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. ~ `. <br />Caei'~nC~ ~taa <br />f,~o.~! Gorn~a~ny ~~~ ~~~~~~~~~~~~~ ~~~ <br />First and Columbia <br />January 27, 1982 F• O. Box 226 <br />Della, Colo. 81416 <br />Office: (303) 874-7561 <br />Mine: (303)856-6402 <br />Dan Mathews <br />Reclamation Specialist <br />Colorado Mined Land Reclamation ~ ~:~„~` <br />423 Centennial Bldg., 1313 Sherman St. <br />Denver, Colorado 80203 ~,,,,i ~ ~„ „ y J <br />... ,. .'. <br />Re: Fan Noise C'~':'i ,. ~.,, ,.... ;'rlLCi::;;5 <br />Dear Dan; <br />In compliance with your Octobei 23, 1981, inspection report the "Sound <br />Blox" wall in front of the Fan has been installed. The completion date <br />was December 31, 1981. <br />Four major. steps have been taken to lessen tiie annoyance of our fan <br />noise: <br />1) Construct a berm on the east, west, and north sides of the <br />fan. <br />2) Apply noise dampener to most of the metal housing, <br />3) Install a noise diffuser on the new fan. <br />4) Construct a noise block wall in front of the fan. <br />The berm was installed in 1980 to reduce the noise for the neighbor <br />500' north of the fan. The berm was in place in April 1981, when the <br />petitions were signed concerning fan noise, traffic regualation, and road <br />construction. The noise dampener was Kinetics type, KDC-E-162 Viscoe <br />Damping Compound. The damping compound was to reduce the vibration noise <br />created by the metal housing. No noise readings were taken before and <br />after this step, there was no noticable noise reduction, The Can was <br />ordered with a special noise dampening diffuser cone in front of the fan. <br />This diffuser is 7' long and is lined with a 4" blanket of fiber glass. <br />The fan with this diffuser was installed on December 19, 1981. The footers <br />and stem wall for the noise wall was installed prior to installation of <br />the fan. Construction of the noise wall was started December 22, 1981, <br />and completed December 31, 1981. <br />Attached is a copy of a portion of our proposed Surface Disturbance <br />Map (2.05.3(2)(b)-1) showing noise reading locations and a table showing <br />before and after noise readings. These readings were taken with a Bendix <br />Model 300 Sound level Meter with an "A" weighted response. This meter <br />