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HomeMy WebLinkAbout1.02 Noise AnalysisNOISE ASSESSMENT BLUE PIT EXPANSION WESTERN SLOPE AGGREGATES, Inc. GARFIELD COUNTY, COLORADO ADDENDUM No. 1 NOISE LEVELS at 25 ft. BEYOND THE PROPERTY BOUNDARY Prepared by: October 2010 el-kt,21—u9-trirt- Howardd N. McGregor Registered Professional Engineer State of Colorado, # 3928 1r+ engineering 1 dynamics ;incorporated E. D. 1. Job # 3785 Page 1 of 4 3925 south kalamath street o englewood, colorado 80110 0 303.761.4367 o Fax 303.761.4379 Alt engineering i �ldynarnics - miorporafed INTRODUCTION The addendum addresses the noise levels that will occur at a distance of 25 ft. beyond the Dee Blue Property Boundary. This property is made up of several contiguous parcels as shown on the attached map. The 25 ft. distance is the requirement set forth in CRS -25-12-103§ (1). The permit boundaries for each mining area are: Mining Area 1 North, Sunnyside Ranch conservation easement, 1450' from permit boundary to property line South, CDOT right of way then residential, 110' from mining to property line East, abandoned land fill (Carbondale Dump), 10' from mining to property line West, abuts to Mining Areas 2 and 3 Mining Area 2 North abuts toMiningArea 3lineSouth, un -mined pit property; CDOTrlght of way then residential, 10' from mining to property East, abuts to Mining Area 1 West, abuts to Mining Area 4 Mining Area 3 North, Conservation easement, undeveloped agricultural, (owned by Dee Blue) 2170' from mining to property boundary South, abuts to Mining Area 2 East, temporary wash plant and stockpile area, farm road, 1820' from mining to property boundary West, abuts to mining area 5 Mining Area 4 North, abuts to Mining Area 5 South, CDOT right of way then residential, 10' from mining to property line East, abuts to Mining Area 2 West, undeveloped agricultural, (Not owned by Dee Blue) 50' from mining to property boundary, Mining Area 5 North, conservation easement, undeveloped agricultural, (Owned by Dee Blue) 1380' from mining to property South, abuts to Mining Area 4 East, abuts to Mining Area 2 West, undeveloped agricultural, (Not owned by Dee Blue) 50' from mining to property boundary, E. D. I. Job # 3785 Page 2 of 4 3925 south kalamath street ® englewood, colorado 80110 ® 303.761.4367 ® Fax 303.761.4379 >' engineering I n dynaniks j . incorporated II. ANALYSIS OF NOISE EMISSION AT 25 FT. BEYOND MINE BOUNDARY A. Mine Development 1. Mining Area 1 This area is already more than 40 ft. below surrounding grade levels and the 80 dB(A) noise level falls within the property boundary in all directions. To the south of the mine and across Hwy 82 there are residences with the closest distance being about 850 ft. If there was no intervening terrain, the noise level from the noisiest mobile equipment, a CAT 10 dozer working at the southern edge of Mining Area 1 would be 62 dB(A). However, between the Mining Area pit floor and the residences to the south of Hwy 82, there is a 50 ft. high natural noise barrier which will reduce the noise by more than 15 dB(A) making the noise levels a the residences 47 dB(A), which is 7 dB(A) less than the daytime noise limit for residentially zoned properties, CRS 25-12-103. As mining continues in Area 1, the depth of the pit floor will increase slightly and the 15 dB(A) noise reduction will increase by several dB. Most of the time the traffic noise from Hwy 82 will cover up the noise from Mining Area 1 in the residential areas to the south. 2. Mining Area 2 To the south of Mining Areas 2 and 4, there is a drop-off of about 64 ft to the residential area across Hwy 82. This drop-off breaks the line of sight because the mobile equipment especially the dozer will be about 200 ft. to the north of the drop-off. This drop-off will reduce the noise at the residences by about 8 dB(A) and the resulting noise level of a CAT D10 dozer will be 59 dB(A). As the dozer or other mobile equipment moves to the north and away from the drop off the noise level will decrease due to both distance and the drop off. To the west, the distance to the property boundary is 1300 ft and the direct line -of -sight noise level for a CAT D10 dozer would be 58 dB(A). Once some of the overburden is removed the mobile equipment will be below grade to the west and the noise level at the property boundary will be further reduced. Also, as the equipment moves to the east, there will be an additional reduction due to distance. To the north the distance to the property boundary is about 1800 ft. and the direct line -of -sight noise level for a CAT D10 dozer would be 56 dB(A). 3. Mining Area 3 To the west Mining Area 3 has the same noise emission levels as Mining Area 2 and would produce a noise level of 56 dB(A) at the western property boundary when there is an unobstructed line -of -sight. To the north, the distance to the property boundary is 1250 ft. and the noise level of a CAT D10 dozer would be 59 dB(A) as compared to the 56 dB(A) from Mining Area 2. 4. Mining Area 4 Mining Area 4 will have the same noise emission levels to the south and north as Mining Area 2, that is 59 dB(A) to the south and 56 dB(A) to the north. However, to the west there is only a distance of 50 ft. to the Cerise Clifford Ranch Properties, which includes the width of the Farm Road Detour that will be constructed. A motor grader such a CAT 130 which produces 76 dB(A) at 100 ft. will be used for the construction and grading of the Farm Road. As with all of the other mobile equipment used during the mine development phase, the noise levels presented are circular noise foot prints which move along the equipment so there is not a continuous noise contour along any of the property boundaries but rather a circular and moving noise contour. The noise levels to the south would be the same as those from Mining Area 2. E. D. I. Job # 3785 Page 3 of 4 3925 south kalamath street c englewood, colorado 80110 0 303.761.4367 0 Fax 303.761.4379 di�; engineering ; ,,. dynamics incorporated Additional noise control to the west from both Mining Areas 4 and 5 will be accomplished by positioning a row of hay bales along the western property line. A row of hay bales, 25 ft . in 76 dB(A) will provide a 5 dB(A) reduction in the noise level at the property boundary plus(t, ) for a CAT D10 dozer. This situation will only occur when the equipment is on grade and at the western edge of the mining area. It is expected that overburden removal in Mining Areas 4 and 5 will be on a continuing basis and will take about two weeks every year. 5. Mining Area 5 To the north the noise emissions during mine development area the same as Mining Area 3 and to the west and south the noise emissions are the same as Mining Area 4 including the construction of the Farm road. All of the noise emissions presented for Mining Areas 2, 3, 4 and 5 are for the worst case conditions when the noise source is at grade levels and as close as possible to the property boundary. It is important that the reader of this report understand that the noise emissions are not continuous noise contours but rather a circular and moving noise foot print. Also all of the dB(A) values presented in paragraphs 1, 2, 3, 4 and 5 are based upon the dB(A) levels of a CAT D10 Which would be the noisiest piece of mobile equipment used during mine development For example, using a CAT D8 would lower all of the noise levels by 2 dB(A). Another way to look at the noise emission foot print is to place a CAT 010 at the four corners intersection of Mining Areas 2, 3, 4 and 5. At this location the 55 dB(A) noise foot print of a CAT 010 would be 1900 ft. in all directions, for a CAT DB, the noise foot print would be 1450 ft. B. Mine Production After mine development is completed the noise levels at the property boundary will not exceed the maximum allowable limits for Residential Zoning at a distance of 25 ft. beyond the property boundaries; CRS 25-12-103. Stationary equipment such as the processing plant will be below grade and the pit walls plus the reduction in noise due to distance will assure that the noise emissions at 25 ft. beyond the property boundary will be less than 55 dB(A). In order to control the noise emissions of the CAT D10 dozer, which has the highest noise emission of all of the mobile mining equipment, the dozer will work at the mine face as follows. First, the dozer will always be below grade by about 7 ft., which is the depth of the overburden that will be removed and stored during mine development (construction). Secondly, the dozer will only be at the very top of the mine face when initially pushing the material down the mine face where it will be scooped up by the front end loader and taken to the processing plant area. The noise barrier effect of the overburden wall or face will, because of its limited height, reduce the noise from the dozer by only 3 dB(A) when it is at the topof the mine face. Under this situation when the dozer is at the most northern edge of Mining Areas 1, 3, and 5 the noise level at 25 ft. beyond the closest property boundary in the northerly directions will not exceed 55 dB(A). As the dozer works to the south, the distance to the property boundaries to the north increase and the noise level decreases. Thirdly, when the dozer is at the most southern location, Mining Areas 1, 2 and 4, the noise level at 25 ft. beyond the property boundary will exceed the 55 dB(A) limit. However, because of the drop off in terrain between the mining areas and Hwy 82, there will be a reduction of 18 dB(A) because the line -of -sight is broken. In addition, there will be a small reduction of about 6 dB(A) due to the distance from the dozer to the residential properties across Hwy 82. The resulting noise level will be 57 dB(A). As soon as the dozer moves to the north the level will drop. As mentioned earlier in this section, this situation will only occur when the dozer is at the top of the mine face. Now, to the west the situation is different because the only noise barrier that would exist would be the face of the overburden and the noise level from a CAT D10 dozer would be 75 dB(A) at 25 ft. beyond the property boundary. This would be acceptable if the land which is now agricultural, would be considered an Industrial Zone which would limit the noise to 80 dB(A). The 55 dB(A) could be achieved by using a quieter dozer such as a D7 which is 3 dB(A) quieter than a D10 and constructing a 15 ft. berm using overburden material giving a total noise berm height of 20 ft. when the overburden depth is included. Hay bales can also be used to accomplish the same. E. D. r. Job u 3785 Page 4 of 4 3925 south kalamath street 0 englewood, colorado 80110 0 303.761.4367 0 Fax 303.761.4379 edI dynamics ncorporated NOISE ASSESSMENT BLUE PIT EXPANSION WESTERN SLOPE AGGREGATES, Inc. GARFIELD COUNTY, COLORADO ADDENDUM No. 1 NOISE LEVELS at 25 ft. BEYOND THE PROPERTY BOUNDARY October 2010 j.6<r-lArv—‘,041. Prepared by: Howard N. McGregor Registered Professional Engineer State of Colorado, # 3928 E. D. I. Job # 3785 Page 1 of 4 3925 south kalamath street • englewood, colorado 80110.303.761,4367 • Fax 303.761.4379 al engineering ,dynamics incorporated INTRODUCTION The addendum addresses the noise levels that will occur at a distance of 25 ft. beyond the Dee Blue Property Boundary. This property is made up of several contiguous parcels as shown on the attached map. The 25 ft. distance is the requirement set forth in CRS -25-12-103§ (1). The permit boundaries for each mining area are: Mining Area 1 North, Sunnyside Ranch conservation easement, 1450' from permit boundary to property line South, CDOT right of way then residential, 110' from mining to property Zine East, abandoned land fill (Carbondale Dump), 10' from mining to property line West, abuts to Mining Areas 2 and 3 Mining Area 2 North abuts to Mining Area 3 South, un -mined pit property; CDOT right of way then residential, 10' from mining to property line East, abuts to Mining Area 1 West, abuts to Mining Area 4 Mining Area 3 North, Conservation easement, undeveloped agricultural, (owned by Dee Blue) 2170' from mining to property boundary South, abuts to Mining Area 2 East, temporary wash plant and stockpile area, farm road, 1820' from mining to property boundary West, abuts to mining area 5 Mining Area 4 North, abuts to Mining Area 5 South, CDOT right of way then residential, 10' from mining to property line East, abuts to Mining Area 2 West, undeveloped agricultural, (Not owned by Dee Blue) 50' from mining to property boundary, Mining Area 5 North, conservation easement, undeveloped agricultural, (Owned by Dee Blue) 1380' from mining to property South, abuts to Mining Area 4 East, abuts to Mining Area 2 West, undeveloped agricultural, (Not owned by Dee Blue) 50' from mining to property boundary, E. D. I. Job # 3785 Page 2 of 4 3925 south kalamath street • englewood, colorado 80110 • 303.761.4367 • Fax 303.761.4379 II. ANALYSIS OF NOISE EMISSION AT 25 FT. BEYOND MINE BOUNDARY A. Mine Development 1. Mining Area 1 This area is already more than 40 ft. below surrounding grade levels and the 80 dB(A) noise level falls within the property boundary in all directions. To the south of the mine and across Hwy 82 there are residences with the closest distance being about 850 ft. If there was no intervening terrain, the noise level from the noisiest mobile equipment, a CAT 10 dozer working at the southern edge of Mining Area 1 would be 62 dB(A). However, between the Mining Area pit floor and the residences to the south of Hwy 82, there is a 50 ft. high natural noise barrier which will reduce the noise by more than 15 dB(A) making the noise levels a the residences 47 dB(A), which is 7 dB(A) less than the daytime noise limit for residentially zoned properties, CRS 25-12-103. As mining continues in Area 1, the depth of the pit floor will increase slightly and the 15 dB(A) noise reduction will increase by several dB. Most of the time the traffic noise from Hwy 82 will cover up the noise from Mining Area 1 in the residential areas to the south. da e tinco=z, engineering 2. Mining Area 2 To the south of Mining Areas 2 and 4, there is a drop-off of about 64 ft to the residential area across Hwy 82. This drop-off breaks the line of sight because the mobile equipment especially the dozer will be about 200 ft. to the north of the drop-off. This drop-off will reduce the noise at the residences by about 8 dB(A) and the resulting noise level of a CAT D10 dozer will be 59 dB(A), As the dozer or other mobile equipment moves to the north and away from the drop off the noise level will decrease due to both distance and the drop off. To the west, the distance to the property boundary is 1300 ft and the direct line -of -sight noise level for a CAT D10 dozer would be 58 dB(A). Once some of the overburden is removed the mobile equipment will be below grade to the west and the noise level at the property boundary will be further reduced. Also, as the equipment moves to the east, there will be an additional reduction due to distance. To the north the distance to the property boundary is about 1800 ft. and the direct Zine -of -sight noise level for a CAT D10 dozer would be 56 dB(A). 3. Mining Area 3 To the west Mining Area 3 has the same noise emission levels as Mining Area 2 and would produce a noise level of 56 dB(A) at the western property boundary when there is an unobstructed line -of -sight. To the north, the distance to the property boundary is 1250 ft. and the noise level of a CAT D10 dozer would be 59 dB(A) as compared to the 56 dB(A) from Mining Area 2. 4. Mining Area 4 Mining Area 4 will have the same noise emission levels to the south and north as Mining Area 2, that is 59 dB(A) to the south and 56 dB(A) to the north. However, to the west there is only a distance of 50 ft. to the Cerise Clifford Ranch Properties, which includes the width of the Farm Road Detour that will be constructed. A motor grader such a CAT 130 which produces 76 dB(A) at 100 ft. will be used for the construction and grading of the Farm Road. As with all of the other mobile equipment used during the mine development phase, the noise levels presented are circular noise foot prints which move along the equipment so there is not a continuous noise contour along any of the property boundaries but rather a circular and moving noise contour. The noise levels to the south would be the same as those from Mining Area 2. E. D. I. Job # 3785 Page 3 of 4 3925 south kalamath street • englewood, colorado 80110 • 303.761.4367 • Fax 303.761.4379 a ,, engineering ics / Ilncodynamrporated Additional noise control to the west from both Mining Areas 4 and 5 will be accomplished by positioning a row of hay bales along the western property line. A row of hay bales, 6 ft. in height, will provide a 5 dB(A) reduction in the noise level at the property boundary plus 25 ft. of 76 dB(A) for a CAT D10 dozer. This situation will only occur when the equipment is on grade and at the western edge of the mining area. It is expected that overburden removal in Mining Areas 4 and 5 will be on a continuing basis and will take about two weeks every year. 5. Mining Area 5 To the north the noise emissions during mine development area the same as Mining Area 3 and to the west and south the noise emissions are the same as Mining Area 4 including the construction of the Farm road. All of the noise emissions presented for Mining Areas 2, 3, 4 and 5 are for the worst case conditions when the noise source is at grade levels and as close as possible to the property boundary. It is important that the reader of this report understand that the noise emissions are not continuous noise contours but rather a circular and moving noise foot print. Also all of the dB(A) values presented in paragraphs 1, 2, 3, 4 and 5 are based upon the dB(A) levels of a CAT D10 which would be the noisiest piece of mobile equipment used during mine development For example, using a CAT D8 would lower all of the noise levels by 2 dB(A). Another way to look at the noise emission foot print is to place a CAT D10 at the four corners intersection of Mining Areas 2, 3, 4 and 5. At this location the 55 dB(A) noise foot print of a CAT D10 would be 1900 ft. in all directions, for a CAT D8, the noise foot print would be 1450 ft. B. Mine Production After the mine development is completed the noise levels at 25 ft. beyond the property boundary will not exceed 55 dB(A), CRS 25-12-103. Stationary equipment such as the processing plant will be on the pit floor which is at a minimum of 20 ft. below grade level and the combined noise reduction due to the existing pit wall, terrain and distance to the property boundary especially to the south will assure that the noise level at 25 ft. beyond the property boundary will be less than 55 dB(A). The southern pit wall which is more than 40 ft. above grade level will provide a minimum of 15 dB(A) reduction. And the reduction in distance to the southern property of Mining Area 1 will provide 10 dB(A) for a total of 25 dB(A). This will reduce the noise level from a CAT D7 dozer to 53 dB(A) at 25 ft. beyond the southern property boundary of Mining Area 1. A berm may be added which will increase the noise reduction. To the southern property boundary of Mining Areas 2 and 4, a 20 ft. berm is required because the property boundary is about 60 ft. from the edge of the mined area and there is no reduction due to distance. A CAT D7 will however, be used for all production work in the Mining Areas. To the west of Mining Areas 4 and 5, a 20 ft. berm will be required for the same reason as described above. To the north of Mining Areas 1, 3 and 5, the reduction due to distance be itself will reduce the noise by 25 dB(A) lowering the noise from the CAT D7 to 53 dB(A). Additional noise reduction will be provided by the pit wall. Now, to the west of Mining Areas 4 and 5 the land is open agricultural land and the Colorado Noise Law is silent as to the noise limits. Normally in these situations where there is no platted residential sites abutting to the property boundary the noise limits are disregarded and the limits are applied to the nearest property beyond the agricultural zoned land. However, in the case of the Blue Pit, a 20 ft. high berm will be constructed at the western property boundary and the noise level at 25 ft. beyond the property boundary will be less than 55 dB(A) only when the mining activity starts in Mining Areas 4 and 5 and not before. E. D. I. Job # 3785 Page 4 of 4 3925 south kalamath street • englewood, colorado 80110 • 303.761.4367 • Fax 303.761.4379 A 6200 6190 6180 6170 6160 6150 6140 6130 6120 6110 6100 6090 6080 6070 6060 West Permit Boundary 20' Hay Bale Berm/ III [11111111 1 1 1 1 1 1 Track Excavator 20' Minimum Depth NW - 64' Mined Out Temporary Slop 1.5:1 0+00 1+00 2+00 3+00 4+00