ton/day)

CO:	23,805,956 * 40 / 1000000	= 952.238 (lbs.)
	952.238 / 2000	= 0.47612 (ton/year)

Seasonally adjusted: 0.47612 * 1.7 / 365 = 0.00222 (ton/day)

NOx:	23,805,956 * 94 / 1000000	= 2,237.76 (lbs.)
	2,237.76 / 2000	= 1.11888 (tons/year)

Seasonally adjusted: 1.11888 / 365 = 0.00307 (tons/day)

 

B. Commercial Natural Gas Consumption

1. Introduction
   Statewide consumption of natural gas by commercial establishments in Texas in 1996 was estimated by EIA at 179 billion cubic feet (1999).

2. Methodology
   The statewide consumption is to be allocated to each county based on the number of employees in the commercial SIC codes (50-87 and 89). The statewide number of employees in these SIC codes was 4,856,183 in 1996 (U.S. Census Bureau, 1999a). The amount of gas was multiplied by the county number of commercial employees and divided by the state number of commercial employees to yield the county's consumption of natural gas. This figure was then multiplied by an emission factor (VOC = 5.5 lb./million cubic feet; CO = 84 lb./million cubic feet; NOx = 100 lb./million cubic feet) (EPA, 1999). The emission amount by pounds was converted to tons per year by dividing by 2000. Finally, the seasonal adjustment factor was applied to yield the emission amount of tons per day. The seasonal adjustment factor for VOC is 0.6 and its annual activity day is 312. The seasonal adjustment factor for CO is 1.4 and its annual activity day is 312. The seasonal adjustment factor for NOx is uniform (1) and its annual activity day is 365 (Texas Air Control Board, 1992).

3. Sample Calculation
   Bandera County has 1,138 employees in commercial SIC code 50-87 and 89. The statewide employment in these SIC code is 4,856,183 (U.S. Census Bureau, 1999a). The natural gas consumed for commercial use in Texas in 1996 is 179 billion cubic feet. If "G" is statewide consumption, "E" is statewide commercial employment; "e" is countywide commercial employment, and "g" is countywide consumption, then:

   g = G * e / E = 17,900,000,000 * 1,138 / 4,856,183 = 4,194,694 (cubic feet)

   VOC:	4194694 * 5.5 / 1000000	= 23.07082 (lbs.)
   	23.07082 / 2000	= 0.01156 (ton/year)

   Seasonally adjusted: 0.01156 * 0.6 / 312 = 0.00002 (ton/day)

   CO:	4194694 * 84 / 1000000	= 352.354 (lbs.)
   	352.354 / 2000	= 0.17618 (ton/year)

   Seasonally adjusted: 0.17618 *1.4 / 312 = 0.00079 (ton/day)

   NOx:	4194694 * 100 / 1000000	= 419.469 (lbs.)
   	419.469 / 2000	= 0.20974 (tons/year)

   Seasonally adjusted: 0.20974 / 365 = 0.00056 (tons/day)

    

   C. Industrial Natural Gas Consumption

   This was reported as point source emissions only. No emissions were calculated for area sources.

    

   Liquid Petroleum Gas Consumption

   A. Residential LPG Consumption

   1. Introduction
      The statewide consumption of liquid petroleum gas (LPG) by residential uses in 1996 was estimated by EIA at 97,104,000 gallons (1999).

   2. Methodology
      Assuming that the ratio of households using LPG in a county to households using LPG in the state stays the same from 1990 to 1996, the statewide LPG usage in 1996 was multiplied by the ratio to yield the amount of LPG usage for each county. The data of housing units using LPG is available from 1990 census.

      The amount of LPG usage for each county was multiplied by an emission factor (VOC = 0.4 lb./1000 gal; CO = 2.1 lb./1000 gal; NOx = 15 lb./1000 gal) (EPA, 1999). (The higher factors for butane were used since no information is available as to whether the LPG is butane, propane, or a mixture of both.) Then the emission amount by gallons was converted to tons per year by dividing by 2000. Finally, the seasonal adjustment factor was applied to yield the emission amount of tons per day. The seasonal adjustment factor for VOC is 0.3 and its annual activity day is 365. The seasonal adjustment factor for CO is 1.7 and its annual activity day is 365. The seasonal adjustment factor for CO is uniform (1) and its annual activity day is 365 (Texas Air Control Board, 1992).

   3. Sample Calculation
      Atascosa County has 2,972 housing units using LPG and Texas has 473,533 housing units using LPG in 1990 (U.S. Census Bureau, 1995). The statewide consumption of natural gas in 1996 by residential users is 97,104,000 gallons. If "P" is statewide consumption, "H" is statewide housing units using LPG; "h" is countywide housing units using natural gas, and "p" is countywide consumption:

   p = P * h / H = 97,104,000 * 2,972 / 473,533 = 609,458.9 (gallons)

   VOC:	6,094,58.9 * 0.4 / 1000	= 243.7836 (lbs.)
   	243.7836 / 2000	= 0.12189 (ton/year)

   Seasonally adjusted: 0.12189 * 0.3 / 365 = 0.00010 (ton/day)

   CO:	609,458.9 * 2.1 / 1000	= 1,279.864 (lbs.)
   	1,279.864 / 2000	= 0.63993 (ton/year)

   Seasonally adjusted: 0.63993 * 1.7 / 365 = 0.00298 (ton/day)

   NOx:	609,458.9 * 15 / 1000	= 9,141.884 (lbs.)
   	9,141.884 / 2000	= 4.57094 (tons/year)

   Seasonally adjusted: 4.57094 / 365 = 0.01252 (tons/day)

    

   B. Commercial LPG Consumption

   1. Introduction
      Statewide consumption of LPG by commercial establishments in Texas in 1996 was estimated by EIA at 1,7136,000 gallons (1999).

   2. Methodology
      The statewide consumption is to be allocated to each county based on the number of employees in the commercial SIC codes (50-87 and 89). The amount of LPG was multiplied by the county number of commercial employees and divided by the state number of commercial employees to yield the county's consumption of LPG. This figure was then multiplied by an emission factor (VOC = 0.4 lb./1000 gal; CO = 2.1 lb./1000 gal; NOx = 15 lb./1000 gal) (EPA, 1999). The emission amount by pounds was converted to tons per year by dividing by 2000. Finally, the seasonal adjustment factor is applied to yield the emission amount of tons per day. The seasonal adjustment factor for VOC is 0.6 and its annual activity day is 312. The seasonal adjustment factor for CO is 1.4 and its annual activity day is 312. The seasonal adjustment factor for NOx is uniform (1) and its annual activity day is 365 (Texas Air Control Board, 1992).

   3. Sample Calculation
      Bandera County has 1,138 employees in commercial SIC code 50-87 and 89. The statewide number of employees in these SIC codes was 4,856,183 in 1996 (U.S. Census Bureau, 1999a). The LPG consumed for commercial use in Texas in 1996 is 17,136,000 gallons. If "P" is statewide consumption, "E" is statewide commercial employment; "e" is countywide commercial employment, and "p" is countywide consumption:

   p = P * e / E = 17,136,000 * 1138 / 4856183 = 4,015.66 (gallons)

   VOC:	4,015.66 * 0.4 / 1000	= 1.6063 (lbs.)
   	1.6063 / 2000	= 0.000803 (ton/year)

   Seasonally adjusted: 0.000803 * 0.6 / 312 = 0.000002 (ton/day)

   CO:	4,015.66 * 2.1 / 1000	= 8.43288(lbs.)
   	8.43288 / 2000	= 0.004216 (ton/year)

   Seasonally adjusted: 0.004216 *1.4 / 312 = 0.000019 (ton/day)

   NOx:	4,015.66 * 15 / 1000	= 60.23486 (lbs.)
   	60.23486 / 2000	= 0.030117 (tons/year)

   Seasonally adjusted: 0.030117 / 365 = 0.000083 (tons/day)

    

   C. Industrial LPG Consumption

   1. Introduction
      The statewide consumption of LPG for industrial uses in 1996 was 16,898,448,000 gallons (EIA, 1999).

   2. Methodology
      The statewide consumption of LPG is to be allocated to each county based on the number of employees in the industrial SIC codes 1-39. The statewide number of employees in these SIC codes was 1,582,890 in 1996. The amount of LPG was multiplied by the county number of industrial employees and divided by the state number of industrial employees to yield the county's consumption of LPG. This figure was then multiplied by an emission factor (VOC = 0.4 lb./1000 gal; CO = 3.6 lb./1000 gal; NOx = 21 lb./1000 gal) (EPA, 1999). The emission amount by pounds was converted to tons per year by dividing by 2000. Finally, the seasonal adjustment factor is applied to yield the emission amount of tons per day. The seasonal adjustment factor for VOC is 1 and its annual activity day is 312. The seasonal adjustment factor for CO is 1 and its annual activity day is 312. The seasonal adjustment factor for NOx is 1 and its annual activity day is 365 (Texas Air Control Board, 1992).

   3. Sample Calculation
      Bexar County has 76,717 employees in industries of SIC codes 1-39. The statewide employment in industries of SIC codes 1-39 is 1,582,890 (U.S. Census Bureau, 1999a). LPG consumed statewide for industries of SIC code 1-39 is 16,898,448,000 gallons. If "P" is statewide consumption, "E" is statewide commercial employment; "e" is countywide commercial employment, and "p" is countywide consumption:

   p = P * e / E = 16,898,448,000 * (76,717 / 1,582,890) = 4,329,699 (gallons)

   VOC:	4,329,699 * 0.4 / 1000	= 1,731.879 (lbs.)
   	1,731.879 / 2000	= 0.86594 (ton/year)

   Seasonally adjusted: 0.86594 / 312 = 0.00278 (ton/day)

   CO:	4,329,699 * 3.6 / 1000	= 15,586.91 (lbs.)
   	15,586.91 / 2000	= 7.79346 (ton/year)

   Seasonally adjusted: 7.79346 / 312 = 0.02498 (ton/day)

   NOx:	4,329,699 * 21 / 1000	= 90,923.67 (lbs.)
   	90,923.67 / 2000	= 45.46183 (ton/year)

   Seasonally adjusted: 45.46183 / 365 = 0.12455 (ton/day)

    

   Wood Consumption

   A. Residential Wood Consumption

   1. Introduction and Methodology
      The residential consumption of wood is calculated according to the following equation (EPA, 1991):

      Residential wood use (ton/year) = 0.0017 / 5.0 * NHUHW * HDG * ARPH
      Where NHUHW = number of housing units heating with wood
      HDG = heating degree days
      ARPH = average room per housing unit

      Residential wood use was multiplied by an emission factor (VOC = 53 lb./ton; CO = 230 lb./ton; NOx = 2.8 lb./ton) (EPA, 1999). The number of pounds was converted to tons per day by dividing by 2000. Then seasonal adjustment was applied. The seasonal adjustment factor for VOC is 0.3 and its annual activity day is 365. The seasonal adjustment factor for CO is 1.7 and its annual activity day is 365. The seasonal adjustment factor for CO is uniform (1) and its annual activity day is 365 (Texas Air Control Board, 1992).

   2. Sample Calculation
      Bexar County has 379 households using wood for home heating (U.S. Census Bureau, 1995), and the county is in a region where there are 1572 heating degree days a year (NOAA, 1999). The average number of rooms per housing unit in the area is five.

   Residential wood use = 0.0017 * 379 * 1572 * 5 / 5 = 2,926.278 (tons)

   VOC:	2,926.278 * 53	= 155,092.73 (lbs.)
   	155,092.73 / 2000	= 77.54637 (ton/year)

   Seasonally adjusted: 77.54637 * 0.3 / 365 = 0.06374 (ton/day)

   CO:	2,926.278 * 230	= 673,043.9 (lbs.)
   	673,043.9 / 2000	= 336.5220 (ton/year)

   Seasonally adjusted: 336.5220 * 1.7 / 365 = 1.56736 (ton/day)

   NOx:	2,926.278 * 2.8	= 8,193.578 (lbs.)
   	8,193.578 / 2000	= 4.09679 (ton/year)

   Seasonally adjusted: 4.09679 / 365 = 0.01122 (ton/day)

    

   Notes:

   Energy Information Administration (EIA), 1999. "State Energy Profiles". [online]. Available: http://www.eia.doe.gov/emeu/sep/map.html [1999, Oct. 1].

   National Oceanographic and Atmospheric Administration (NOAA), 1999. "Annual Climatological Summary". [online]. Available: http://www.ncdc.noaa.gov/ol/documentlibrary/hcs/hcs.html, http://waffle.nal.usda.gov/agdb/okcdc.html [1999, Oct. 2].

   Texas Air Control Board, 1992. 1990 Base Year Ozone Emission Inventory of Volatile Organic Compound (VOC), Nitrogen Oxides (NOx) and Carbon Monoxide (CO) Emissions for Dallas/ Fort Worth, Texas Nonattainment Area. Austin, Texas.

   U.S. Census Bureau, 1995. 1990 Census Lookup. [online]. Available: http://venus.census.gov/cdrom/lookup [1999, Oct. 1].

   U.S. Census Bureau, 1999a. County Business Patterns. [online]. Available: http://tier2.census.gov/cbp/cbp_sts.htm [1999, Oct. 1].

   U.S. Census Bureau, 1999b. County Population Estimates. [online]. Available: http://www.census.gov/population/www/estimates/countypop.html [1999, Oct. 1].

   U.S. Environmental protection Agency (EPA), 1991. Procedures for the preparation of Emission Inventories for Carbon Monoxide and precursors of Ozone, Volume I. (National Technical Information Service), Springfield, Virgina.

   U.S. Environmental protection Agency (EPA), 1999. Compilation of Air Pollutant Emission Factors AP-42, Fifth Edition, Volume I: Stationary Point and Area Sources. [online]. Available: http://www.epa.gov/ttn/chief/ap42.html [1999, Oct. 1].

    

   Breweries

   Breweries are emitters of VOC's (including ethanol, acetate, myrcene, etc.) due to the various steps utilized in the manufacturing of beer.

   Methodology

   Emission factors are based on brewery size (i.e. "large" >60,000 barrels per year, "small and micro" <60,000 barrels per year). This factor will be multiplied by the production level of the breweries (in barrels) to obtain the pounds of VOC emitted per year. This figure will be converted to tons per year and tons per day. The number of days the facility was in production was determined for each facility from the survey data. Then a sum is taken for the county. When production figures were not accessible, best estimates were used. This was the case for a few of the microbreweries or brewpubs within the region. In such instances, production was estimated to be equal to that of establishments of similar size.

   Sample Calculation:

   The production level of a microbrewery is 1200 barrels per year with an emission factor of 56.8 lbs./1000 barrels (.0568 lbs. per barrel). Activity was two days per week, or 104 days per year.

   .0568 lbs./barrel * 1200 barrels/year = 68.16 lbs. VOC/year
   68.16 lbs./yr * 1 ton/2000 lbs. = 0.0341 tons VOC/year
   0.0341 tons VOC/year * 1 year/ 104 activity days = 0.000164 tons VOC/ day

   Only microbreweries were found outside of Bexar County, these however would not respond to the survey. They are very small operations and are assumed to emit less than .01 tons per day of VOC.

   Notes:

   Radian Corporation, February 1992. VOC Emissions from Breweries. Research Triangle Park, North Carolina.

    

   Wineries

   Emissions from wineries are a consequence of the biological process of fermentation of grapes, the filtration process which removes grape solids from grape juice, and the fugitive emissions from the wine bottling process. The primary emission resulting from this process is ethanol. The wineries within the AACOG Region are located in rural areas and, since they are not large establishments, do not report as point sources.

   Methodology

   Emissions factors for red and white wines are different. The production of white wine has an emission factor of 1.76 lbs. /1000 gallons produced, whereas red wine has an emission factor of 5.52 lbs./1000 gallons produced. To determine emissions, the number of gallons produced was multiplied by the emission factor of each wine and converted to tons. In addition, a seasonal adjustment was made in order to compensate for the fact that approximately 95 % of the wine is produced in the months of August and September. This estimate was made by the Texas Wine Research Marketing Institute and will be used to adjust figures in the following manner:

   0.95/2 months * 12 months = 5.7 (Seasonal Adjustment Factor).
   Activity days are assumed to be 7 days a week.

   Sample Calculation:

   If the production of one winery in a Texas county is 15,498 gallons, divided equally between red and white wines, the emissions will be as follows.

   15,498/2 = 7,749 gallons each for red and white wine annually
   7,749 gallons/ yr. * 1.76 lbs./1000 gallons for white wine = 13.682 lbs./yr.
   Converting to tons: 13.682 / 2000 = 0.0068 tons VOC /yr. from white wines
   Seasonally adjusted: .0068 * 5.7/ 365= .0001 tons/day for white wine production

   7,749 gallons/yr. * 5.52 lbs./1000 gallons for red wine = 42.77 lbs./yr.
   Converting to tons: 42.77/2000 = 0.0214 tons VOC/ yr. from red wines
   Seasonally adjusted: .0214 * 5.7/ 365= .0003 tons/day from red wine production

   Within the AACOG Region, only Gillespie and Kendall counties have emissions from wineries.

   Notes:

   Texas Wine Research Marketing Institute, Texas Wine & Wine Grape Industry Fact Sheet. Texas Tech University, Lubbock, Texas.

   U.S. Environmental Protection Agency, May 1991. "Stationary Point and Area Sources", Compilation of Air Pollutant Emission Factors AP-42, Fifth Edition, Volume I: Research Triangle Park, North Carolina.

    

   Bakeries

   The primary VOC emitted from bakeries is ethanol, which is formed by the fermentation of yeast. Although it is a natural, biological process some commercial bakeries may exceed 100 tons per year in emissions. As is typical with biological processes, emissions are dependent on a number of variables, such as the length of rising time for the yeast, the amount of fermentable sugars in the dough and the temperature of fermentation.

   Methodology

   Most bakeries use sponge-dough. So the emission factor used will be taken from this category. The businesses using yeast products were identified for each county using SIC codes 2051 and 5461 and the number of employees recorded. All bakeries with more than 50 employees were removed from the list. According to the Radian memo, bakeries with more than 50 employees should be treated as point sources and are not included in the area source emissions. The remaining employees in each county are multiplied by a per employee emission factor of 0.11 tons of VOC. The seasonal adjustment is 1. Bakeries operate 7 days a week, so to calculate tons per day the tons per year is divided by 365.

   Sample Calculation:

   (Bakery employees/county) * (per employee emissions factor) = tons VOC/year

   Comal County
   46 employees * 0.11 tons VOC = 5.06 tons of VOC per year
   5.06 tons per year / 365 = 0.013863 tons per day

   Notes:

   Texas Workforce Commission, 1995. Austin, Texas

   Adams, Lucy, April 24, 1992. VOC Emissions from Bakeries. Radian Corporation, Research Triangle Park, North Carolina.

    

   Consumer & Commercial Solvents

   This section involves all non-industrial solvents that are used in commercial or consumer applications. The solvent-containing products in this category include personal care products, household products, automotive aftermarket products, adhesives and sealants, household pesticides, coatings, and other miscellaneous commercial or consumer products that may emit VOCs. The primary solvents used in the formulation of these products are generally ethanol and isopropanol.

   Personal care products include hair products, deodorants and antiperspirants, perfumes, colognes, and nail care products. Household products primarily consist of cleaning products for hard surfaces, clothing, carpet, dishes, waxes, polishes, air fresheners, and charcoal fluids. As a side note, this subdivision of commercial and consumer products may also contain propane, butane, and isobutane. Automotive consumer products are divided into two categories: (1) detailing products, and (2) maintenance and repair products. Detailing products include those used for cleaning, polishing, and waxing. Maintenance and repair products include engine and parts cleaners, carburetor/fuel injection cleaners, lubricants, antifreeze, radiator cleaners, and brake fluids. Adhesives include cements, glues, and pastes. Pesticides include substances or mixtures that are used to prevent, destroy, repel, or mitigate pests and, finally, the coatings portion of this product group includes aerosol spray paints and related products such as paint removers.

   Solvents contained in these types of products are primarily released during product use. However, residual amounts of solvent may also remain in discarded product packaging, enter the municipal solid waste streams, and be disposed of in landfills. The VOC emission factors presented in this inventory section have been adjusted to account for biodegradation of VOCs that enter the wastewater stream, but not those that enter landfills. Landfill emissions are covered in the landfill emissions section of the Emissions Inventory.

   Methodology

   The methodology employed to calculate emissions from consumer and commercial products uses per capita emission factors for the product categories of interest. Multiply per capita emission factors by population data for the base year of interest to obtain total VOC emissions for that year. The following example demonstrates this method.

   Sample Calculation:

   The equation to estimate VOC emissions from all consumer and commercial products is:

   Population * Per Capita Emission Factor = Emissions
   If the population of the Bexar County is 1,358,865 persons, the VOC emissions from all commercial and consumer products are:
   1,358,865 persons * 7.84 lb. VOCs/person/yr. = 10653501.6 lb. VOC/yr.
   Divide that number by 2000 to convert to tons/yr.
   (10653501.6 lb. VOC/year)/2000 = 5326.75 tons VOCs/yr.

   Consumer and commercial product use is not influenced by the seasons. The use of consumer and commercial products is generally assumed to occur 7 days a week throughout the year. Thus, the annual emissions estimate is divided by 365 in order to calculate a daily emission estimate.

   Notes:

   Environmental Protection Agency (EPA), August 1996. Emissions Inventory Improvement Program/Area Sources Committee Volume III: Chapter 5. Research Triangle Park, North Carolina.

   Texas Water Development Board, 1998. Population Projections 1990-2050: Most Likely Scenario. Austin, Texas.

    

   Surface Coating

   The surface coating industry contains many different types of coatings, which include paints, varnishes, printing inks, polishes, sealers, etc. Typically, coatings provide protection or decoration to a substrate or surface. In a typical coating sequence, three coatings are used: a primer, an intermediate coat, and a topcoat. The majority of emissions that are produced during surface coatings are due to evaporation of the solvents contained in the coatings. The most commonly used solvents include organic compounds such as ketones, esters, aromatics, and alcohols. Other constituents of surface coatings, such as metals and particulates, may also be emitted during coating operations.

   Methodology

   Per employee emissions factors were used in calculating the emissions for the categories listed below. The EPA’s Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone, Volume I ¹ was used to acquire the emission factors and the activity days per week, which is five days, for each category. The Texas Work Force Commission ² provided data on the number of employees by SIC codes for each of the following categories. Three of the categories SIC codes below were not available, thus the per capita emission factors were utilized. County populations were provided by Texas State Data Center ³. The point source emissions were subtracted from the area source categories to prevent any overlapping.

   SIC Codes and Emission Factors for Surface Coating Operations.

   Category	SIC Code(s)	Lbs./Yr. Per Employee	Lbs./Yr. Per Capita
   Furniture and Fixtures	25	944	2
   Metal Containers	341	6,029	1.3
   Automobiles	3711	794	1.1
   Machinery & Equipment	35	77	0.7
   Appliances	363	463	0.2
   Other Trans. Equip.	37, except 3711 & 373	35	0.2
   Sheet, Strip, & Coil	3479	2,877	.05
   Factory Finished Wood	2426-9, 243-245, 2492, 2499	131	0.3
   Electrical Insulation	3357, 3612	290	0.1
   Other Product Coatings	N/A	N/A	0.6
   High-Performance Maintenance	N/A	N/A	0.8
   Marine Coatings	373	308	0.2
   Other Spec. Purpose Coatings	N/A	N/A	0.8

   Sample Calculation:

   Comal County (FIPS 48091) employment in SIC code 363 = 131 employees

   Appliances emission factor = 463 lb. VOC per employee

   131 * 463 lb. VOC per person = 60,653 lbs. VOC

   60,653 / 2,000 = 30.327 tons / year VOC

   30.327 / 260 = .11664 tons / day VOC

   Activity Days = 260

   The seasonal adjustment factor was uniform and activity days were 5 days a week.

   Notes:

   1. U.S. Environmental Protection Agency, May 1991. Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone, Volume I. (Office of Air Quality Planning and Standards), Research Triangle Park, North Carolina, p. 4-22 – 4-25.

   2. Texas Workforce Commission, 3rd quarter 1998. Texas Workforce Commission Employer Location File. Austin, Texas.

   3. Texas State Data Center Texas A&M University, July 1996. Texas State Data Center Population Estimates Program. College Station, Texas.

    

   Dry Cleaners

   Volatile Organic Compounds emitted from dry cleaners are from the solvents used in the dry cleaning process. VOC's may be emitted in the dry cleaning process or during solvent reclamation processes. Petroleum solvents most commonly used in the dry cleaning process are Stoddard solvent (mineral spirits) and 140-F. Synthetic solvents used in the dry cleaning process include PERC (Percholoroethane), TCA (Trichloroethane), and CFC-113 (Chloroflorocarbons).

   Methodology

   Following are the steps used in deriving the data for dry cleaners.

   1. Separated 1996 dry cleaners into coin-operated dry cleaners and commercial dry cleaners. Coin-operated dry cleaning units are self-service machines that are found in Laundromats, while commercial dry cleaners provide numerous drop-off/pick-up outlet stores that are serviced by a single dry cleaning plant. Commercial dry cleaners are responsible for the greatest amount of emissions.
   2. A survey was mailed to all commercial dry cleaners in the inventory area that asked: solvent types used; amount of each type of solvent purchased for inventory year; listing of equipment types at the facility; controls in place at the facility; operating days per hour that the machines were in use; number of machines in use; and facility employment for the inventory area.
   3. Seven out of 114 surveys were returned over a two-week period. A staff member then called the remaining 107 commercial dry cleaners, and 31 commercial dry cleaners responded. Phone interviews were then conducted asking the same questions as the survey. The staff decided to take the mean for the number of employees, amount of solvent used, hours of operation the machines were in use, the number of machines, and type of solvent for the remaining commercial dry cleaners in the inventory area using statistical analysis offered in Arcview.
   4. Filled in the remaining missing data on the spreadsheet for the 76 dry cleaners that didn't respond to the survey and telephone interview by interpolating the existing data.
   5. Conducted telephone interview with industrial launderers to find out if they were using any solvents in the dry cleaning process. The five industrial launderers in the inventory area are not using any solvents. They are using soap and detergent as these industrial launderers provide uniform and other rental services to businesses, industrial, and institutional customers.

   To calculate the emissions from commercial dry cleaners alternative one of the Emissions Inventory Improvement Program Volume III, chapter 4 was used for SIC codes 7216 and 7218. The number of employees was determined through the survey and multiplied by the per employee emissions factor of 1800 lbs./year/employee. The weekly adjustment factor calculated from the surveys was 312 (6 day week). Seasonal Adjustment Factor is 1.

   Sample calculation:

   Atascosa County = 25 employees
   Emissions Factor = 1800 lbs./year/employee
   Activity Days = 312

   25 employees * 1800 lbs./yr/employee = 45,000 lbs./year
   45,000 lbs./year / 2000 = 22.5 tons/year
   22.5 tons/year / 312 = .071885 tons/day

   ---

   Sample Survey

   Name of Facility:	______________________________________________________
   Street Address:	______________________________________________________
   City/State:	______________________________________________________
   Contact Person:	______________________________________________________
   Telephone Number:	______________________________________________________

    

   Please check the appropriate box describing your operation.

   Solvent Used	Amount Purchased
   	Annually (gallons)
   PERC (Perchloroethylene)	____________________________
   Petroleum (Stoddard Solvent)	____________________________
   Other Petroleum Solvents	____________________________
   CFC-113 (Trichlorofluoroethane)	____________________________
   TCA (1,1,1-Trichloroethane)	____________________________
   Other	____________________________

    

   For each machine at your facility, please provide the following information:

   Machine Type	Load Capacity (pounds of Garments)	Estimated Solvent use per Load (gallons of solvent	Controls in Place
   _____________	_____________	_____________	_____________
   _____________	_____________	_____________	_____________
   _____________	_____________	_____________	_____________
   _____________	_____________	_____________	_____________
   _____________	_____________	_____________	_____________

   For your entire facility, please estimate the amount of solvent sent for off-site disposal or recycling:

   Solvent Type	Estimated (gallons/year)
   PERC (Perchloroethylene)	____________________________
   Petroleum Solvents: ______________	____________________________
   ______________	____________________________
   ______________	____________________________
   TCA (1,1,1-Trichloroethane)	____________________________
   CFC-113 (Trichlorofuoroethane)	____________________________
   Other (Please Specify):____________	____________________________
   ____________	____________________________
   ____________	____________________________

    

   For your facility, please estimate the average days per week and hours per day that dry cleaning equipment is operating:

   _____________ days per week _______________hours per day
   Please list the number of employees at this facility:
   _____________ employees

    

   ---

   Notes:

   U.S. Environmental Protection Agency, May 1991. Emission Inventory Improvement Program/Area Source Committee Volume III: Chapter 4. Research Triangle Park, North Carolina.

    

   Autobody Refinishing

   Automobile refinishing shops are business establishments that perform replacement, repair or refinishing of vehicles which must be regulated for volatile organic compound (VOC) emissions. These emissions can be most accurately calculated via the material balance method. Since the emissions come from the solvents in the automotive paint, calculating the emissions from the amount of paint consumed by the shops is logical. The amount of paint used and the amount of solvent in the paint is recorded and with this information a more precise estimate of emissions released into the air can be generated. Shop emissions based upon average paint sales for auto body shops categorized by annual sales is the objective of this effort to characterize emissions typical from these shops.

   Paint is expensive and the high cost is reflected in the rates of auto body repair. The charges a paint store or "jobber" bills to the auto body shop is partially passed on to the customer, where approximately 6% of the total bill comes from coating materials provided by the store to the auto body shop. Paint stores or jobbers ordinarily have computer software that tracks the monthly purchases of clients thus allowing the auto body shops to ascertain the amount and types of coating purchases made by way of their supplier.

   Auto body refinishing shops are common in metropolitan areas and present in rural areas and range in size, service and quality. Approximately 80% of the shops in Texas are deemed small and 65% of these shops are located near metroplex areas. The amount of material coatings used at an auto body shop should be employed to estimate emissions since the workloads at any given shop varies from day to day. It is required by Texas regulations that every shop has a complete set of Material Safety Data Sheets (MSDS sheets) of all the coatings and related products used to ensure safety of employees, visitors and others.

   The MSDS sheet contains safety information and physical data regarding the contents of the material. Furthermore, product information regarding the physical properties of the coating and proper use of the product may be provided on data sheets. The amount and type of solvent or solvents in the coating should be described briefly in the contents of both types of sheets. Evaporation of all volatile organic materials is presumed for the purposes of calculating the emissions of coatings.

   Methodology

   Estimations of emissions from an auto body shop can be calculated by keeping track of coating sales and referring to the appropriate MSDS sheet or data sheet to obtain data regarding the solvents or VOC's the product possesses. Although the product information sheets should be well organized and easy to read, occasionally the data required must be extrapolated from the data provided or it may not be at all present.

   The Physical Data section of the MSDS sheet often furnishes weight and volume percent of volatile contents or the VOC density. Commonly given is the weight of a gallon of paint or coating. The amount or weight of the VOC's from each gallon of paint or coating is determined by utilizing this data. The manufacturer often includes ranges of product density, percent of volatile by weight and percent of volatile by volume. Conversely, the exact amount of VOC's less water and exempt solvents is given. Precise calculations are thus difficult to perform due to this uncertainty.

   Example: Physical Data included in a MSDS sheet

   • Evaporation rate: Less than ether
   • Vapor Density: Heavier than air
   • Solubility in water: Miscible
   • Percent volatile by volume: 33.9
   • Percent volatile by weight: 60.28
   • Boiling range: 129° F to 711° F
   • Gallon weight: 11.46 pounds
   • Solvent Density: 6.89 pounds
   • Flash Point Range: 20° F to 73° F

   The solvent density of this example is the maximum amount of volatiles that will evaporate from usage of a gallon of this primer. Using the solvent density for the amount of primer that evaporates is the best representation of potential emissions although this is a worse case scenario. The amount of solvent in the coating is assumed to evaporate unless otherwise stated by the manufacturer. In certain coatings, the solvent becomes part of the curing process where the solvent would chemically react with a solid and therefore would be retained in the coating.

   The solvent density should equal or approximately be to the gallon weight multiplied by the percent volatile by weight, thus:

   Example:
   gallon weight * % volatile by weight = solvent density
   11.46 pounds of paint/gallon * 60.28 % = 6.9 pounds of solvent/gallon

   The solvent content in pounds from data provided by the manufacturer is derived in this manner. The number of gallons multiplied by the amount of pounds representing VOC's will provide the emissions from the gallons used in the calculation.

   Sample Calculation:

   20 gallons of primer consumed
   6.9 pounds per gallon of VOC for the primer
   20 gallons * 6.9 pounds of VOC per gallon = 138 pounds of VOC

   These examples provide the basis on which to calculate emissions from auto body shops. Auto body shops have many purchase orders, use many types of coating materials and possess many MSDS or data sheets used for research. Using these types of references and documentation, precise calculations for emissions estimations can be obtained.

   Estimating emissions via the purchases of coating materials by auto body shops becomes the main surrogate for determining emissions when employing the material balance method. To account for the actual or representative amounts of solvents contained in the coating products that are releasing emissions during use, a material balance methodology must be utilized. Purchase profiles can be determined for auto body shops by using coating material sales records from national sales data and paint purchase data from individual auto body shops.

   An auto body shop listing or database of shops in the area is needed to resolve emission estimates for a designated area of study. In Texas, the determination of the average number shops which fall into the assigned categories of small, medium, large, and mega auto body shops can be achieved by studying the trends and sales volume from a list body shops. Based on annual sales and general shop size, shops are allocated into a category. In some databases, a representative field indicating activity such as "annual sales" may not be available. In those instances an associated surrogate can be applied to categorize a shop as small, medium, etc. including the number of employees, number of spray booths or other variable that is related.

   When the annual sales of an auto body shop is unknown, the annual sales relationship to number of employees is selected as $100,000 per employee, the potential business for annual sales an employee represents at a shop. Shops are that have 5 or less employed are designated as small and annual sales from these shops are below $500,000 on average. Medium shops have annual sales between $500,000 and $1,000,000 while large shops make above $1,000,000 but less than $2,500,000. Mega shops make above $2,500,000 annually.

   Example Formula:
   AAA Body & Paint has 4 employees and annual income is unknown.
   4 employees *$100,000 dollars/employee = $400,000; Category = small shop

   Notes:

   DuPont Automotive Finishes: DuPont Material Safety Data Sheets For Compliance with OSHA Standar 29 CFR § 1910.1200. 1999, E.I. du Pont Nemours and Company.

   DuPont Automotive, April 1998. DuPont Automotive ChromaSystem™ Technical Manual.

   Van Nostrand Reinhold Company, 1971. The Condensed Chemical Dictionary 8th Edition. NY, Litton Educational Publishing, Inc.

   Merriam-Webster, Incorporated, 1994. Merriam-Webster's Collegiate Dictionary 10th Edition. Springfield, Massachusetts, U.S.A.

   American Business Information, 1999, Inquiry for Standard Industrial Code 7532.

   Texas Natural Resource Conservation Commission (TNRCC), 1997. "Auto body Initiative Inspections for FY 1997 & American Business Information, SIC Code 7532", 1997 Auto body Shops multi-Media Inspection Check List. Austin, Texas.

    

   Graphic Arts

   The graphic art industry can be divided by technology used, type of substrate used, and type of product or end use. The predominant emissions from graphic arts printing are VOCs contained in the printing inks, fountain solutions, and cleaning solutions. Many of these VOCs are also likely to be hazardous air pollutants (HAPs).

   Graphic art printing inks vary widely in composition, but all consist of three major components: pigments composed of finely divided organic and inorganic materials; binders composed of organic resins and polymers; and solvents composed mostly of organic compounds. Furthermore, emissions can originate from proofing presses, cleaning operations, ink storage tanks, and ink mixing operations. Though they are relatively minor compared to the printing process emissions, they do contribute overall.

   Methodology

   The emissions for the AACOG region from graphic art processes were estimated as area sources since there were are no printing facilities reported in the point source database. The methodology employed calculates graphic art emissions from the inventory area by obtaining the pounds of inks produced in the United States for 1996. Apportion the nationwide ink amount produced for the inventory year to the state level by the ratio between state and national employment in printing and publishing (SIC 27). The equation used to employ this method was the following:

   Annual Ink Sales for State =	[Annual Ink Sales for US (lbs.)] *	[Printing Employment in State]
   		[Printing Employment in US]

   Sample Equation

   Annual Ink Sales for Texas (lbs.) =	[240,120,000] *	[71100]
   		[1,514,900]

   Total Ink Sales for Texas	=	11,269,741.9 lbs. per year
   	=	5634.87 tons per year
   	=	21.67 tons per day (for a 5-day work week, no seasonal adjustment)

   Next, apportion the nationwide ink amount produced for the inventory year to the inventory region (county) level by the ratio between county and state employment in printing and publishing, using the non-point-source employment in facilities with SIC Codes of 27. Also, apportion the statewide ink sales data for each type of printing to the county by the ratio of the printing employment in the county for each printing type to the state printing employment via the following method:

   Annual Ink Sales for Inventory Region =

   [Annual Ink Sales for State] *	[Printing Employment in Inventory Region]
   	[Printing Employment in State]

   Sample Calculation:

   Annual Ink Sales for Bexar County =	[11,269,741.9] * [5012]
   	[71100]

   Annual Ink Sales for Bexar County =	794,429.63 lbs. per year
   =	397.2 tons per year
   =	1.53 tons per day (for a 5-day work week, no seasonal adjustment)

   Then, apportion the inventory region ink sales to each type of printing, using the estimated percentage product market share of ink sales for each type of printing.

   Use uncontrolled emission factors for ink, fountain solution, and cleaning solution, in the amount of pounds of VOCs emitted per pound of ink used. To calculate uncontrolled emissions for a single printing type use the following method:

   Uncontrolled VOC Emissions = ASIS * [ IEF + FSEF + CSEF ]
   Where:	ASIS	= Area Source Ink Sales
   	IEF	= Ink Emission Factor
   	FSEF	= Fountain Solution Emission Factor
   	CSEF	= Cleaning Solution Emission Factor

   Sample Calculation:

   Rotogravure Process = (VOC Emissions)	[ (794,430) (0.18) ] * [ (0.70) + (0) + (0.03) ]
   =	[ (142,997) ] * [ (0.73) ]
   =	104,388 lbs. per year
   =	52.19 tons per year
   =	0.20 tons per day (for a 5-day work week, no seasonal adjustment)

   Once the component VOC emission factors for graphic arts processes have been calculated for a single printing type, these data can be summed to give the total uncontrolled VOC emissions. The emission totals for Bexar County are represented in the following table. The calculations have been performed using a 5-day workweek and no seasonal adjustment.

   Component Emission Factors Totals for Graphic Arts.

   Type of Printing		Tons of VOC Emitted per Day per Pound of Ink Used (Ink, Fountain Solution, and Cleaning Solution Totals)
   Rotogravure		0.20
   Flexography		0.17
   Offset Lithography
   	Heatset	0.89
   	Nonheatset Web	0.42
   	Nonheatset Sheet	1.70
   	Newspaper	0.12
   Letterpress		0.03
   Screen		0.00
   Planographic		0.00
   Bexar County Emissions Total		3.53

    

   Notes:

   U.S. Environmental Protection Agency, May 1991. Procedures for the Preparation of Emissions Inventories for Carbon Monoxide and Precursors of Ozone. Volume I. Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.

   U.S. Environmental Protection Agency, Emission Inventory Improvement Program (EIIP)/Area Source Committee Volume III: Chapter 7. Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.

    

   Wastewater Emissions

   The state of Texas assumed the authority to administer the National Pollutant Discharge Elimination System (NPDES) program in Texas on Sept. 14, 1998. NPDES is a federal regulatory program to control discharges of pollutants to surface waters of the United States. The Texas Natural Resource Conservation Commission's (TNRCC's) Texas Pollutant Discharge Elimination System (TPDES) program now has federal regulatory authority over discharges of pollutants to Texas surface water, with the exception of discharges associated with oil, gas, and geothermal exploration and development activities, which are regulated by the Railroad Commission of Texas.¹

   Accordingly, the TNRCC permitting records provide a record of all in the state who create wastewater discharge according to the following guidelines:²

   1. Discharges of waste from industry and municipal treatment works, including publicly owned treatment works (POTWs)
   2. Discharges and land application of waste from concentrated animal feeding operations (CAFOs)
   3. Discharges of storm water associated with industrial activities, including construction sites
   4. Discharges of storm water associated with city storm sewers, known formally in the regulations as municipal separate storm sewer systems (MS4s)
   5. Oversight of municipal pretreatment programs operated by publicly owned treatment works
   6. Disposal and use of sewage sludge

   AACOG requested permitting information from TNRCC for all municipalities, school districts, trailer parks, municipal utility districts (MUDs), etc., which have been charged with handling wastewater discharge from industries, wastewater collection systems, and other miscellaneous sources. The data requested includes daily average flows and operating days parameters, as well as a list of geographical coordinates (latitude and longitude) to allow geocoding of discharge locations in the future. Within the 184 records (representing 52 permitted entities) in the TNRCC data set, there are just four unique Standard Industrial Classification codes. They are:

   SIC codes for Wastewater Systems.

   SIC code	SIC code description 3	Number of records
   4952	Sewerage Systems	178
   8211	Elementary & Secondary Schools	4
   5411	Grocery stores - retail	1
   4941	Water Supply Systems, except irrigation	1

   These classifications fall within two broad categories of wastewater treatment plants defined by the Environmental Protection Agency (EPA): Publicly owned waste treatment (POWTs) facilities and Package plants. POWTs are government-owned entities charged with the handling of wastewater discharge from industries, wastewater collection systems, and other miscellaneous sources. Package plants refer to small, automated (usually) domestic waste treatment plants that do not require full-time supervision. In general, these facilities treat less than one million gallons per day (MGD).

   Methodology

   For both categories, it is first assumed that the industrial wastewater contribution represents the bulk of the volatile organic constituents of the influent waste stream.⁴ With this assumption, emission factors can be derived by dividing the total estimated VOC emissions by the total industrial flow. The results of this calculation provide an emission factor of 110 pounds of VOC emitted per million gallons of industrial wastewater discharged to a POTW or package plant. This factor is recommended for estimating VOC emissions from POTWs and package plants where measured emissions data are not available. The EPA-recommended default values are 16 percent industrial wastewater of total wastewater flow. ⁵

   The data provided by TNRCC included the daily flow averages in MGD, per site, for each month in 1996, and the days of operation for each month. These figures were used to estimate the average tons per day (TPD) of Volatile Organic Compounds (VOCs) per county for an average ozone day in 1996 as well as the annual per county tons per year (TPY) of VOCs.

   The daily average flows were multiplied by the number of days operated per month at each location to estimate the monthly volume (in millions of gallons) of wastewater per site. The per-site monthly volumes were summed by county, once for those months in the ozone season and also for the entire year. The ozone season sum was divided by the number of days in the ozone season to attain an average 1996 ozone day wastewater flow rate (gallons per day) per county. This ozone day average was multiplied by 0.16 to approximate the industrial waste component of this waste stream. This result was multiplied by 110 to convert the figure to pounds of VOC per county per day. Finally, this number was divided by 2000 to give the average 1996 ozone season VOC total in tons per day (TPD) per county.

   Sample Calculation:

   A sample calculation of tons per day of VOC during an average ozone season day is given for Atascosa County:

   (County sum, 10⁶ gallons per month summed over ozone season/days in 1996 ozone season) * (16%*lbs VOC/million gallons ww) / (tons/lb.)

   (280.22083/244) * [(0.16*110)/(2000)] = (1.14844601) * (0.0088) = 0.01010632 TPD VOC, Atascosa Co.

   The table below gives the per county wastewater flow in millions of gallons per day for an average ozone day in 1996. In addition, this table lists the per county wastewater flow as an annual average for 1996, in millions of gallons (annually). This last column is achieved by summing the monthly totals as described above.

   Annual Average and Ozone Day Wastewater Flow by County.

   County Name	Wastewater Flow in Millions of Gallons per Day, Average Ozone Day, 1996	Wastewater Flow, 1996 Annual Average, Millions of Gallons
   ATASCOSA	1.148	417
   BANDERA	0.059	24
   BEXAR	128.263	46,290
   COMAL	3.380	1,213
   FRIO	0.831	295
   GILLESPIE	0.729	279
   GUADALUPE	3.080	1,102
   KARNES	0.832	304
   KENDALL	0.589	217
   KERR	2.136	777
   MEDINA	1.458	538
   WILSON	0.704	253

   The availability of month-specific records obviated the need to calculate a seasonal factor. Waste water treatment was considered a seven-day-per-week operation for the sewerage SIC codes; no daily factors were considered. It is also to be noted that this category of emissions produces only VOC gases.

    

   Notes:

   ¹ Texas Pollutant Discharge Elimination System (TPDES), October 14, 1999. Texas Natural Resource Conservation Commission (TNRCC), http://www.tnrcc.state.tx.us/water/quality/tpdes/index.html.

   ² TPDES Program Summary, October 14, 1999. TNRCC, http://www.tnrcc.state.tx.us/water/quality/tpdes/summary.pdf.

   ³ Standard Industrial Classification Search, October 15, 1999. http://www.osha.gov/oshstats/sicser.html, Occupational Safety & Health Administration (OSHA), U.S. Department of Labor.

   ⁴ U.S. Environmental Protection Agency, May 1991. Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone, Vol. I: General Guidance for Stationary Sources. Research Triangle Park, North Carolina.

   ⁵ Ibid.

    

   Asphalt Paving

   Asphalt concrete is grouped into three universal categories: hot-mix, cutback, and emulsified. Hot-mix asphalt is the most commonly used paving asphalt for surfaces 2 to 6 inches thick, while cutback and emulsified asphalt is used in tack and seal operations. Emissions from asphalt paving operations occur when asphalt mixtures are applied and as they cure.

   Hot mix was not calculated for this emissions inventory study, hot mix produces minimal emissions, which are about one order of magnitude lower than the national estimates of cutback asphalt paving (EIIP, VIII, Ch.17). Hot mix asphalt is prepared at a plant where strict controls are placed on emissions from the plant and those emissions are calculated in the section on asphalt plants.

   Cutback asphalt is used primarily in tack and seal operations, and for priming roadbeds for hot-mix application. Cut back asphalt is prepared by diluting asphalt cement with petroleum distillates. Cutback asphalt has the highest diluent content of the three asphalt categories and emits the highest levels of VOCs per ton used. Other materials such as cold-mix-cold-lay have almost entirely replaced cutback asphalt in the AACOG region. According to the Texas Department of Transportation most businesses no longer us cutback asphalt1. One of the largest asphalt suppliers in our area has not used cutback asphalt since 1987.

   Adding water and an emulsifying agent, such as soap produces emulsified asphalt, although it can contain up to 12% solvent (EIIP, V.III, Ch. 17). Emulsified asphalt is used in most of the same applications as cutback asphalt but is lower emitting, energy saving, and a safer alternative to the cutback asphalt (Moulthrop, et al 1997).

   Methodology

   Only medium cure (MC-30) cutback asphalt was found in the AACOG region. VOC emissions from cutback asphalt were calculated by acquiring the gallons of material used and applying an emissions factor derived from the evaporation rate of the cutback asphalt, 70% for medium cure. The medium cure has a density of 7.8 lb. per gallon and contains 34% by weight of diluent. This was then divided by 2000 lbs. to convert it to tons. The medium cure derived factor was 0.0009282 tons/gallon of diluent.

   Sample Calculation:

   Medium cure emission factor calculation:
   7.8 lb. per gallon * 0.34 diluent * 0.7 evaporation rate / 2000 = 0.0009282 tons per gallon

   Emissions calculation:
   1996 medium cure usage of 10748.7 gallons/year
   Seasonal Adjustment Factor = 1
   Activity Days = 365
   10748.7 gallons * 0.0009282 tons/gallon = 9.9769 tons/year
   9.9769 / 365 days = 0.02733 tons/day

   VOC emissions from emulsified asphalt were calculated by acquiring the gallons of material used and applying an emissions factor. The composite emission factor of 0.22 lbs. per gallon was provided by EPA's Procedures for the Preparation of Emissions Inventories for Precursors of Ozone, Volume I.

   Emissions Calculation:
   Emulsified Asphalt usage of 184775.6 gallons/year
   Seasonal Adjustment Factor = 1
   Activity Days = 365
   184775.6 * 0.22 lb. per gallon / 2000 = 20.3252 tons/year
   20.3252 / 365 = 0.05569 tons/day

   The information was not broken down into county usage so population statistics were used to determine the amount of emissions for each county. This was determined to be a reliable breakdown based on a phone conversation with the Texas Department of Transportation3. Bexar County accounted for nearly 80% of the total population of the AACOG region in 1996.

    

   Notes:

   Patrick Downing at Texas Department of Transportation, San Antonio, Texas.

   Tom Singley of Martin Marieta, San Antonio, Texas.

   U.S. Environmental Protection Agency. Emission Inventory Improvement Program (EIIP)/Area Source Committee Volume III: Chapter 17. Research Triangle Park, North Carolina.

   U.S. Environmental Protection Agency, May 1991. Procedures for the Preparation of Emissions Inventories for Precursors of Ozone, Volume I. Research Triangle Park, North Carolina.

    

   Degreasing

   Degreasing is the physical process of using organic solvents or solvent vapor to remove grease, fats, oils, wax or soil from items made of metal, glass or plastic. The types of equipment used for degreasing are categorized as batch and in-line cleaning machines. Furthermore, batch cleaners are categorized as either batch cold cleaning machines or batch vapor cleaning machines. Nonaqeous solvents used in the process include distillates, chlorinated hydrocarbons, ketones, and alcohols.

   The metalworking industries are the major users of solvent degreasing. These include automotive, electronics, plumbing, aircraft, refrigeration, and business machine industries. The printing, chemical, plastics, rubber, textiles, glass, paper, and electric power industries also use solvent degreasing operations.

   Methodology

   VOC emissions from degreasing operations were calculated using EPA-approved emission factors.¹ These factors were developed for degreasing based on equipment type and SIC (see table below). By multiplying the emission factor times the number of people employed within each applicable SIC, the total emissions for each degreasing category were determined. SIP Inventory Guidance suggests uniform activity throughout the year (no seasonal adjustment) and a six-day workweek when facility-specific information is unavailable. The calculations performed here are based on this default.

   SIC Codes and Emission Factors for Degreasing.

   Subcategory	SIC	Per Employee Factor (lb. VOC/year/employee)
   Cold Cleaning
   Automobile Repair	417, 423, 551, 552, 554-556, 753	270
   Manufacturing	25, 33-39	24
   Vapor and In-Line Cleaning
   Electronics and Electrical	36	29
   Other	25, 33-39, 417, 423, 551, 552, 554-556, 753	9.8

   Sample Calculation:

   The emissions from vapor and inline cleaning from the electronics and electrical industries (SIC 36) in Bexar County were calculated as follows:

   Number of people employed in the electronic/electrical industry in Bexar County = 2,574
   2,574 * 29 (emission factor) = 74,646 lbs. of VOC/year
   74,646 / 2000 = 37.32 tons of VOC/year
   Based on a six-day workweek, the daily emission rate from the electronic/electrical industry in Bexar County is:
   34.32 / 312 = 0.11 tons of VOC per working day

   Notes:

   1. U.S. Environmental Protection Agency, September 1997. Emission Inventory Improvement Program Volume III: Chapter 6 Solvent Cleaning. Research Triangle Park, North Carolina.

   2. Texas Workforce Commission, 1995. Texas Workforce Commission Employer Location File. Austin, Texas.

    

   Traffic Markings

   Traffic markings consist of centerlines, edge stripes and directional markings found on highways as well as markings on paved and unpaved surfaces, such as parking lots. Various materials are used to make traffic markings, including solvent-based paints, water-based paints, thermoplastics, preformed tapes, field-reacted materials, and permanent markers. Three of these materials emit VOCs in appreciable amounts: water- and solvent-based non-aerosol paint, water- and solvent-based aerosol paint, and preformed tapes applied with adhesive primer. VOC emissions are generated from the evaporation of organic solvents during and shortly after the application of marking materials.

   Methodology

   Several steps are involved in calculating emissions from traffic markings.¹ These steps include:

   1. Determining the amount of U.S. traffic paint usage for the inventory year from data listed in U.S. Census Bureau records (Paint and Allied Products List MA28F).
   2. Apportioning the national traffic paint usage to the state level based on spending for highway maintenance. The Federal Highway Administration lists this information for both the national and state level.
   3. Apportioning the state estimate of traffic paint usage to the county level using the proportion of county to state population.
   4. Determining the VOC emissions rate by multiplying the county traffic paint usage by the national average emission factor of 3.36 lb./gallon (developed by the National Paint and Coatings Association).
   5. Converting emission estimates from pounds/year to tons/year. The daily resolution of traffic paints is considered to be five days a week and a seasonal adjustment factor of 1.3 is applied to the daily emissions rate to account for summer or ozone season.

   The U.S. traffic paint usage for 1996 was 36,944,000 gallons.² Disbursement of funds for highway maintenance totaled $24,318,908,000 for the U.S. and $1,893,021,000 for Texas.³ In 1996 the population of the State of Texas was 18,932,954 and the population of Bexar County was 1,358,865.⁴ Using this information, VOC emissions from traffic markings are calculated as follows:

   Sample Calculation:

   Texas Traffic Paint Usage =	[TX Highway Disbursements/U.S. Highway Disbursements] * U.S. traffic paint usage
   =	[1,893,021,000 / 24,318,908,000] * 36,944,000
   =	2,875,777 gallons

   
   

   County Traffic Paint Usage	= [County population/State population] * state paint usage
   Bexar traffic paint usage	= [1,358,865/18,932,954] * 2,875,777 gallons
   	= 206,401 gallons per year

   
   

   County VOC emissions	= County traffic paint usage * VOC emission factor
   Bexar County VOC emissions	= 206,401 gallons per year * 3.36 lb./gallon
   	= 693,507.36 lb. per year
   	= 346.75 tons per year
   	= 1.73 tons per day (for 5-day work week, seasonally adjusted)

    

   Notes:

   1. U.S. Environmental Protection Agency, May 1997. Emission Inventory Improvement Program Volume III, Chapter 14 Traffic Markings. Research Triangle Park, North Carolina.
   2. U.S. Census Bureau, 1996. Paint and Allied Products MA28F. Available: http://www.census.gov/cir/www/ma28f.html.
   3. Federal Highway Administration, 1996. National and State Highway Maintenance Disbursement Statistics. Available: http://www.fhwa.dot.gov/ohim/1996/section4.html.
   4. Texas Water Development Board, 1998. Population Projections 1990-2050: Most Likely Scenario. Austin, Texas.

    

   Agricultural Fertilizer

   Fertilizers are used to supply essential plant nutrients to improve crop production. The fertilizer predominately used in this South Texas region is ammonium sulfate (NH4)2SO4 applied in a solid form. The application time(s) and rate are dependent upon specific soil type, the crop to be grown, the weather at the application time, and the equipment available to the individual farmer.

   The "typical" application rates and times for this region are shown in the table below together with the EPA latent emissions factors (draft) for the fertilizer applications in this area:

   Crops, Application Schedule, Emission Factors.

   CROP	When Applied	Total Weight/Acre	Nitrogen /Acre	Emission Factor for Application lbs./pollutant per ton Nitrogen Applied
   				NO	NH3	N2O
   Corn	March-April	2,100 lbs.	60 lbs.	138	0.405	12.1
   	May	700 lbs.	20 lbs.	138	0.405	12.1
   Cotton	March-April	2,100 lbs.	60 lbs.	138	0.405	12.1
   	May	700 lbs.	20 lbs.	138	0.405	12.1
   Small Grains	March-April	2,100 lbs.	60 lbs.	138	0.405	12.1
   Sorghum	March-April	2,100 lbs.	60 lbs.	138	0.405	12.1
   	May	700 lbs.	20 lbs.	138	0.405	12.1
   Hay (Bermuda)	March-April	2,100 lbs.	60 lbs.	138	0.405	12.1
   Peanuts	June	1,000 lbs.	30 lbs.	138	0.405	12.1

   The emissions were calculated on a county-wide basis for this report, but were obtained from each four kilometer grid square and can easily calculated for grid entry into a photochemical model. The following table is a snapshot taken from a spreadsheet used for agricultural data entry. For each grid cell in the AACOG domain there is a corresponding data entry cell as shown in this snapshot.

   Sample Fertilizer Grid Data Cell.

   Cell Number	29-48
   Range	.85
   Corn	.10
   Hay
   Peanuts
   Sorghum	.05
   Vegetables
   Cotton
   Small Grains
   Urban
   Water

   Fertilizer is applied at or just before planting for crops in this region. Most crops require around 2100 lbs. of ammonium sulfate fertilizer be applied to each acre of crops to achieve an effective application of 60 lbs. of nitrogen to each acre. A secondary side-dressing of 700 lbs. of amonium nitrate is used to achieve an effective application rate of 20 lbs. of nitrogen per acre(indicated as side-dressing). Bermuda grass used for hay production is fertilized with 2100 lbs. per acre in the early spring while peanuts are fertilized only at planting with approximately 1000 lbs. of fertilizer per acre.

   The application of fertilizer is very dependent upon the prevailing weather conditions. Dry and anticipated dry conditions make fertilization harmful as it will burn the crops. Sufficient moisture must be present to achieve the full rates shown in the approximations above. Additionally, the farmer will not spend the money to fertilize his crops if he anticipates a substandard yield or market conditions which would make the expenditure of funds on fertilizer counter productive.

   Sample Calculation:

   Percent of Grid Cell * Total acres of Grid = Acres in specific crop production in the Grid Cell
   Then:
   5,791 Acres of Corn * Emission Rate Per Acre (60 lbs.) = 347,430 Lbs.of Emission
   NO: 347,430 Lbs. * 138 / 2000 = 11.9 Tons/yr. NO / 156 = 0.07 Tons/day
   NH3: 347,430 Lbs. * 0.405 / 2000 = 0.04 Tons/yr. NH3 / 156 = 0.0002 Tons/day
   N2O: 347,430 Lbs. * 12.1 / 2000 = 1.05 Tons/yr. N2O / 156 = 0.006 Tons/day

   Emissions are converted to tons/day by dividing each category by 156 days, which represents emissions (6 days a week) accounted for in the Ozone season, May through October.

   Notes:

   U.S. Environmental Protection Agency, 1999. EPA AP-42, Volume I, Fifth Edition (draft), Research Triangle Park, North Carolina.

    

Fertilizer Emission Results.

	Atascosa	Bandera	Bexar	Comal	Frio	Gillispie	Guadalupe	Karnes	Kendall	Kerr	Medina	Wilson
CORN
Acres	5,791	0	9,390	2,454	5,922	2,361	31,421	8,697	198	0	5,189	19,145
Spring Planting
Lbs. Nitrogen	347,430	0	563,412	147,234	355,320	141,660	1,885,254	521,820	11,880	0	311,358	1,148,676
Pollutants (Tons per Year)
NO	11.99	0	19.44	5.08	12.26	4.89	65.04	18.00	0.41	0	10.74	39.63
NH3	0.04	0	5.45	1.42	3.44	1.37	18.24	5.05	0.11	0	3.01	11.11
N2O	1.05	0	1.70	0.45	1.07	0.43	5.70	1.58	0.04	0	0.94	3.47
Side - Dressing
Lbs. Nitrogen	115,810	0	187,804	49,078	118,440	47,220	628,418	173,940	3,960	0	103,786	382,892
Pollutants (Tons per Year)
NO	4.00	0	6.48	1.69	4.09	1.63	21.68	6.00	0.14	0	3.58	13.21
NH3	0.01	0	1.82	0.47	1.15	0.46	6.08	1.68	0.04	0	1.00	3.70
N2O	0.35	0	0.57	0.15	0.36	0.14	1.90	0.53	0.01	0	0.31	1.16
	Atascosa	Bandera	Bexar	Comal	Frio	Gillispie	Guadalupe	Karnes	Kendall	Kerr	Medina	Wilson
SORGHUM
Acres	2,579	0	9,845	3,211	10,114	2,385	21,821	9,262	120	0	4,221	30,116
Spring Planting
Lbs. Nitrogen	154,715	0	590,694	192,672	606,840	143,100	1,309,250	555,720	7,200	0	253,236	1,806,942
Pollutants (Tons per Year)
NO	5.34	0	20.38	6.65	20.94	4.94	45.17	19.17	0.25	0	8.74	62.34
NH3	0.02	0	5.71	1.86	5.87	1.38	12.67	5.38	0.07	0	2.45	17.48
N2O	0.47	0	1.79	0.58	1.84	0.43	3.96	1.68	0.02	0	0.77	5.47
Side - Dressing
Lbs. Nitrogen	51,572	0	196,898	64,224	202,280	47,700	436,417	185,240	2,400	0	84,412	602,314
Pollutants (Tons per Year)
NO	1.78	0	6.79	2.22	6.98	1.65	15.06	6.39	0.08	0	2.91	20.78
NH3	0.01	0	1.90	0.62	1.96	0.46	4.22	1.79	0.02	0	0.82	5.83
N2O	0.16	0	0.60	0.19	0.61	0.14	1.32	0.56	0.01	0	0.26	1.82
	Atascosa	Bandera	Bexar	Comal	Frio	Gillispie	Guadalupe	Karnes	Kendall	Kerr	Medina	Wilson
PEANUTS
Acres	28,903	0	0	0	0	0	76	0	0	0	198	20,930
Lbs. Nitrogen	867,081	0	0	0	0	0	2,265	0	0	0	5,931	627,903
Pollutants (Tons per Year)
NO	29.91	0	0	0	0	0	0.08	0	0	0	0.20	21.66
NH3	0.09	0	0	0	0	0	0.00	0	0	0	0.00	0.06
N2O	2.62	0	0	0	0	0	0.01	0	0	0	0.02	1.90
	Atascosa	Bandera	Bexar	Comal	Frio	Gillispie	Guadalupe	Karnes	Kendall	Kerr	Medina	Wilson
SMALL GRAINS
Acres	29,459	0	9,178	5,032	6,532	0	17,113	5,495	568	755	7,146	23,632
Lbs. Nitrogen	1,767,528	0	550,662	301,938	391,920	0	1,026,804	329,700	34,080	45,300	428,784	1,417,932
Pollutants (Tons per Year)
NO	60.98	0	19.00	10.42	13.52	0	35.42	11.37	1.18	1.56	14.79	48.92
NH3	0.18	0	5.33	2.92	3.79	0	9.93	3.19	0.33	0.44	4.15	13.72
N2O	5.35	0	1.67	0.91	1.19	0	3.11	1.00	0.10	0.14	1.30	4.29
	Atascosa	Bandera	Bexar	Comal	Frio	Gillispie	Guadalupe	Karnes	Kendall	Kerr	Medina	Wilson
HAY
Acres	28,901	5,560	9,207	14,344	10,225	22,381	37,798	32,353	10,747	8,006	593	37,055
Lbs. Nitrogen	1,734,060	333,600	552,438	860,640	613,500	1,342,860	2,267,856	1,941,180	644,820	480,360	35,580	2,223,306
Pollutants (Tons per Year)
NO	59.83	11.51	19.06	29.69	21.17	46.33	78.24	66.97	22.25	16.57	1.23	76.70
NH3	0.18	3.23	5.34	8.33	5.94	12.99	21.94	18.78	6.24	4.65	0.34	21.51
N2O	5.25	1.01	1.67	2.60	1.86	4.06	6.86	5.87	1.95	1.45	0.11	6.73
	Atascosa	Bandera	Bexar	Comal	Frio	Gillispie	Guadalupe	Karnes	Kendall	Kerr	Medina	Wilson
TOTALS Pollutants (Tons per Year)
NO	173.82	11.51	91.15	55.74	78.95	59.43	260.69	127.91	24.30	18.14	42.20	283.24
NH3	0.51	3.23	25.56	15.63	22.14	16.67	73.09	35.87	6.81	5.09	11.78	73.42
N2O	15.24	1.01	7.99	4.89	6.92	5.21	22.86	11.22	2.13	1.59	3.70	24.84

 

Agricultural Pesticide Applications

Pesticides are defined as any substance used to kill or retard the growth of insects, rodents, fungi, weeds, or microorganisms. Pesticides used in the home and garden are included as part of the consumer/commercial solvent use category. This section calculates emission estimates for agricultural pesticides.

Methodology

An emission factor of 3.5 lb. (averaged from the recommended 2-5 lbs.) per harvested acre was used to calculate the VOC emissions from pesticide application. The factor was computed by determining the number of acres in each grid cell to produce the following crops which typically involve a pesticide application:

Table of Harvested Crops in the AACOG Region.

Corn

Peanuts

Sorghum

Horticulture

Cotton

Small Grains

The resulting emissions were applied to each grid cell and summed to reach the total for each county.

Sample Calculation per grid cell.

Sample Pesticides Grid Data Cell.

Cell Number	29-48
Range	.85
Corn	.10
Hay
Peanuts
Sorghum	.05
Vegetables
Cotton
Small Grains
Urban
Water

Sample Spreadsheet Calculating VOC Emissions from the Percentage of Crops in each Grid Square.

		Acres Harvested	Emission Factor	VOC Emissions
Cell Number	29-48
Range	85%	0	-	0
Corn	10%	395.36	3.5 lbs/acre	1383.76 lbs.
Peanuts		0	-	0
Sorghum	5%	197.68	3.5 lbs/acre	691.88 lbs.
Vegetables		0	-	0
Cotton		0	-	0
Small Grains		0	-	0
Total Emissions				2075.64 lbs.
Tons per year				1.03

 

Adjustment Factors.

EPA's Procedures for the Preparation of Emission Inventories for Precursors of Ozone, Volume I provided the emission factor, as well as the seasonable adjustment factor and activity days per week. The seasonal adjustment factor is 1.3 and the activity days per week is 6 to yield tons per day.

Sample Calculation.

Total acres harvested in Sample County * Emission Factor =
    593.04 * 3.5 lbs/acre = 2076 lbs./yr. VOC.
Then:
    (2076 lbs./yr. VOC) / 2000 = 1.04 Tons/yr. VOC.
    (1.04 Tons/yr. VOC) / 312 * 1.3 = 0.0043 Tons/day VOC

Notes:

TRC Environmental Corporation, 1997. Agricultural and Nonagricultural, Volume III: Chapter 9 of the Emission Inventory Improvement Program. Available online: http://www.epa.gov/ttn/chief/eiip/iii09.pdf

 

Municipal Waste Landfills

Emissions are produced from municipal solid waste landfills by three mechanisms: volatilization, chemical reaction and biological decomposition of liquid and solid compounds into other chemical species. Factors affecting volatilization include partial pressure of the constituent: constituent concentration at the liquid-air interface: temperature: and confining pressure. Chemical reactions are also affected by temperature, as well as: waste composition: moisture content: and the practice of separate disposal areas for different waste types. Factors affecting biological decomposition are nutrient and oxygen availability: refuse composition: age of landfill: moisture content: temperature: pH: and waste that is toxic to bacteria. The study below was developed to analyze VOC emissions from the six municipal waste landfills in the AACOG region. Since one of these sites has been classified as a Type IV landfill, consisting of only construction and demolition waste and has insignificant VOC emissions, it was removed from the study.

Methodology

The EPA's Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone, Volume I¹ was implemented to calculate VOC emissions using a factor of 35.36 tons per year per million tons of refuse. The Alamo Area Council of Governments, Department of Natural Resources/Transportation, provided data on refuse tonnage² for the study area. The study area includes the following landfills:

• BFI (Tessman Road), Bexar County
• WM (Coval Gardens), Bexar County
• WM (Comal County), Comal County
• City of Fredericksburg, Gillespie County
• City of Kerrville, Kerr County

A survey was also included in the study to more accurately account for the municipal waste landfill VOC emissions. The survey would provide data on landfill footprints, permitted emissions and estimated actual emissions for the five municipal waste landfills in the AACOG region. However, response from this survey proved unsuccessful with only two of the five landfills responding, thus the methodology used for the remaining landfills was derived from the EPA’s Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone, Volume I. The Comal and Covel landfills³ were the only two municipal waste landfills to provide us with data on VOC emissions for 1996.

Sample Calculation:

Kerr County 1996 tons of refuse per day = 89.63 tons

(13.6 tons VOC/yr/106 tons) * (2.6) = 35.36

89.63 * 365 days * 35.36 tons refuse/ 1,000,000 tons = 1.157 tons per year VOC

1.157 tons/365 = 0.003 tons per day

The seasonal adjustment factor was uniform and activity days was 7 days a week.

Notes:

¹ Office of Air Quality Planning and Standards, May 1991. Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone, Volume I. U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, p. 3-19.

² Department of Natural Resources/Transportation Department, 1998. Solid Waste Management in the AACOG Region 1990-2010. Alamo Area Council of Governments, San Antonio, Texas.

³ Waste Management Inc. VOC Emissions for Comal and Covel Municipal Waste Landfill. San Antonio, Texas.

---

Sample Letter Requesting Landfill Information

October 8, 1999

 

Mitch Noto
Browning Ferris Industries
PO Box 207910
San Antonio, Texas 78220

 

Dear Mr. Noto:

The Alamo Area Council of Governments is presently working on the National Ambient Air Quality Standards Emissions Inventory for the San Antonio area. I have been tasked with the responsibility for identifying landfill emissions. I would appreciate your help with this matter.

Please provide the following data in the identified three categories. With regard to the emissions, please segregate the VOC emissions from other non-reactive organic emissions if at all possible. Your data, coupled with that from other facilities, should allow us to document and model the landfill gas emissions for our region:

Landfill footprint in acres
	1995 ________________
	1996 ________________
	1999 ________________
Projected	2005 ________________
Permitted emissions
	1995 ________________
	1996 ________________
	1999 ________________
Projected	2005 ________________
Estimated Actual emissions
	1995 ________________
	1996 ________________
	1999 ________________
Projected	2005 ________________

As you know, the San Antonio region is currently experiencing a significant degradation of our regional air quality. The primary sources are mobile emissions form motor vehicles, which are being modeled separately. Please do not include the emissions from either your on road or off road equipment in the information you provide.

Thank you in advance for your assistance.

Sincerely,

 

Tony Wood

---

 

Architectural Surface Coatings

Surface coatings include paint, primer, varnish, lacquer and the solvents used as thinners or as solutions for cleanup. When these coatings are applied to the interior or exterior of buildings or structures, they are categorized as architectural surface coatings. The majority of surface coatings are applied to domestic, industrial, institutional, and governmental structures. VOCs are emitted during the application of the coatings as well as during the drying process.

Methodology

Emissions from architectural surface coatings are calculated using population-based usage and emissions factors.¹ Surface coatings fall under two categories: solvent- and water-based coatings. Per capita usage factors, based on 1996 national averages, and VOC emission factors have been developed for both solvent- and water-based coatings. The formulas for calculating VOC emissions generated by the two types of surface coatings are as follows:

VOC Emissions from Solvent-Based = Coatings

County Population

* Solvent Usage Factor

* Solvent VOC Emissions Factor

VOC Emissions from Water-Based = Coatings

County Population *

Water-Based Usage Factor

* Water-Based Emissions Factor

Adding the two emission estimates together provides the total VOC emissions for a population.

Example:

The following table lists the per capita usage factors and VOC emission factors for estimating emissions from solvent- and water-based coatings. The per capita usage factor was obtained by dividing the quantity of architectural coatings shipped in the U.S. in 1996 ² by the total U.S. population³ for the same year. Emission factors are based on weighted averages from a 1990 survey study (EPA 1993a).⁴

Architectural Coating Emissions Factors.

Architectural Coating Category	Usage Factor	VOC Emission Factor
Solvent-based	0.54 gallons/person	3.87 lb./gallon
Water-based	1.85 gallons/person	0.74 lb./gallon

In order to determine the emissions for a summer or ozone season day, a seasonal adjustment factor of 1.3 was used. Thus, the calculation used for determining VOC emissions from solvent-based coatings in Bexar County is as follows:

1996 Bexar County Population⁵: 1,358,865

VOC Emissions, Solvent-Based Coatings =	1,358,865	* 0.54 gal. / person	* 3.87 lb./gallon
=	2,839,756.08 lbs. per year / 2000 tons/lb.
=	1,419.88 tons/year
while	1,419.88 tons/year / 365 days = 3.89 tons/day
and	3.89 tons/day * 1.3 = 5.06 tons of VOCs from Solvent-Based Coatings/Day

Notes:

¹ Environmental Protection Agency, November 1995. Emission Inventory Improvement Program Volume III, Chapter 3 Architectural Surface Coatings. Research Triangle Park, North Carolina.

² U.S. Census Bureau’s Paint and Allied Products MA28F website, 1996. http://www.census.gov/cir/www/ma28f.html.

³ U.S. Census Bureau’s National Population Statistics website, 1996. http://www.census.gov/population/estimate/nation/popclockest.txt.
http://www.census.gov/prod/www/abs/popula.html

⁴ U.S. Environmental Protection Agency, 1990. Survey Study (1993a). Research Triangle Park, North Carolina.

⁵ Texas Water Development Board, 1998. Population Projections, 1990-2050: Most Likely Scenario. Austin, Texas.

 

Under Ground Storage Tank Breathing Loss

This is a category for the 1996 Emissions Inventory dealing with old underground storage tanks containing volatile organic compounds (VOC) that have been unearthed for removal. Underground storage tank (UST) emissions of VOC have been re-estimated for the entire State of Texas, using an updated database from the Petroleum Storage Tank division of the Texas Natural Resource Conservation Commission (TNRCC).

Methodology

The number of underground storage tank removals for each county was obtained from the Petroleum Storage Tank Division of the TNRCC. These figures were used to determine the number of tanks that were removed from the AACOG area.

Remediated Tanks in 1996.

County	Tanks
Atascosa	46
Bandera	7
Bexar	284
Comal	53
Frio	30
Gillespie	8
Guadalupe	57
Karnes	9
Kendall	41
Kerr	28
Medina	106
Wilson	14

Technical guidance was available in the form of a memorandum from Radian, Inc., which estimated a median value of 28 pounds of VOC compounds per tank remediation, based upon an analysis of soil removed and its hydrocarbon content in parts per million. The statistic only applies to tanks remediated during the ozone season, and also assumes that the duration of emissions is approximately 30 days. Therefore, the equation to estimate emissions, including conversion to tons per day, is:

Sample Calculation:

E_{voc, tpd} = (((number of tanks*28)/2000)/4)/3

VOC emissions = 46 tanks from Atascosa *28 / 2000 / 4 / 3 = 0.0537 tons/day

Notes:

Radian Corporation, May 1992. Memorandum: VOC Emissions from Leaking Underground Storage Tanks. Research Triangle Park, North Carolina.

Texas Natural Resource Conservation Commission, August 1998. List of Underground Storage Tanks Removed in 1996. Austin, Texas.

 

Underground and Above Ground Storage Tanks

Working and breathing losses from petroleum storage tanks result in the emission of volatile organic compounds (VOCs). These emissions will be added and referred to as total losses. Emissions from above and under ground storage tanks were estimated using the TANKS 4.0 model, which is available through the Technology Transfer Network (TTN) Bulletin Board System maintained by the United States Environmental Protection Agency (EPA). The TANKS model was designed to estimate emissions for specific liquids being stored. Once specific tank and fluid properties are entered, the model uses AP-42 methodology and emission factors to calculate total losses in lbs. per year. The Texas Natural Resource Conservation Commission (TNRCC) provided the database of tanks within the AACOG Region.

Methodology

To effectively estimate losses from the petroleum storage tanks within the AACOG Region without entering all 9,000 active tanks into the model, categories were defined. The database of storage tanks was culled to remove tanks at gas stations, diesel tanks, empty tanks, tanks abandoned in place and tanks removed from the ground (for USTs). Emissions for gas stations were calculated in the Gasoline Distribution section. All tanks remaining in the database were then sorted by volume and substance stored in order to allow for further categorization.

The next categorization consisted of identifying volumes that would provide good specifications to estimate emissions for a range of volumes. For example, if storage tanks with capacities of 500 gallons and 1500 gallons were chosen, then losses from the tank with a 500-gallon capacity would be used to estimate emissions for all tanks with a volume of up to 500 gallons. Losses from the tank with a volume of 1500 gallons would then be used to estimate emissions for tanks with a capacity greater than 500 and less than or equal to 1500 gallons. These categories were spaced out over the range of volumes for each type of fuel.

Specific tank properties are required to be able to effectively run the TANKS model. The database made available by the TNRCC did not detail all properties required. Properties required by the model include tank height, throughput, turnovers, diameter, color, roof type and radius, whether or not the tank is heated and pressure settings. The TANKS model contains defaults for color, condition and pressure settings. TNRCC provided a formula that helped to define tank dimensions. To estimate throughput, total gas sales for the region was divided by total volume of above and under ground storage tanks. This yielded a turnover rate of fifty-two times per year. To arrive at a throughput value, the volume for each respective volume category multiplied the turnover rate by the TANKS model. The throughput value for other fuels was assumed to be equal to that of gasoline. Because little or no information existed on the turnover of new and used oils, a value of four was assigned, assuming one turnover per weather season of the year. All vertical tanks were assumed to be fixed roof tanks with dome shaped roofs.

Once a report was generated via the TANKS model, a spreadsheet of the categories and losses for each category was made. To be able to account for losses due to the volume of each tank within the region, the capacities of all tanks storing gas were added to determine total volume for each of the categories. Once total volume was determined, dividing the total volume by the representative volume for each respective category derived the number of tanks per category. To yield total losses within the region, losses from representative tanks were multiplied by the number of tanks within each category.

The database of storage tanks made available by the TNRCC did not contain information as to the exact location of each tank. An attempt was made to cross-reference each tank with a database of owners of tanks within the AACOG region. Unfortunately, the owner file only contained the owner’s main address, not the location of the actual tank. To assign emissions to each county within the region, gas sales within the region were used to estimate total volumes within each county as a function of percentage of total gasoline sales within the twelve county area.

Sample Calculation:

To yield turnover and throughput rates, total gas sales for the region were divided by total gas tank volume for the region. Total gas tank volume = 16,488,370 gallons. Total gas sales for the region = 863,149,225 gallons.

863,149,225 gallons / 16,488,370 gallons = 52.34 turnovers per year.
This value was rounded to 52 turnovers per year.

To yield throughput values, turnover was multiplied by representative volume for each category.

52 turnovers * 2000 gallons = 104,000 gallons/yr.

To calculate tank dimensions, TNRCC provided the following formulas.
Radius R = cube root of (Volume/15 pi) for vertical tanks; height is equal to diameter. R = cube root of (Volume/30 pi) for horizontal tanks; length = 4R.

Examples:	Vertical tank with a volume of 2000 gallons
	R = cube root (2000/15 pi) = 3.5 ft
	Height and diameter = 7 ft
	Horizontal tank with a volume of 2000 gallons
	R = cube root (2000/30 pi) = 2.8 ft
	Diameter = 5.6 ft, length = 11.2 ft

To estimate emissions

Example: Emissions for all ASTs with a volume of up to 1,250 gallons storing gasoline.
Representative Tank ID- # 154023, volume = 1,250 gallons, losses = 0.001017 tons per day.
Total volume within the category = 7,500. Tanks per category = 6.

0.001017 tons per day * 6 tanks = 0.006100 tons per day from tanks within this category.

To estimate emissions by county

Example: Bexar County

Percentage of total gas sales for the region that Bexar county is responsible for = 79.36%
Total Emissions from ASTs storing gas = 2.0365 tons per day.

Emissions in Bexar County = 79.36 * 2.0365 = 1.6161 tons per day from ASTs storing gasoline.

Notes:

Julie Farland, 1999. Texas Natural Resource Conservation Commission. Austin, Texas.

U.S. Environmental Protection Agency; AP-42: Organic Liquid Storage Tanks. Chapter 7, Section 7.1. Research Triangle Park, North Carolina.

TANKS 4.0 Emissions Estimation Software.

 

Automobile Body Incineration

Autobody incineration can be used as a means of disposal of out of use automobiles and automobile parts that would otherwise occupy landfill or junkyard space. An attempt to acquire information regarding autobody incineration in this region via the appropriate SIC codes yielded no results. The practice of autobody incineration is not currently practiced within the AACOG Region. Consequently, no emissions were calculated for this category.

 

Fires

Fires are a source of pollutants with the potential to produce large amounts of emissions over a short period of time. The category of fires is broken into the following four sub-categories: structure, residential, vehicle and open. Activity data for Bexar County was obtained through a Fire Profile Report from the National Fire Data Center.¹ Data for surrounding counties in the AACOG Region was obtained by extrapolating figures for individual counties, based on a per capita percentage of fire activity throughout the state of Texas.² Activity for all categories of fires was seven days a week.

 

    Structure Fires

Structures are traditionally classified as either residential or non-residential. For the purposes of this emissions inventory, all non-residential structures will be referred to as structure fires and all residential structure fires will be referred to as residential fires and will be covered later in this section. Fuel loading estimates are necessary to convert the number of fires into a value compatible with emission factors, which are based upon the total weight of material burned. A lack of satisfactory data pertaining to square footage for both structures in general and structures involved in fires led to the need for alternative methods of calculating emissions. A fuel loading factor of 1.15 tons per structure fire was used as well as a methodology developed by the California Air Resources Board (CARB).³

Sample Calculation:

VOC (Tons per Day) for Bexar County = 1533 fires *0.0055* 1.15/365 = 0.026565 tons/day

Where 1533 equals the number of fires, 0.0055 tons is the emission factor for VOC emissions per fire, 1.15 is the fuel loading factor (CARB) and 365 is the number of activity days per year.

    Residential Fires

The availability of average square footage data for residences in the AACOG Region allowed for a more detailed estimation of emissions resulting from these fires.⁴ A fire count for Bexar County was made available through the San Antonio Fire Department.⁵ Fires in surrounding counties were estimated by the alternative method mentioned in the overview of the Fires category. The fuel loading factor is based upon an estimate for combustible structural materials and building contents per floor space for a typical residence. CARB’s estimates are: 16.3 pounds per square foot for combustible structural mass and 7.91 pounds per square foot of combustible building content. Also figured into calculations is the CARB estimate of average loss rate, which is 7.3% of combustible structural content. Pounds are then converted to tons in order to yield tons per day.

The formula for Fuel Loading is:

Fuel Loading = (Combustible Structural Materials + Combustible Building Contents) * (Loss Rate)

Sample Calculation:

Combustible Structural Material = (16.3 lbs./sq. ft.* 1593 sq. ft.)/2000 lbs./ton = 12.98295 tons/sq. ft.

Combustible Building Content = (7.91 lbs./sq. ft.* 1593 sq. ft.)/2000 lbs./ton = 6.300315 tons/sq. ft.

Fuel Loading = (12.98295 tons/sq. ft. + 6.300315 tons/sq. ft.)* (0.073) = 1.4076783 tons/ fire

Actual Emissions/Day = (emission factor * activity * fuel loading) activity days/yr.

VOC (tons/day)= (0.0055*1209 fires*1.14076783 tons/fire) /365 days/yr = 0.026565 tons VOC/ day

    Vehicle Fires

Data concerning vehicle fires in Bexar County was gathered through the National Fire Data Center. Numbers for vehicle fires in the surrounding counties were estimated based on population, as listed in the EIIP, Volume III, as an alternative method. To determine fuel loading, an estimate must be made on how much material burns in a vehicle fire. The estimate used for this parameter is that each vehicle contains approximately 500 pounds (.25 tons) of material that can burn in a fire, based on the average weight of a vehicle being about 3,700 pounds (CARB, 1995).

Sample Calculation:

The emission factor for VOC is 4 lbs./ton burned (EPA,1996) Converting to tons, 4/2000 = 0.002 tons.

Tons NOx/day	= (Activity * fuel loading * Emission Factor)/ 365 days/yr.
	= (1723 fires * 0.25 tons/fire * 0.002 tons VOC)/365 days/yr.
	= 0.0094425 tons VOC/ day resulting from vehicle fires.

    Open Burning

Data concerning the open burning of residential and commercial solid waste is in very short supply. This led to the use of alternative methods in order to estimate emissions from open burning in the AACOG Region for the target year of 1996. According to current regulations, counties with a population less than 30,000 are not responsible for providing waste collection services. In these counties, residents must handle disposal of their waste by: transporting waste to regional landfills, contracting haulers individually, landfilling waste on their property, or burning household waste on their property. The practice in the AACOG Region⁶ however, holds that approximately 28 percent of the population in counties with a total population under 30,000 do not landfill their solid waste. Figures were also calculated for Atascosa and Medina counties, which have populations over 30,000 by only a small margin. This figure will be used to determine the amount of household solid waste burned in the AACOG Region.

Estimations of emissions from the burning of commercial waste in rural areas were made using EPA Guidance.⁷ Following the method used for residential solid waste, open burning is assumed to take place only in rural areas.

Sample Calculation:

CO emissions in Frio County resulting from open burning of solid waste.

Residential

(0.0043 tons/day ⁸) * 4183 households = 17.9869 tons of combustible waste per day

17.9869 tons/day * 0.285714 ⁹ = 5.1391091 tons of waste burned/day

CO = (5.1391091 tons waste burned/ day)x(0.0425 tons CO/ ton waste burned ¹⁰) = 0.2184121 tons CO/day

Commercial

0.024 tons commercial waste burned per capita ⁷ in rural areas.

Population in Frio County = 14641

Tons commercial waste/yr burned in Frio = .024 * 14641 = 351.384 tons

CO = (351.384 tons/yr) * (.0425 tons CO/ ton waste burned)/(365 days) = 0.040914575 tons CO/day

TOTAL CO = (0.2184121 tons CO/day) + (0.040914575 tons CO/day) = 0.25932714 tons CO/day

 

    Slash and Prescribed Burning

Slash and prescribed burning are primarily of use as forest management tools. These entail the deliberate burning of waste logs and underbrush in order to prepare land for the planting of new trees. Emissions for slash and prescribed burning were not calculated because of the lack of valid information from any state or federal agency.

 

    Orchard Heaters

Orchard heaters are used to prevent frost damage to fruit and fruit trees. The heaters are used to keep ambient temperatures within the accepted range of temperatures in which fruit production can be optimized.

After consulting agricultural agents in the outlying counties of the AACOG Region, it was found that orchard heaters were not in use and therefore, no emissions were calculated for this category.

Notes:

¹ This information was gathered at http://www.usfa.fema.gov/nfirs/

² Fires in county = Fires in state* county population/ state population. This method is listed as the first alternative method in EIIP Volume III.

³ This method is listed in EIIP Volume III and is derived from the CARB Emission Inventory Procedure Manual, Vol. III: Methods for Assessing Area Source Emissions, developed by the California Environmental Protection Agency: Air Resources Board.

⁴ Numbers for Bexar: US Dept of Housing and Urban Development, 1995. Numbers for surrounding counties: US Census Bureau, 1995.

⁵ San Antonio Fire Department; Responses by Type http://www.ci.sat.tx.us/safd/FDRESPONSESbytype.html

⁶ Solid Waste Management in the AACOG Region, 1990-2010. 1993 Update, financed by the Texas Natural Resource Conservation Commission.

⁷ U.S. Environmental Protection Agency. Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone: Volume I: General Guidance for Stationary Sources. Triangle Research Park, North Carolina.

⁸ Total combustible waste generated per household, EPA – Generation of Household Waste, 1997.

⁹ Percentage of households in rural AACOG Region not landfilling waste, Solid Waste Management in the AACOG Region, 1993 Update.

¹⁰ Emission factor from EIIP Volume III.

 

Explosives Detonation

Explosives are chemicals capable of extremely rapid combustion resulting in explosion or detonation. Carbon monoxide is the primary pollutant produced by the detonation of explosives. Nitrogen oxides are also formed, but only very limited data is available on these emissions. The emissions to be calculated deal mainly with the detonation of industrial explosives and firing of small arms. The major source of industrial detonation of explosives within the AACOG Region is the mining and quarry operation industry and will be covered in the point source databse. Military bases within the region do perform detonation of explosives and firing of small arms, but military applications are excluded from this discussion. The overlap with mining and quarry operations as well as a lack of information regarding the firing of small arms by private citizens resulted in no emissions being calculated for this category.

 

Catastrophic/Accidental Releases

Accidental spills and releases of petroleum products or other chemicals can come from sources such as tanker trucks, refueling stations or ruptured pipelines. Factors affecting emissions include the type of fuel or petroleum product and the time taken to clean up the spill (if cleaned).

Information on spills in the region was acquired through the Texas Railroad Commission . Information provided categorized spills by material and amount. Also given were location, date, company and type of clean-up effort.

Methodology

Once amounts for each spill are acquired, an estimate must be made on how much of the spill will be lost to evaporation. Estimates are that 10% of crude lost will evaporate, 20% of gas well liquid (condensate) will evaporate, and 100% of gasoline and diesel will evaporate. The number of gallons lost will be multiplied by an emission factor made available from AP-42. These factors are in pounds per gallon, based on the density of the material spilled. The pounds will then be converted into tons per day. The seasonal adjustment factor is 1 and activity is seven days per week.

Sample Calculation:

In 1996, 722 gallons of crude were spilled in Frio County. The following formula was used to illustrate the method described above.

Emission =((gallons spilled) * ( percent evaporated) * (emission factor- in tons/gallon))/365 days.

Tons/day VOC in Frio	= ((722 gallons of crude) * (0.1) * (0.0035))/365 days
	= 0.000692329 tons/day

Catastrophic/Accidental Releases Summary

During 1996, the study area had 2,255 gallons of VOC containing materials spilled. This yielded 0.000762329 tons VOC per day. See the corresponding table for totals by county for spills and resulting emissions for 1996.
Belinda Wolf, Texas Railroad Commission, Environmental Services. (512) 463-3296

 

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