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2022-04-26 Criste - Noise memos for the PCFrom: Consulting Planner Sent: Tuesday, April 26, 2022 9:51 AM To: Tania Flores Cc: Cheri Flores; Danny Castro Subject: Noise memos for the PC Attachments: 12642-16 Noise Memo.pdf; CM Resort Noise Memo_042622.pdf Tania, Please distribute these two documents to the Commission. Nicole Sauviat Criste Consulting Planner City of La Quinta 0 URBAN CROSSROADS CROSSROADS urbanxroads.com April 26, 2022 Mr. Garrett Simon CM Wave Development LLC 2440 Junction Place, Suite 200 Boulder, CO 80301 SUBJECT: THE WAVE AT CORAL MOUNTAIN LQRRD RESPONSE TO COMMENTS Dear Mr. Garrett Simon: Urban Crossroads, Inc. is pleased to submit this summary of the La Quinta Residents for Responsible Development (LQRRD) response to the comments related to noise. 1. The comment was made that when you double the distance from a noise source, you drop 6 decibels of sound. 1 would certainly like to reference this weekend's Coachella Fest. If sound truly drops off like this, why do we hear the music from Coachella all over town. Section 2.3 of the Coral Mountain Specific Plan Noise Impact Analysis (NIA) describes the sound propagation, or the way noise reduces with distances. As discussed in the NIA, the way noise reduces with distance depends on type of noise source (stationary point source, or line source), the ground absorption, atmospheric effects and shielding. For noise analysis purposes, sound levels are commonly assumed to attenuate (or decreases) at a rate of 6 dB for each doubling of distance from a point source and at a rate of 3 dB for each doubling of distance from a line source. The noise levels associated with the Coachella Fest are vastly different in both frequency content and source levels than those expected with the wave basin/wave machine activity for the proposed The Wave at Coral Mountain Project. It is also important to recognize that NIA demonstrates that the operational noise levels associated with The Wave at Coral Mountain Project will satisfy the City of La Quinta daytime exterior noise level standards with no planned nighttime operational noise source activity. This does not suggest that the wave basin/wave machine activity will be inaudible at times, only that the Project will not result in significant noise level increase above the existing ambient noise conditions. 2. The effect of the starting of the machinery to generate the wave on Coral Mountain was not studied. Also, with the bi-directional nature of the wave, no impact of wave noise going back against Coral Mountain was even considered. And the sound is generated for up to a 'z mile. It is not a "point" sound, but a "line" sound. This statement is factually incorrect. As described in Section 10.1.1 of the NIA, Urban Crossroads, Inc. collected reference noise level measurements at eight different locations around the Surf Ranch. The reference noise levels describe the peak noise events associated with all the noise source activities including, wave announcements over the public address system, move of the wave sled through the lagoon, mechanical equipment buildings, in addition to cable and metal 12642-16 Noise Memo Mr. Garrett Simon CM Wave Development LLC April 26, 2022 Page 2 of 3 rollers. However, based on our observations, the primary noise source is simply the movement of water from each wave in the lagoon. The noise analysis describes the wave basin/wave machine activity as an area source and not as a single line or point source. The area source type is used to ensure that noise source from the entire wave basin/wave machine is included in the analysis. These actual noise readings were then used to evaluate projected noise levels at the Coral Mountain project site using a 3-dimensional noise prediction model that considers changes in topography, walls and other features that affect noise transmission. Coral Mountain and the desert land between the wave basin and Coral Mountain are considered a soft surface that will likely absorb rather than reflect noise back towards sensitive receiver locations. The direct line of sight between the noise source and the receiver is the primary path of sound transmission that was considered in the Coral Mountain Specific Plan Noise Impact Analysis. Field studies conducted by the FHWA have shown that the reflection from barriers and buildings does not substantially increase noise levels (1). If all the noise striking a structure was reflected back to a given receiving point, the increase would be theoretically limited to 3 dBA. Further, not all the acoustical energy is reflected back to same point. Some of the energy would go over the structure, some is reflected to points other than the given receiving point, some is scattered by ground coverings (e.g., grass and other plants), and some is blocked by intervening structures and/or obstacles (e.g., the noise source itself). Additionally, some of the reflected energy is lost due to the longer path that the noise must travel. FHWA measurements made to quantify reflective increases in traffic noise have not shown an increase of greater than 1-2 dBA; an increase that is not perceptible to the average human ear. 3. The other thing we would like to respectfully request for the Commissioners to review is the document we included in your packet "Surf Wave Parks — Assessing the Sound of Fun". Airborne generation of noise from breaking waves has been shown to be complex, containing tonal, modulating and broadband components, which are all additive when assessing noise dose. These sounds are the Low Frequency Sounds we discussed in our presentation that travel long distances and need to be evaluated when placed in environmentally sensitive areas. With the way the surf basin is situated, and that there would be 50 hertz frequencies in the "C" range generated by the surf. This memo supports our findings that the primary noise source is simply the movement of water from each wave in the lagoon. In addition, the City of La Quinta has adopted the A -weighted frequency response to control community noise impacts. A -weighted decibels (dBA) approximate the subjective response of the human ear to broad frequency noise source by discriminating against very low and very high frequencies of the audible spectrum. They are adjusted to reflect only those frequencies which are audible to the human ear. Although the A - Weighted response is used for most applications, C-Weighting is usually used for Peak measurements and in some entertainment noise measurement, where the transmission of bass noise can be a problem. 12642-16 Noise Memo `�► URBAN CR055ROADS Mr. Garrett Simon CM Wave Development LLC April 26, 2022 Page 3 of 3 A review of the unweighted (Z) spectral content of the reference noise level measurements shows a level of 54.0 dB at 50 hz with most of the noise content in the range of 500 to 1000 hz of 63.9 dB. The unweighted (Z) frequency content of the reference noise level measurements does not support the use of the C-Weighting. 4. Until further evidence of noise generated from such parks is available, control of such noise will be difficult to evaluate, and authorities should demonstrate caution when assessing such proposals placed in noise sensitive areas. The evidence shows that wave basin/wave machine will satisfy the City of La Quinta daytime exterior noise level standards. In addition, the NIA demonstrates that the Project will contribute a less than significant operational noise level increase to the existing daytime ambient noise environment at all existing off -site receiver locations. Respectfully submitted, URBAN CROSSROADS, INC. Bill Lawson, P.E., INCE Principal 12642-16 Noise Memo URBAN CROSSROADS IVJeridian Consultants LOS ANGELES 706 S. Hill Street, 11th Floor Los Angeles, CA 90014 (213) 335-3434 MEMORANDUM WESTLAKE VILLAGE 920 Hampshire Road, Suite A5 Westlake Village, CA 91361 (805) 367-5720 Date: April 26, 2022 To: Nicole Criste, Contract Planner, City of La Quinta From: Tony Locacciato, AICP, Partner Subject: Coral Mountain Resort Environmental Impact Report Noise Analysis This memo provides information in response to questions from community members on how the noise that would be generated by the wave basin in the proposed Coral Mountain Resort Project compares to noise generated by the ongoing Coachella and Stagecoach Music Festivals, held annually over three consecutive weeks in April at the Empire Polo Club in Indio, approximately 4.5 miles northeast of the Coral Mountain Project site. The Empire Polo Club is located between Avenues 50 and 52 and east of Madison Street. The City of Indio prepared an Environmental Impact Report (EIR) for the Music Festivals Plan Project, certified in 2013, to support the issuance of a long-term permit for these music festival events. This EIR includes analysis of the sound systems used at these outdoor music festivals and the level of noise experienced by the surrounding community. The most notable noise source associated with these events is from the sound systems for each of the multiple concert stages. Noise monitoring of the 2012 Music Festivals was conducted and noise modeling was prepared based on configuration of the speakers used at each stage. This analysis determined the primary source of noise was from the main stage and for this reason, computer modeling of the sound system was completed that served as the basis for the noise analysis in the EIR. The sound system for the large outdoor main stage consists of a series of hanging loudspeaker arrays on either side of the stage along with loudspeakers mounted on the stage deck, and delay loudspeaker arrays set up in front of the stages. The bottom of the loudspeaker arrays on either side of the main stage are located approximately 20 feet above ground level and top of these speaker arrays are located approximately 50 feet above ground level. This sound system is designed and operated to produce a sound level of 105 dBA at the front of house (FOH) equipment area where music is mixed for the audience. The FOH is located approximately 150 feet from the front of the main outdoor stage. Attached are two figures from the Music Festivals Plan EIR that show the sound levels from the modeling for the Coachella and Stagecoach Music Festivals. The festival grounds are configured differently for the Coachella Music and Arts and Stagecoach Country Music Festivals with the main stage located along Avenue 50 and oriented to the south for the Coachella Festival and along Monroe Street and oriented to the west for the Stagecoach Festival. Page 2 Coral Mountain Resort EIR Noise Analysis As shown in these figures, sound levels of 69 dBA and above are largely contained on the festival site, located between Madison Street, Avenue 50, Monroe Street, and Avenue 52. Noise levels above 50 dBA are experienced east of Jefferson Street and north of Avenue 54. The City of Indio conducts noise monitoring during these events at 6 locations around the edge of the festival site during these events. The maximum 10-minute average noise level along Madison Avenue between Avenues 50 and 52 during the first weekend of the Coachella Music Festival this year was approximately 75 dBA. The noise sources and levels generated by the sound system at the main stage at these festivals are not comparable to the noise sources and levels associated with proposed wave basin, as documented in the Coral Mountain Resort Final EIR. As described above, the outdoor sound system at the main stage generates a sound from the large speaker arrays hung above the stage of approximately 105 dBA at a distance of 150 feet from the stage. Depending on local atmospheric conditions, including air temperature and wind, sound from the festival sound system may be heard miles away from the festival site. Noise monitoring was conducted at the Surf Ranch in Lemoore, California in April 2020 and August 2021, as presented in Appendix K.3 to the Coral Mountain Resort Final EIR to determine the level of noise generated by this wave basin. The highest measured noise level from the cable roller system that pulls the foil that generates the wave, and movement of water in the basin, was 75.7 dBA Leq at a distance of 12 feet from the wave basin, which equates to a noise level of 63.3 dBA at a distance of 50 feet. To understand how sound levels reduce over distance, as explained in Chapter 5 of the Noise of the Occupational Safety and Health Administration Technical Manual, as a principle of physics, sound pressure levels decrease by 6 dB, on a Z-weighted (i.e., unweighted) scale, each time the distance from the point source is doubled. This is a common way of expressing the inverse -square law in acoustics as shown below: For example, as shown above, if a point source produces a sound pressure level of 90 dB at a distance of 1 meter, the sound pressure level is 84 dB at 2 meters, 78 dB at 4 meters, and so forth. This principle holds true regardless of the units used to measure distance. Page 3 Coral Mountain Resort EIR Noise Analysis The noise analysis of the proposed wave basin in the Coral Mountain Resort EIR was prepared using a 3- dimensional noise model that takes into account changes in topography, walls and other features that will affect noise transmission. This analysis determined the highest level of noise level from the wave basin, approximately 51 dBA, would be at the home located approximately 0.2 miles east of the wave basin on Calle Conchita. Exhibit A, attached, presents a comparison of the noise levels generated by the Indio Music Festivals sound system and the proposed wave basin by distance based on the inverse -square law in acoustics. For comparison purposes, the noise level generated by the sound system at the main stage at the Indio Music Festivals of 105 dBA at a distance of 150 feet would be approximately 63 dBA at a distance of 3.6 miles, 57 dBA at a distance of 7.3 miles, and 51 dBA at a distance of 14.5 miles from the festival site. As described above, the festival site is located approximately 4.5 mile from the Coral Mountain Resort Project Site. Sound levels from the sound system at the festival would be between 57 and 63 dBA at the Coral Mountain Resort Project Site and in surrounding areas of La Quinta. As shown in the comparison in Exhibit A, the sounds levels from the proposed wave basin would be lower in the area surrounding the Coral Mountain Resort Project Site, with the noise from the basin being reduced to less than 40 dBA at a distance of 800 feet from the wave basin. In conclusion, the level of noise generated by the wave basin is not comparable to the noise generated by the sound system at the music festivals in Indio. The type of sound generated by the wave basin does not include the broad frequency of sound generated by the music festival sound system, would be generated at ground level, as opposed to being generated above ground level, and would generates a much lower sound level than the sound system used at the music festivals. Desert 1000 2000 APPROXIMATE SCALE IN FEET 4000 yr �:' �� .4 Legend Festival Site Areas not in {'5" Festival Site Sound Levels - dbA (by color) Red >99 dbA Light Orange >87 dbA Yellow >81 dbA Dark Green >69 dbA >50 dbA SOURCE: L-Acoustics - 2012; Google Earth - 2012 FIGURE 4.4-8 Meridian C nste/#ants Existing Festivals — 2012 Coachella Sound Levels 002-001-12 Desert 1000 2000 APPROXIMATE SCALE IN FEET 4000 yam Legend Festival Site Areas not in {'5" Festival Site Sound Levels - dbA (by color) Red >99 dbA Light Orange >87 dbA Yellow >81 dbA Dark Green >69 dbA >50 dbA SOURCE: L-Acoustics - 2012; Google Earth - 2012 FIGURE 4.4-9 Meridian C nste/#ants Existing Festivals — 2012 Stagecoach Sound Levels 002-001-12 EXHIBIT A - INDIO MUSIC FESTIVAL AND WAVE BASIN SOUND LEVELS BY DISTANCE INDIO MUSIC FESTIVAL SOUND LEVELS WAVE BASIN SOUND LEVELS dBA Noise Level Distance in Feet Distance in Miles dBA Noise Level Distance in Feet Distance in Miles 105 150 0.0 63.3 50 0.0 99 300 0.1 57.3 100 0.0 93 600 0.1 51.3 200 0.0 87 1,200 0.2 45.3 400 0.1 81 2,400 0.5 39.3 800 0.2 75 4,800 0.9 33.3 1,600 0.3 69 9,600 1.8 27.3 3200 0.6 63 19,200 3.6 21.3 6,400 1.2 57 38,400 7.3 15.3 12,800 2.4 51 76,800 14.5 9.3 25,600 4.8 45 153,600 29.1 3.3 51,200 9.7