Ariz. Admin. Code § tit. 18, ch. 2, APPENDICES, app 15
A15.1. Applicability
This appendix applies to unpaved roads at the primary copper smelter located in Hayden, Arizona at latitude 33º0'15"N and longitude 110º46'31"W.
A15.2. Opacity Test Method
The purpose of this test method is to estimate the percent opacity of fugitive dust plumes caused by vehicle movement on unpaved roads. This method can only be conducted by an individual who has received certification as a qualified observer. Qualification and testing requirements can be found in Section A15.4 of this appendix.
A15.2.1. Step 1
Stand at least 16.5 feet from the fugitive dust source in order to provide a clear view of the emissions with the sun oriented in the 140º sector to the back. Following the above requirements, make opacity observations so that the line of vision is approximately perpendicular to the dust plume and wind direction. If multiple plumes are involved, do not include more than one plume in the line of sight at one time.
A15.2.2. Step 2
Record the fugitive dust source location, source type, method of control used, if any, observer's name, certification data and affiliation, and a sketch of the observer's position relative to the fugitive dust source. Also record the time, estimated distance to the fugitive dust source location, approximate wind direction, estimated wind speed, description of the sky condition (presence and color of clouds), observer's position to the fugitive dust source, and color of the plume and type of background on the visible emission observation from both when opacity readings are initiated and completed.
A15.2.3. Step 3
Make opacity observations, to the extent possible, using a contrasting background that is perpendicular to the line of vision. Make opacity observations approximately 1 meter above the surface from which the plume is generated. Note that the observation is to be made at only one visual point upon generation of a plume, as opposed to visually tracking the entire length of a dust plume as it is created along a surface. Make two observations per vehicle, beginning with the first reading at zero seconds and the second reading at five seconds. The zero-second observation should begin immediately after a plume has been created above the surface involved. Do not look continuously at the plume but, instead, observe the plume briefly at zero seconds and then again at five seconds.
A15.2.4. Step 4
Record the opacity observations to the nearest 5 percent on an observational record sheet. Each momentary observation recorded represents the average opacity of emissions for a 5-second period. While it is not required by the test method, EPA recommends that the observer estimate the size of vehicles which generate dust plumes for which readings are taken (e.g. midsize passenger car or heavy-duty truck) and the approximate speeds the vehicles are traveling when readings are taken.
A15.2.5. Step 5
Repeat Step 3 (Section A15.2.3 of this appendix) and Step 4 (Section A15.2.4 of this appendix) until you have recorded a total of 12 consecutive opacity readings. This will occur once six vehicles have driven on the source in your line of observation for which you are able to take proper readings. The 12 consecutive readings must be taken within the same period of observation but must not exceed 1 hour. Observations immediately preceding and following interrupted observations can be considered consecutive.
A15.2.6. Step 6
Average the 12 opacity readings together. If the average opacity reading equals 20 percent or lower, the source is in compliance.
A15.3. Silt Content Test Method
The purpose of this test method is to estimate the silt content of the trafficked parts of unpaved roads. The higher the silt content, the more fine dust particles that are released when cars and trucks drive on unpaved roads.
A15.3.1. Equipment
A15.3.1.1. A set of sieves with the following openings: 4 millimeters (mm), 2 mm, 1 mm, 0.5 mm and 0.25 mm (or a set of standard/ commonly available sieves), a lid, and collector pan.
A15.3.1.2. A small whisk broom or paintbrush with stiff bristles and dustpan 1 ft. in width. (The broom/brush should preferably have one, thin row of bristles no longer than 1.5 inches in length).
A15.3.1.3. A spatula without holes.
A15.3.1.4. A small scale with half-ounce increments (e.g., postal/ package scale).
A15.3.1.5. A shallow, lightweight container (e.g., plastic storage container).
A15.3.1.6. A sturdy cardboard box or other rigid object with a level surface.
A15.3.1.7. A basic calculator.
A15.3.1.8. Cloth gloves (optional for handling metal sieves on hot, sunny days).
A15.3.1.9. Sealable plastic bags (if sending samples to a laboratory).
A15.3.1.10. A pencil/pen and paper.
A15.3.2. Step 1
Look for a routinely traveled surface, as evidenced by tire tracks. (Only collect samples from surfaces that are not damp due to precipitation or dew. This statement is not meant to be a standard in itself for dampness where watering is being used as a control measure. It is only intended to ensure that surface testing is done in a representative manner.) Use caution when taking samples to ensure personal safety with respect to passing vehicles. Gently press the edge of a dustpan (1 foot in width) into the surface four times to mark an area that is 1 square foot. Collect a sample of loose surface material using a whiskbroom or brush and slowly sweep the material into the dustpan, minimizing escape of dust particles. Use a spatula to lift heavier elements such as gravel. Only collect dirt/ gravel to an approximate depth of 3/8 inch or 1 cm in the 1 square foot area. If you reach a hard, underlying subsurface that is < 3/8 inch in depth, do not continue collecting the sample by digging into the hard surface. In other words, you are only collecting a surface sample of loose material down to 1 cm. In order to confirm that samples are collected to 1 cm in depth, a wooden dowel or other similar narrow object at least one foot in length can be laid horizontally across the survey area while a metric ruler is held perpendicular to the dowel.
At this point, you can choose to place the sample collected into a plastic bag or container and take it to an independent laboratory for silt content analysis. A reference to the procedure the laboratory is required to follow is at the end of this section.
A15.3.3. Step 2
Place a scale on a level surface. Place a lightweight container on the scale. Zero the scale with the weight of the empty container on it. Transfer the entire sample collected in the dustpan to the container, minimizing escape of dust particles. Weigh the sample and record its weight.
A15.3.4. Step 3
Stack a set of sieves in order according to the size openings specified above, beginning with the largest size opening (4 mm) at the top. Place a collector pan underneath the bottom (0.25 mm) sieve.
A15.3.5. Step 4
Carefully pour the sample into the sieve stack, minimizing escape of dust particles by slowly brushing material into the stack with a whiskbroom or brush. (On windy days, use the trunk or door of a car as a wind barricade.) Cover the stack with a lid. Lift up the sieve stack and shake it vigorously up, down and sideways for at least 1 minute.
A15.3.6. Step 5
Remove the lid from the stack and disassemble each sieve separately, beginning with the top sieve. As you remove each sieve, examine it to make sure that all of the material has been sifted to the finest sieve through which it can pass (e.g., material in each sieve [besides the top sieve that captures a range of larger elements] should look the same size). If this is not the case, re-stack the sieves and collector pan, cover the stack with the lid, and shake it again for at least 1 minute. (You only need to reassemble the sieve(s) that contain material, which requires further sifting.)
A15.3.7. Step 6
After disassembling the sieves and collector pan, slowly sweep the material from the collector pan into the empty container originally used to collect and weigh the entire sample. Take care to minimize escape of dust particles. You do not need to do anything with material captured in the sieves; only the collector pan. Weigh the container with the material from the collector pan and record its weight.
A15.3.8. Step 7
If the source is an unpaved road, multiply the resulting weight by 0.38. The resulting number is the estimated silt loading. Then, divide by the total weight of the sample you recorded earlier in Step 2 (Section A15.3.3 of this appendix) and multiply by 100 to estimate the percent silt content.
A15.3.9. Step 8
Select another two routinely traveled portions of the unpaved road and repeat this test method. Once you have calculated the silt loading and percent silt content of the 3 samples collected, average your results together.
A15.3.10. Step 9
Examine results. If the average silt loading is less than 0.33 oz/ft2, the surface is STABLE. If the average silt loading is greater than or equal to 0.33 oz/ft2, then proceed to examine the average percent silt content. If the source is an unpaved road and the average percent silt content is 6 percent or less, the surface is STABLE. If your field test results are within 2 percent of the standard (for example, 4-8 percent silt content on an unpaved road), it is recommended that you collect 3 additional samples from the source according to Step 1 (Section A15.3.2 of this appendix) and take them to an independent laboratory for silt content analysis.
A15.3.11. Independent Laboratory Analysis
You may choose to collect 3 samples from the source, according to Step 1 (Section A15.3.2 of this appendix), and send them to an independent laboratory for silt content analysis rather than conduct the sieve field procedure. If so, the test method the laboratory is required to use is: U.S. Environmental Protection Agency (1995), "Procedures for Laboratory Analysis of Surface/Bulk Dust Loading Samples", (AP-42 Fifth Edition, Volume I, Appendix C.2.3 "Silt Analysis"), Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.
A15.4. Qualification and Testing
A15.4.1. Certification Requirements
To receive certification as a qualified observer, a candidate must be tested and demonstrate the ability to assign opacity readings in 5 percent increments to 25 different black plumes and 25 different white plumes, with an error not to exceed 15 percent opacity on any one reading and an average error not to exceed 7.5 percent opacity in each category. Candidates shall be tested according to the procedures described in Section A15.4.2 of this appendix. Any smoke generator used pursuant to Section A15.4.2 of this appendix shall be equipped with a smoke meter which meets the requirements of Section A15.4.3 of this appendix. Certification tests that do not meet the requirements of Sections A15.4.2 and A15.4.3 of this appendix are not valid. The certification shall be valid for a period of 6 months, and after each 6-month period the qualification procedures must be repeated by an observer in order to retain certification.
A15.4.2. Certification Procedure
The certification test consists of showing the candidate a complete run of 50 plumes, 25 black plumes and 25 white plumes, generated by a smoke generator. Plumes shall be presented in random order within each set of 25 black and 25 white plumes. The candidate assigns an opacity value to each plume and records the observation on a suitable form. At the completion of each run of 50 readings, the score of the candidate is determined. If a candidate fails to qualify, the complete run of 50 readings must be repeated in any retest. The smoke test may be administered as part of a smoke school or training program, and may be preceded by training or familiarization runs of the smoke generator, during which candidates are shown black and white plumes of known opacity.
A15.4.3. Smoke Generator Specifications
Any smoke generator used for the purpose of Section A15.4.2 of this appendix shall be equipped with a smoke meter installed to measure opacity across the diameter of the smoke generator stack. The smoke meter output shall display in-stack opacity, based upon a path length equal to the stack exit diameter on a full 0 percent to 100 percent chart recorder scale. The smoke meter optical design and performance shall meet the specifications shown in Table 1 of this appendix. The smoke meter shall be calibrated as prescribed in Section A15.4.3.1 of this appendix prior to conducting each smoke reading test. At the completion of each test, the zero and span drift shall be checked, and if the drift exceeds plus or minus 1 percent opacity, the condition shall be corrected prior to conducting any subsequent test runs. The smoke meter shall be demonstrated, at the time of installation, to meet the specifications listed in Table 1 of this appendix. This demonstration shall be repeated following any subsequent repair or replacement of the photocell or associated electronic circuitry, including the chart recorder or output meter, or every 6 months, whichever occurs first.
A15.4.3.1. Calibration
The smoke meter is calibrated after allowing a minimum of 30 minutes warm-up by alternately producing simulated opacity of 0 percent and 100 percent. When stable response at 0 percent or 100 percent is noted, the smoke meter is adjusted to produce an output of 0 percent or 100 percent, as appropriate. This calibration shall be repeated until stable 0 percent and 100 percent readings are produced without adjustment. Simulated 0 percent and 100 percent opacity values may be produced by alternately switching the power to the light source on and off while the smoke generator is not producing smoke.
A15.4.3.2. Smoke Meter Evaluation
The smoke meter design and performance are to be evaluated as follows:
A15.4.3.2.1. Light Source
Verify, from manufacturer's data and from voltage measurements made at the lamp, as installed, that the lamp is operated within plus or minus 5 percent of the nominal rated voltage.
A15.4.3.2.2. Spectral Response of Photocell
Verify from manufacturer's data that the photocell has a photopic response (i.e., the spectral sensitivity of the cell shall closely approximate the standard spectral-luminosity curve for photopic vision which is referenced in (b) of Table 1 of this appendix).
A15.4.3.2.3. Angle of View
Check construction geometry to ensure that the total angle of view of the smoke plume, as seen by the photocell, does not exceed 15º. Calculate the total angle of view ([phi]v) as follows:
Total Angle of View = 2 tan-1 (d/2L)
where:
d = The photocell diameter + the diameter of the limiting aperture; and
L = The distance from the photocell to the limiting aperture. The limiting aperture is the point in the path between the photocell and the smoke plume where the angle of view is most restricted. In smoke generator smoke meters, this is normally an orifice plate.
A15.4.3.2.4. Angle of Projection
Check construction geometry to ensure that the total angle of projection of the lamp on the smoke plume does not exceed 15º. Calculate the total angle of projection ([phi]p) as follows:
Total Angle of Projection = 2 tan-1 (d/2L)
where:
d = The sum of the length of the lamp filament + the diameter of the limiting aperture; and L = The distance from the lamp to the limiting aperture.
A15.4.3.2.5. Calibration Error
Using neutral-density filters of known opacity, check the error between the actual response and the theoretical linear response of the smoke meter. This check is accomplished by first calibrating the smoke meter, according to Section A15.4.3.1 of this appendix, and then inserting a series of three neutral-density filters of nominal opacity of 20 percent, 50 percent, and 75 percent in the smoke meter path length. Use filters calibrated within plus or minus 2 percent. Care should be taken when inserting the filters to prevent stray light from affecting the meter. Make a total of five nonconsecutive readings for each filter. The maximum opacity error on any one reading shall be plus or minus 3 percent.
A15.4.3.2.6. Zero and Span Drift
Determine the zero and span drift by calibrating and operating the smoke generator in a normal manner over a 1-hour period. The drift is measured by checking the zero and span at the end of this period.
A15.4.3.2.7. Response Time
Determine the response time by producing the series of five simulated 0 percent and 100 percent opacity values and observing the time required to reach stable response. Opacity values of 0 percent and 100 percent may be simulated by alternately switching the power to the light source off and on while the smoke generator is not operating.
Ariz. Admin. Code tit. 18, ch. 2, APPENDICES, app 15