Air Quality Specialist Report

Transcription

1 United States Department of Agriculture Forest Service Rocky Mountain Region Air Quality Specialist Report La Garita Hills Project Submitted by: _Vaughn Thacker, Forest Soil Scientist Smoke emissions updated by Kent Smith, Fire & Fuels and Diana McGinn 3/2017 1

2 Contents Relevant Laws, Regulation, and Policy that Apply 3 Methodology and Analysis Process 5 Assumptions 5 Affected Environment (Existing and Desired Conditions) 5 Description of Alternatives 7 Direct and Indirect Effects 10 Cumulative Effects 11 Design Criteria 11 References 12 Appendix A 13 2

3 Relevant Laws, Regulations and Policy that Apply The Clean Air Act, passed in 1970 and amended in 1977 and 1990, requires the Environmental Protection Agency (EPA) to set standards for air pollutants to protect the public health and welfare. The standards, known as National Ambient Air Quality Standards, limit the amount of these pollutants that can be present in the atmosphere. The EPA has set standards for six common pollutants known as criteria air pollutants ozone (O3), particulate matter (PM), nitrogen dioxide (NO2), sulfur dioxide (SO2), lead (Pb), and carbon monoxide (CO). There are standards for two categories of particulate matter one for suspended particles less than 10 micrometers in diameter (PM10) and one for fine particles less than 2.5 micrometers in diameter (PM2.5). Primary standards are designed to protect public health, while secondary standards are designed to protect public welfare. These standards are shown in Table XX. Units of measure for the standards are parts per million (ppm) by volume, parts per billion (ppb) by volume, and micrograms per cubic meter of air (µg/m 3 ). Table XX: National Ambient Air Quality Standards Pollutant Primary / Averaging Level Form Secondary Time Primary 8-hour 9 ppm Not to be exceeded more than once per CO year 1-hour 35 ppm Pb Both Rolling μg/m 3 (1) Not to be exceeded Month NO 2 Primary Both 1-hour Annual 100 ppb 53 ppb (2) 98th percentile, averaged over 3 years Annual mean 8-hour ppm Both Annual fourth-highest daily maximum 8- O3 hour concentration, averaged over 3 years Primary Annual 12 g/m 3(5) Annual mean, averaged over 3 years Particle PM 2.5 Secondary Annual 15 g/m 3 Annual mean, averaged over 3 years Both 24-hour 35 µg/m 3 98th percentile, averaged over 3 years PM 10 Both 24-hour 150 µg/m 3 year on average over 3 years Not to be exceeded more than once per SO2 Primary 1-hour 75 ppb (4) 99th percentile of 1-hour daily maximum concentrations, averaged over 3 years Secondary 3-hour 500 ppb (2) year Not to be exceeded more than once per Source: 1 Final rule signed October 15, The official level of the annual standard is expressed in ppm, but is shown here in ppb for the purpose of clearer comparison to the 1-hour standard. 3 Final rule signed March 12, The 1997 ozone standard (0.089 ppm, annual fourth-highest daily maximum 8-hour concentration, averaged over 3 years) and related implementation rules remain in place. 4 Final rule signed June 2, The 1971 annual and 24-hour SO2 standards were revoked in that same rule making. However, these standards remain in effect until one year after an area is designated for the 2012 standard, except in areas designated nonattainment for the 1971 standards, where the 1971 standards remain in effect until implementation plans to attain or maintain the 2010 standards are approved. 5 The final rule is effective March 18, Unlike most other criteria pollutants, ozone is not emitted to the atmosphere directly; it is formed when nitrogen oxides and volatile organic compounds react in the presence of sunlight. In general, ozone concentrations in the lower atmosphere are highest during warmer months and lower in the cooler months. In some parts of the western U.S., high winter-time ozone 3

4 concentrations have been monitored. The project area is not in an airshed with monitored high winter-time ozone concentrations. The chemical reactions that form ozone are complicated and nonlinear, making it difficult to predict ozone concentrations that will result from increasing the amount of the ozone precursors (i.e., nitrogen oxides and volatile organic compounds) in the atmosphere. The effect of adding nitrogen oxides or volatile organic compounds to the atmosphere on the concentration of ozone depends upon the ratio of the two precursors already present. Ozone formation is also highly dependent on meteorological conditions, including temperature, wind speed, and solar radiation. Ozone in the lower atmosphere is harmful to human health and vegetation. Some fine particulates (PM2.5), particularly ammonium sulfate and ammonium nitrate particles, can also be formed in the atmosphere from the interaction of either SO2 or NOx and ammonium. These types of PM2.5 particles are referred to as secondary particulates, while particles emitted directly from a source are referred to as primary particulates. Fine particulate matter (PM2.5) is chiefly comprised of five mass types: organic mass, elemental carbon (also known as soot or black carbon), ammonium sulfates, ammonium nitrates, and crustal materials (i.e., soil). Primary fine particulate emissions result from combustion processes (including fossil fuel combustion and biomass combustion that occurs in wildfires) and include black carbon. In general, however, black carbon and crustal materials comprise a relatively small proportion of the fine particulate mass suspended in the atmosphere. Visibility is a measure of not only how far one can see, but how well one can see important characteristics of the landscape such as form, color, geologic features, and texture. Visibility is limited by the presence of particles and gasses in the atmosphere that scatter and absorb light. In the Clean Air Act, Congress established a national goal of remedying any existing, and preventing any future, impairment to visibility that is caused by manmade pollution in selected areas called mandatory federal Class I areas (42 USC 7491). These Class I areas consist of 156 national parks, wildlife refuges, wilderness areas, and Native American lands located throughout the country. The Class I areas closest to the project area are Black Canyon of the Gunnison Wilderness Area, Great Sand Dunes Wilderness Area, La Garita Wilderness Area, and the Weminuche Wilderness Area. In order to meet the goal set by Congress in the Clean Air Act of remedying existing manmade visibility impairment in mandatory federal Class I areas, the EPA promulgated the Regional Haze Rule in This rule requires states to develop plans to reduce manmade pollution in Class I areas. Visibility impairment is caused by small particles suspended in the atmosphere that scatter or absorb light as it travels toward an observer. Visibility impairment affects not only how far one can see, but how well one can distinguish features of the landscape such as form, color, and texture. The Interagency Monitoring of Protected Visual Environments (IMPROVE) program has been established to monitor visibility conditions at Class I areas and provide information on the causes of visibility impairment. This network of monitors includes 110 particulate samplers located near Class I areas that provide estimates of visibility for using in tracking progress toward meeting the national visibility goal. 4

5 Methodology and Analysis Process Scope of Analysis This section describes the effects to air quality in the vicinity of the LGH analysis area including nearby private lands or developments and the La Garita Wilderness Area, a Class I airshed (located less than 2 miles west of the analysis area boundary). The town of Saguache is located about 2 miles north from the northeast corner of the analysis area. The small community of La Garita is located about 5 miles southeast of the southern corner of the analysis area. Description The La Garita Hills analysis area is located south west of the town of Saguache, Colorado. It emcompasses approximately 187,778 acres located in the soutwester protion of the Saguache Ranger District. It encompass all or part of 17 watersheds (HUC 6 level) on Forest Service and BLM lands. The area also includes may private in-holdings that provide residents seasonal and year-round use. The area is used for dispersed camping, hiking, fishing, hunting, snowmobliling, and cross-country skiing. Four developed recreational facilities and two trail systems are within the project area. The area encompasses a wide variety of vegetation types, from low elevation piñon-juniper woodlands to high elevation Engelmann spruce-subalpine fir. This range of vegetation types provides habitats for many wildlife species including, Rio Grande Cutthroat trout, mule deer, elk, bear and beaver. Affected Environment Existing Condition Current conditions of air quality in Colorado are detailed in the Colorado Air Quality Control Commission: Report to the Public ( default/files/ pdf). The project area is located in Colorado s San Luis Valley Air Quality Region which includes the San Luis Valley including Alamosa, Conejos, Costilla, Rio Grande and Saguache Counties. Recreation, including camping, fishing and hunting, and agriculture are the primary industries in this region. All of the area complies with federal air quality standards according to the Colorado air quality control commission report. In addition all the surrounding air quality regions, south central (Pueblo), South Western (Pagosa Springs, and Durango), and Central Mountains (Salida, Creede, Lake City) also comply with federal air quality standards. This is also true of compliance with the National Ambient Air Quality Standards. Air quality in the area is generally good. Areas that meet federal ambient air quality standards are classified as being in attainment, while areas not meeting standards are classified as being in nonattainment. On April 30, 2012, the EPA finalized its ozone nonattainment designations with respect to the 2008 ozone standard ( 5

6 designations/2008standards/final/region8f.htm). EPA identified only one nonattainment area in Colorado for ozone that includes part or all of Denver, Adams, Arapahoe, Boulder, Broomfield, Douglas, Jefferson, Larimer, and Weld counties (roughly the Denver-Boulder-Greeley-Fort Collins metropolitan areas). This area is located along the Front Range approximately 150 miles to the northeast of the project area. EPA has not identified any current nonattainment areas in Colorado for any of the other criteria pollutants. In the 2013 Colorado Air Quality Data Report ( for the monitoring period , Alamosa, and Crested Butte, had exceedance events in 2012 and 2013 while Durango and Pagosa Springs had exceedance events in These exceedance events were for PM10. Exceedance events are singular events and do not by themselves make an area or station noncompliant with state and/or federal standards. This is just to point out that monitoring is being done and that while some exceedance events do occur in the area standards are still being met. Visibility is tracked using data from the IMPROVE monitoring system. There are two IMPROVE monitoring Stations located near the project area. The first is located at the Great Sand Dunes Visitors Center approximately 40 miles to the east across the San Luis Valley from the Project area the second is within the Weminuche Wilderness. This air quality site is located on the south end of Engineer Mountain at an elevation of about 9,070 ft and is approximately 65 miles to the west of the project area. Under the Regional Haze Rule, visibility is tracked on the clearest and haziest days. The clearest days are defined as the clearest 20% of days in each year, and the haziest days are defined as the haziest 20% of days in each year. Visibility impairment is measured in terms of a haze index called the deciview (dv). The deciview value increases as visibility impairment increases. The means of the haziest 20% and clearest 20% from the Weminuche IMPROVE monitoring site are plotted in Figure A. Data collected over the ten year period indicate a statistically significant (p<0.01) improving trend on the clearest trends, and no trend on the haziest days. Figure A. Annual mean Deciview on the clearest and haziest days at the Weminuche IMPROVE Visibility Monitor 6

7 Desired Conditions. General Desired Conditions Generally speaking desired conditions would be to continue or reduce current levles of emissions and pollutions. Generally levels are within acceptable standards and are expected to remain that way other than some isolated events related to large fires that are within the area or up wind from these watershed. Description of Alternatives See chapter 2. Direct and Indirect Effects Alternative 1 Since no actvities would occur, so no additional emissions would occur. Alternatives 2, 3, 4 The proposed activities associated with the project actions can directly affect air quality. These activities could include the combustion of fossil fuel from equipment used to cut, haul, and transport logs or masticate trees during thinning operations. It also would include burning of large logging slash piles, prescribed broadcast burns, and hand pile or other burning activities associated with WUI treatments. Vehicle emissions from timber harvest or thinning operations would occur. Impacts from emissions would be short-term on an intermittent basis over the life the project. Gas or diesel powered equipment would result in Sulphur dioxide, particulates, volatile organic compounds, carbon dioxide, and nitrogen oxide emissions. Operations that occur during the summer could increase the amount visible dust. Any dust abatement used on road 41G or other road, as needed, would reduce dust from all road traffic. The possibility of relocation road segments as well as re-construction/maintenance of roads is likely to some extent for all alternatives. Generally, this would result in the increase of fine particles as dust as ground is disturbed and surfacing and base materials applied, as needed. In addition, volatile organic compounds, soot, nitrogen oxides (NOx), sulfur dioxide, particulates, carbon dioxide and monoxide would be emitted in this process. After the roadwork is complete, vehicles that move along the road will emit these chemicals in increased amounts as compared to current conditions. Emissions from harvest equipment would increase during harvest activities; however the impacts would occur on a short-term basis and be localized to the area of harvest. Pile burning is likely in both the areas of timber harvest as well as WUI treatment areas. Prescribed broadcast burning is also proposed as part of these alternatives. Pile burning would 7

8 result in emissions typically associated with wood combustion, particularly volatile organic compounds, nitrogen oxides, soot, particulates, carbon dioxide, and carbon monoxide. Fires could also emit hazardous air pollutants, such as polynuclear aromatic hydrocarbons and aldehydes (such as formaldehyde). Since prescribed fires and slash burning are conducted under controlled conditions, they are less intense than wildfires, and are much smaller in size, it can be reasonably expected that the emissions resulting from these activities would be considerably lower than those from an uncontrolled wildfire. All burning operations would require smoke permits issued by the Colorado Air Pollution Control Division (CAPCD). The smoke permit includes specific parameters that must be met to limit adverse short-term air quality impacts from smoke to Class I airsheds and local communities to ensure that adverse effects are minimized. The requirement for a smoke permits prior to ignition, is relied on to help regulate and protect against excessive emmisions and meet Clean Air Act requirements during project implementation. There is the potential for both a large number of acres to be broadcast burned and a large number of slash piles to be generated and burned over the course of completing proposed project activities for all action alternatives. Both types of burning activities would occur periodically over 10 to 15 years, as individual projects are implemented and effects to air quality would occur as described above. If a biomass market developed, a portion of the slash material would be hauled away to be used elsewhere versus burned on-site. Particulate Matter 2.5 (PM2.5 ) Emmissions Since exposure to fine particles in the PM2.5 size range (< 2.5 microns in width) have the most potential to affect human health, this air qualtiy attribute was used to compare the action alternatives quantitatively. Based on acres harvested per year on the Forest from 2014 through 2016, the average is approximately 2,060 acres, since harvested acres have been increasing over the past few years in order to salvage spruce beetle mortality trees while they have value. Piles are generally burned after they have a time to cure, usually one to two years following harvest. Based on the proceedures and assumptions used in Hardy (1996) along with recent experience on the Forest burning machined piled slash, each pile burned would generate about 14 pounds of PM2.5 per ton of slash consumed. It is estimated an average slash pile would contain about 25 tons of wood per pile, so each large slash pile could generate about 300 to 400 total pounds of PM2.5. Based on the estimated acres of landings for each alternative, assuming the maximum number acres were harvested for each alternative, Forest logging operation were focused only in the analysis area, and one slash pile per landing, the amounts of PM2.5 generated by pile burning over 10 to 15 years are shown in the table below. On an annual basis, about 515 piles would be burned to keep pace with logging operations, assuming one landing per 4 acres harvested which would be approximately 154,5000 to 206,000 pounds of PM2.5 emissions. These emissions would occur in the winter months when snow is present. For prescribed broadcast burning, the RGNF is assigned an 3,000 acre annual target. Depending on weather, type of vegetation, and other variables, the Forest may burn fewer acres and in some years more acres are achieved. Based on FOFEM (First Order Fire Effects Model) outputs, 8

9 emission values for typical fuel loadings that could occur in similar forested types proposed for broadcast burning the LGH analysis area, about 288 pounds per acre of PM2.5 emissions could be generated. Emmissions from burning in grass dominated vegetation would be much less due to the rapid combustion and low fuel loadings, so this type was omitted from the calculations; shrub areas were included with the forested acres. The total emission amounts that could be generated over 10 to 15 years, if prescribed broadcast burning occurred on the maximum number of forested/shrub acres proposed, are shown in the table below. On an annual basis, if 3,000 acres of forest were broadcast burned about 864,000 pounds of PM2.5 emissions would be generated. These emissions could occur in spring through fall, depending on burn objectives. PM2.5 generated (pounds) Alternative 2 Alternative 3 Alternative 4 Pile burning 678, , , , , ,000 Broadcast burning 12,502,080 16,845,120 11,568,960 In comparing alternatives 2, 3 and 4 the emmision sources would be the same and the effects similar really only varying in scale. As indicated, alternative 2 would have the highest potential for PM2.5 emissions from burning logging slash piles, but alternative 3 could have the highest total PM2.5 emissions, since more acres of broadcast burning are proposed. Since alternative 3 proposes the fewest acres of timber harvest, this alternative would have fewer emissions from pile burning and logging equipment operations. Alternative 4 would have intermediate levels of total emissions. Since any approved activities would occur over several years, it is not anticipated that any of the proposed alternatives will have a measurable impact on local air quality. Cumulative Effects Common to all Alternatives Emissions generated by implementing an action alternative would contribute somewhat to local pollution, but all affects would be short-term and limited. The requirement for all prescribed burn activities in Colorado to obtain a smoke permits issued by the Colorado Air Pollution Control Division (CAPCD) also helps reduce cumulative impacts in local airsheds. Once individual project activities are completed in a particular area, any additional dust or smoke impacts would cease and have no further overlap in time or space with other pollution sources. As a result, proposed activities within the analysis area are not expected to contribute to any violation of National Ambient Air Quality standards or to contribute measurably to any increase in visibility impairment at nearby Class I areas. All alternatives, therefore, would comply with the Clean Air Act. References Forest Service Rio Grande National Forest Land and Resource Management Plan, FEIS, ROD, and Annual Monitoring Reports. Hardy, Colin C Guidelines for estimating volume, biomass, and smoke production for piled slash. USDA Forest Service. PNW-GTR pgs. 9

10 Appendix A GRSA1 PM 10 GRSA1 PM 2.5 WEMI 1 PM 10 WEMI 1 PM