ENVIRONMENTAL NOISE REPORT SANDSTONE SEPULVEDA

Transcription

1 ENVIRONMENTAL NOISE REPORT SANDSTONE SEPULVEDA DATE 09/17/2015 PAGES - 13 TO Abhijeet Mankar Johnson Fain amankar@johnsonfain.com Donna Shen Tripp Craig Lawson & Co., LLC donna@craiglawson.com FROM James Black Executive Summary We have conducted an environmental noise study of the proposed Sandstone Sepulveda project in order to evaluate sound transmission from the amenity decks and rooftop HVAC equipment to surrounding residential properties of interest, on the bluff above. We measured ambient noise levels and built a 3D sound prediction model to determine the noise effects of the planned development. Our predictive findings indicate that, at the most problematic time of the day, the noise levels produced by the amenity decks planned functions (i.e. people talking and using raised voices) and rooftop HVAC equipment as modeled will meet the quantitative requirements given in the local noise ordinance. Additionally, they and the intended uses of the south-facing balconies should not violate the loud, unnecessary and unusual noise prohibition of the noise ordinance.

2 Objective We understand that the sound generated by the Sandstone Sepulveda amenity decks and rooftop HVAC equipment is of interest due to its potential noise impact on nearby residences on the bluff above. Figure 1 below illustrates the relationship between these. We measured ambient noise levels at the site and evaluated environmental noise transmission from representative planned amenity deck functions and rooftop HVAC equipment to these residences. The intent of this evaluation was to explore if the new development as planned would comply with local noise ordinances and be a good neighbor in regards to noise generated on its amenity decks and by its rooftop HVAC equipment. Figure 1: Relationship of Planned Amenity Decks and Rooftop HVAC Equipment to Residences on Bluff Above SANDSTONE SEPULVEDA

3 Background (Ambient) Noise Background noise levels play an important role in the perception of environmental noise impacts. Therefore, we performed field measurements of the ambient background noise levels at the site to quantify this. This consisted of two types of measurements. To measure the spatial and spectral distribution of the ambient noise, we measured at several locations around the development. These measurements were performed with a Bruel & Kjaer Type 2250 Sound Level Meter, a Type I device. The meter had a current calibration certificate and a windscreen was used. To measure the temporal distribution of the noise, we used a Casella CEL-24 Type II logging meter. This meter was left at the site over a 24-hour period to quantify the noise fluctuations over time. Figure 2 below identifies the measurement locations. At each location identified, measurements were made with the Bruel & Kjaer Location #1 is where the logging measurements were also performed. Figure 2: Measurement Locations The measurements were used to calibrate a 3D sound prediction model. This model takes into account phenomena important to the propagation of sound, such as distance attenuation, reflections off of hard surfaces, absorption from soft surfaces, shielding from barriers and berms, diffraction, etc. Figure 3 below illustrates the results of this model for comparison with the measured levels of Table 1 below. SANDSTONE SEPULVEDA

4 Figure 3: Modeled Ambient Noise Levels of Current Site TABLE 1: MEASURED SITE NOISE LEVELS [DECIBELS, LAEQ] Location # Location # Location # Location # Location # Location # SANDSTONE SEPULVEDA

5 The purpose of creating this model was to predict the noise levels at locations on the residential properties, including facades, which could not be reached or were not practical to measure. Additionally, the model allowed prediction of how the ambient noise levels will be affected by the new Sandstone Sepulveda building. It can be seen in Figure 4 below that the new Sandstone Sepulveda building will shield the residences from the main noise sources (I-405 and Sepulveda), reducing their ambient noise levels. Figure 4: Modeled Ambient Noise Levels [dba] of Future Site Ambient noise levels at the residential facades that would likely experience the highest amenity deck and rooftop HVAC equipment noise levels were also calculated using the model. Figure 5 below illustrates an example of this. SANDSTONE SEPULVEDA

6 Figure 5: Modeled Façade Ambient Noise Levels [dba] of Future Site One last thing to consider regarding the ambient noise levels is how they change over time. This site is near a major urban center with significant traffic at all hours so the change is relatively minor. However, ambient noise levels were measured as dropping off after midnight until 2 AM (2 dba drop total), when they started to pick up again (see Figure 6 below). Due to this, an evaluation of the Sandstone Sepulveda noise sources should consider that at the quietest time of day, the masking ambient noise could be 2 dba less than reported above. 70 Measured Ambient Noise Levels [dba] Sound Pressure Level [dba] :00:00 PM 2:00:00 PM 4:00:00 PM 6:00:00 PM 8:00:00 PM 10:00:00 PM 12:00:00 AM 2:00:00 AM 4:00:00 AM 6:00:00 AM 8:00:00 AM 10:00:00 AM 12:00:00 PM Figure 6: Change in Measured Ambient Noise Levels over 24-hours SANDSTONE SEPULVEDA

7 Rooftop HVAC Equipment Noise To model the sound generated by the Sandstone Sepulveda rooftop HVAC equipment, we used outdoor units from a similar project. These representative units, of various common sizes, were distributed amongst the units shown in the architectural model. Sound power levels were those published by the representative unit manufacturer. Figure 7 below illustrates the rooftop HVAC unit noise dba ratings mapped over the relevant area. Figure 8 illustrates the same mapped over the relevant residential neighbor facades. Figure 7: Rooftop HVAC Noise Mapped Over the Relevant Area [dba] Figure 8: Rooftop HVAC Noise Mapped Over the Residential Neighbor Facades [dba] SANDSTONE SEPULVEDA

8 CRITERIA We have reviewed the City of Los Angeles s Noise Ordinance, CHAPTER XI, NOISE REGULATION. For reference, we have extracted portions of the Ordinance relevant to the part of the analysis below. Please refer to for the entire ordinance. ARTICLE 1, GENERAL PROVISIONS, SEC DEFINITIONS. (a) "Ambient Noise" is the composite of noise from all sources near and far in a given environment, exclusive of occasional and transient intrusive noise sources and of the particular noise source or sources to be measured. Ambient noise shall be averaged over a period of at least 15 minutes at a location and time of day comparable to that during which the measurement is taken of the particular noise source being measured. (Amended by Ord. No. 156,363, Eff. 3/29/82.) (k) "Sound Level" (Noise level) in decibels (db) is the sound measured with the "A" weighting and slow responses by a sound level meter; except for impulsive or rapidly varying sounds, the fast response shall be used. (Amended by Ord. No. 156,363, Eff. 3/29/82.) ARTICLE 1, GENERAL PROVISIONS, SEC MINIMUM AMBIENT NOISE LEVEL. (Amended by Ord. No. 156,363, Eff. 3/29/82.) Where the ambient noise level is less than the presumed ambient noise level designated in this section, the presumed ambient noise level in this section shall be deemed to be the minimum ambient noise level for purposes of this chapter. TABLE II SOUND LEVEL "A" DECIBELS (In this chart, daytime levels are to be used from 7:00 a.m. to 10:00 p.m. and nighttime levels from 10:00 p.m. to 7:00 a.m.) At the boundary line between two zones, the presumed ambient noise level of the quieter zone shall be used. SANDSTONE SEPULVEDA

9 ARTICLE 2, SPECIAL NOISE SOURCES, SEC AIR CONDITIONING, REFRIGERATION, HEATING, PUMPING, FILTERING EQUIPMENT. (Amended by Ord. No. 156,363, Eff. 3/29/82.) (a) It shall be unlawful for any person, within any zone of the city to operate any air conditioning, refrigeration or heating equipment for any residence or other structure or to operate any pumping, filtering or heating equipment for any pool or reservoir in such manner as to create any noise which would cause the noise level on the premises of any other occupied property or if a condominium, apartment house, duplex, or attached business, within any adjoining unitto exceed the ambient noise level by more than five (5) decibels. A brief summary of how the ordinance applies to this part of the project is, since the site ambient noise levels exceed the appropriate values in Table II Sound Level "A" Decibels, The Sandstone Sepulveda rooftop HVAC equipment cannot exceed the ambient by more than 5 dba. ANALYSIS The area of the residential properties that has the most potential to be problematic is the area indicated by a red circle in Figure 9 below. This is the area that receives some of the highest rooftop HVAC equipment noise levels and relatively low ambient masking noise levels. Figure 9: Area of Residential Properties that Has the Most Potential to be Problematic SANDSTONE SEPULVEDA

10 Table 3 below provides the modeled ambient and rooftop HVAC noise levels for the potentially most problematic area of the residential properties, at the most problematic time, 2 AM. TABLE 3: MODELED NOISE LEVELS AT POTENTIALLY MOST PROBLEMATIC RESIDENTIAL AREA Ambient Noise Levels Rooftop HVAC Equipment Noise Levels dba dba It can be seen in Table 3 that the rooftop HVAC equipment noise levels as modeled do not exceed the ambient noise levels by more than 5 dba and therefore meet the noise ordinance. SANDSTONE SEPULVEDA

11 Amenity Deck Noise To model the sound generated by the Sandstone Sepulveda amenity decks, we placed point sources representing people talking in normal voices and using raised voices. We distributed these two types approximately evenly over the amenity decks where the Landscape SD Plans indicated they would be used (e.g. seating areas). In total, there were just over 30 of these sources modeled (see dark dots in Figure 9 below). Figure 9: Amenity Deck Source Layout The sources described above resulted in the levels illustrated below in Figures 10 through 11. Note that the scale is different (-20 db) than above. Figure 10: Modeled Amenity Deck Noise Levels [dba] of Future Site SANDSTONE SEPULVEDA

12 Figure 11: Modeled Façade Amenity Deck Noise Levels [dba] of Future Site CRITERIA Additional criteria from the City of Los Angeles s Noise Ordinance, CHAPTER XI, NOISE REGULATION that could apply to this portion of the project is extracted below. ARTICLE 6, GENERAL NOISE, SEC LOUD, UNNECESSARY AND UNUSUAL NOISE. Notwithstanding any other provisions of this chapter and in addition thereto, it shall be unlawful for any person to willfully make or continue, or cause to be made or continued, any loud, unnecessary, and unusual noise which disturbs the peace or quiet of any neighborhood or which causes discomfort or annoyance to any reasonable person of normal sensitiveness residing in the area. The standard which may be considered in determining whether a violation of the provisions of this section exists may include, but not be limited to, the following: (a) The level of noise; (b) Whether the nature of the noise is usual or unusual; (c) Whether the origin of the noise is natural or unnatural; (d) The level and intensity of the background noise, if any; (e) The proximity of the noise to residential sleeping facilities; SANDSTONE SEPULVEDA

13 (f) The nature and zoning of the area within which the noise emanates; (g) The density of the inhabitation of the area within which the noise emanates; (h) The time of the day and night the noise occurs; (i) The duration of the noise; (j) Whether the noise is recurrent, intermittent, or constant; and (k) Whether the noise is produced by a commercial or noncommercial activity. A brief summary of how the ordinance applies to this part of the project is, there is no quantitative limit in the code for the planned uses of the amenity decks. However, loud, unnecessary and unusual noise is prohibited. ANALYSIS The planned uses of the amenity decks (i.e. groups of people talking or using raised voices) were modeled to not exceed 35 dba on the neighboring residential properties of interest (see Figures 10 & 11). This is at least 15 dba below (see Table 3) the modeled ambient noise levels. This noise from the planned functions should be less than ambient and satisfy the code s prohibition of loud, unnecessary and unusual noise. South Facing Balconies Noise As part of our study, we were asked to provide comment on impacts of the south-facing balconies to the residential properties on the bluff above. It is our understanding that the intended use of these balconies is only to have the residents themselves and possibly a guest or two sitting outside to relax in the outdoors. We understand the developers limited the size of the balconies so that they would not accommodate parties (as well as limiting the number of south-facing balconies in general). Similar to the amenity decks, there is no objective criteria for unamplified human voices. The only applicable criteria the code provides is that the sound from the balconies should not be loud, unnecessary and unusual noise. It is not expected that the intended use (i.e. only up to a few people having a conversation, relaxing or enjoying the outdoors) will violate the prohibition of loud, unnecessary and unusual noise criteria. SANDSTONE SEPULVEDA