Oldman 2 Wind Farm Limited

Transcription

1 Decision D Spring 2017 Post-Construction Sound Survey at Receptors B, J and K August 1, 2017

2 Alberta Utilities Commission Decision D Proceeding Application A001 August 1, 2017 Published by the: Alberta Utilities Commission Fifth Avenue Place, Fourth Floor, 425 First Street S.W. Calgary, Alberta T2P 3L8 Telephone: Fax: Website:

3 Contents 1 Decision summary Introduction and background Comprehensive noise survey Sound level meters and microphone locations Portable weather stations Representative conditions and facility operating conditions Isolation analysis Comments from residents Three hours of cumulative data Low frequency noise Results Commission findings Validity of comprehensive noise survey Compliance with daytime and nighttime permissible sound levels Decision Decision D (August 1, 2017) i

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5 Alberta Utilities Commission Calgary, Alberta Decision D Spring 2017 Post-Construction Sound Survey Proceeding at Receptors B, J and K Application A001 1 Decision summary 1. In this decision, the Alberta Utilities Commission must decide whether the Oldman 2 Wind Farm Spring 2017 Post-Construction Sound Survey Receptors B, J, and K, submitted by at the direction of the Commission demonstrates compliance with permissible sound levels set out in Rule 012: Noise Control. 2. For the reasons set out below, the Commission finds that the Oldman 2 Wind Farm Spring 2017 Post-Construction Sound Survey Receptors B, J, and K demonstrates compliance with daytime and nighttime permissible sound levels, in accordance with Rule Introduction and background 3. In Decision D , 1 the Commission directed (Oldman 2) to conduct a follow-up post-construction comprehensive noise study at receptors B, J, and K because it determined that the comprehensive sound level survey submitted did not satisfy the requirements of Rule 012 at these receptors. On March 28, 2017, the Commission granted Oldman 2 a time extension for filing the follow-up post-construction comprehensive noise study at receptors B, J and K because of the delay in obtaining access to the lands on which receptors B and K are located to set up noise monitoring units. The new deadline of May 19, 2017 was set for the filing of the follow-up post-construction comprehensive noise study. 4. Oldman 2 submitted the Oldman 2 Wind Farm Spring 2017 Post-Construction Sound Survey Receptors B, J, and K (comprehensive noise survey) pursuant to Decision D on May 25, The comprehensive noise survey was conducted by SLR Consulting (Canada) Ltd. (SLR). A notice of application was issued on June 6, 2017, and no statements of intent to participate were received. 5. The Commission issued information requests to Oldman 2 on June 22, 2017 and responses were received on July 4, The Commission considers July 4, 2017 as the close of record for Proceeding Decision D :, Oldman 2 Wind Farm Post-Construction Sound Survey at Six Locations, Proceeding 21191, Application A001, December 7, Decision D (August 1, 2017) 1

6 3 Comprehensive noise survey 7. SLR conducted the noise study over 23 daytime and nighttime periods commencing on March 21, 2017 and ending on April 13, 2017 at three receptor locations. 2 In the study, the receptor locations were identified as B (Trodden), J (Dingreville), and K (Vaughan) The permissible sound levels at the three receptor locations were previously established at 50 decibels A-weighted (dba) Leq daytime and 40 dba Leq nighttime. 9. Receptor B was described as being in an area that is relatively flat and consisting of mostly open fields with short grass and open to the prevailing winds. The nearest wind turbine is located approximately 1,390 metres to the west-northwest Receptor J was described as being in the river valley with small rolling hills to the west and east with a large hill directly to the north. The nearest wind turbine is approximately 785 metres northwest of Receptor J on top of the hill Receptor K was described as being in the river valley with large hills surrounding it on all sides except to the south. The nearest wind turbine is located approximately 725 metres to the north-northeast. SLR described the location as being quite sheltered from the wind SLR stated that ground conditions were typical for early spring. It added that summertime conditions would have longer grasses that are more sound-absorptive and tend to reduce sound levels at the monitoring locations. 3.1 Sound level meters and microphone locations 13. SLR set up Brüel & Kjaer Model 2250 Type 1 sound level meters with Brüel & Kjaer Model 4952 microphones, fitted with Brüel & Kjaer UA1679 primary windscreens and Brüel & Kjaer EH-2152 secondary windscreens at each of the three receptor locations. SLR stated that although the Brüel & Kjaer system is capable of internally correcting for the attenuation of the primary and secondary windscreens, the correction was not implemented until March 23, As a result, data collected between March 21 and March 23, 2017 was considered invalid and removed from the data set. 7 The sound level meters were programmed to record continuous oneminute A-weighted and C-weighted Leq sound levels, as well as Lmin and Lmax, L10, L50 and L95 sound levels. One-third octave band spectral data was recorded for Leq, L10, L50 and L95 values. 2 Exhibit X0002, OM2 Post Construction Sound Survey Spring Receptors B, J, and K report -E, PDF page Exhibit X0002, OM2 Post Construction Sound Survey Spring Receptors B, J, and K report -E, PDF page Exhibit X0002, OM2 Post Construction Sound Survey Spring Receptors B, J, and K report -E, PDF page Exhibit X0002, OM2 Post Construction Sound Survey Spring Receptors B, J, and K report -E, PDF page Exhibit X0002, OM2 Post Construction Sound Survey Spring Receptors B, J, and K report -E, PDF page Exhibit X0002, OM2 Post Construction Sound Survey Spring Receptors B, J, and K report -E, PDF page Decision D (August 1, 2017)

7 14. The microphones at receptors J and K were located 15 metres from the dwellings in the direction of the nearest wind turbines. The microphones were mounted on tripods at an approximate height of 1.5 metres. 8 At Receptor B, a large hedge prevented locating the microphone at the prescribed location. Consequently, SLR used its professional judgement to locate the microphone in an alternate location with similar exposure to Receptor B and to the noise emissions from the nearest wind turbine. 15. SLR stated that all sound level meters were field calibrated at the start of the sound surveys using a Brüel & Kjaer 4231 calibrator (Serial Number ) that was factory calibrated on October 7, Because the sound level meter settings were changed on March 23, 2017 to apply the correction for the windscreens, a recalibration of the measurement systems was performed. The March 23, 2017 calibration of the sound level meters was conducted using a Brüel & Kjaer 4231 calibrator (Serial Number ), which was laboratory certified on March 4, 2016 and was also used to verify the calibration of the sound level meters at the end of the field measurement period. SLR noted that the calibrator, laboratory certified on March 4, 2016, was beyond its one-year calibration due date by 19 days when calibration of the equipment was conducted at the end of the survey. 9 SLR stated that in an effort to verify the accuracy of this calibrator it took the non-standardized approach of comparing the sound level of the calibration with tones of two of its factory calibrated calibrators (Serial Number and Serial Number ) which showed a measured offset of 0.0 db. In response to a subsequent information request, SLR provided a factory calibration record of the Model 4231 calibrator Serial Number that confirmed that the calibrator performance was within the acceptance criteria when received by the calibration laboratory on June 5, Portable weather stations 16. SLR set up Vaisala WXT520 portable weather stations at each of the receptor locations on tripods at a height of 1.5 metres above ground level to record the average, minimum, and maximum values of temperature, wind speed, wind direction, relative humidity, and precipitation. The measurement interval for the meteorological data was initially set to five minutes, but was changed to one minute at 24:00 hours on March 29, The interval duration was decreased to allow for higher-resolution isolation analysis with the intent of preserving more valid data Representative conditions and facility operating conditions 17. SLR stated that in order to meet environmental protection criteria, the turbines were set to commence operation only at wind speeds greater than 5.5 m/s during the time period from 30 8 report -E, PDF page 8. 9 Exhibit X0001, OM2 Post Construction Sound Survey Spring 2017 Receptors B, J, and K appendicies, PDF page Exhibit X0012, AUC IR Round 1 - Receptors B J K - SLR Response (E) 11.0 OM2-AUC-2017JUN22-011, PDF page 10 and PDF page report -E, PDF page 12. Decision D (August 1, 2017) 3

8 minutes before dusk until 30 minutes after dawn. In addition, Turbine T20 was operated in reduced power output mode during all nighttime periods Oldman 2 conducted an analysis of historical wind data collected at the pre-construction mast 901 between February 2003 and February 2013 to evaluate the likelihood of downwind conditions being experienced at receptors J and K when the nearest wind turbine is operating at its maximum sound power level. The analysis found that receptors J and K would have been downwind of wind turbine T9 when hub-height wind speeds reached between 9.7 m/s and cutout speed of 25 m/s only 0.11 per cent and 0.85 per cent of the time, respectively. Due to the very low rate of occurrence, downwind conditions were not considered by Oldman 2 to be representative of the prevailing wind conditions at receptors J and K. 3.4 Isolation analysis 19. SLR isolated the noise data using a combination of automated and manual identification methods with the intent to determine whether or not wind turbine noise exceeded the permissible levels at the receptor locations. All isolation methods were verified by listening to many instances of each type of isolated event to ensure the identification algorithms were working correctly and were not isolating representative data. 13 SLR conducted isolation analyses of sound level data collected based on wind turbine power output, wind speed and direction, wind noise, abnormal noise events, precipitation, snow cover and lost data. 20. SLR removed data where the closest turbine was operating at less than 78 per cent of its rated capacity. SLR stated that at 78 per cent rated output, the wind turbine is expected to produce the maximum sound power level based on information provided by the turbine manufacturer. This maximum sound power level is maintained when the rated output of the closest turbine is between 78 and 100 per cent. 14 SLR submitted tables showing wind turbine operating conditions at the Oldman 2 Wind Farm during the monitoring period The measured data was removed for durations where the receptor was not downwind (± 45 ) of the nearest wind turbine. Wind direction was based on the heading of the wind turbine nacelle, which is automatically oriented into the wind with drive motors. SLR gave two reasons for using the nacelle heading of the wind instead of using the wind direction at the receptor locations. Firstly, wind is often affected by structures and terrain in the immediate vicinity of the monitoring location, and is not representative of the average wind direction in the area between the wind turbine and the microphone. Secondly, directional characteristics of the wind turbine sound radiation are such that the noise levels are higher in front and behind the turbine than they are to the sides of the turbine. Using the nacelle direction therefore ensures that the predominant direction of radiation from the wind turbine is oriented toward the receptor Exhibit X0002, OM2 Post Construction Sound Survey at Six Locations, PDF page report -E, PDF page report -E, PDF page Exhibit X0001, OM2 Post Construction Sound Survey Spring 2017 Receptors B, J, and K appendicies, PDF pages 6 to report -E, PDF page 14 and Decision D (August 1, 2017)

9 22. Wind-induced noise in the microphone is generated by wind passing over the microphone windscreen, and blowing over obstacles, structures, trees, and shrubs located near the microphone. SLR pointed out that data provided by the manufacturer of the secondary windscreen indicates that the wind-induced noise due to the windscreen alone is approximately 40 dba at a wind speed of six metres per second. With respect to Receptor J, SLR stated that the wind noise contribution was significant with respect to the 40 dba nighttime permissible sound level for wind speeds above five m/s at the microphone, and was significant with respect to the 50 dba daytime permissible sound level for wind speeds above eight m/s at the microphone. With respect to receptors B and K, SLR stated that wind noise contribution was significant with respect to the 40 dba nighttime permissible sound level for wind speeds above 3.5 m/s at the microphone, and was significant with respect to the 50 dba daytime permissible sound level for wind speeds above six m/s at the microphone. 17 SLR provided further clarification in information response 0M2-AUC-2017JUN stating that [f]or a given wind speed, wind-induced noise was assumed similar at all receptors as the windscreen and microphone were the same model. However, the wind masking noise of the wind turbines by sound of the wind through vegetation and around structures at each microphone location was not the same at all Receptors. 18 In its analysis, SLR did not utilize data exceeding these wind speed thresholds. SLR isolated windinduced noise by removing data where the wind speed measured near each receptor location exceeded the above-noted wind speeds. 23. Abnormal noise events such as distant trains and train whistles, dogs barking, birds, and farm machinery were identified and isolated by listening to the audio recordings. SLR stated that noise generated by the wind turbines is not expected to have short-duration sound level spikes, and is not expected to approach 70 dba at the receptor locations. To that extent, SLR identified and isolated bird sounds based on sound levels in the two khz and four khz octave band above 30 db Leq 1min. and greater than the sound level in the one khz octave band. SLR further stated that such prominence of high frequency noise content is typical of small birds at short distances, but is not typical of distant wind turbine noise A vent fan operated frequently for short periods of time throughout the survey at Receptor K. SLR explained the vent fan noise included a tone in the 1,250 Hz one-third octave band and was identified and isolated if the L90 sound level in the 1,250 Hz one-third octave and was between 30 and 34 dba and exceeded the sound level in the 1,000 Hz band. 20 SLR considered moving the microphone to another location, but was unable to find a suitable alternative microphone location that would have met the requirements of Rule 012 and that would have sufficiently reduced the vent noise Measured data were also removed for durations where any precipitation occurred at the receptor location. Data measured up to five minutes before and five minutes after the recorded 17 report -E, PDF page Exhibit X0012, AUC IR Round 1 - Receptors B J K - SLR Response (E) OM2-AUC-2017JUN PDF page report -E, PDF page report -E, PDF page Exhibit X0012, AUC IR Round 1 - Receptors B J K - SLR Response (E) OM2-AUC-2017JUN PDF page 5. Decision D (August 1, 2017) 5

10 precipitation were also removed because rainfall noise may have been present but not yet detected by the weather station s rainfall sensor. Measured data were also removed for durations where snow covered a significant portion of the ground in the study area. Snow fell early in the morning on April 3, 2017 but had melted by the morning of April 5, The cellular connection used to stream data from the sound level meters to cloud-based storage was lost at various times throughout the course of the survey. Typically, when the cellular connection is lost, the sound level data and weather records are stored locally and are recovered once a connection is re-established; however, there were a number of short periods where data was lost and unrecoverable Comments from residents 27. SLR stated that residents at receptors B, J and K were provided Appendix 4 Noise Complaint Investigation Forms from Rule 012 but that no forms were completed. 28. In discussions with SLR, Mr. Robert Trodden at Receptor B indicated that wind turbine noise was most audible during west and southwest winds, and turbines located to the east and west are occasionally audible at his residence. 29. Mr. George Dingreville at Receptor J indicated that he has some hearing loss and cannot hear the wind turbine noise. 30. Mrs. Betty Vaughan at Receptor K indicated that she regularly hears wind turbine noise, but elected to not complete the Noise Complaint Investigation Form. 3.6 Three hours of cumulative data 31. SLR acknowledged that Rule 012 requires that a minimum of three cumulative hours of valid data be obtained in a daytime or nighttime period for the daytime or nighttime Leq value for that period to be considered valid and that if multiple daytime or nighttime periods are deemed valid, the highest daytime and nighttime Leq values are to be used to assess compliance. SLR explained that a major constraint in obtaining valid data is the limited durations where the wind speed at hub-height was sufficient to produce maximum sound power levels but the wind speed at the microphone height is low enough such that the wind noise on the microphone does not excessively influence the measured sound level. Although SLR utilized secondary windscreens to minimize the wind noise as much as practical, wind noise remained the primary reason for the isolation of data while the wind turbines were producing maximum sound power. 32. Sufficient durations of valid downwind data were not collected at receptors J and K due to the limited occurrence of downwind conditions during the monitoring surveys. The wind turbine nearest to receptors J and K (T9) was operating above 78 per cent of the rated power for a total of hours over the course of the survey. However, during these hours, receptors J and K were downwind of wind turbine T9 for a total duration of only 0.5 hours and 0.0 hours, respectively. After further isolation for wind noise, abnormal noise events, 22 report -E, PDF page Decision D (August 1, 2017)

11 precipitation, and snow cover, only nine minutes (0.2 hours) of valid data remained at Receptor J. 3.7 Low frequency noise 33. SLR conducted an evaluation of low frequency noise (LFN) for each of the three receptors in accordance with Rule 012. This is a two-part analysis with the first part determining the difference between the C-weighted isolated sound level (dbc) and the A-weighted isolated sound level (dba). The second part of the LFN test is to determine if there is a clear tonal component between 20 Hz and 250 Hz. 34. SLR collected third octave data in the event that a check for tonal component was required. SLR determined that the difference between the C-weighted and the A-weighted isolated sound levels exceeded 20 db in a number of instances. However, SLR explained that wind generates high levels of low frequency sound and these measured exceedances are likely caused by wind induced noise as opposed to wind turbine source noise. In addition, SLR stated that the third octave band analysis did not identify the presence of any audible tone and that the turbine manufacturer indicates that these wind turbines produce no tonal audibility above three db. SLR concluded that a LFN condition does not exist because the wind turbines do not generate a tonal component between 20 and 250 Hz. 3.8 Results 35. SLR stated that three hours of valid data were collected in multiple daytime periods at receptors B and J. However, three hours of cumulative valid data were not obtained in any single daytime period at Receptor K. Additionally, three hours of cumulative valid data were not obtained in any single nighttime period at receptors B, J or K. SLR acknowledged that Section 4.6.1(2)(c) of Rule 012 defines representative conditions for post-construction compliance surveys as requiring downwind conditions. Receptor B is the only one of the three receptors that is located downwind of the nearest turbine with respect to the prevailing wind direction. Correspondingly, it was only at Receptor B that significant downwind sound level data was obtained. Very little valid downwind data was collected during the three week survey at receptors J and K. At these two locations SLR analysed the nighttime data with and without downwind direction isolation analysis criteria. 36. In instances where three hours of valid data were not obtained in a single daytime or nighttime period, SLR assessed compliance by comparing the energy-average sound pressure level (Leq) of all of valid daytime or nighttime data collected over the duration of the study to the respective permissible sound level. 23 In response to an information request, SLR provided the tabulated results depicting the overall measured sound level and the isolated sound level with the valid number of hours for each daytime and nighttime measurement period at each receptor location during the sound survey report -E, PDF page Exhibit X0012, AUC IR Round 1 - Receptors B J K - SLR Response (E) 3.0 OM2-AUC-2017JUN22-003, PDF page 13 to 22. Decision D (August 1, 2017) 7

12 37. Data results were presented for the daytime and nighttime periods with and without downwind direction isolation analysis criteria implemented. Data provided without downwind direction isolation analysis criteria allowed for an increase in the amount of valid hours analyzed. 38. SLR stated that the intent of the comprehensive noise survey was to evaluate compliance of the wind turbine noise with respect to the permissible sound levels. As such, the reported isolated values may include contributions from extraneous noise events or wind noise that did not require isolation to show compliance with the permissible levels. 39. It is SLR s opinion that the isolated comprehensive sound levels are appropriate for comparison to the permissible sound levels set out in Rule 012 because they are typical of the prevailing wind directions in the study area and are representative of conditions typically experienced at receptors J and K. 40. SLR concluded that the comprehensive noise survey results show that the isolated sound levels are below the daytime and nighttime permissible sound levels at all three receptor locations and the survey results indicate that the Oldman 2 Wind Farm is in compliance with Rule 012 at all three receptor locations. 4 Commission findings 41. In making its decision on this application, the Commission must consider whether the comprehensive noise survey at receptors B, J and K was conducted in accordance with Rule 012 and determine whether the nighttime and daytime permissible sound levels at receptors B, J and K are in compliance with Rule Validity of comprehensive noise survey 42. The Commission accepts that when the comprehensive noise survey was conducted, the microphones were placed in suitable locations 15 metres from each of the three receptor locations in the direction of the nearest wind turbine as stipulated in Rule The Commission finds that the sound level meters and the primary and secondary windscreens used in the comprehensive noise survey meet with the Type 1 requirements for sound level meters stipulated in Rule 012. Although the sound level meters were factorycalibrated within the specified period in accordance with the rule, and field calibration was conducted both before and after the measurement periods at each receptor location, when the sound level meters were re-calibrated on March 23, 2017 at the end of the collection of the data for the comprehensive noise survey, a different calibrator was used. Further, despite the fact that this second calibrator was beyond its one-year calibration period by 19 days, its accuracy was verified by comparing it to the tones of two factory-calibrated calibrators. It was shown to also conform to laboratory standards on the basis of its subsequent calibration certificate which indicates that the instrument is Within Acceptance Criteria. 25 Accordingly, the Commission is satisfied that the calibrators used during the survey met the minimum requirements of Rule Exhibit X0012, AUC IR Round 1 - Receptors B J K - SLR Response (E), PDF page Decision D (August 1, 2017)

13 44. The Commission accepts that the wind and weather monitoring equipment used in the comprehensive noise survey at receptors B, J and K satisfy the requirements of Rule 012 and that the wind and weather monitoring equipment was located within 100 metres of the microphone locations, which is also required by Rule The Commission considers the isolation analysis performed on the representative daytime and nighttime data using audio recordings and observations to be reasonable. It also accepts that a level of 78 per cent of electrical output power is representative of the maximum output sound power level for the nearest wind turbines based on the acoustic emission data provided by the manufacturer of the wind turbine. 46. The Commission acknowledges that obtaining three hours of valid cumulative downwind data was a challenge during the three-week noise survey, and that Receptor B was the only one of the three receptors that is located downwind of the nearest wind turbine with respect to the prevailing wind direction and for which a significant amount of valid downwind data was obtained. Sufficient valid downwind data (three cumulative hours) was not obtained for each nighttime period at receptors J and K. However, a review of historical annual wind data collected at the pre-construction mast 901 between February 2003 and February 2013 indicates that these dwellings are not located in a downwind direction with respect to the predominant wind direction and showed that receptors J and K would have been downwind of the nearest wind turbine (T9) with hub-height wind speeds between 9.7 m/s and cut-out (25 m/s) only 0.11 per cent and 0.85 per cent of the time, respectively. Without using the isolation analysis filter for downwind conditions, the amount of data collected at receptors J and K increased from having no valid data collected to a total of 6.4 hours and 4.5 hours, respectively. In light of the low rate of occurrence of downwind conditions from the nearest wind turbine for receptors J and K in this survey, the Commission exempts Oldman 2 from the collection of valid downwind data at receptors J and K. It considers that in these circumstances, it was reasonable to use the average of the cumulative valid daytime and nighttime measurements over the three week comprehensive noise survey for the evaluation of compliance with the permissible sound level. 47. Furthermore, noting that wind turbines are not likely to produce short-duration sound level spikes in the two khz and four khz octave band, and also that sound levels from the wind turbines are not likely to approach 70 dba at the receptor locations, the Commission finds that based on field observations, the review of the audio recordings, and the octave band analysis of the data conducted by SLR, it was reasonable to use automated isolation of extraneous bird sounds at Receptor B. 48. The Commission is satisfied that the potential for a low frequency noise condition does not exist with the wind turbines because third octave band analysis did not identify the presence of any audible tone, and the turbine manufacturer states that these wind turbines produce no tonal audibility above three db. 49. Based on the above findings, the Commission accepts that the comprehensive noise survey at receptors B, J and K was conducted in keeping with Rule 012. Decision D (August 1, 2017) 9

14 4.2 Compliance with daytime and nighttime permissible sound levels 50. In the following tables prepared by SLR, the isolated sound levels determined in the comprehensive noise survey are summarized and compared to the permissible sound levels set out in Rule 012. Table H: Comparison of Isolated Sound Levels to AUC Daytime Permissible Sound Levels Receptor ID Date of Daytime Period Hours of Valid Data in Daytime Period Isolated Daytime Comprehensive Sound Level (dba Leq) AUC Daytime Permissible Sound Level (dba Leq) Margin of Compliance (dba Leq) B April 1-2, J April 9-10, K All Periods Note 1: Calculated as the energy-average of all valid nighttime data Note 2: Measured sound levels and the isolated sound level with the valid number of hours for each daytime and nighttime measurement period at each receptor location during the comprehensive noise survey found in Exhibit X0012 PDF pages 13 to 22 Table I: Comparison of Isolated Sound Levels to AUC Nighttime Permissible Sound Levels Receptor ID Date of Nighttime Period Hours of Valid Data in Nighttime Period Isolated Nighttime Comprehensive Sound Level (dba Leq) AUC Nighttime Permissible Sound Level (dba Leq) Margin of Compliance (dba Leq) B All Periods J All Periods K All Periods Note 1: Calculated as the energy-average of all valid nighttime data Note 2: Measured sound levels and the isolated sound level with the valid number of hours for each daytime and nighttime measurement period at each receptor location during the comprehensive noise survey found in Exhibit X0012 PDF pages 13 to Given the above-noted results and these particular circumstances, the Commission accepts that the comprehensive noise survey at receptors B, J and K was conducted in keeping with Rule 012 and finds that the Oldman 2 Wind Farm complies with the established daytime and nighttime permissible sound level of 50 dba Leq and 40 dba Leq at the three receptor locations. 10 Decision D (August 1, 2017)

15 5 Decision 52. The Commission is satisfied that the comprehensive noise survey conducted at receptors B (Trodden), J (Dingreville) and K (Vaughan) demonstrates compliance with the daytime and nighttime permissible sound levels as prescribed in Rule 012. The Commission finds that has satisfied the direction in paragraph 84 of Decision D , which states: As a result, the Commission orders Oldman 2 to conduct a follow-up postconstruction comprehensive noise study for receptors B (Trodden), J (Dingreville), and K (Vaughan) under representative conditions to verify that the Oldman 2 Wind Farm complies with Rule 012 during the daytime and nighttime period. Such followup noise study must be conducted and filed with the Commission by April 30, Dated on August 1, Alberta Utilities Commission (original signed by) Anne Michaud Commission Member Decision D (August 1, 2017) 11