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ENVIRONMENTAL ASSESSMENT <br /> An initial sound study of mine operations was completed by Engineering Dynamics, Inc. (EDI) (EDI 2013). <br /> This sound study, as well as a vibration study, were included in the Summary of Analytical Activities in <br /> Response to Neighborhood Comments in Conjunction with a Permit Expansion of GCCE— King II Mine by <br /> CDS Environmental Services LLC, (CDS) dated May 8, 2014 (CDS 2014). <br /> The studies were reviewed by Dr. Catherine T. Aimone-Martin of Aimone-Martin Associates on behalf of <br /> LPC. Dr. Aimone-Martin's comments were presented in her report titled "Review of Noise and Vibration <br /> from CR 120 Truck Traffic and Mining Operations at the GCCE King II Mine" dated September 7, 2015 <br /> (Aimone-Martin 2015). <br /> Wave Engineering, Inc. (Wave) performed an additional sound study that included background noise <br /> measurements without coal-hauling trucks running, measurements of haul trucks passing by on gravel <br /> and paved road surfaces, and computer modeling to assess the noise impact of haul trucks on the <br /> residences along CR 120. The computer model was also used to evaluate the potential noise mitigation <br /> offered by sound barriers, speed limitations, and limiting the hours of trucks. <br /> The following items from Wave's report (2016), King II Mine Noise Assessment, are noted: <br /> • Measurements were taken at approximately 50 ft from CR 120 centerline and at a second location <br /> near residences; <br /> • Baseline noise at residences is well below noise from traffic, with the highest background value <br /> being recorded at 10 A-weighted decibels (dBA) due to wind gusts exceeding 10 mph; <br /> • As expected,travel uphill and with a loaded haul truck, increased noise considerably; <br /> • The speed at which trucks travel has a significant effect on noise—approximately an 8 dBA <br /> increase between 12 and 22 mph. During the study, trucks slowed to 10 mph on gravel road <br /> portions near residences; <br /> • Haul trucks traveling at 10 mph on flat portions of the road did not have an alternative effect; and <br /> • All haul trucks measured had noise levels below 86 dBA, a cited limit established by the State of <br /> Colorado. <br /> Subsequent to these studies, the gravel portions of the road near residences have been paved to reduce <br /> vehicle noise (personal communication, Sarah Vance GCCE 2018). <br /> There is no county or state code or ordinance that currently limits noise levels from trucks. C.R.S. Section <br /> 25-12-107 allows counties to limit heavy truck noise levels to 86 dBA 50-ft from the centerline of the lane <br /> of travel.All trucks that were measured in the Wave study were well below this level. Background ambient <br /> noise levels were measured (without truck noise) at four locations along CR 120 during a weekend, with <br /> continuous day and night measurements. Depending upon the location, ambient sound levels ranged <br /> from about 37 dBA to 52 dBA during the day and 29 dBA to 48 dBA at night. <br /> Since LPC does not have an applicable noise standard for coal mine facilities, C.R.S. Section 25-12-103 <br /> standards are used to establish maximum permissible noise levels in residential, commercial, and <br /> industrial locations. These standards set limits for residential properties of 55 dBA daytime (7:00 a.m.to <br /> Dunn Ranch Area Coal Lease by Application COC-78825 and Mine Plan Modification EA 3-21 <br />