Prepared by: 1900 Elkin Street, Suite 200. Alexandria, VA Prepared for: Costco Wholesale Horseshoe Drive, Suite 150. Sterling, VA 20166

Transcription

1 Updated: Supplemental Report to the Air Quality, Noise, and Odor Analysis Report Submitted on November 19, 2012 for the Proposed Costco Gas Station in Wheaton, MD Prepared by: 1900 Elkin Street, Suite 200 Alexandria, VA Prepared for: Costco Wholesale Horseshoe Drive, Suite 150 Sterling, VA January 16, 2013 David A. Sullivan, CCM Date Dennis J. Glinka, CCM Date Page 1

2 Introduction Meetings between Costco and the Montgomery-National Capital Park and Planning Commission (M-NCPPC) staff on December 3, 2012 and January 10, 2013 provided opportunities to discuss all of the results presented in the Costco environmental report that was submitted on November 19, The meetings resulted in requests by the M-NCPPC staff for Costco to provide additional graphics and further clarification in several areas. These changes were requested to be provided in a supplemental report to promote greater clarity in the results. This supplemental report addresses the requests from the M-NCPPC staff, and in Section 7.0 an updated queuing analysis. This revised version of the supplemental report replaced in its entirety the December 18, 2012 preceding supplemental report. 1.0 Clarifications / Refinements to Report Submitted November 2012 Several minor errors were identified and corrected based on subsequent review of the modeling results by (Sullivan Environmental). These errors were all minor, with less than a 1 percent difference being noted in the modeled concentrations. The corrections were made to clarify the record. The corrected tables (refer to Tables 1.1 and 1.2) correspond to Tables 1-14 and 1-15 in the November 19, 2012 Costco environmental report. Exit sources from the gas station fueling area were refined to reflect corrected area source sizes and locations. A typographical error in the incremental contribution of gasoline delivery trucks to PM 2.5 concentration also was corrected. More details on the refinements can be found in Appendix AE of the November 19, 2012 report. Please note that the VOC urban scenario was not re-run as indicated in Appendix AE. This is because it was shown through the more conservative rural scenario for VOC s (Table 1.2) that the relative change was very small and similar or smaller changes would be expected for the corresponding urban scenario run. Page 2

3 Table 1.1 Page 1 of 2: [Table 1-14 in November 2012 report]: Predicted Rural Concentrations for PM 2.5 (µg/m 3 ) Updated Rural Values Original rural values Page 3

4 Table 1.1 Page 2 of 2: [Table 1-14 in November 2012 report]: Predicted Urban Concentrations for PM 2.5 (µg/m 3 ) Updated Rural Values Original rural values Page 4

5 Table 1.2 [Table 1-15 in November 2012 report]: Predicted Rural and Risk for VOCs (µg/m 3 ) Updated Rural Values Original rural values Page 5

6 2.0 Noise Issues / Screening Wall Specific points of clarification were requested by M-NCPPC staff, which is addressed in Sections 2.1 and 2.2 below. 2.1 Acoustic Benefits are Negligible Versus the Terrain / Line of Sight Drop For all practical purposes, the 8-foot acoustic wall (with a green wall towards the residences) is more appropriately identified as a screening wall. While the wall will have acoustic reduction properties, the drop in terrain towards the closest homes (and associated break in the line of site) already reduces noise impacts. The noise modeling results shown in Section 2.2 are presented both with and without the screening wall. As shown, the differences are generally relatively minor. The noise levels, presented as L dn values in Section 2.2, clearly show that noise levels are far below the county noise level guidelines. 2.2 Isopleth plot of Noise L dn values The M-NCPPC staff requested that the predicted noise levels be provided as 24-hour L dn values. The L dn values apply a 10 dba penalty during the hours of 10:00 P.M. through 7:00 A.M. In this case, the L dn values take into account the small window when the penalty values apply to the gas station, i.e., 6:30 A.M. to 7:00 A.M. The incremental gas station travel along the Southern Ring Road, queuing-related noise, and travel within the Costco parking lot and parking garage were considered in the earlier runs (December 18, 2012) and also were included in this latest analysis. In addition, in this updated analysis a conservative representation of the contributions from the Costco warehouse and Dick s Sporting Goods also was included along the Southern Ring Road. A total of 260 cars (above existing background) were assumed along the Southern Ring Road, which is based on the following: Scenario # vehicles New trips for gas only 69 Pass by trips for gas only 78 Costco warehouse / Dick s Sporting Goods Total Of the 191 vehicles going to the Costco warehouse or Dick s Sporting Goods (based on the Traffic Study), it was conservatively assumed that approximately 60 percent (113) traveled along the Southern Ring Road, and 40 percent (78 vehicles) travelled along the Northern Ring Road (and well removed from the noise receptors under review). Page 6

7 Table 2.1 summarizes the TNM model predicted noise levels, showing the 24-hour L dn noise levels with and without the 8-foot acoustic wall with the 53 dba background noise levels included. Figure 2.1 presents a plot of 24-hour L dn noise levels. Table 2.1: TNM Model Predicted 1-Hour Noise Levels (dba) without in Comparison with the Predicted 24-Hour L dn Noise Levels (dba) including Page 7

8 Figure 2.1: Predicted 24-Hour L dn Noise Levels (dba), without 8-ft Barrier, Plus 53 dba Max 24-Hour L dn south of yellow buffer nearby residences = 54.4 dba Max 24-Hour L dn west of yellow buffer zone near pool = 55.4 dba [Note: The red, blue, and green lines represent the modeled traffic areas, and the yellow dots represent the modeled noise receiver locations. The yellow lines represent the buffer zone boundary.] Page 8

9 3.0 Urban/Rural Bar Chart Comparisons for Predicted Concentrations Urban/rural comparison bar charts were created for predicted concentrations of CO, PM 2.5, and NO 2 for the three key receptors for the nearby homes, school, and pool. These comparison charts are provided as Figures 3.1 through 3.3. In each of these comparative charts, the sources are subdivided, such as gasoline operations and queues, warehouse, the ring road, all other roadways, and the background concentrations for each are shown separately. Above each bar in these charts are the percentages representing the contribution of the gasoline queue and other gasoline operation sources relative to the totals for all sources (including background concentrations). The latest plots were created as two-dimensional stacked bar charts, which are more easily interpreted than the three-dimensional charts previously used. A second set of comparison charts is also provided in Figures 3.4 through 3.6 for these same pollutants and sources, but with three specific source groupings as requested by the M-NCPPC staff: Incremental sources: Consists of all gasoline queue and gasoline station-related operational sources. This relates to all incremental gas station sources, including roadway emissions from vehicles traveling to the gas station, ingress and egress from the gas station fueling area, queuing at the gas station, and exhaust from gasoline delivery trucks. Pipeline sources: Consists of the Costco warehouse sources (e.g., loading dock and parking lots). Existing sources: Refers to the summation of the conservative background treatment plus specific modeling of nearby roadway sources. A small amount of incremental gas station related emissions are embedded in the presented Ring Road contributions and other roadway contributions, but based on comparative traffic data these contributions are minor, i.e., approximately 3 to 7 percent of the total. Page 9

10 Figure 3.1: Maximum Predicted 8-hour CO Concentrations (µg/m 3 ) for the Closest Residence, the Stephen Knolls School, and the Kenmont Swim and Tennis Center Special Receptors Urban Concentrations (µg/m 3 ) Rural Concentrations (µg/m 3 ) Page 10

11 Figure 3.2: Predicted Annual Average PM 2.5 Concentrations (µg/m 3 ) for the Closest Residence, the Stephen Knolls School, and the Kenmont Swim and Tennis Center Special Receptors Urban Concentrations (µg/m 3 ) Rural Concentrations (µg/m 3 ) [Note: Refer to section of this supplement (Section 4.0) for further perspective on the degree of conservatism in the background treatment for this scenario] Page 11

12 Figure 3.3: Predicted Annual Average NO 2 Concentrations (µg/m 3 ) for the Closest Residence, the Stephen Knolls School, and the Kenmont Swim and Tennis Center Special Receptors Urban Concentrations (µg/m 3 ) Rural Concentrations (µg/m 3 ) [Note: for Annual Average NO 2 has been updated to 6.8 µg/m 3 (see Section 4.0)] Page 12

13 Figure 3.4: Maximum Predicted 8-hour CO Concentrations (µg/m 3 ) for the Closest Residence, the Stephen Knolls School, and the Kenmont Swim and Tennis Center Special Receptors Urban Concentrations (µg/m 3 ) Rural Concentrations (µg/m 3 ) Existing: contains a small 3 to 7% incremental vehicle contribution from all roads Page 13

14 Figure 3.5: Predicted Annual Average PM 2.5 Concentrations (µg/m 3 ) for the Closest Residence, the Stephen Knolls School, and the Kenmont Swim and Tennis Center Special Receptors Urban Concentrations (µg/m 3 ) Rural Concentrations (µg/m 3 ) Existing: contains a small 3-7% incremental vehicle contribution from all roads Page 14

15 Figure 3.6: Predicted Annual Average NO 2 Concentrations (µg/m 3 ) for the Closest Residence, the Stephen Knolls School, and the Kenmont Swim and Tennis Center Special Receptors Urban Concentrations (µg/m 3 ) Rural Concentrations (µg/m 3 ) Existing: contains a small 3-7% incremental vehicle contribution from all roads [Note: for Annual Average NO 2 has been updated to 6.8 µg/m 3 (see Section 4.0)] Page 15

16 4.0 Concentrations Costco used a conservative approach (acts to overstate) to estimate the general background concentrations, i.e., the contribution from sources other than those specifically modeled for each criteria pollutant (PM 2.5, CO, and NO 2 ) and averaging time. concentrations in the Costco analyses were based on the highest measured concentration measured in Montgomery County, and surrounding areas as necessary 2, for the most recent available three years, i.e., 2009 through 2011 that were available when the modeling was conducted. This is the most conservative option that is used for air quality analyses submitted to the U.S. Environmental Protection Agency (EPA) or the Maryland Department of the Environment (MDE). There are other less conservative options that also are acceptable to regulatory agencies. This approach inherently overestimates concentration for two major reasons: (1) the method assumes that the timing of the peak modeled concentration at each location (such as the Kenmont Tennis and Swim center and the Stephen Knolls School) coincide with the peak concentration measured in the County over past three years 3, and (2) the method does not consider the downward trend in concentrations. 4.1 Assumes Peak Modeled Concentrations All Coincide with Peak Concentration It is highly unlikely for any modeled location that the worst-case modeled concentration would occur on the same hour, day, and year as the maximum measured concentration in the County for the applicable averaging period. This is especially so for the 1, 8, and 24 hour analyses. For example, based on straight probability, over a three-year period there are 1,095 days. All else being equal, the odds of the maximum measured and modeled 24-hour concentrations coinciding are 1 out of 1,095. For the 1 and 8-hour averages the odds are 1 out of 26,290, and 1 out of 3,285, respectively. For comparison with the National Ambient Air Quality Standards (NAAQS), The Costco modeling included all gas station operations, ingress/egress from the gas station, the travel of cars to the gas station along County roads for the incremental analysis, and also included general 2 Note that NO 2 monitoring data are not available for Montgomery County. Arlington, Virginia was used as the background value for this pollutant. 3 This effectively would not occur in reality because in this example, the two locations are effectively in opposite directions from the gas station. Page 16

17 traffic along Georgia Avenue, Veirs Mills Road, and University Boulevard, the parking lots and loadings docks at the Costco warehouse, and gasoline deliveries. Adding the conservative background concentration values, as described above, to the total modeled concentrations produce airborne concentrations that would be expected to be significantly higher than would be computed if all sources were explicitly modeled. Of course, it is not feasible to model all sources that significantly contribute to the air quality in the Wheaton area, either singly or on a collective basis. This is why EPA and MDE, and all other regulatory agencies in the U.S., rely on conservative background methods to maintain a tractable analysis when evaluating new or modified facilities. Table 4.1 below, copied directly from Appendix D of the Costco modeling protocol (October 30, 2012), summarizes the conservative background concentrations to be used in this modeling analysis. Table 4.1: Summary of Measured Concentrations for CO, NO 2, and PM 2.5 Used in Estimating Conservative Concentrations 4 [Note that this table has been updated to now include the actual annual average NO 2 background concentrations for the Arlington air quality monitoring site. This update of 6.8 µg/m 3 is a change from the original assumption of conservatively using the 1-hour NO 2 concentration of 28 µg/m 3 as the annual average, as stated in the model protocol.] 4 For the November 19, 2012 report, 28 µg/m 3 was conservatively used for both the maximum 1-hour and annual average periods for NO 2. The actual annual average NO 2 background concentration based on the conservative default approach described above is 6.8 µg/m 3. Page 17

18 As requested by the M-NCPPC staff, Figure 4.1 graphically shows the relative locations of the AQ monitors to the proposed Costco gasoline site that were chosen to represent the conservative background concentrations. Figure 4.1: Relative Locations of AQ Monitors to the Proposed Gas Station Site Page 18

19 Tables 4.2 through 4.4 present the street addresses of these specific monitoring sites identified in Table 4.1 and Figure 4.1 for each corresponding pollutant and averaging time. Table 4.2: Addresses of AQ Monitors used for the 1-Hour and 8-Hour CO Concentration Analysis Table 4.3: Addresses of AQ Monitors used for the 1-Hour and Annual Average NO 2 Concentration Analysis Table 4.4: Addresses of AQ Monitors used for the 24-Hour and Annual Average PM 2.5 Concentration Analysis Page 19

20 In section of the main report (November 19, 2012), Tables 1-16 through 1-20 were presented as comparative analyses to show the results using the default conservative background treatment as directly used in this modeling analysis compared to the results using background concentrations that match in date and time to the modeled maximums. These original tables are shown in this report as Tables 4.5 through 4.9 (note: the original table numbers are bracketed to facilitate comparison) with the additional site name and street address information provided for each corresponding monitoring site provided below each table. In order to provide perspective on the degree of conservatism in the background term, more realistic representation of background concentrations are shown in Tables 4.5 through 4.9. The term actual background refers to the highest concurrently measured concentration among the County and nearby air quality monitors listed earlier in this section. The highest measured concentration for the hour, day, or year is matched in time to the timing of the actual modeled peak concentration. The term actual background is used for perspective only and was not used in the modeled tables and figures in the Costco report submitted in November 2012 or this supplemental report. Page 20

21 Table 4.5: [Table 1-16]: Comparison of Maximum Modeled 1-Hour CO Concentrations Based on Conservative Representation of Concentrations in Comparison to Actual Measured Concentrations based on Matched Time Period [NAAQS = 40,000 µg/m 3 ] Receptor Maximum Modeled Value (μg/m3) Without Conservative (μg/m3) Actual For Time Period Of Maximum With Conservative With Actual Closest Residence 13,809 1,488 1,259 [12/25/06] 15,297 15,068 Stephen Knolls School 13,480 1,488 1,259 [12/25/06] 14,968 14,739 Kenmont Swim and Tennis Center 12,646 1,488 1,488 [12/11/06] 14,134 14,134 The AQ monitoring site name and street address is: (# ) S 18 th Street and Hayes Street, Arlington, VA since the Beltsville monitoring site was not operating in Page 21

22 Table 4.6 [Table 1-17]: Comparison of Maximum Modeled 8-Hour CO Concentrations Based on Conservative Representation of Concentrations in Comparison to Actual Measured Concentrations based on Matched Time Period Data [NAAQS = 10,000 µg/m 3 ] Receptor Maximum Modeled Value (μg/m3) Without Conservative (μg/m3) Actual For Time Period Of Maximum With Conservative With Actual Closest Residence 2,798 1, [12/16/2010] 3,943 3,256 Stephen Knolls School 3,555 1, [12/16/2010] 4,700 4,013 Kenmont Swim and Tennis Center 3,361 1, [01/06/2008] 4,506 3,933 The AQ monitoring site name and street address is: Howard University Beltsville Laboratory (# ), Old Baltimore Pike, Beltsville, MD. Page 22

23 Table 4.7 [Table 1-18]: Comparison of Maximum Modeled 1-Hour NO 2 Concentrations Based on Conservative Representation of Concentrations in Comparison to Actual Measured Concentrations based on Matched Time Period Data [NAAQS = 190 µg/m 3 ] Receptor Maximum Modeled Value (μg/m3) Without Conservative (μg/m3) Actual For Time Period Of Maximum With Conservative With Actual Closest Residence [03/21/08] Stephen Knolls School [12/02/09] Kenmont Swim and Tennis Center [01/11/08] The AQ monitoring site street address is: (# ) S 18 th Street and Hayes Street, Arlington, VA Page 23

24 Table 4.8 [Table 1-19]: Comparison of Maximum Modeled 24-Hour PM 2.5 Concentrations Based on Conservative Representation of Concentrations in Comparison to Actual Measured Concentrations based on Matched Time Period Data [NAAQS = 35 µg/m 3 ] Receptor Maximum Modeled Value (μg/m3) Without Conservative (μg/m3) Actual For Time Period Of Maximum With Conservative With Actual Closest Residence [12/22/06] Stephen Knolls School [11/15/06] Kenmont Swim and Tennis Center [11/25/06] The AQ monitoring site name and street address is: Lathrop E. Smith Environmental Education Center (# ), 5110 Meadowside Lane, Rockville, MD 5 Note the modeled maximum 24-hour for Stephen Knolls School occurred on 11/14/2006. But the measured data set for the Rockville station was not available for that date. However it was determined that the original default of 11/25/2006 was not representative and has since been changed conservatively represent the higher measured concentration around that time of 17.2 µg/m 3, which was for 11/15/2006.] Page 24

25 Table 4.9 [Table 1-20]: Comparison of Modeled Annual Average PM 2.5 Concentrations Based on Conservative Representation of Concentrations in Comparison to Actual Measured Concentrations based on Matched Time Period Data [NAAQS = 12 µg/m 3 ] The proposed new standard decreased from 15 µg/m 3 Receptor Maximum Modeled Value (μg/m3) Without Conservative (μg/m3) Actual For Time Period Of Maximum With Conservative With Actual Closest Residence [2009] Stephen Knolls School [2009] Kenmont Swim and Tennis Center [2009] The AQ monitoring site name and street address is: Howard University Beltsville Laboratory (# ), Old Baltimore Pike, Beltsville, MD. 6 The maximum values for the Stephen Knolls School and the Kenmont Swim and Tennis center occurred in 2009 as indicated above. The maximum value for the closest residence occurred in 2008, but outside the period with data availability. As a default, it is assumed that 2009 would be a reasonable indicator of background concentrations for the closest residence as well. Page 25

26 µg/m³ 4.2 Downward Trend in Concentration is Important Factor Fine particulates (PM 2.5 ) provide a useful example of the trends in air quality, and how these trends can increase the degree of conservatism in the background treatments as used in the Costco environmental report. Figure 4.2 presents the three-year running averages 7 (applied to the most recent years). Figure 4.2: Trends in PM 2.5 Concentrations Based on Rockville, Beltsville, and Arlington Monitoring Sites (three-year running averages from 2005 through 2012) Rockville Beltsville Arlington Year By 2012, the highest background value for fine particulates is approximately 10.8 µg/m 3. This value is comparable to the annual PM 2.5 Design Value for background as reported by the Washington Council of Governments, as shown in Figure The term 3-year running average in Figure 4.2 represents the average concentrations based on the year shown and the preceding two years. For example, the 3-year running averages for 2010 is the annual average of 2008, 2009 and Page 26

27 Figure 4.3: Annual PM 2.5 Design Value Concentration from Washington Council of Governments ~ End of µg/m 3 On this basis, the highly conservative background concentration of 12.1 µg/m 3 for annual average fine particulates (PM 2.5 ) is significantly higher than would be anticipated to occur in 2013 and beyond when the gas station will be operational. Based on the downward trends in the preceding plots, it would be anticipated that the fine particulate background concentration would be at or below 10 µg/m 3 by the time the gas station is operational in It also should be noted in this example that as time goes on, that the background value will be expected to continue to fall as the fleet turnover further reduces particulate emissions from gasoline and diesel vehicles in the metropolitan area and beyond. It is also useful to consider when interpreting modeling results relate to National Ambient Air Quality Standards (NAAQS) that there are U.S. EPA defined significant impact levels (SILs) as established by the U.S. Environmental Protection Agency. While the proposed gas station does Page 27

28 not require a specific air quality permit, the terminology regarding significance is useful to consider for context. If the maximum predicted impacts are less than the defined significant impact levels, the new facility is considered to be in compliance with the National Ambient Air Quality Standards for that pollutant. For annual fine particulates (PM 2.5 ), the significant impact level 8 applicable to this region is 0.3 µg/m 3. The incremental maximum modeled impacts from the incremental fine particulate standard from the Costco gas station operations is µg/m 3, which is six times lower than the EPA significance level. 9 Levels below the significance impact levels are considered insignificant by the EPA and other regulatory agencies. 8 Federal Register, Volume 75, No. 202 Page October 20, Based on the most directly applicable urban results (apply most directly to the closest home, Stephen Knoll School and Kenmont Tennis and Swim Center, which have flow generally over the mall property, i.e. concrete, buildings, and a road), which are considered to be urban land use per U.S. EPA methodology. Page 28

29 5.0 Odor: Percent Wind Flow from Fueling Area towards Nearby Residences In the original modeling report, it was estimated that light odors would be detected in the outdoor environment at the nearest residences. It was stated that odors would occur 2 to 2.5 percent of the time. This range was based on the original proposed location of the gas station and an earlier wind frequency distribution prior to using minute-by-minute wind data. Since that time the gas station design has been relocated and the meteorological data upgraded with 1-minute processing. Figure 5.1 presents the annualized five-year wind rose frequency for Washington National Airport (DCA) for the more refined wind data, using the standard 16-major compass headings during the operational hours of the gas station (6:30 A.M. to 9:30 P.M.). This five-year wind rose is overlaid onto the base map and centered directly on the location of the proposed gasoline station in Figure 5.1. A tabular summary of this wind frequency data is also provided in Table 5.1. These data show direct wind direction frequency data and a second column that provides a factoring of these annualized wind derived values, i.e., the frequency during operational hours was multiplied times the factor of 15/24 (to account for the fraction of hours per day the gas station operates) and by 13/16 (to account for the observations of the odor monitoring studies at Costco Sterling that showed observable (light) odors during 13 of 16 odor tests). Based on this analysis, the nearest homes located just to the SSW of the proposed gasoline station will have a potential of observing light odors approximately 2.6 percent of the time, and the other nearby homes to the SSE will be affected approximately 4.9 percent of the time. Based on the comparative odor studies conducted at the Costco Sterling gas station in August and December, it was found that the odors were substantially lighter during the summertime period, which had only 6 of the 9 odor tests with detectable values, with faint odors within a range of 35 to 65 feet from the fueling area. The comparative data from Sterling collected in should be interpreted as conservative representations of operations at Wheaton because of the enhanced controls at Wheaton that will reduce emissions associated with fueling, and the downward trend in emissions from fueling as a function of time as the transition progresses from Stage II controls associated with venting to the underground tank to full reliance on the on-board canister systems in the mobile source fleet. Page 29

30 Figure 5.1: Five-Year Annualized DCA Wind Rose Overlaid on Base Map Centered on the Proposed Costco Gasoline Station Page 30

31 Table 5.1: Five-Year ( ) Wind Frequency Distribution for Washington National Airport (DCA) based on the Gasoline Station Operational Hours of 6:30 A.M. to 9:30 P.M. [Note: Annualized= Annualized wind frequencies from DCA wind rose using hours 6 A.M. to 10 P.M Factored= Annualized Frequencies * (15 Operating hours / 24 hours) * (13/16 odor test periods with detectable odors)] Page 31

32 6.0 Updated Concentration and Risk Figures Figures 6.1 through 6.7 are refined isopleth maps for CO, NO 2, PM 2.5, and VOCs, which contain an expanded scale presentation of the data as compared to the presentation in the report submitted on November 19, The original figure numbers are displayed and bracketed to facilitate comparison with the report. The updated figures here display the same data but with refinements to the scale of view to more fully display concentrations near major roadways compared to locations near the gas station. It is evident in this larger view that locations near roadway sources show substantially larger impacts in comparison to the gas station contributions. Roadways such as Georgia Avenue and University Boulevard to the northwest and southeast of the gas station are typically the most dominant. Figure 6.8 was only updated to eliminate the star in the original descriptive text that was to be used for the nearby homes. The inclusion of the star would have made it difficult to identify the key isopleth lines and associated 70-year risk values around the nearby homes; it was omitted in this final version. It should be noted that the plots in Section 6 are based on the more conservative (tend to overstate) rural land use, which affects the rate of atmospheric dilution. EPA has designed a specific, yet simplified procedure to evaluate urban versus rural treatments, based on evaluating land use within a 3-km radius of a facility. On that basis, the designation would be rural, which is shown in these plots. For the closest locations, including the closest residence, the Kenmont Swim and Tennis facility, and the Stephen Knolls School, the more accurate treatment would be urban because of the influence of the structures and ground surfaces at the Wheaton Mall. It should be noted when reviewing the rural figures, the incremental contribution from the Costco sources (including the warehouse) is approximately 2 to 3 times higher than would be expected for these nearby locations. Figures 3.1 through 3.6 provide perspective on the urban and rural differences for the three nearby locations mentioned above. Page 32

33 Figure 6.1: [Figure 1-14 in November 2012 report] Refined Predicted Highest Second-High 1-Hour CO Isopleth Concentrations (μg/m 3 ) plus 1,488 μg/m 3 Rural Land use NAAQS = 40,000 μg/m 3 [Note: Peak concentrations are occurring within intersections and traffic corridors] Page 33

34 Figure 6.2: [Figure 1-15 in November 2012 report] Refined Predicted Highest Second-High 8-Hour CO Isopleth Concentrations (μg/m 3 ) plus 1,145 μg/m 3 Rural Land use NAAQS = 10,000 μg/m 3 Page 34

35 Figure 6.3: [Figure 1-16 in November 2012 report] Refined Predicted 98th Percentile 1-Hour NO 2 Isopleth Concentrations (μg/m 3 ) plus 28 μg/m 3 Rural Land use NAAQS = 190 μg/m 3 [Note: Peak concentrations are occurring within the intersections] Page 35

36 Figure 6.4: [Figure 1-17 in November 2012 report] Refined Predicted Annual Average NO 2 Isopleth Concentrations (μg/m 3 ) plus 6.8 μg/m 3 Rural Land use NAAQS = 100 μg/m 3 [Note: The annual average background NO 2 concentration was changed to 6.8 μg/m 3 since the main report (see Section 4.0).] Page 36

37 Figure 6.5: [Figure 1-18 in November 2012 report] Refined Predicted 98th Percentile 24-Hour PM 2.5 Isopleth Concentrations (μg/m 3 ) plus 28 μg/m 3 Rural Land use NAAQS = 35 μg/m 3 Page 37

38 Figure 6.6: [Figure 1-19 in November 2012 report] Refined Predicted Annual Average PM 2.5 Isopleth Total (All Modeled Sources) Concentrations (μg/m 3 ) plus 12.1 μg/m 3 Rural Land use NAAQS = 12 μg/m 3 (new standard; previous standard was 15 μg/m 3 ) [Note: The more typical (less conservative) representation of background PM 2.5 annual average concentrations is ~ 10.6 µg/m 3, as compared to the 12.1 μg/m 3 conservative value. More importantly, it should be noted that the maximum contribution from the incremental gas station operations is μg/m 3, which is 0.08 percent of the standard and an insignificant contribution.] Page 38

39 Figure 6.7: [Figure1-22 in November 2012 report] Refined Predicted Annual Average VOC Isopleth Concentrations (μg/m 3 ) for VOC Rural Land use Scenario 2 (All Sources) µg/m µg/m 3 34 µg/m µg/m 3 10 In the November 2012 report, two scenarios were used to represent gasoline marketing emissions. Scenario 1 was retained because it was described in the protocol. Scenario 2 is a more refined version, and is shown here, because it more accurately represents improvement in fueling emissions due to the presence of on-board refueling controls on the later model vehicles. Page 39

40 Figure 6.8: [Figure 1-24 in November 2012 report] Predicted 70-Year VOC Risk per Million Analysis 11 Based on More Conservative Rural Analysis Closest Residential receptor = 1.7 per million Stephen Knolls School = 0.2 per million Kenmont Swim and Tennis Center (Pool) = 0.6 per million 11 Assuming 100 percent occupancy Page 40

41 6.0 Queue Data A queuing study was performed at the Costco Sterling, Virginia gas station on Friday, January 11, 2013 and Saturday, January 12, The objective was to obtain data to represent typical weekday and weekend queues at a similar gas station that sold 13,900,000 gallons of gasoline in The data collection covered the full 15-hour operational period of the station, i.e. from 6:30 A.M. through 9:30 P.M. Minute-by-minute data were collected for each lane over the 15 hour (900 minute) daily periods. Friday, January 11, 2013 had sales of 40,625 gallons, as compared to a yearly average day 12 in 2012 of 38,082 gallons. Saturday, January 12, 2013 had sales of 35,447 gallons. This sales data shows the days associated with queue monitoring were representative of typical conditions, i.e. +/- 7 percent of the daily average sales for Date Day of Week Table 6.1 summarizes the results. Maximum 1-hour Queue Maximum 8- hour queue Daily Average Queue Length 1/11/2013 Friday /12/2013 Saturday Weekly average Queue data adjusted for difference In gas station volume 14 Assumed Queues in Modeling Report Difference (assumed measured) Percent difference +4 % % -1 % On the basis of the more comprehensive measured queue data for a representative full weekday and full weekend day, it was found that the assumed queue data accurately represented expected conditions at a similar (but larger) gas station for the 1-hour and annual average periods. The maximum 8-hour queues were approximately 50 percent higher than modeled. This only applies to the 8-hour CO concentrations. Factoring the queuing contribution by a factor of 32/20 would 12 Value determined from 13.9 million gallons sold in Based on a weighted average of [( Friday Queue x 5) + (Saturday Queue x 2)]/7 = weekly average cars in queue during 15-hour operational hours 14 Queues times [12,000,000 / 13,900,000] = 0.86 Page 41

42 increase CO at the closest home from being 28 percent to 32 percent of the 10,000 µg/m 3 NAAQS standard. Page 42