Arizona Administrative Code › Title 18 - ENVIRONMENTAL QUALITY › Chapter 2 - DEPARTMENT OF ENVIRONMENTAL - QUALITY AIR POLLUTION CONTROL › APPENDICES › Appendix 15 - Test Methods For Determining Opacity and Stabilization of Unpaved Roads

Current through Register Vol. 30, No. 28, July 12, 2024
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.