#• \ ®! % ^ *1 PRO*^ 2020 National Emissions Inventory Technical Support Document: Dust - Construction -Road ------- ------- EP A-454/R-23 -00 lv March 2023 2020 National Emissions Inventory Technical Support Document: Dust - Construction -Road U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Air Quality Assessment Division Research Triangle Park, NC ------- Contents List of Tables i 22 Dust - Construction -Road 22-1 22.1 Sector Descriptions and Overview 22-1 22.2 EPA-developed estimates 22-1 22.2.1 Activity data 22-1 22.2.2 Allocation procedure 22-3 22.2.3 Emission factors 22-3 22.2.4 Controls 22-4 22.2.5 Emissions 22-4 22.2.6 Sample calculations 22-5 22.2.7 Improvements/Changes in the 2020 NEI 22-7 22.2.8 Puerto Rico and Virgin Islands 22-7 22.3 References 22-7 List of Tables Table 221: SCCs in the Construction Dust sector 22-1 Table 22-2: Spending per mile and acres disturbed per mile by highway type 22-2 Table 22-3: Sample calculations for urban interstate, urban other arterial, and urban collector road construction 22-5 l ------- 22 Dust - Construction -Road 22.1 Sector Descriptions and Overview Construction dust refers to residential and non-residential construction activity, which are functions of acreage disturbed for construction. This sector will be divided below when describing the calculation of EPA's emissions. Table 22-1 lists the nonpoint SCCs associated with this sector in the 2020 NEI. The SCC level 1 and 2 descriptions is "Industrial Processes; Construction: SIC 15 -17" for all SCCs. Table 22-1: SCCs in the Construction Dust sector SCC SCC Level Three SCC Level Four 2311010000 Residential Total 2311020000 Industrial/Commercial/Institutional Total 2311030000 Road Construction Total 22.2 EPA-developed estimates The calculations for estimating the emissions from road construction involve first estimating the acres disturbed from new road constructed in each county. The amount of state-level road construction spending by road type is available from the Federal Highway Administration (FHWA) and is converted to acreage disturbed using conversion factors from the Florida Department of Transportation (FLDOT). The state-level acreage disturbed by road type is summed together and distributed to the counties based on the proportion of building starts in each county. Emissions factors for PM10 and PM25 are calculated based on precipitation-evaporation values and dry silt content in each county. The total amount of acres disturbed is multiplied by these emissions factors to estimate emissions of PM from road construction. 22.2.1 Activity data The activity data for this source category is the acreage disturbed from new road construction, which is estimated using data from FHWA's Highway Statistics, State Highway Agency Capital Outlay, Table SF- 12A [ref 1] and FLDOT's Generic Cost per Mile Models [ref 2], From the FHWA table, the following construction types are used: New Construction, Relocation, Added Capacity, Major Widening, and Minor Widening. Each of the following road types have spending broken out for each construction type: 1. Interstate, urban 2. Interstate, rural 3. Other arterial, urban 4. Other arterial, rural 5. Collectors, urban 6. Collectors, rural Construction spending for each road type is summed across all construction types to determine the total annual highway spending for each road type. 22-1 ------- HS = \' s ;,r / Js,r t—'ct (1) Where: HSs,r = Annual highway spending for road type r in state s, in dollars ct = Construction type Ss,r = Annual spending per construction type in state s for road type r, in dollars State expenditure data are converted to miles of new road and acres disturbed per mile of new road by applying conversions based on data obtained from FLDOT. The conversions are shown in Table 22-2, and the acres disturbed per mile conversions are calculated by multiplying the FLDOT's total affected roadway width (including all lanes, shoulders, and areas affected beyond the road width) in feet by the number of feet in a mile and converting the resulting land area from ft2 to acres [ref 2], Total affected roadway with is the sum of the numbers of lanes (assumed at 12 feet each), number of shoulders, and area affected beyond the road width (25 feet). There are 5,280 feet in a mile, and 43,560 ft2 in an acre. RC, HS s,r m,s,r TDM RCa,s,r — RCm,s,r ^ ADM (2) (3) Where: RCm,s,r = Miles of FHWA road type r constructed in state s RCa/S,r = Acres of land disturbed for construction of FHWA road type r in state s HSs,r = Annual highway spending for road type r in state s TDM = Conversion of dollars spent to road miles constructed, in thousand dollars per mile ADM = Conversion of road miles constructed to acres disturbed, in acres per mile Table 22-2: Spending per mile and acres c isturbed per mile by hig nway type Road Type Thousand Total Affected Acres Disturbed Dollars per mile Roadway Width (ft)* per mile Urban Areas, Interstate 9,636 94 11.4 Rural Areas, Interstate 4,796 89 10.8 Urban Areas, Other Arterials 4,829 63 7.6 Rural Areas, Other Arterials 2,643 55 6.6 Urban Areas, Collectors 4,829 63 7.6 Rural Areas, Collectors 2,643 55 6.6 The acres of land disturbed by road type can then be summed across all road types in a state to calculate the total state-level acreage disturbed due to new road construction. A. -I RC, a,s (4) Where: 22-2 ------- As = Acres of land disturbed for all road construction in state s RCas = Acres of land disturbed for construction of FHWA road type r in state s The process used to distribute the state-level amount of acreage disturbed to the counties is discussed in the next section. 22.2.2 Allocation procedure Building permits data, used as a surrogate for road construction activity, from the U.S. Census Bureau are used to allocate the state-level acres disturbed by road construction to the county-level [ref 3], Specifically, the ratio of the county-to state-level number of building starts is calculated and multiplied by the state-level acreage disturbed (from equation 4) to estimate the county-level acreage disturbed by road construction. Buildr BFracc = (5) Buuds Ac = As X BFracc (6) Where: BFracc = The fraction of building starts in countyc Buildc = The number of building starts in county c Builds = The number of building starts in state s Ac = Acres of land disturbed for road construction in county c As = Acres of land disturbed for all road construction in state s 22.2.3 Emission factors Due to regional variances in soil moisture and silt content, uncontrolled emissions factors for PM10 and PM25 are adjusted for each county. The initial uncontrolled PM10 emissions factor from construction of roads is 0.42 tons/acre-month [ref 4], This emission factor represents the large amount of dirt moved during the construction of roadways, reflecting the high level of cut and fill activity that occurs at road construction sites. To account for the soil moisture level, the uncontrolled PM10 emissions are weighted using the 30-year average precipitation-evaporation (PE) values from Thornthwaite's PE Index. Average precipitation evaporation values for each state are estimated based on PE values for specific climatic divisions within a state [ref 4], The average PE value for the test sites from which the PM10 emissions factor was developed is 24. Equation 7 adjusts the county-level uncontrolled emissions factor based on this PE value. To account for the silt content, the uncontrolled PM10 emissions are weighted using average silt content for each county. EPA uses the National Cooperative Soil Survey Microsoft Access Soil Characterization Database to develop county-level, average silt content values for surface soil [ref 5], The U.S. Department of Agriculture and the National Cooperative Soil Survey define silt content of surface soil as the percentage of particles (mass basis) of diameter smaller than 50 micrometers (nm) found in the surface soil. Note that this definition is different than the U.S. Environmental Protection Agency's definition that includes all particles (mass basis) of diameter smaller than 75 micrometers. This 22-3 ------- database contains the most commonly requested data from the National Cooperative Soil Survey Laboratories including data from the Kellogg Soil Survey Laboratory and cooperating universities. The average silt content for the test sites from which the PM10 emissions factor was developed is 9%. Equation 7 adjusts the county-level uncontrolled emissions factor based on this silt content value. 24 Sc UEFPM10c = EFPM1 o X —— X —- (7) PES 9% Where: UEFpmio,c = Uncontrolled PMioemission factor corrected for soil moisture and silt content in state s and county c, in tons/acre-month EFpmio = Initial PMio emissions for road construction, 0.42 tons/acre-month PES = Precipitation-evaporation value for state s Sc = Percent dry silt content in soil for county c Once uncontrolled PMio adjustments have been made, uncontrolled PM2.5 emissions are set to 10% of PMio. UEFPm25,c = 0-10 x UEFpMio,c (8) Where: UfFP/v)io,c = Uncontrolled PMio emission factor corrected for soil moisture and silt content in state s and county c, in tons/acre-month UEFPm25,c = Uncontrolled PM2.5 emission factor corrected for soil moisture and silt content in county c, in tons/acre-month Primary PM emissions are equal to filterable emissions as there are no condensible dust emissions from road construction. Emission factors for these sources are provided in the "Wagon Wheel Emission Factor Compendium" on the 2020 NEl Supporting Data and Summaries site. 22.2.4 Controls Dust emissions from road construction are generally controlled by watering the construction site. The Midwest Research Institute recommends using a control efficiency of 50% for PM10 and PM25 emissions from road construction [ref4], EFP c = 0.50 X UEFpc (9) Where: EFp,c = Controlled emissions factor of pollutant p in county c UEFP/C = Uncontrolled emissions factor of pollutant p in county c 22.2.5 Emissions The total annual dust emissions from road construction in each county are multiplied by the emissions factors calculated in equation 9. The duration of construction activity for road construction is assumed to be 12 months. 22-4 ------- Ep C — Ac x EFp c x M (10) Where: Ac EFpmio,c EFpM25,c M Annual emissions of pollutant p in county c Acres of land disturbed for road construction in county c Controlled PMioemission factor corrected for soil moisture and silt content in state s and county c, in tons/acre-month Controlled PM2.5 emission factor corrected for soil moisture and silt content in county c, in tons/acre-month Duration of construction activity in months 22.2.6 Sample calculations Table 22-3 lists sample calculations to determine the dust emissions from road construction. The values in these equations are demonstrating program logic and are not representative of any specific NEI year or county. Table 22-3: Sample calculations for urban interstate, urban other arterial, and urban collector road construction Eq. # Equation Values Result 1 HSs,r = y $s,r t—ict $1,000 + $9,155,000 $9,156,000 spent on urban interstate construction $1,276,000 + $2,471,000 $3,747,000 spent on urban other arterial construction $2,583,000 $2,583,000 spent on urban collector construction 2 HSsr nr m's,r TDM $9,156,000 6,895,000 $ per mile 1.328 miles of urban interstate constructed $3,747,000 4,112,000 $ per mile 0.911 miles of urban other arterial constructed $2,683,000 4,112,000 $ per mile 0.628 miles of urban collector constructed 3 RCa s r = RCms r x ADM 1.328 miles x 11.4 acres per mile = 15.1 acres disturbed from urban interstate construction 22-5 ------- Eq. # Equation Values Result 0.911 rruZes x 7.6 acres per rruZe 6.9 acres disturbed from urban other arterial construction 0.628 rruZes x 7.6 acres per rruZe 4.8 acres disturbed from urban collector construction 4 As = ^ RCa,s 15.1 acres + 6.9 acres + 4.8 acres 26.78 acres disturbed from urban road construction 5 Buildr 185 building starts in county 0.194 fraction of building starts J-} 1 / CvC/j Builds 952 building starts in state 6 Ac = As x BFracc 26.78 acres x 0.194 5.20 acres disturbed from urban road construction 7 24 UEFpmio c = EFpmio x —— P£s x^ 9% 0.42 tons/acre 24 — month x 132 41,45% x 9% 0.3517 tons per acre-month uncontrolled PM10 emissions from road construction 8 U E FpM2S,c. = 0-10 x UEFPM10,c O.lOx 0.3517 tons/acre — month 0.0352 tons per acre-month PM25 emissions from road construction 9 EFPc — 0.50 X UEFpC 0.50 x 0.3514 tons per acre — month 0.1758 tons per care-month controlled PM10 emissions from new road construction 0.50x 0.0352 tons per acre — month 0.0176 tons per care-month controlled PM25 emissions from new road construction 10 EPiC Ac X EFp c X M 5.2 acres x 0.1758 tons/acre — month x 12 10.98 tons PM10 from urban road construction 5.2 acres x 0.0176 tons/acre — month x 12 1.98 tons PM25 from urban road construction 22-6 ------- 22.2.7 Improvements/Changes in the 2020 NEI No changes were made to methods for the 2020 NEI. Activity data was updated to reflect best available data for the NEI cycle. 22.2.8 Puerto Rico and Virgin Islands Since insufficient data exists to calculate emissions for the counties in Puerto Rico and the US Virgin Islands, emissions are based on two proxy counties in Florida: 12011, Broward County for Puerto Rico and 12087, Monroe County for the US Virgin Islands. The total emissions in tons for these two Florida counties are divided by their respective populations creating a tons per capita emission factor. For each Puerto Rico and US Virgin Island county, the tons per capita emission factor is multiplied by the county population (from the same year as the inventory's activity data) which served as the activity data. In these cases, the throughput (activity data) unit and the emissions denominator unit are "EACH". 22.3 References 1. Federal Highway Administration. Table SF-12A, State Highway Agency Capital Outlay -2020. 2. Florida Department of Transportation. Generic Cost per Mile Models for 2020 3. U.S. Census Bureau. 2015. Annual Housing Units Authorized by Building Permits. ASCII files by State, MSA, County or Place, co2020a. 4. Midwest Research Institute. 1996. Improvement of Specific Emission Factors (BACM Project No. 1). Prepared for South Coast Air Quality Management District. 5. U.S. Department of Agriculture, National Cooperative Soil Survey, NCSS Microsoft Access Soil Characterization Database. 6. Midwest Research Institute. 1999. Estimating Particulate Matter Emissions from Construction Operations, Final Report. Section 5.7.1. prepared for the Emission Factor and Inventory Group, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency. 22-7 ------- United States Office of Air Quality Planning and Standards Publication No. EPA-454/R-23-001v Environmental Protection Air Quality Assessment Division March 2023 Agency Research Triangle Park, NC ------- |