4-9-12: VISUAL DETERMINATION OF FUGITIVE DUST EMISSIONS:
A. Method: Opacity shall be determined by a visual observation made by a currently certified evaluator in accordance with U.S. EPA, 40 CFR, part 60, appendix A, method 9, using the procedures set forth in subsections A1 and A2 of this section. A copy of the observer’s certification shall accompany the vision emission evaluation (VEE).
1. Time Averaged Opacity Method: This procedure is used for continuous fugitive dust emission sources, such as earthmoving, grading, and trenching, that produce emissions continuously. The certified observer should do the following:
a. Position: Stand at a position at least twenty feet (20') from the fugitive dust source in order to provide a clear view of the emissions with the sun oriented in the one hundred forty degree (140°) sector to the back. Consistent as much as possible with maintaining the above requirements, make opacity observations from a position such that the line of sight is approximately perpendicular to the plume and wind direction. The observer may follow the fugitive dust plume generated by mobile earthmoving equipment, as long as the sun remains oriented in the one hundred forty degree (140°) sector to the back. As much as possible, do not include more than one plume in the line of sight at one time.
b. Field Records: Record the name of the site, fugitive dust source type (e.g., earthmoving, grading, trenching), 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 and respective sun location. 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), and observer’s position relative to the fugitive dust source, and color of the plume and type of background on the visible emission observation when opacity readings are initiated and completed.
c. Observations: Make opacity observations, to the extent possible, using a contrasting background that is perpendicular to the line of sight. Make opacity observations at a point just beyond where material is no longer being deposited out of the plume (normally three (3) feet above the surface from which the plume is generated). The initial 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 momentarily at fifteen (15) second intervals. For fugitive dust from earthmoving equipment, make opacity observations at a point just beyond where material is not being deposited out of a plume (normally three (3) feet above the mechanical equipment generating the plume).
d. Recording Observations: : Record the opacity observations to the nearest five percent (5%) every fifteen (15) seconds on a VEE record sheet. Each momentary observation recorded represents the average opacity of emission for a fifteen (15) second period. If a multiple plume exists at the time of an observation, do not record an opacity reading. Mark an “x” for that reading. If the equipment generating the plume travels outside of the field of observation, resulting in the inability to maintain the orientation of the sun within the one hundred forty degree (140°) sector or if the equipment ceases operating, mark an “x” for the fifteen (15) second interval reading. Readings identified as “x” shall be considered interrupted readings.
e. Data Reduction For Time Averaged Method: Opacity observations of emissions from stationary sources shall be conducted in accordance with EPA method 9.
2. Intermittent Emissions Method: This procedure is for evaluating intermittent fugitive dust emissions. Intermittent fugitive dust sources include activities that produce emissions intermittently such as screening, dumping, and stockpiling, where predominant emissions are produced intermittently.
a. Position: See subsection A1a of this section.
b. Field Records: See subsection A1b of this section.
c. Opacity Observations: Opacity observations shall use procedures similar to method 9, but the requirement for observation to be made at fifteen (15) second intervals over a six (6) minute period shall not apply. (Ord. 2007-12-005, 12-6-2007)