CHAPTER 2 - NON-ROAD EMISSIONS

1996 Emission Inventory for the Alamo Area Council of Governments Region

 

Non-Road Emissions Chapter Contents

    Recreational Boating
    Recreational Vehicles
    Railroads
    Agricultural Equipment
    Logging Equipment
    Equipment Sources
           Residential Equipment
               AACOG Survey Research Project
               AACOG Residential Consumer Telephone Survey
           Light Commercial Equipment
           Industrial Equipment

Recreational Boating

Estimation of emissions from recreational boating activity in the AACOG Region is made difficult because the region contains very little water surface area (~76 square km.) with respect to the entire state of Texas (~6560 square km.). Proximity to Coastal Waterways further complicates estimation of recreational boating emissions within the AACOG Region, as many boaters may be registered and reside within the region, but may choose to do their boating either outside the region or on coastal waters. In addition to these problems, no agency closely monitors boating activity within the state of Texas, resulting in a lack of useful information on the subject.

Only five of the twelve counties within the AACOG Region have waterways compatible with recreational boating. Emissions resulting from recreational boating exist in Bexar, Bandar, Comal, Guadalupe, and Medina Counties.

Methodology

Recreational boating emissions were calculated by the Environmental Protection Agency for all non-attainment areas in Texas with the exception of the Dallas/Fort Worth non-attainment area. The North Central Texas Council of Governments (NCTCOG) used figures for Harris County, Texas to extrapolate emissions based on population. Calculation of emissions for the AACOG Region will mirror these methods, along with EPA approved revisions, as used by the NCTCOG.

Total emissions for Harris County were divided by the population of Harris County and then multiplied by the total population of the AACOG Region. This yielded total emissions figures by pollutant of VOC 5180.99 tons/yr., CO 13617.83 tons/yr., and NOx 205.31 tons/yr., for the entire region. This method greatly overestimated emissions for some of the counties whose surface waters may not be sufficient enough to provide recreational boating activity. To alleviate this, counties were allocated a "water fraction", based upon the square kilometers of water surface area located within the county, with respect to the total water surface area of the AACOG Region.

Sample Calculations

Emission values for boating categories, by pollutant, for Harris County in 1990 were as follows:

The population in Harris County for 1990 was 2,818,199; the population for the AACOG Region in 1996 was 1,712,331. Thus, extrapolating the Harris County numbers to the AACOG Region:

As mentioned above, total emissions for the AACOG Region were 5181 tons/yr. VOC, 205 tons/yr. NOx, and 13618 tons/yr. CO. To extrapolate emissions figures for each county, a "water fraction" has to be allocated. Bexar County has a total of 19.90 square kilometers of water surface, or 0.261 (~26%) of the 76.29 total square kilometers of surface water for the AACOG Region. Seasonal adjustment was one. Days of activity per week was seven.

Sample Calculations for Bexar County are as follows:

Spatial Allocation

Recreational Boating Emissions were allocated based on the percent of lake surface area in each grid cell. River surface area was not used in the spatial allocation because there are few boats that use the rivers. Therefore, only lake surface area was used in the calculation.

Notes:

North Central Texas Council of Governments (NCTCOG), 1994. "Emissions Inventory Report", EIIP Technical Report, Volume IV. Dallas, Texas.

 

Recreational Vehicles

The recreational vehicle category consists of emissions produced from equipment used in recreational activities. All terrain vehicles, golf carts, and specialty vehicle carts are included in this category. Emissions estimates for the AACOG region were produced for each of these types of equipment.

Methodology

Recreational equipment emissions within the 12-county AACOG region were calculated through the use of the EPA's Non-road Emission Inventory Model. This model can be used to estimate past, current, and future inventories for most non-road equipment categories. It can produce emission estimates for all criteria pollutants, as well as carbon dioxide, down to the county level.

The model contains several parameters that can be adjusted to fit desired scenarios. For the purposes of this emissions inventory, the following parameters were used to produce a separate run for each county in the AACOG region:

Example Data for Atascosa Weekday

These parameters were used for each county to produce an emissions report, in tons/day on a typical weekday, for each type of non-road equipment. A separate set of reports was run for each county for a typical weekend day. Annual emissions were calculated by multiplying the typical tons/day emissions by the number of weekdays, and weekend days in 1996.

Notes:

The Environmental Protection Agency's Non-road Emission Inventory Model.

Gary Dolce, Greg Janssen, Richard Wilcox, December 1998. Geographic Allocation and Growth in EPA's NONROAD Emission Inventory Model. U.S. Environmental Protection Agency, Triangular Research Park, North Carolina.

 

Railroads

Diesel-electric locomotives use a diesel engine and an alternator or generator to produce the electricity required too power the traction motors. Emissions produced by these diesel engines include hydrocarbons, carbon monoxide, nitrogen oxides, sulfur dioxide, and particulate matter.

Methodology

Railroads can be separated into three classes based on size: Class I, Class II, and Class III. Locomotives within each of these classes can perform two different types of operations: line haul and yard (or switch). Class I represents the type of railroad system in our region of study. Two steps are necessary in order to assess locomotive emissions within an inventory area. First, railroad operations are separated into two distinct categories: class I line haul and yard operations. Second, emissions for each pollutant are calculated for each of the categories using the recommended methods described in section 6.2 of Procedures for Emission Inventory Preparation Volume IV: Mobile Sources.

For Class I line haul locomotives, emissions are calculated by multiplying the amount of fuel consumed in the inventory area by the appropriate emission factors.

The recommended method for yard locomotives is different from the method used for line haul locomotives. Multiplying the number of yard locomotives operating within the inventory area by the amount of emissions generated by each unit during the year proved most effective.

The following are the assumptions used in deriving the fuel consumption data:
  1. The fuel consumption factors used were 1.367 gallons per 1000 gross ton miles (GTM) for Union Pacific Railroad and 1.592 gallons per 1000 GTM for Southern Pacific Railroad. These are system average fuel consumption factors for the respective railroads for 1996.
  2. Gross Ton Miles used to calculate the fuel consumption includes locomotive weight.
  3. The equation used in calculating the fuel consumption for line haul locomotives is GTM x Fuel Consumption Factor x miles of track in segment.
  4. Fuel consumption for switching operations was calculated based on an equivalent number of locomotives operating 24 hours per day, 365 days per year (Union Pacific Railroad Company).
Railroad emissions were only counted in counties were railroads exist and are active. The following counties were included in the emissions inventory: Atascosa, Bexar, Comal, Frio, Guadalupe, and Medina.

Notes:

U.S. Environmental Protection Agency, 1992. Procedures for Emission Inventory Preparation. Volume IV: Mobile Sources. Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.

Union Pacific Railroad Company, 1998. Letter and data received from Glenn Thomas, Director, Environmental Field Operations - Southern Region. Omaha, Nebraska.

Spatial Allocation

Railroad emissions for Class 1 Line haul were spatial allocated based on the location of active railway lines in the AACOG region. The railway geographical cover was carefully examined to determine if there were any railway lines that were no longer active. Once the inactive railway lines were removed from the covered, the amount of railway miles in each grid cell was calculated. Emissions were applied based on the percentage of railway line miles in each grid cell. Yard locomotive emissions we allocated based on the percentage of railway sidings in each grid cell.

 

Agricultural Equipment

Purposes of the Agricultural Emissions Inventory

The agricultural emissions inventory was designed to accomplish two goals:

  • Determine the total agricultural emissions for each county in AACOG's twelve county area for the year 1996.
  • Provide the mechanism to determine the representative emissions which would occur on any given day in a specified month within a given grid square for processing in the photochemical model.

The Photochemical model for the region required data from Atascosa, Bexar, Comal, Frio, Guadalupe, Karnes, Medina, and Wilson counties placed into each four kilometer grid cell as established by the Texas Natural Resources Conservation Commission (TNRCC). This emission inventory is designed to estimate agricultural emissions for the 1996 Net inventory and for a photochemical modeling episode for our region.

Data Gathering Methodology

The methodology employed was a bottom-up approach where the Texas Agricultural Extension Service County Extension Agent in each of the above counties and the United States Department of Agriculture Farm Service Agency (USDA/FSA) director met with the AACOG staff in the Farm Service office. AACOG prepared a map of each county generated by the AACOG GIS computer system containing the county road network together with cities, rivers, creeks and lakes. These features were necessary to orient the location of each grid cell to its location on the aerial photographs. The map was then overlaid with the state-wide UAM four kilometer grid system with each grid cell marked with it's unique numerical identifier.

The USDA/FSA maintains a complete set of aerial photographs of each county in 1:40,000 scale flown in a north to south direction with each print enlarged to approximately four square feet. The photographs were arranged in a grid system which closely matched the UAM grid system making it relatively easy to relate the land usage in a photograph directly to each UAM grid square.

The aerial photograph was first matched to its corresponding grid square and the grid square boundaries established. Next, the County Agent and Director of the Farm Service Agency identified all agricultural activity ongoing in the aerial photograph using the field notes posted on the photographs and their extensive knowledge of the farm acreage and the crops cultivated to estimate the percent of land in each grid square being cultivated for:

  • Sorghum
  • Small Grains
  • Corn
  • Hay
  • Peanuts
  • Vegetables
  • Cotton
  • Other Crops (orchards, plant nursery's, etc.).
Additionally, estimates were made for each of the following which when added to the crop information gives a complete of the land usage in each grid square. The additional land uses estimated are:
  • Urban development
  • Range land - land left unimproved from its native condition, and
  • Water - lakes.
Another technique available in counties where the soil type survey had been completed, was locating a Farm Service Agency Soil Interpretative Map of the county which was almost exactly the same size as the AACOG generated grid map. With the AACOG map overlaid on the soil interpretive map it became relatively easy to determine the location of known farming operations within each grid square and the exact crops cultivated within one percent of the four kilometer grid.

When necessary, a square template was cut with the inside made the exact size of the four-kilometer grid square by sized to the scale of the aerial photographs. The template could be easily oriented upon the aerial photograph and only the contents of the grid square being surveyed in view. The aerial photographs were frequently marked with the cultivated fields, their size and case number making it easy for the agents to identify both the size of the cultivated fields and the crops grown on them.

The small grains, sorghum, corn and cultivated fields were first identified and sized, followed by hay meadows, then any special use land such as urban or water, and after all cultivated used defined, the remainder was determined to be "unimproved rangeland." The County Agent and the Resources Conservation Agent were almost always in agreement as to the size and use of fields.

As they determined the composition of each grid square they would dictate their estimate to a recorder who would enter the data into an Excel file such as the one below:

Typical Agricultural Grid Data Cell

Cell Number   29-48  
Range 0.85
Corn 0.10
Hay  
Peanuts  
Sorghum 0.05
Vegetables  
Cotton  
Small Grains     
Urban  
Water  

In the cell above, the agricultural activity report shows 10% of the land in cell 29-48 was in corn production, 5% was in sorghum production, and the remainder 85% was not producing any commercial crops and was called "Range" as a default to ensure 100% of the land was accounted for.

Agricultural Activity

Agricultural activity involving the in-field use of farm machinery is linked to the crop being raised which determines what specific activity is required and the South-central Texas climatology determines in which month each specific cultivation activity will usually occur. Each cultivation activity in this report was determined from the consensus of the agricultural experts based on their observations of farm activity over approximately the last 20 years. The following table described the historical cultivation activity for each crop on this region.

Typical Agricultural Activity by Month for the AACOG Region

Agricultural Activity
  Crop     Plow     Plant     Fertilize     Cultivate     Harvest  
Corn Dec Feb Feb-Apr Apr Jul
Hay Jan Mar Apr N/A Jun-Aug
Peanuts Apr Jun N/A N/A Sep-Nov
Small Grains Sep Oct-Dec Jan N/A May
Sorghum Jan Apr Mar May Jul
Vegetables Activity is year around
N/A = Not Applicable

The agents were then asked how many acres the average farmer could cover in one hour doing the plowing, planting, fertilizing, cultivating and harvesting operations. The following table describes the time required to complete one acre of agricultural activity for each crop. These rates reflect the size, horsepower, and number of rows tilled by the typical tractor and combine in this region.

Average Rate to Accomplish Each Agricultural Activity in the AACOG Region

Agricultural Activity
  Crop     Plow     Plant     Fertilize     Cultivate     Harvest  
Corn 4 acres/hr 4 acres/hr 25 acres/hr 4 acres/hr 3 acres/hr
Hay 6 acres/hr 8 acres/hr N/A N/A 6 acres/hr - cut
12 acres/hr-rake
2 acres/hr - bale
Peanuts 5 acres/hr 5 acres/hr N/A 8 acres/hr 1 acres/hr
Small Grains 6 acres/hr 8 acres/hr N/A N/A 3 acres/hr
Sorghum 4 acres/hr 4 acres/hr 25 acres/hr 4 acres/hr 3 acres/hr
Vegetables Most work done by hand or small equipment
Cotton No significant cotton produced in these counties
N/A = Not Applicable

Off-Road Agricultural Equipment Inventory

The off-road agricultural equipment used to perform the operations was first identified in the 1997 USDA Census of Agriculture, Texas State and County Data, Volume 1. This data was discussed with the county agent in each county to determine the engine size of the tractor/combine, the fuel used, and the approximate age of the vehicle. The agents reported that agricultural tractors/combines are either six or eight row equipment, predominately six row. For this study, using six row equipment was judged to best represent the farming practices in the counties surveyed.

Off-Road Agricultural Equipment Emission Factors

The emissions factors for this equipment were obtained from the U.S. EPA Office of Mobile Sources, Assessment and Modeling Division Report No. NR-009A dated February 13, 1998 and revised June 15, 1998. The average engine size was just over 50 horsepower (HP), diesel fueled, and manufactured between 1988 and 1997. The emissions per hour values from the table were hydrocarbons (HC) 0.99, carbon monoxide (CO) 3.49, nitrous oxides (NOx) 8.30, and particulate matter (PM) 0.72. Listed below are the emissions per hour values for combine use. These were used in calculating the resulting emissions for each grid cell.

Integrating the Data Elements

The relationship between the number of acres in any crop and the time it takes to perform the agricultural operation remains fairly constant. If a second piece of equipment is used, the time is reduced by 1/2. The basis for this estimation is then the number of acres in production of each specific crop type and the equipment size and use rate multiplied by the average equipment and fuel source to arrive at the off-road agricultural engine emissions produced in each grid square. The cell emissions can then be summed to produce the county agricultural off-road emissions.

Sample Calculation:

A mathematical model was developed to process the data and factors in the following manner:

  1. The percent of land in each crop category (small grains, corn, etc.) is multiplied by 3,953.68 to determine the number of acres for that crop in the specific grid cell.
  2. The number of acres is then divided by the hourly rate required to perform each agricultural activity (plowing, harvesting, etc.) to determine the number of hours each piece of farm equipment is used in the grid cell.
  3. The number of hours in use is then multiplied by the EPA emission factors for HC, CO, NOx, and PM, for both tractor and combine, to determine the emissions in each grid cell.
  4. The emissions from both tractor and combine are summed to total the yearly emissions for each grid cell, and then summed to determine the yearly county emissions.
  5. The Agricultural Activity Table can be used to determine the month(s) in which any particular agricultural activity is being performed and those emission factors separately totaled to determine emissions within any specific month.
  6. After emissions are summed they are then converted from lbs. to tons.
  7. Hydrocarbon emissions are then converted to VOC numbers by multiplying by 1.005, as suggested by Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources.
  8. 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.
The following tables visually represent the mathematical model. The first table begins with the crop, its percentage of the grid square converted into acres, then the application of the hourly activity rates resulting in the hours of equipment use.

Sample Spreadsheet Model to Convert
Percent of Grid to time by Agricultural Activity

CropPercent of GridAcresTime in Hours / PlowTime in Hours / PlantTime in Hours / CultivateTime in Hours / FertilizeTime in Hours / Harvest
Range903558.3100000
Corn10395.3698.898.898.815.81131.77
Hay0000000
Peanuts0000000
Sorghum0000000
Vegetables0000000
Cotton0000000
Small Grains0000000
Urban0000000
Water0000000
TOTALS1003953.6798.898.898.815.81131.77

The resulting hours (in this case 312.2 hrs for tractor and 131.77 hrs for combine) are then multiplied by the equipment specific emissions rates as determined by the EPA and are visually shown below:

Sample Spreadsheet Model to Multiply Activity Times by Emission Factors to produce Total Emissions (Tractor Emissions)

Tractor Emission Factors g/hp-hrTotal Emissions
 HCsNOxCOVOCsNOxCO
Range (90%)000000
Corn (10%)0.688.32.70.111.300.42
Hay0.688.32.7000
Peanuts0.688.32.7000
Sorghum0.688.32.7000
Vegetables0.688.32.7000
Cotton0.688.32.7000
Small Grains000000
Urban000000
Water000000
312.2 hrsTons Per Year0.111.300.42

100hp Tractor Emission Factors g/hp-hr50-100hp Combine Emission Factors g/hp-hr
HCsCONOxPMHCsCONOxPM
0.6802.7008.3800.4020.9903.4908.3000.722

Notes:

U.S. Environmental Protection Agency, 1992. Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources. Research Triangle Park, North Carolina.

U.S. Department of Agriculture, National Agricultural Statistics Service, 1999. 1997 Census of Agriculture, Texas State and County Data, Volume 1, Geographic Area Series. Washington, D.C.

U.S. Environmental Protection Agency, 1999. CFR Part 86 and Part 89, Certification Guidance for Heavy Duty On-Highway and Non-road CI Engines.

 

Construction Equipment

This category consists of emissions produced from equipment used in construction activities. Emission estimates for the AACOG region were calculated for diesel, 2-stroke, and 4-stroke vehicles in the following categories of construction equipment:

These are the categories used in the EPA's Non-road Emission Inventory Model.

Methodology

The methodology used in producing construction equipment emission estimates for the AACOG region is based on the methodology used by the North Central Texas Council of Governments. The methodology involves:

  1. Determining county equipment populations for each category. This is accomplished by apportioning national equipment populations down to the county level through the use of a county construction employment to national construction employment ratio.
  2. Estimating HC, NOx, and CO annual emissions by multiplying the county equipment populations by the average annual hours of use, average rated horsepower, typical load factor, and emissions factor for each type of equipment. Hydrocarbon emissions are then converted to VOC numbers by multiplying by 1.005, as suggested by Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources. A 1995 commercial environmental impact survey of eight counties in the twelve county AACOG region was used to provide annual hours of use and average rated horsepower for ten of the construction equipment categories.
  3. Converting the tons/year estimate into an estimate for a typical weekday (tons/day), and a typical weekend day (tons/day) for the summer or ozone season. The 1995 survey was also used in this step to provide percentages of construction activity that occurs during the week and on weekends.
Annual Emissions

As outlined above, the first step in this process is the estimation of county equipment populations for each category. These populations were estimated through the use of a county construction employment to national construction employment ratio. The populations for each county were calculated based on the following formula:

Sample Calculation:

The 1996 U.S. equipment population of diesel powered cranes was 94,312. National construction employment for 1996 was 5,206,925, and 1996 construction employment in Bexar County was 29,799. Using this information, an estimate of diesel powered cranes used in Bexar County can be calculated as follows:

Diesel Cranes in Bexar County =

National equipment populations for 1996 were obtained from EPA’s Non-road Emission Inventory Model. County employment numbers for 1996 were obtained from the Texas Employment Commission. National employment numbers came from Census Bureau’s 1996 County Business Patterns.

Once county level equipment populations were calculated, emissions of volatile organic compounds (VOC), nitrogen oxides (NOx), and carbon monoxide (CO) were calculated for each category using the following formula:

County equipment populations were obtained from the first step. A 1995 survey of eight counties in the twelve county AACOG region was used to provide local values for annual hours of use (HRS), and the average rated horsepower (HP). This survey provided these values for the following equipment:

Local annual hours of use (HRS) and the average rated horsepower (HP) were calculated by averaging all of the survey results for each type of equipment.

In the absence of reliable local data, the values for HRS, HP, LF, and EF were obtained from the EPA. Annual hours of use (HRS) were obtained from the EPA’s Non-road Emission Inventory Model, while the remaining factors, HP, LF, and EF were obtained from the EPA Non-road Engine and Vehicle Emission Study (NEVES) Report (1991). This report includes HP and LF estimations for two inventories, inventory A, and inventory B. Inventory A consists of commercial and publicly available data while inventory B consists of industry data provided to the EPA that is not publicly available. For HP and LF, averages of the values for inventories A and B were used.

Emission factors (EF) for 2-stroke, 4-stroke, and diesel powered equipment were also obtained from this report. Only one EF value for diesel powered equipment was given for each equipment category, while two sets of emission factors were given for gasoline powered equipment. The first set of emission factors was not adjusted for in-use effects. These emission factors are almost exclusively based on tests of new engines. The second set was estimated to include in-use effects such as engine malfunctions, improper maintenance, and engine wear. The second set of emission factors was considered to best represent the equipment in the study. For this reason, the second set of emission factors for gasoline powered construction equipment was used.

Sample Calculation:

Continuing with our example used above, there are an estimated 539.74 diesel powered cranes in Bexar County. Using the 1995 AACOG equipment survey, these cranes are operated an average of 735 hrs/year (HRS), and have an average rated horsepower (HP) of 136.7. From the 1991 NEVES report, the typical load factor (LF) for these cranes is 0.43, and the emissions factor (EF) for carbon monoxide is 4.2.

This figure is then converted into tons/year by first converting the figure into kilograms, then pounds, and then tons.

(grams/year) / (1 kilogram/1000 grams) ( 2.204 lbs./1 kg ) (1 ton/2000 lbs.) = (tons/year)

Thus 97,973,062 (grams/year) = 108 (tons/year) of CO

This same procedure is then used for NOx and VOCs to produce estimates of these pollutants.

 

Summer Season Daily Emission Estimates

Summer season daily emissions were estimated for both weekdays and weekends using the following formulas obtained from the NCTCOG methodology:

The national default of construction activity occurring during the summer is 30%, according to the methodology used by NCTCOG.

For the percentages of construction activity that occurs on weekdays versus weekend days, the 1995 equipment survey for the AACOG region was used. The average hours of construction equipment use on weekdays and weekends was totaled and averaged. This survey estimates that 93.5% of construction activity occurs during the week for this region, with the remaining 6.5% occurring on the weekends.

Example:

Bexar County produced an estimated 11,119.34 (tons/year) of CO in 1996. The summer weekday and weekend day emissions can then be calculated as follows:

Spatial Allocation

Construction equipment emissions could be allocated to grid cells by plotting construction sites. The problem would be in locating the construction sites. One way this may be accomplished is by geo-coding the location and value of building permits. Building permits were plotted and then the value of construction was allocated to grid cells. Then construction equipment emissions were then allocated to each grid cell based on the estimated cost of the construction.

Notes:

North Central Texas Council of Governments, 1996. 1996 Emissions Inventory. Dallas, Texas.

The Environmental Protection Agency’s Non-road Emission Inventory Model

U.S. Environmental Protection Agency, 1992. Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources. Research Triangle Park, North Carolina.

U.S. Census Bureau, "National Construction Employment Statistics," 1996 County Business Patterns.

Texas Employment Commission. County Level Construction Employment Statistics. Austin, Texas.

U.S. Environmental Protection Agency, 1991. Non-road Engine and Vehicle Emissions Study Report (NEVES). Research Triangle Park, North Carolina.

Alamo Area Council of Governments, 1995. Commercial Environmental Impact Survey, San Antonio, Texas.

 

Mining Equipment

This category consists of emissions produced from equipment used in mining activities. In 1996, the AACOG region contained only one mining operation, the San Miguel Lignite Mine located in Atascosa County. Two uranium mines existed in Karnes County, but they were not operating in 1996. Therefore, emission estimates for the AACOG region were calculated for only the San Miguel Lignite Mine. The mine operates using the following types of equipment:

(2) Huron Easi Miners
(3) graders
(9) dozers		 (9) 90 & 110-ton coal haulers
(4) scrapers
(1) 12-m3 front-end loader

Methodology

The methodology used in producing mining equipment emission estimates for the AACOG region involves the following steps:

  1. Determining the average annual hours of use, average rated horsepower, typical load factor, and VOC, NOx, and CO emissions factors for each type of equipment used in the mining operations.
  2. Estimating VOC, NOx, and CO annual emissions by multiplying the equipment populations by the average annual hours of use, average rated horsepower, typical load factor, and emissions factor for each type of equipment.
  3. Converting the tons/year estimate into an estimate for a typical weekday (tons/day), and a typical weekend day (tons/day).
Annual Emissions

As outlined above, the first step in this process is the determination of the annual hours of use (HRS), average rated horsepower (HP), typical load factor (LF), and VOC, NOx, and CO emissions factors (EF) for each type of equipment used in the San Miguel Lignite Mine. These values for HRS, HP, LF, and EF were obtained from the EPA. The EPA has nonroad equipment grouped into several different types of equipment. In order to obtain these values from the EPA, the equipment used at the San Miguel mine had to first be matched with similar EPA equipment categories. The equipment used at the mine was grouped into the following EPA categories:

Categories for the San Miguel Lignite Mine.

San Miguel EquipmentEPA Category Used
2 Huron Easi Miners2 Diesel - Excavators
9 90 & 110-tonne coal haulers9 Diesel - Off-highway Trucks
3 Graders3 Diesel Graders
4 Scrapers4 Diesel Scrapers
9 Dozers9 Diesel - Rubber Tire Dozers
1 Front-end Loader1 Four-Stroke Rubber Tire Loader

Annual hours of use (HRS) were then obtained from the EPA’s Nonroad Emission Inventory Model for each category. The remaining factors, HP, LF, and EF were obtained from the EPA Nonroad Engine and Vehicle Emission Study (NEVES) Report (1991). This report includes HP and LF estimations for two inventories, inventory A, and inventory B. Inventory A consists of commercial and publicly available data while inventory B consists of industry data provided to the EPA that is not publicly available. For HP and LF, averages of the values for inventories A and B were used.

Emission factors (EF) for 4-stroke, and diesel powered equipment were also obtained from this report. Only one EF value for diesel powered equipment was given for each equipment category, while two sets of emission factors were given for gasoline powered equipment. The first set of gasoline powered emission factors was not adjusted for in-use effects. These emission factors are almost exclusively based on the tests of new engines. The second set was estimated to include in-use effects such as engine malfunctions, improper maintenance, and engine wear. The second set of emission factors was considered to best represent the equipment in the survey. Thus, the second set of emission factors for gasoline powered commercial equipment was used.

After obtaining the values for these variables, and grouping the San Miguel equipment into EPA categories, the next step in this process is producing emissions estimates. Mining equipment emissions of volatile organic compounds (VOC), nitrogen oxides (NOx), and carbon monoxide (CO) were calculated using the following formula:

Sample Calculation:

The San Miguel Lignite mine operates 4 diesel powered scrapers. According to the EPA’s Nonroad Inventory Emission Model, scrapers are used an average of 914 hours per year. From the 1991 NEVES Report, the average rated horsepower (HP) for these scrapes is 300.5, the typical load factor (LF) is 0.72, and the emissions factor (EF) for carbon monoxide is 5.0 grams/hp*hr.

Emissions (grams/yr.) for CO= EP * HRS * HP * LF * EF
= 4 * 914 (hrs/yr.) * 300.5 (hp) * 0.72 * 5.0 (g/hp-hr)
= 3,955,061 (g/year)

This figure is then converted into tons/year by first converting the figure into kilograms, then pounds, and then tons.

Thus 3,955,061 (grams/year) = 4.35 (tons/year) of CO.

This same procedure is then used for NOx and VOCs to produce estimates of these pollutants.

Daily Emission Estimates

Daily emissions were estimated for both weekdays and weekends using the following formulas:

Weekday emissions= Annual emissions x (% of commercial equipment use occurring on weekdays) / (the number of weekdays during 1996)

Weekend emissions= Annual emissions x (% of commercial equipment use occurring on weekend days) / (the number of weekend days during 1996)

There were 262 weekdays in 1996, and 104 weekend days. The San Miguel mine normally does not operate on weekends, so weekend emissions were not figured.

Sample Calculation:

Atascosa County produced an estimated 31.981 (tons/year) of CO in 1996 from mining equipment use. The weekday emissions can then be calculated as follows:

Spatial Allocation

Mining Emissions were allocated based on the location of the San Miguel mine. Then, the emissions were aggregated to the grid cell were the mine is located.

Notes:

Dolce, Gary, December 1998. Geographic Allocation and Growth in EPA’s Nonroad Emission Inventory Model. U.S. Environmental Protection Agency, Ann Arbor, MI.

The Environmental Protection Agency’s Nonroad Emission Inventory Model

U.S. Environmental Protection Agency, 1991. Nonroad Engine and Vehicle Emissions Study Report. Research Triangle Park, North Carolina.

 

Logging Equipment

Three different types of searches were conducted to determine if logging activities occurred in the 12-county AACOG region. One of these involved scanning a USEPA website that provides logging information geographically. The website indicated that logging in Texas is primarily restricted to the eastern side of the state; there were no logging activities listed for south-central Texas. Similarly, the U.S. Census Bureau's website lists no logging activities in the AACOG region. A final search was conducted using a list of businesses in the 12 AACOG counties. None of the Standard Industrial Codes for businesses in the region matched the SIC for logging.

 

Equipment Sources

The aim of the survey on residential equipment was to provide a foundation for methodological specifications that will allow for better assessments of the county-level activity emissions estimates from residential equipment. Residential equipment can be categorized as equipment operated in residential areas by commercial lawn care service providers as well as by private homeowners for the purpose of lawn and garden maintenance. Lawnmowers, rotary tillers, lawn and garden tractors, leaf blowers, and chainsaws are examples classified in this category. As far as contributing to air pollutant emissions, these mechanisms are major sources when aggregated.

The development of the San Antonio Household survey was based upon a model of the residential survey performed by Austin. Modifications to the survey were necessary to make it more applicable to our study area. The University of Texas at San Antonio (UTSA) was contracted to perform a random household survey. The contractors offered advice on demographic questions and the development of instructions for the surveyor. In order to be representative of the population in our study area, the survey was translated into a Spanish language version as well. UTSA requested a list of phone prefixes in the eight county study area in order to conduct the telephone survey. Students using the computer lab at UTSA performed the random household surveys.

Methodology

The following calculations were performed for each equipment type for Bexar County and each of the surrounding counties. The equipment types are leaf blowers, chainsaws, tillers, other lawn/garden equipment, 2 stroke push mowers, 4 stroke push mowers, and rear engine riding mowers. It is assumed lawn/garden equipment is used 28 weeks out of the year thus:

The results obtained for Bexar County were scaled by taking households surveyed in Bexar County and dividing by total number of households in the county. Results for each of the surrounding seven counties were scaled in the same manner by taking number of households surveyed in each of the seven surrounding counties divided by total number of households in each of the seven counties. The resulting scale factors were multiplied by the HC, CO, and NOx totals for each equipment type in Bexar and the surrounding counties.

Scaling Formula Example:

Bexar County:

Surrounding Counties: The percentage of households relative to the total number of households in the seven counties was calculated to apportion emissions to each of the seven surrounding counties.

Tons/ASD (avg. summer day) was determined by dividing HC, CO, and NOx totals for each of the counties by 196. The seasonal adjustment factor was calculated as follows:

Sample Calculation:

The annual emissions for the residential equipment was based on the standard emission formula:

Emissionsannual=  (Number of units * Load Factor * Hours * Emission Factor)
      * (HorsePoweravg horsepower assumed)

For example the leaf blower VOC emission calculation is shown below for Bexar County:

leaf blower hp/hr/yr. = leaf blower hr/yr. * avg. hp * Load Factor
= 2293 * 2 * .50
= 2293 hp/hr/yr.

VOC g/yr. subtotal = crank VOC + exhaust VOC + reference EF * leaf blower hp-hr-yr
= 452.11 + 0 + 6.61 * 2293
= 1,051,845 g/yr.

VOC g/yr. total = VOC g/yr. subtotal + evaporation Emission Factor * Number of units
= 1,051,845 g/yr. + 91 * 0.61
= 1,051,845 g/yr. + 55.51 g/yr.
= 1,051,900 g/yr.

Once the emissions totals for the seven counties surrounding Bexar County for the 1994 emission inventory were determined the emissions for the eleven surrounding counties were determined by their population ratio to the seven counties. For example:

The individual 11 county emissions were calculated based on population ratio of each county to the 11 county total.

For example:

Once the county tons/year was determined a tons/day was calculated with a seasonal adjustment factor.

For example:

The emissions of the counties for the year 1996 was calculated based on the ratio of 1996 to 1994 population from data provided by the Texas Water Development Board.

For example:

 

AACOG Survey Research Project

Sampling Design

The telephone sampling strategy was designed to provide an equal probability that households with telephones would be contacted. A sequence of over 9000 random four-digit numbers was generated. These numbers were assigned to three-digit phone prefixes in 38 "wire center" areas throughout the San Antonio area in proportion to the population in those areas, and to prefixes in the surrounding counties in proportion to the population in each county.

This type of random digit dialing generates many invalid, business, fax and never answered phone numbers, but it provides an equal likelihood of accessing all residential phones whether they are listed or unlisted. By making calls during weekday evenings, weekend days and periodic weekday afternoons, opportunities were available for all potential respondents to be included in the final sample. The table below provides an overview of the results of the total telephone calls made. Of the 1,506 contacts made, 774 produced a favorable response, for better than a 50% response rate. A total of 384 respondents were successfully 'interviewed in Bexar County and 390 interviews were completed in the surrounding counties.

Outcome of All Phone Calls Initiated.
ResponseNumberPercent
No Answer601766.4
FAX4444.9
Answering machine7248.0
Spanish-Called Back600.7
Call Back3143.5
Refused7328.1
Yes (Me or Other)7748.5
TOTAL8079100.1

The following tables detail the race and ethnic distribution of the individuals included in the analysis. The following table displays the information for the complete sample, the next table for Bexar County only, and the last table for the surrounding AACOG counties.

Survey Respondents Race/Ethnicity for Complete AACOG Sample.
Race/EthnicityNumberPercent
African American374.8
Hispanic19224.8
White51566.5
Asian70.9
Native American10.1
Other222.8

While Hispanics are underrepresented in this sample, this is typical of telephone survey data. The proportion responding to this survey is expected based on results from other telephone surveys. The higher proportion of Hispanics responding in Bexar county compared to the surrounding counties is consistent with Census information reporting a larger proportion of Hispanics residing in Bexar county.

Survey Respondents Race/Ethnicity for Bexar County.
Race/EthnicityNumberPercent
African American236.2
Hispanic12232.7
White21256.8
Asian41.1
Native American10.3
Other113.0

Survey Respondents Race/Ethnicity for Surrounding Counties.
Race/EthnicityNumberPercent
African American143.5
Hispanic7017.5
White30375.6
Asian30.8
Other112.7

Residential Consumer Telephone Survey

  1) Date
Date of Interview [JUST PRESS ENTER]
  2) Time Call
Time Call Begins [JUST PRESS ENTER]
  3) CallSheet
Call Sheet Number (Enter number from the top of the call sheet)
  4) Phone
Phone Number
  5) CallNumber
Number of attempts calling this phone number
  6) Speak

Hello, my name is ___________. I'm calling from the University of Texas at San Antonio's Survey Research Laboratory. We are performing a residential environmental impact survey for San Antonio and surrounding counties. We would like your help in finding out how local residents use lawn and garden equipment. This will help us design programs to reduce air and water pollution. It will take less than five minutes to complete the survey. Is there someone there age 18 or older who can answer questions about lawncare? IF PHONE IS ANSWERED IN SPANISH, SAY "Excuse me I have a wrong number." HANG UP AND GIVE THE NUMBER TO A SPANISH SPEAKER.

Hola, mi nombre as ___________. Estoy llamando desde la Universidad de Texas en San Antonio. Estamos haciendo un estudio de preguntas sobre el impact del media ambiente. Me gustaria su ayuda para saber como los residentes de San Antonio usan las maquinas de cortar el zacate (o hierbas). Esto nos ayudara a reducir la polucion del aire. Solo tardare unos minutos. ¿Podria contestarme estas preguntas?

7) housecomp
Do you live in a single-family home, a small multi-family unit, or an apartment complex?
¿Vive en casa de una sola familia, de mas que una familia, o un apartamento?

8) lawncare
This section of the survey is on gas-powered lawn and garden equipment:
    Who does most of the lawn/garden maintenance around your home?
Este parte de las preguntas son sobre maquinas para cortar al zacate (o hierbas) que usan gasolina:
     ¿En su casa, quien corta el zacate (o las hierbas)?

9) %lawnmx
What percent of your yard work involving gasoline-powered tools (lawnmower, leaf blower, chain saw, etc.) is done on the weekend? (INCLUDING BY PROFESSIONAL LAWN SERVICE)
¿Que porciento, cuando estas cortando el zacate con maquinas que usan gasolina, haces el fin de semana?

10) lawnmow
What kind of lawnmower is used at your home?
¿Que tipo do maquina usa usted en su casa para cortar el zacate?

11) fuel
For fuel, does the gasoline-powered mower use: 2-stroke blended gas or just gasoline?
¿Cuando usa la maquina, le pone: aceite con gasolina mesclado, o gasolina solo?

12) summer
How many hours par summer week is the gasoline-powered lawnmower used?
Cuantas horas por semana en el verano usa la maquina para cortar el zacate?

13) leafblow
What is your average weekly use of a gas-powered leafblower in the summer?
Cuantas horas por semana usas una maquina que usa gas, para quitar hojas?

14) chainsaw
What is your average weekly use of a gas-powered chainsaw during the summer?
Cuantas horas por semana usas una cierra de cadena que usa gas?

15) tiller
What is your average weekly use of a gas-powered tiller during the summer?
Cuantas horas por semana usas una maquina que usa gas par cultivar la tierra?

16) othtool
What is your average weekly use of any other gasoline-powered equipment?
    [IF YES:] What kind of equipment, and how much time per week are they used?
Cuantas horas por semana usas otras maquinas para mantener la yarda, que usan gas?
    [IF YES:] Como se llaman, y cuanto tiempo las usa?

17) airqual
What is your overall impression of San Antonio’s air quality? Do you think it is bad, below average, acceptable/average, good, or excellent?
Cual es su opinion de la calidad del aire en San Antonio? Es muy malo, malo, termino medio, bueno, o excelente?

18) source
Compared to commercial activities, how much of the air pollution in this area do you think is due to private citizen's activities such as driving, yard equipment, home chemical use, etc.?
Cree que la polucion esta causada por los residentes con el trafico de los coches, el equipo de cortar el zacate, el uso de productos quimicos en casa, comparando con los usos comerciales?

19) priority
How much of a priority to you is the protection of the air quality of San Antonio and the surrounding area? would you say it is very unimportant, unimportant, moderately important (neutral), important, or extremely important?
Como es de importante la calidad del aire en San Antonio para usted? No es muy importante, no es importante, termino medio, importante, o muy importante?

20) age
What is your current age? (ENTER ACTUAL AGE. 89=89+; 90=DX/NA)
Finalmente, me gustaria preguntarle unas cosas sobre usted. Que es su edad?

21) race
How would you identify your race or ethnic classification?
Cual es su raza?

22) income
Which of the following categories would you say beat describes your yearly family income?
Cuales de las seguientes categorias es el mejor descripto del sueldo al ano de su familia?

23) educ
What is the highest number of years of education you have completed?
Cuantos anos de educacion tiene?
[21 = DON'T KNOW / NO ANSWER]

24) zipcode
What is the zipcode for your residence?
    That's the end of the survey! Thank you for taking time to help us improve the environment of San Antonio and surrounding communities.
Que es; su distrito do postal, o "zipcode"?
    Eso es todo. Muchas gracias por su participacion en la ayuda a la Universidad para saber su opinion del los impactos en el aire de San Antonio.

Notes:

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

 

 

This category consists of emissions produced from equipment used in commercial activities. Emission estimates for the AACOG region were calculated for diesel, 2-stroke, and 4-stroke vehicles in the following categories of commercial equipment:

These are the categories used in the EPA’s Nonroad Emission Inventory Model.

Methodology

The methodology used in producing commercial equipment emission estimates for the AACOG region involves the following steps:

  1. Determining the number of wholesale establishments (SIC 50) in each county for 1996. This information was provided by the Census Bureau’s 1996 County Business Patterns.
  2. Estimating commercial equipment populations for each county. The number of wholesale establishments in each county was used to estimate the commercial equipment population in each category for the twelve counties. This was accomplished by first obtaining national equipment population estimates from EPA’s Nonroad Model. A ratio of the number of wholesale establishments in each county, to the number of national wholesale establishments was then established. This ratio was used to apportion the national equipment populations down to the county level.
  3. Estimating VOC, NOx, and CO annual emissions by multiplying the county equipment populations by the average annual hours of use, average rated horsepower, typical load factor, and emissions factor for each type of equipment. A 1995 commercial environmental impact survey of eight counties in the twelve county AACOG region was used to provide annual hours of use and average rated horsepower for three of the commercial equipment categories.
  4. Converting the tons/year estimate into an estimate for a typical weekday (tons/day), and a typical weekend day (tons/day). The 1995 survey was also used in this step to provide percentages of commercial equipment activity that occurs during the week and on weekends.
Annual Emissions

As outlined above, the first step in this process is the estimation of county equipment populations for each category. A ratio of the number of wholesale establishments in each county, to the number of national wholesale establishments was used to estimate the county equipment populations. The populations for each county were calculated based on the following formula:

Equip. (Type n) County Pop= Equip (Type n) National Population * (Wholesale establishments in each County / Wholesale establishments nationally)

Sample Calculation:

The 1996 U.S. equipment population of 4-stroke welders was 380,445. The number of national wholesale establishments was 531,220, and the number of Bexar County wholesale establishments was 2,103 in 1996. Using this information, an estimate of 4-stroke welders used in Bexar County can be calculated as follows:

4-stroke Welders in Bexar County = National pop of 4-stroke welders * (Bexar Cty Wholsl Est./National Wholsl Est.)
= 380,445 * (2,103 / 531,220)
= 1506.1 4-stroke welders in 1996 Bexar County

National equipment populations for 1996 were obtained from EPA’s Nonroad Emission Inventory Model. The 1996 wholesale establishment numbers for the twelve counties and the nation as a whole, were obtained from Census Bureau’s 1996 County Business Patterns.

Once county level equipment populations were calculated, emissions of volatile organic compounds (VOC), nitrogen oxides (NOx), and carbon monoxide (CO) were calculated for each category using the following formula:

Emissions (grams/yr.) for VOC, CO, and NOx = EP * HRS * HP * LF * EF

WhereEP = equipment population for the county
HRS = annual hours of use
HP = average rated horsepower
LF = typical load factor
EF = average emissions of pollutant per unit of use

County equipment populations were obtained from the first step. A 1995 survey of eight counties in the twelve county AACOG region was used to provide local values for annual hours of use (HRS), and the average rated horsepower (HP). This survey provided these values for the following equipment:

Local annual hours of use (HRS) and the average rated horsepower (HP) were calculated by averaging all of the survey results for each type of equipment.

In the absence of reliable local data, the values for HRS, HP, LF, and EF were obtained from the EPA. Annual hours of use (HRS) were obtained from the EPA’s Nonroad Emission Inventory Model where local data did not exist. The remaining factors, HP, LF, and EF were obtained from the EPA Nonroad Engine and Vehicle Emission Study (NEVES) Report (1991). This report includes HP and LF estimations for two inventories, inventory A, and inventory B. Inventory A consists of commercial and publicly available data while inventory B consists of industry data provided to the EPA that is not publicly available. For HP and LF, averages of the values for inventories A and B were used.

Emission factors (EF) for 2-stroke, 4-stroke, and diesel powered equipment were also obtained from this report. Only one EF value for diesel powered equipment was given for each equipment category, while two sets of emission factors were given for gasoline powered equipment. The first set of gasoline powered emission factors was not adjusted for in-use effects. These emission factors are almost exclusively based on the tests of new engines. The second set was estimated to include in-use effects such as engine malfunctions, improper maintenance, and engine wear. Due to the fact that the second set of emission factors is most likely closer to reality, the second set of emission factors for gasoline powered commercial equipment was used.

Sample Calculation:

Continuing with our example used above, there are an estimated 1,506.1 4-stroke welders in Bexar County. Using the 1995 AACOG equipment survey, these welders are operated an average of 404.6 hrs/year (HRS), and have an average rated horsepower (HP) of 35. From the 1991 NEVES report, the typical load factor (LF) for these welders is 0.51, and the emissions factor (EF) for carbon monoxide is 670.7 grams/hp*hr.

Emissions (grams/yr.) for CO= EP * HRS * HP * LF * EF
= 1506.1 * 404.6 (hrs/yr) * 35 (hp) * 0.51 * 670.7 (g/hp-hr)
= 7,295,351,367.48 (g/year)

This figure is then converted into tons/year by first converting the figure into kilograms, then pounds, and then tons.

Thus 7,295,351,367.48 (grams/year) = 8,041.6 (tons/year) of CO.

This same procedure is then used for NOx and VOCs to produce estimates of these pollutants.

Daily Emission Estimates

Daily emissions were estimated for both weekdays and weekends using the following formulas:

There were 262 weekdays in 1996, and 104 weekend days. For the percentages of commercial equipment use that occurs on weekdays versus weekend days, the 1995 equipment survey for the AACOG region was used. The average hours of commercial equipment use on weekdays and weekends were totaled and averaged. This survey estimates that 97.1% of commercial equipment use occurs during the week, with the remaining 2.9% occurring on the weekends.

Sample Calculation:

Bexar County produced an estimated 20,445 (tons/year) of CO in 1996 from commercial equipment use. The weekday and weekend day emissions can then be calculated as follows:

Spatial Allocation

Commercial equipment emissions was allocated to 4 kilometer grid cells by mapping wholesale establishments. Emissions, derived from AACOG's 1995 "Commercial Environmental Impact Survey" usage and EPA's emission factors, was then be allocated to each grid cell based on the number of establishments within the grid cell. The location of the establishments are provided by the Texas Workforce Commission, which provides the x and y coordinates of each establishment location.

Notes:

Dolce, Gary, December 1998. Geographic Allocation and Growth in EPA’s Nonroad Emission Inventory Model. U.S. Environmental Protection Agency, Ann Arbor, MI.

The Environmental Protection Agency’s Nonroad Emission Inventory Model

U.S. Department of Commerce, Bureau of the Census,1998. 1996 County Business Patterns. Washington D.C. Alamo Area Council of Governments Regional Data Center

U.S. Environmental Protection Agency, 1991. Nonroad Engine and Vehicle Emissions Study Report. Research Triangle Park, North Carolina.

Alamo Area Council of Governments, 1995. Commercial Environmental Impact Survey. San Antonio, Texas.

 

Alamo Area Council of Governments
Commercial Environmental Impact Survey
Internal Combustion Exhaust

The Alamo Area Council of Governments (AACOG) is conducting a study to assess and quantify local air quality within the San Antonio Metropolitan area and contiguous counties by performing an emission inventory. AACOG has defined the study area to include Bexar, Kendall, Comal, Guadalupe, Wilson, Atascosa, Medina, and Bandera Counties. Our goal is to provide better information and services to businesses and individuals, and help minimize additional regulation on the community. The purpose of this survey is to gather data on emissions produced by several types of equipment in the region, and to find out how air quality issues are perceived by the business community.

The study area does not presently exceed Environmental Protection Agency (EPA) air quality standards. However, if the standards are exceeded in the future we will be classified as nonattainment which will result in expensive and stringent regulations for your business and the community. By filling out this confidential survey, you will be providing valuable data that will be used to evaluate cost-effective approaches to pollution control. Thank you for taking the time to provide this information.

Instructions:

If you have other internal combustion equipment that is not shown, please include it as well.

NOTE: IF YOUR BUSINESS HAS MORE EQUIPMENT THAN WILL FIT IN THE SPACE PROVIDED, PLEASE MAKE ADDITIONAL COPIES OF THE SURVEY.

Completed surveys can be faxed to (210) 225-5937, or mailed to:
Alamo Area Council of Governments
118 Broadway, Suite 400
San Antonio, Texas 78205-1999

If you have any questions or comments, please call us at 225-5201.
Please Respond by January 27, 1995

  Internal Combustion Equipment Type   Engine Type Gasoline 2-cycle / Gasoline 4-cycle / Diesel / Propane / Natural Gas   Approx. Horse-Power Rating   Number of Units Typically Operated   Avg. No. of Hours and Time of Day Each Unit Operated (MON-FRI)   Avg. No. of Hours and Time of Day Each Unit Operated (SAT & SUN) 
Industrial Equipment
1 Generators          
2 Pumps          
3 Compressors          
4 Welders          
5 Pressure Washers          
6 Aerial Lifts          
7 Forklifts          
8 Sweepers          
9 Scrubbers          
 10  Other General Industrial or Material Handling Equipment          
Construction Equipment
 11  Bore / Drill Rigs          
 12  Excavators          
 13  Concrete / Industrial Saws          
 14  Cement & Mortar Mixers          
 15  Cranes          
 16  Graders          
 17  Crushing / Processing Equipment          
 18  Rough Terrain Forklifts          
 19  Loaders          
 20  Dozers          
 21  Tractors          
 22  Backhoes          
 23  Dumpsters / Tenders          
 24  Other Construction Equipment          
Lawn and Garden Equipment
 25  Trimmers / Edgers          
 26  Lawn Mowers          
 27  Leaf Blowers / Vacumns          
 28  Rear Engine Riding Lawn Mowers          
 29  Front Mowers          
 30  Chainsaws          
 31  Shredders          
 32  Tillers          
 33  Lawn & Garden Tractors          
 34  Chippers / Stump Grinders          
 35  Commercial Turf Equipment          
 36  Other Lawn & Garden Equipment          
On-Site Vehicles (Used Primarily On Property)
 37  Light-Duty Truck          
 38  Heavy-Duty Truck          
 39  Utility Cart          
 40  Other Vehicles          

How many people do you currently employ? _____________

If you were in business in 1992, by what percent do you believe your business has increased between 1992 and the present? _____________

OPTIONAL
This part of the survey gives you an opportunity to express your perceptions and ideas on the issues of air pollution and air quality.

  Very
Good		 Very
Bad
1. What is your overall impression of
air quality in the San Antonio area
and the contiguous counties?   		1       2       3       4       5
2. How do you feel about the current
level of local air quality protection?   		1       2       3       4       5
3. How often do you consider the impact
of your business’ activities on local air quality?    		1       2       3       4       5
4. What steps, if any, would you suggest for improving air quality in the region
(i.e., suggestions for individuals, the city, county or state)?

 

 

 

 
5. Would you be willing to reduce
your emissions on an ozone alert day?		 Yes      No
6. If you answered yes to question 5,
what steps would you be willing to take on ozone advisory days?

 

 

 

 
7. Please list any suggestions you might have for other businesses
to help reduce volatile hydrocarbon emissions on ozone advisory days.

 

 

 

 

This category consists of emissions produced from equipment used in industrial activities. Emission estimates for the AACOG region were calculated for diesel, 2-stroke, and 4-stroke vehicles in the following categories of commercial equipment:

Methodology

The methodology used in producing industrial equipment emission estimates for the AACOG region involves the following steps:

  1. Determining the number of employees in manufacturing (SIC 20) for each county in 1996. This information was provided by the Census Bureau’s 1996 County Business Patterns.
  2. Estimating industrial equipment populations for each county. The number of employees in manufacturing for each county was used to estimate the industrial equipment population in each category for the twelve counties. This was accomplished by first obtaining national equipment population estimates from EPA’s Nonroad Model. A ratio of the number of employees in manufacturing in each county, to the number of employees in manufacturing nationally was established. This ratio was used to apportion the national equipment populations down to the county level.
  3. Estimating VOC, NOx, and CO annual emissions by multiplying the county equipment populations by the average annual hours of use, average rated horsepower, typical load factor, and emissions factor for each type of equipment. A 1995 commercial environmental impact survey of eight counties in the twelve county AACOG region was used to provide annual hours of use and average rated horsepower for three of the industrial equipment categories.
  4. Converting the tons/year estimate into an estimate for a typical weekday (tons/day), and a typical weekend day (tons/day). The 1995 survey was also used in this step to provide percentages of industrial equipment activity that occurs during the week and on weekends.
Annual Emissions

As outlined above, the first step in this process is the estimation of county equipment populations for each category. A ratio of the number of employees in manufacturing for each county, to the number of manufacturing employees nationally was used to estimate the county equipment populations. The populations for each county were calculated based on the following formula:

Sample Calculation

The 1996 U.S. equipment population of diesel powered forklifts was 164,851. The number of manufacturing employees nationally was 18,558,100, and the number of manufacturing employees in Bexar County was 40,363 in 1996. Using this information, an estimate of the population of diesel powered forklifts used in Bexar County can be calculated as follows:

National equipment populations for 1996 were obtained from EPA’s Nonroad Emission Inventory Model. The 1996 manufacturing employee numbers for the twelve counties and the nation as a whole were obtained from Census Bureau’s 1996 County Business Patterns.

Once county level equipment populations were calculated, emissions of volatile organic compounds (VOC), nitrogen oxides (NOx), and carbon monoxide (CO) were calculated for each category using the following formula:

Emissions (grams/yr.) for VOC, CO, and NOx = EP * HRS * HP * LF * EF
Where   EP   = equipment population for the county
HRS = annual hours of use
HP   = average rated horsepower
LF   = typical load factor
EF   = average emissions of pollutant per unit of use

County equipment populations were obtained from the first step. A 1995 survey of eight counties in the twelve county AACOG region was used to provide local values for annual hours of use (HRS), and the average rated horsepower (HP). This survey provided these values for the following equipment:

Local annual hours of use (HRS) and the average rated horsepower (HP) were calculated by averaging all of the survey results for each type of equipment.

In the absence of reliable local data, the values for HRS, HP, LF, and EF were obtained from the EPA. Annual hours of use (HRS) were obtained from the EPA’s Nonroad Emission Inventory Model where local data did not exist. The remaining factors, HP, LF, and EF were obtained from the EPA Nonroad Engine and Vehicle Emission Study (NEVES) Report (1991). This report includes HP and LF estimations for two inventories, inventory A, and inventory B. Inventory A consists of commercial and publicly available data while inventory B consists of industry data provided to the EPA that is not publicly available. For HP and LF, averages of the values for inventories A and B were used.

Emission factors (EF) for 2-stroke, 4-stroke, and diesel powered equipment were also obtained from this report. Only one EF value for diesel powered equipment was given for each equipment category, while two sets of emission factors were given for gasoline powered equipment. The first set of gasoline powered emission factors was not adjusted for in-use effects. These emission factors are almost exclusively based on the tests of new engines. The second set was estimated to include in-use effects such as engine malfunctions, improper maintenance, and engine wear. Due to the fact that the second set of emission factors is most likely closer to reality, the second set of emission factors for gasoline powered industrial equipment was used.

Sample Calculation:

Continuing with our example used above, there are an estimated 358.5 diesel forklifts in Bexar County. Using the 1995 AACOG equipment survey, these forklifts are operated an average of 973.4 hrs/year (HRS), and have an average rated horsepower (HP) of 94.3. From the 1991 NEVES report, the typical load factor (LF) for these welders is 0.3, and the emissions factor (EF) for NOx is 14.0 grams/hp*hr.

This figure is then converted into tons/year by first converting the figure into kilograms, then pounds, and then tons.

(grams/year) / 1000 = (kilograms/year) * 2.2045855 = (pounds/year) / 2000 = (tons/year)

Thus 138,210,642 (grams/year) = 152.35 (tons/year) of NOx

This same procedure is then used for CO and VOCs to produce estimates of these pollutants.

Daily Emission Estimates

Daily emissions were estimated for both weekdays and weekends using the following formulas:

There were 262 weekdays in 1996, and 104 weekend days. For the percentages of industrial equipment use that occurs on weekdays versus weekend days, the 1995 equipment survey for the AACOG region was used. The average hours of industrial equipment use on weekdays and weekends were totaled and averaged. This survey estimates that 92.6% of industrial equipment use occurs during the week, with the remaining 7.4% occurring on the weekends.

Sample Calculation:

Bexar County produced an estimated 778.5 (tons/year) of NOx in 1996 from industrial equipment use. The weekday and weekend day emissions can then be calculated as follows:

Spatial Allocation

Industrial equipment emissions will be allocated to 4-kilometer grid cells by mapping manufacturing facilities and categorizing them based on the number of employees that are employed. Emissions, derived from AACOG's 1995 "Commercial Environmental Impact Survey" usage and EPA's emission factors, will then be allocated to each grid cell based on the number of employees within the grid cell. The location of the establishments and employment numbers are provided by the Texas Workforce Commission, which provides the x and y coordinates of each establishment location.

Notes:

Dolce, Gary, December 1998. Geographic Allocation and Growth in EPA’s Nonroad Emission Inventory Model. U.S. Environmental Protection Agency, Ann Arbor, MI.

The Environmental Protection Agency’s Nonroad Emission Inventory Model

U.S. Department of Commerce, Bureau of the Census,1998. 1996 County Business Patterns. Washington D.C. Alamo Area Council of Governments Regional Data Center

U.S. Environmental Protection Agency, 1991. Nonroad Engine and Vehicle Emissions Study Report. Research Triangle Park, North Carolina.

Alamo Area Council of Governments, 1995. Commercial Environmental Impact Survey. San Antonio, Texas.

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