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• Location 4 was chosen to represent Residence D. Measurements were taken at a point on Residence D's driveway approximately 300 feet south of SH-133. This residence is the most critical receptor for the purposes of this study. While second to Residence C in proximity to the proposed fan site, it experiences much lower background noise levels because it is further removed from both the Gunnison River and SH-133. No measurements were taken in the vicinity of Residences A or C. It is expected that Residence F, will experience ambient levels similar to residence D. It is, however, about 5000 feet further from the fan site. Residence C is located within about 700 feet of the Gunnison River. It is expected to experience ambient noise levels similar to Residence B. 5.2 Description of Measurements Noisy level measurements were taken .by survey personnel at each of the four measurement locations discussed above. In addition, acontinuously-operating noise monitor was sited at Location 3. • The handheld measurements are discussed first, followed by the ooeration of the continuous monitor. Handheld measurements were taken with a Rion Model NA-29 Sound Level Meter'. The meter was ooerated to sample and record the C-weighted noise level every one-half second over a 12 minute period. Given the relatively constant nature of the ambient noise level in the project study area, this time period was considered adequate to gain a representative sample. °~ From this data the A-weighted' L10, L90, and Leq noise levels were calculated. The L10 is the noise level exceeded 10 percent of the time during a specified period. It is used to quantify time-varying noise sources such as traffic. The L90 is the level exceeded 90 percent of the time during a specified period. It is used to quantify constantly occurring, or background noise. The Leq is the "energy-average" noise level. Octave band noise levels were also measured. Only the L90 data will be discussed in this report. In addition, a RTA Sound Lagging Meter was installed at Location 35. This meter was configured to sample the A-weighted sound level every one-tenth second and automatically compute and record the hourly L10, L90, and Leq noise levels. The meter was placed into operation at 5:00 p.m. on Tuesday, • April 26, and retrieved at 3:00 p.m. on Wednesday, April 27. It was checked for proper operation at approximately 2:00 a.m. on the 27. 5