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Home My WebLink About1.05 Supplemental Application Materials 12.12.2022GIenn Hartmann Sent: To: Cc: From: Attachments: Hello Glenn! Sincerely, Angie Fowler, PE Water Servrbes Sector Leader Angie Fowler <AngieF@sgm-inc.com > Monday, December 12,2022 1 1:36 AM Glenn Hartmann Alex Nees; Chris Hurley; Tony Roberts RE: Supplemental Memos for Rifle Pit 2022 -1 2 -0 1-N o ise M e m o-Attach-D. pdf Subject: 1. 2. Revised Noise Memo with attachments included with this email. There will be no activity, including the removalof vegetation, within the 35-foot Wetland setback. SSGM t 18 W S¡xth St Suite ?00 Glenr,vood Springs, Cü 8l ó01 9ro.384.9027 I Wû.618.9973 cell wvrw, *grn"in{,cûm n3û From: G len n Ha rtma nn <gha rtma nn @ga rfie ld-cou nty.com > Sent: Monday, December L2,2O2211:06 AM To: Angie Fowler <AngieF@sgm-inc.com> Subject: Supplemental Memos for Rifle Pit Hi Angie: Thanks very much for your memorandum and responses to the conditions. Just a couple follow-up questions came up as we prepared to upload the submittal into the overall Application package. The Noise Study appeared to be missing the Attachments A (Propagation Map) and B (Field Collected Noise Data) Regarding the wetland setback, the note on the map "Affected Lands (A.K.A. Limits of Disturbed Area) Min. 35- Ft. away from Ex. Wetland Boundaries" reflects compliance with the Waterbody Setback standards that do not allow for any removalof vegetation within the setback. Just checking to confirm with you that the mapping graphics are consistent with that statement. Or if you have any other updates on this topic that would be great. Please or email to discuss the above items. Thank you in advance for your ass¡stance. Glenn Glenn Hartmann Principal Planner 97O-945-t377 xL57O o a 1 Ghartmannlôea elcl-countv.com From: Angie Fowler <AlrgleF@sglu-irtc,coln> Sent; Friday, December 9,2022 2:04 PM To: Glenn Hartmann <ghartmann@garf¡e >; Chris Hurley <churlev@ihcscott.com> Cc: Alex Nees <¿!g4l@lgûU-nc-.co.¡1>; Tony Roberts <troberts@ihcscot > Subject: Memos for Rifle Pit Hello Glenn! A memo documenting responses to some of the staff s recommendations at the September Planning Commission is attached. Please let me know if you have any questions! Sincerely, Angie Fowler, PE Water Servrbes Sector Leader SSGM I l8 W Si$h $, Su¡la ?O0 Glernvor¡d Sp"'ng", C0 8ló01 9ro.384.9027 / ç7A.6ì8.9973 cell www,sgnr"inc,{:Ft:1 mtr 2 gSGM IHG Scott's Rifle Pit #1 - Noise Standard Gompliance TO:Glenn Hartmann, Principal Planner Planning Division - Community Development Garfield County FROM:Alexander Nees Senior Ecologist DATE: December 1,2022 SUBJEGT: NTC ltem 3c: Documentation of compliance with LUDC noise standards for gravel operations Dear Glenn: SGM has completed additional noise modeling to determine compliance with the noise standards contained in Table 7-1002 of the Land Use and Development Code (LUDC). This additional modeling was completed in response to the Staff Recommendations developed following the Planning Commission meeting of September 28,2022.lt is meant to reolace, rather than supplement, the noise assessment that was reviewed in that meeting (Land Use Permit Application, May 9, 2022 [Revised August 20221, Section 2.12.3). The Rifle Pit #1 operation is surrounded by residential uses, and Table 7-1002 establishes an A- weighted decibel threshold of 55 dB(A) as the maximum allowable daytime noise impact, measured at 25 feet beyond the subject property. IHC Scott is not proposing nighttime operations, so only daytime standards are addressed here. ln summary, our analysis indicates that the proposed gravel extraction operation would be conducted in such a manner that the volume of sound generated would not constitute a public nuisance or hazard, and in compliance with the threshold standards in Table 7-1002. . The stationary location of the gravel processing (see Sound Propagation Map, attachment A) has been moved to a location approximately 750 feet from the nearest adjacent property. ¡ The noise generated by the processing equipment has been measured at 94.3 dB under real- world operating conditions (see field-collected noise data, attachment B). . Calculations for the attenuation of sound propagation in the outdoor setting (using ISO 9613 standards) indicate that distance attenuation alone is sufficient to ensure that the sound levels at adjacent properties are well below the 55 dB(A) threshold requirement. cLENWOOD SPRINGS I l8 West Sixth St, Suite 200 | Glenwood Springs, CO 81601 | 970.945.1004 a Perimeter berms, surface absorption, screening vegetation, and existing background noise would further reduce the effective apparent noise impact to adjacent properties, but are not modeled in detail here since they are not necessary to show compliance with the standards in Table 7-1002. Design Alterotions Since the original noise assessment was provided to your office, several substantive design changes have been made to the proposalthat drastically alter the noise considerations, and that necessitate a new noise assessment as provided in this memo. These changes are generally driven by the transition from the originally-proposed dry-mining design to the current proposal for wet mining, and include the specific relevant issues: . The crushing operation has been moved to the south side of the property, and will be stationary throughout the mine's operation phase. Unlike a standard dewatered pit operation, the wet mining process does not allow for mobile processing equipment, since excavated areas are allowed to fillwith water immediately. Therefore the stationary noise generator location needs to be modeled at the appropriate specific location (see Sound Propagation Map, attachment A). . The processing operation will take place essentially at grade, rather than within the excavated pit, again due to the requirements of the wet mining process. Therefore, the noise levels are not attenuated due to a below-grade location as is typical in a standard dewatered gravel operation. . IHC Scott has slightly changed the processing equipment, including a newer, quieter crusher than was originally proposed. The anticipated noise production can also be further refined through comparison to substantially-similar, currently operating gravel mines (see Data Collection below). Doto Collection To generate the most realistic estimate for anticipated noise production levels at the Rifle Pit #1, IHC Scott measured the actual noise produced at their currently-operating nearby gravel operation, located on leased property at 6533 346 County Road, Silt, CO 81652. This gravel operation uses a suite of equipment that is substantially-similar to that proposed for the Rifle Pit #1, including crusher, processor, and trailer-contained generating equipment. The noise readings were collected along six transects, all centered on the center of operations (see attachment B). The highest reading collected was 94.3 dB, which was used for the point source model described below. Note that the data collection was performed at typical dewatered pit site, where the processing equipment is located below grade. Sound reflection off the sides of the pit are likely to amplify noise standards above what would be expected in an at-grade operation such as Rifle Pit #1. The noise levels collected at the 346 County Road site are therefore likely to be a slight over-estimate of noise production at the Rifle Pit #1 site. OSGM Page | 2 Modeling Approoch The sound modeling was completed with the use of 3D computer sound modeling software. All models in this report were performed with the dBmap.net noise mapping tool1, using the ISO 9613 standard for outdoor sound propagation. . A single 94.3 dB point noise source was placed at the location of the processing facility on the Rifle Pit #1 property. . Linear distances to the receiver points for the adjacent properties were calculated in a GIS and imported into the model. Receiver points were located at the closest possible point to the noise source that was 25 feet within the subject property. . The software calculated noise attenuation due to distance and provided anticipated noise impact levels for each adjacent property as follows: o Colorado River Ranch (North side): 35.8 dB o Shidelerosa (East side): 39.5 dB o Ward (South side): 41.5 dB o Nicola (South side):40.65 dB o Robinson (West side): 39.7 dB Sound levels at the specified receiver points are predicted solely based on the location of the sound source (the processing facility) and the linear distance to the specified receiver points. The topography and reflective properties of the local terrain, buildings and barriers, and existing noise levels are not included in the analysis. The predicted sound levels only take into consideration the sound produced by the processing facility and do not account for other sources, such as traffic, other human activity, or environmental factors. No discussion is provided regarding the relative prominence of the facility noise within the existing soundscape, although previously- collected data indicate a relatively high level of existing noise, associated predominantly with traffic on lnterstate 70 at the south boundary of the project. Mode/ing Approach, AssumpÍions, & limiÍolions The modeling used the following assumptions, all of which are conservative estimates that would generally increase the estimated noise impacts. The reported dB levels therefore generally represent a worst case scenario for noise levels apparent at the adjacent properties. o No topography or screening berms were included. A perimeter berm will be part of the site as mandated by regulation, but is not necessary to achieve noise compliance. . The absorption of sound due to vegetation or soft ground surface is not included: the model uses the assumption of a perfectly-reflective and flat ground surface, which dramatically increases the propagation of noise produced at the site. r No allowance is made for the impact of lnterstate 70's noise levels or facilities (frontage lanes, jersey barriers or other components). ln conclusion, our analysis indicates that the proposed gravel extraction operation would be in compliance with the threshold standards in Table 7-1002, based solely to the distance between the processing facility and adjacent properties. Additional mitigating factors that are present but not included 1 Provided by MAS Environmental LTD, available online at https://noisetools.neUdbmap/ ESGM Page | 3 in our calculations include the perimeter berm, ground absorption, and existing background noise associated with lnterstate 70. The fact that the facility achieves compliance with the LUDC standards of 55 dB threshold even without the incorporation of mitigating factors adds significant confidence to the conclusion that the Rifle Pit #1 operation will be within the LUDC standards. Sincerely, Alex Nees Senior Ecologist & Team Leader gSGM 259 Gmnd Ave, Suite 200 Grsnd Junction, CO 81501 970.384.9004 / 01O.742.6145 cell wwwsgnr-inc.com Aftachments: A. Revr.sed Sound Propagation Map B. Field-Collected Noise Data OSGM Page | 4 gSGM I ¡8 W Sirrl¡ Sr., SuÍ¡ Gle¡'md spritrs!. CO NOISE MEASUREMENTS MAP Scott Contracting lnc. 200 Dale: 1 1h1n022 Måpby: KNRI Ch6ck€d by:AN scalo: 1:3,600 1 inch = 300 feet )fr sourc$: ESRI, Ga.field county Gls D€pt. lV0lNol934l Aii€Ph1W2-Pêmiüii0HÐ3EFWXOôG8& dlr.'î?rygþw'il'þ nv<&f+tÆru^ñ^,'$i''ò,rr0$fl fiezZ;2ry ? V:ø3 ?tr¡r/l/ l-fffinty Utro&Lar7åÇ.->À,\ñì<vWnN.fl^tZ-ßrt'î"ø¿t æ\9.tzt-tz/ e4Uf$ h$A Sound Readings Every 25' from the Crusher Chris Hurley (on what readings you need, distance, etc.) 4 . (7201889-4402 Louis Bustamante (pit general questions) . (720) 880-9678 Chris Adrian, General Super (pit tocation) o (7201490-7449 X (pit 25 ft. 50 fr. 75 ft. r00 ft. 125 ft. 1 50 ft. 175 ft. 200 ft. 225 ft. 250 ft. 275 ft. 300 ft. ÐT,a +1 ,3 + b,l is located hereìrs tocateo W4 'v á'-''*"þ- ø/4,'î/l/'*î f*w"7,ulffi ..3o'ío {hr¡ll il'YltYe rêØÊ"-ë: t6n* a( fi1r7fr'5)þ '""ø' I ¿?¿ruutk* L6d ø ?+.1 +//, 3 L,ve 73 X (pit is [ocated here) 2srr. q4'I 50 ft. 75 ft. r00 ft. 125 ft. 150 ft. 175 ft. 200 fr. 225 ft. 250 ft. 275 ft. 300 fr. Ø t,b 1.p,..q Ør,,8 ++.+ +v. Òw,/ 1f¿o, t 73. G 6. a aB,z Sound Readings Every 25'from the Crusher Chris Hurley (on what readings you need, distance, etc.) . (720) 889-4402 Louis Bustamante (pit general questions) . (7201880-9678 Chris Adrian, Generat Super (pit tocation) . {7241490-7449 ;Àó¡t felt l,t-e afoW aa¿*"* 1- lzgtazt*rf/'***" bta C 25 ft. 50 ft. 75 ft. 100 ft. 125 ft. 1 50 fr. 175 ft. 200 fr. zz5 ft. 250 ft. 275 ft. 300 ft. Sound Readings Every 25' from the Crusher Chris Hurley (on what readings you need, distance, etc.) o (7201889-4402 Louis Bustamante (pit general questions) . (7201880-9678 Chris Adrian, General Super (pit tocation) . (7201490-7449 X (pit is located here) P L*s Cþvtúlcl fiØfu'U P//b? +/- I bf fu Ò"/¿6//* ât//ê 4 løæep 3¿4{" ^- ù'//'a* 6wWP ã þ Y¿ ¡rfuuè Sa-"-L B*-" i¿ þ25 4* 4z) euit'ø Tþq€,ê þørz l* *7 tl'u:a"g hu €lø ê4vrz- -vb I Llrl¿'Þ Sound Readings Every 25' from the Crusher Chris Hurtey (on what readings you need, distance, etc.) . (720) 889-4402 Louis Bustamante (pit general questions) . (7201880_9678 Chris Adrian, Generat Super (pit Location) . (7201490-74/19 X (pit is tocated here) ,5 46,1 F&L 25 ft. 50 fr. 75 ft. 100 ft. 125 ft. 150 ft. 175 ft. 200 fr. 275 ft. 250 fr. 275 ft. 300 ft. ]7, +//*r/* ß.o',- ,0 öâ,,b ú'a I øø¿¿ 7o*¿o tu 5', &, bú,3 /¿; ? /6/'eo? Lrlft G"*/ 5, ø? / ¿yr /il//¿'2F +a,+ çàþa^'¿e/t /6¿//¿?'* /bt/ â. Eer¿yfu-øøaa ,+ ébs¿,>¿a*/ e/ã;,/h"*rVre 7r +f ã¿¿- Lnt F 25 ft. 50 fr. 75 ft. 100 fr. 125 ft. ,l50 ft. 175 ft. 200 ft. 225 ft. 250 fr. 275 ft. 300 fr. Sound Readings Every 25' from the Crusher Chris Hurtey (on what readings you need, distance, etc.) o (720') 88g-44A2 Louis Bustamante (pit general questions) . (7201880-9ó78 Chris Adrian, General Super (pit location) o (770149A-7449 X (plt is located here) 7 3, S st4 Tê{Ð4 il¿"útP'fu-. Þ'f/'. l¿na GI 50 ft. 75 ft. 100 fr. 125 ft. 150 fr. f75 ft. 200 ft. 225 ft. 250 ft. 275 ft. 300 fr. Sound Readings Every 25' from the Crusher Chris Hurley (on what readings you need, distance, etc.) . (7201889-4402 Louis Bustamante (pit general questions) o (7201880-9678 Chris Adrian, General Super (pit tocation) . (720149A-7449 X (pit is located here) 25 ft. Bí,a vh 3 ++,2 72.? +ó, 5 ø 47zcØ ''?r".2 orø{ç ' f, t/an/'/æe