Project: Truckee Springs Master Plan Environmental Noise Assessment January 30, 2015

Transcription

1 Project: Truckee Springs Master Plan Environmental Noise Assessment January 30, 2015 jcb Project # Prepared for: SCO Planning Engineering & Surveying 140 Litton Drive, Suite 240 Grass Valley, CA Attn: Mr. Rob Wood Prepared by: j.c. brennan & associates, Inc. Jim Brennan President Member: Institute of Noise Control Engineering 1287 High Street, Auburn, California * (p) * (530) (f)

2 INTRODUCTION This section discusses the existing noise environment in the project vicinity, and identifies potential noise impacts and mitigation measures related to development of the Truckee Spring Master Plan. Specifically, this section analyzes potential noise impacts due to and upon development of the project relative to applicable noise criteria and to the existing ambient noise environment. PROJECT DESCRIPTION The Truckee Springs Master Plan is approximately 26 acres in size, and is intended to create new residential and/or lodging development opportunities. the project will include new public amenities such as pedestrian and bike trail connectivity to the existing Town trail network. One of the goals is to allow for walkability to the downtown and public access to the Truckee River. PROJECT LOCATION The proposed Truckee Springs Master Plan consists of approximately 26 acres of undeveloped land situated within the Truckee River corridor at the end of South River Street, within the Town s Downtown Study Area. The site is located adjacent to the Downtown Commercial Core, across from the Town-owned West River Street property, previously used by Nevada County as a Corporation Yard. Primary access to the site is via. South River Street which intersects Brockway Road. As an alternative route for vehicle access, a potential bridge connection to West River Street is identified within this Master Plan. Figure 1 shows the project location, and Figure 2 provides a closer view of the project site. CRITERIA Town of Truckee General Plan Noise Element Goals and Policies The following Town of Truckee General Plan Noise Element goals and policies relative to this project. Goal 1: Minimize community noise exposure to excessive noise by ensuring compatible land uses relative to noise sources. Policy 1.1: Allow new development only if consistent with the ground transportation noise compatibility guidelines and policies of this Element. Noise measurements used in establishing compatibility shall be measured in dba CNEL and based on worst case 1

3 noise levels, either existing or future, with future noise levels to be predicted based on projected 2025 levels. Policy 1.2: Require new development to mitigate exterior noise to normally acceptable levels in outdoor areas where quiet is a benefit such as in the backyards of single-family homes. Policy 1.3: Enforce the California Noise Insulation Standards for interior noise levels attributable to exterior sources for all proposed new single- and multi-family residences. (Note: This is an interior noise level of 45 db Ldn/CNEL) Goal 2: Address noise issues through the planning and permitting process. Policy 2.1: Require mitigation of all significant noise impacts as a condition of project approval. Policy 2.2: Require preparation of a noise analysis which is to include recommendations for mitigation for all proposed projects which may result in potentially significant noise impacts to nearby noise sensitive land uses. Policy 2.3: Require preparation of a noise analysis which is to include recommendations for mitigation for all proposed development within noise impacted areas that may be exposed to levels greater than normally acceptable. Policy 2.4: Discourage the construction of sound walls and require development projects to evaluate site design techniques, building setbacks, earthen berms, alternative architectural layouts and other means to meet noise reduction requirements. Goal 3: Reduce noise levels from sources such as domestic uses, construction and car stereos, and from mobile sources, including motor vehicle traffic and aircraft operations. Policy 3.13: Require the following standard construction noise control measures to be included as requirements at construction sites in order to minimize construction noise impacts. 2

4 Equip all internal combustion engine driven equipment with intake and exhaust mufflers that are in good condition and appropriate for the equipment. Locate stationary noise generating equipment as far as possible from sensitive receptors when sensitive receptors adjoin or are near a construction project area. Utilize quiet air compressors and other stationary noise-generating equipment where appropriate technology exists. The project sponsor shall designate a disturbance coordinator who would be responsible for responding to any local complaints about construction noise. The disturbance coordinator will determine the cause of the noise complaint and will require that reasonable measures warranted to correct the problem be implemented. The project sponsor shall also post telephone number for excessive noise complaints in conspicuous locations in the vicinity of the project site. Additionally, the project sponsor shall send a notice to neighbors in the project vicinity with the information on the construction schedule and the telephone number for noise complaints. The Town of Truckee Noise Element guidelines which are applicable to the land uses located in the project vicinity are provided in Table 1. Town of Truckee Development Code The Town of Truckee Development Code essentially contains the Noise Ordinance referred to in the Town of Truckee Noise Element policies. Section of the development code states that noise complaints associated with the types of commercial uses (loading docks, stationary noise sources, etc.) would be directed to the Community Development Department. Section states that exterior noise levels, when measured at a noise-sensitive receiving land use, shall not exceed the noise level standards set forth in Table 2 (Table 3-8 in the Code). In the event that the ambient noise environment exceeds the Table 2 standards, the applicable standards shall be adjusted to equal the ambient noise level. In addition, the Table 2 standards shall be reduced by 5 db for simple tone noises, noises consisting primarily of speech or music, or for recurring impulsive noises. 3

5 Table 1 Noise Compatibility Guidelines 4

6 Table 2 Noise Standards by Receiving Land Use Town of Truckee Development Code Cumulative Duration of Intrusive Sound Noise Metric Daytime (7 am to 10 pm) Nighttime (10 pm - 7 am) Hospital, Library, Religious Institution, Residential or School Uses: Cumulative period of 30 minutes per hour L Cumulative period of 15 minutes per hour L Cumulative period of 5 minutes per hour L Cumulative period of 1 minute per hour L Level not to be exceeded for any time during hour L max Commercial Uses: Cumulative period of 30 minutes per hour L Cumulative period of 15 minutes per hour L Cumulative period of 5 minutes per hour L Cumulative period of 1 minute per hour L Level not to be exceeded for any time during hour L max Note: Each of the noise limits specified above shall be reduced by 5 dba for impulsive or simple tone noises or for noises consisting of speech or music. If the existing ambient noise levels exceed that permitted in the first four noise-limit categories, the allowable limit shall be increased to encompass the ambient. Section Exceptions states that the provisions of the chapter do not apply to noise sources associated with non-single family residential construction provided that the activities do not take place before 7 a.m. or after 9 p.m. on any day except Sunday, or before 9 a.m. or after 6 p.m. on Sunday. The provisions of the chapter do not apply to noise sources associated with single family residential construction on a single family lot. 5

7 1 0.2 AC AC : 24-hr Noise Measurement Locations Truckee Springs Master Plan Figure : 1 Project Location and Noise Measurement Locations : 65 db Ldn Noise Contour : 60 db Ldn Noise Contour Figure Prepared: January 2015

8 2 1 Truckee Springs Master Plan Figure : 2 Project Location and Noise Measurement Locations : 24-hr Noise Measurement Locations : 65 db Ldn Noise Contour Figure Prepared: January 2015 : 60 db Ldn Noise Contour

9 ENVIRONMENTAL SETTING and IMPACT ANALYSIS Acoustical Terminology 1 Acoustics is the science of sound. Sound may be thought of as mechanical energy of a vibrating object transmitted by pressure waves through a medium to human (or animal) ears. If the pressure variations occur frequently enough (at least 20 times per second), then they can be heard and are called sound. The number of pressure variations per second is called the frequency of sound, and is expressed as cycles per second or Hertz (Hz). Noise is a subjective reaction to different types of sounds. Noise is typically defined as (airborne) sound that is loud, unpleasant, unexpected or undesired, and may therefore be classified as a more specific group of sounds. Perceptions of sound and noise are highly subjective. Often, someone s music is described as noise by another. Measuring sound directly in terms of pressure would require a very large and awkward range of numbers. To avoid this, the decibel scale was devised. The decibel scale uses the hearing threshold (20 micropascals), as a point of reference, defined as 0 db. Other sound pressures are then compared to this reference pressure, and the logarithm is taken to keep the numbers in a practical range. The decibel scale allows a million-fold increase in pressure to be expressed as 120 db, and changes in levels (db) correspond closely to human perception of relative loudness. The perceived loudness of sounds is dependent upon many factors, including sound pressure level and frequency content. However, within the usual range of environmental noise levels, perception of loudness is relatively predictable, and can be approximated by A-weighted sound levels. There is a strong correlation between A-weighted sound levels (expressed as dba) and the way the human ear perceives sound. For this reason, the A-weighted sound level has become the standard tool of environmental noise assessment. All noise levels reported in this section are in terms of A-weighted levels, but are expressed as db, unless otherwise noted. The decibel scale is logarithmic, not linear. In other words, two sound levels 10 db apart differ in acoustic energy by a factor of 10. When the standard logarithmic decibel is A-weighted, an increase of 10 dba is generally perceived as a doubling in loudness. For example, a 70 dba sound is half as loud as an 80 dba sound, and twice as loud as a 60 dba sound. Community noise is commonly described in terms of the ambient noise level, which is defined as the all-encompassing noise level associated with a given environment. A common statistical tool to measure the ambient noise level is the average, or equivalent, sound level (L eq ), which corresponds to a steady-state A weighted sound level containing the same total energy as a time varying signal over a given time period (usually one hour). The L eq is the foundation of the 1 For an explanation of these terms, see Appendix A: "Acoustical Terminology" 8

10 composite noise descriptor, L dn, and shows very good correlation with community response to noise. The day/night average level (L dn ) is based upon the average noise level over a 24-hour day, with a +10 decibel weighing applied to noise occurring during nighttime (10:00 p.m. to 7:00 a.m.) hours. The nighttime penalty is based upon the assumption that people react to nighttime noise exposures as though they were twice as loud as daytime exposures. Because L dn represents a 24-hour average, it tends to disguise short-term variations in the noise environment. Table 3 lists several examples of the noise levels associated with common noise sources. Appendix A provides a summary of acoustical terms used in this report. Effects of Noise on People The effects of noise on people can be placed in three categories: Subjective effects of annoyance, nuisance, and dissatisfaction Interference with activities such as speech, sleep, and learning Physiological effects such as hearing loss or sudden startling Environmental noise typically produces effects in the first two categories. Workers in industrial plants can experience noise in the last category. There is no completely satisfactory way to measure the subjective effects of noise or the corresponding reactions of annoyance and dissatisfaction. A wide variation in individual thresholds of annoyance exists and different tolerances to noise tend to develop based on an individual s past experiences with noise. Thus, an important way of predicting a human reaction to a new noise environment is the way it compares to the existing environment to which one has adapted: the so-called ambient noise level. In general, the more a new noise exceeds the previously existing ambient noise level, the less acceptable the new noise will be judged by those hearing it. With regard to increases in A-weighted noise level, the following relationships occur: Except in carefully controlled laboratory experiments, a change of 1 dba cannot be perceived; Outside of the laboratory, a 3 dba change is considered a just-perceivable difference; A change in level of at least 5 dba is required before any noticeable change in human response would be expected; and A 10 dba change is subjectively heard as approximately a doubling in loudness, and can cause an adverse response. Stationary point sources of noise including stationary mobile sources such as idling vehicles attenuate (lessen) at a rate of approximately 6 db per doubling of distance from the source, depending on environmental conditions (i.e. atmospheric conditions and either vegetative or manufactured noise barriers, etc.). 9

11 Table 3 Typical Maximum Nose Levels Common Outdoor Activities Noise Level (dba) Common Indoor Activities Rock Band Jet Fly-over at 300 m (1,000 ft) Gas Lawn Mower at 1 m (3 ft) Diesel Truck at 15 m (50 ft), at 80 km/hr (50 mph) Food Blender at 1 m (3 ft) Garbage Disposal at 1 m (3 ft) Noisy Urban Area, Daytime Gas Lawn Mower, 30 m (100 ft) Commercial Area Heavy Traffic at 90 m (300 ft) Vacuum Cleaner at 3 m (10 ft) Normal Speech at 1 m (3 ft) Quiet Urban Daytime Quiet Urban Nighttime Large Business Office Dishwasher in Next Room Theater, Large Conference Room (Background) Quiet Suburban Nighttime Library Quiet Rural Nighttime Bedroom at Night, Concert Hall (Background) Broadcast/Recording Studio Lowest Threshold of Human Hearing Lowest Threshold of Human Hearing Source:Caltrans, Technical Noise Supplement, Traffic Noise Analysis Protocol. October Existing Background Noise Levels - (Interstate 80 and Union Pacific Railroad) The primary noise sources in the project vicinity include Interstate 80 (I-80) traffic and the Union Pacific Railroad (UPRR) mainline, both of which are located to the north across the Truckee 10

12 River. To a lesser extent, aircraft operations from the Truckee-Tahoe Airport also may be considered a potential noise source. j.c. brennan & associates, Inc. conducted two sets of continuous 24-hour noise level measurements on the project site, on January 23-24, The intent of the noise level measurements was to determine the project noise exposure to the both I-80 and the UPRR operations. Sound level meters were programmed to collect hourly noise level data, including the hourly averages, hourly maximum levels and hourly statistical noise levels. In addition, the meters were programmed to identify individual train passbys and the noise levels associated with each train passby at the project site. Figures 1 and 2 show the noise measurement site locations. The results of the noise level measurements are shown in Table 4. Figures 3 and 4 graphically show the results of the noise level measurements. Appendix B contains the results of the continuous 24-hour noise level measurements. Equipment used for all noise level measurements included Larson-Davis-Laboratories (LDL) Model 820 precision integrating sound level meter. The sound level meter was calibrated in the field using an LDL Model CAL200 acoustical calibrator to ensure accuracy. Table 4 Existing Ambient Noise Monitoring Results January 23-24, 2015 Site Location Duration Continuous 24-hour Noise Measurement Sites Average Measured Hourly Noise Levels, (dba) Daytime Nighttime (7:00 am - 10:00 pm) (10:00 pm - 7 am) 24-hr Ldn Leq L50 Lmax Leq L50 Lmax 1 Northeast portion of project site 24 hrs Northwest corner of project site 24 hrs Source - j.c. brennan & associates, Inc Based upon Table 4, portions of the project site are exposed to a combined railroad and I-80 traffic noise level in excess of the normally acceptable exterior noise level standard of 60 db Ldn for residential uses. However, the site is considered a mixed-use development, and based upon the measured noise levels, only a small portion of the site will be exposed to noise levels in excess of 65 db Ldn, which is the noise level standard for residential uses located in a mixeduse development. Figures 1 and 2 show the locations of the 60 db and 65 db Ldn combined noise contours on the project site. Mitigation measures will be provided in this report. 11

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14 Truckee Tahoe Airport Noise Levels To determine future noise levels on the project site due to aircraft operations from the Truckee Tahoe Airport, the Year 2020 noise contours, as contained within the Truckee Tahoe Airport Master Plan were evaluated. Based upon the future 2020 airport noise contours, the project site is located outside of the 55 db CNEL contour. This is considered Normally Acceptable. Figure 5 shows the future 2020 noise contours. Although aircraft operations are audible at the project site, aircraft operations do not contribute to the overall measured ambient noise levels. Overall Interior Noise Levels Modern construction typically provides a 25 db exterior-to-interior noise level reduction with windows closed. Therefore, sensitive receptors exposed to exterior noise of 70 db Ldn, or less, will typically comply with the Town of Truckee 45 db Ldn interior noise level standard. Additional noise reduction measures, such as acoustically rated windows are generally required for exterior noise levels exceeding 70 db CNEL. Based upon the background noise levels, the interior noise levels are expected to comply with the Town of Truckee interior noise level standard. 13

15 Project Site Source: Truckee Tahoe Airport Land Use Compatibility Plan Exhibit 3G Truckee Springs Master Plan Figure 5: Truckee Tahoe Airport Noise Contours and Project Site Location Figure Prepared January 2015

16 Sound Transmission and Impact Insulation Requirements Title 7 of the California Civil Code, states the following regarding noise transmission between attached residential units, Attached structures shall be constructed to comply with interunit noise transmission standards set by the applicable government building codes, ordinances, or regulations in effect at the time of the original construction. If there is no applicable code, ordinance, or regulation, this paragraph does not apply. The California State Building Code acoustical requirements, contained in the California Code of Regulations, Part 2, Title 24 establish the specific acoustical requirements for attached dwellings. The CBC requires that each floor/ceiling and party wall assembly separating dwelling units shall provide airborne and impact sound insulation equal to that required to meet a Sound Transmission Class (STC) rating of 50 and an Impact Insulation Class (IIC) rating of 50, based upon laboratory tests. Field tested assemblies in occupied rooms are required to meet a Noise Isolation Class (NIC) of 45, and a Field Impact Insulation Class (FIIC) of 45. The proposed project potentially includes multi-family residential development and tourist accommodation development. Where common wall and floor/ceiling assemblies occur between dwelling units or between corridors and dwelling units, these assemblies will be required to comply with the STC and IIC requirements of Title 24. Appendix C provides examples of common wall and floor/ceiling assemblies which will meet the STC and IIC requirements of 50: 15

17 Noise Impact Assessment Methodology Associated with Construction During the construction of the project including roads, water and sewer lines and related infrastructure, noise from construction activities would add to the noise environment in the project vicinity. Activities involved in construction would generate maximum noise levels, as indicated in Table 5, ranging from 76 to 90 db at a distance of 50 feet. Construction activities would be temporary in nature and are anticipated to occur during normal daytime working hours. Noise would also be generated during the construction phase by increased truck traffic on area roadways. A substantial project-generated noise source would be truck traffic associated with transport of heavy materials and equipment to and from construction sites. This noise increase would be of short duration, and would likely occur primarily during daytime hours. Table 5: Construction Equipment Noise Type of Equipment Maximum Level, db at 50 feet Backhoe 78 Compactor 83 Compressor (air) 78 Concrete Saw 90 Dozer 82 Dump Truck 76 Excavator 81 Generator 81 Jackhammer 89 Pneumatic Tools 85 Source: Roadway Construction Noise Model User s Guide. Federal Highway Administration. FHWA-HEP January Policy 3.13 provides requirements for construction activities. These requirements will b followed to reduce construction noise level impacts. MITIGATION MEASURES The following mitigation measures are recommended for the combined exterior I-80 traffic / UPRR railroad noise levels: 1. Residential uses should be located outside of the 65 db Ldn noise level contour shown on Figures 1 and 2; 16

18 2. Hotel/Motel or tourist accommodation units may be located anywhere on the project site; 3. If school uses are proposed, they should be located outside of the 65 db Ldn noise level contour shown on Figures 1 and 2. The following design considerations should be included in any tourist accommodation units or multifamily dwelling units: 1. Where common wall and floor/ceiling assemblies occur between dwelling units or between corridors and dwelling units, these assemblies will be required to comply with the STC and IIC requirements of Title 24. Appendix C provides examples of the types of assemblies which will comply with the STC and IIC requirements. Other types of assemblies should have laboratory test results showing compliance. 17

19 Appendix A Acoustical Terminology Acoustics Ambient Noise Attenuation A-Weighting Decibel or db CNEL Frequency Ldn Leq Lmax L(n) Loudness Noise Peak Noise RT 60 The science of sound. The distinctive acoustical characteristics of a given space consisting of all noise sources audible at that location. In many cases, the term ambient is used to describe an existing or pre-project condition such as the setting in an environmental noise study. The reduction of an acoustic signal. A frequency-response adjustment of a sound level meter that conditions the output signal to approximate human response. Fundamental unit of sound, A Bell is defined as the logarithm of the ratio of the sound pressure squared over the reference pressure squared. A Decibel is one-tenth of a Bell. Community Noise Equivalent Level. Defined as the 24-hour average noise level with noise occurring during evening hours (7-10 p.m.) weighted by a factor of three and nighttime hours weighted by a factor of 10 prior to averaging. The measure of the rapidity of alterations of a periodic signal, expressed in cycles per second or hertz. Day/Night Average Sound Level. Similar to CNEL but with no evening weighting. Equivalent or energy-averaged sound level. The highest root-mean-square (RMS) sound level measured over a given period of time. The sound level exceeded a described percentile over a measurement period. For instance, an hourly L50 is the sound level exceeded 50% of the time during the one hour period. A subjective term for the sensation of the magnitude of sound. Unwanted sound. The level corresponding to the highest (not RMS) sound pressure measured over a given period of time. This term is often confused with the AMaximum@ level, which is the highest RMS level. The time it takes reverberant sound to decay by 60 db once the source has been removed. Sabin The unit of sound absorption. One square foot of material absorbing 100% of incident sound has an absorption of 1 sabin. Threshold of Hearing The lowest sound that can be perceived by the human auditory system, generally considered to be 0 db for persons with perfect hearing. Threshold of Pain Approximately 120 db above the threshold of hearing. Impulsive Simple Tone Sound of short duration, usually less than one second, with an abrupt onset and rapid decay. Any sound which can be judged as audible as a single pitch or set of single pitches.

20 Appendix B hr Continuous Noise Monitoring - Site 1 1/23/2015-1/24/2015 Hour Leq Lmax L50 L90 Statistical Summary 12: Daytime (7 a.m p.m.) Nighttime (10 p.m. - 7 a.m.) 13: High Low Average High Low Average 14: Leq (Average) : Lmax (Maximum) : L50 (Median) : L90 (Background) : : Computed Ldn, db : % Daytime Energy 66% 21: % Nighttime Energy 34% 22: : : : : : : : : : : : : :

21 Appendix B hr Continuous Noise Monitoring - Site 2 1/23/2015-1/24/2015 Hour Leq Lmax L50 L90 Statistical Summary 12: Daytime (7 a.m p.m.) Nighttime (10 p.m. - 7 a.m.) 13: High Low Average High Low Average 14: Leq (Average) : Lmax (Maximum) : L50 (Median) : L90 (Background) : : Computed Ldn, db : % Daytime Energy 59% 21: % Nighttime Energy 41% 22: : : : : : : : : : : : : :

22 A Partitions Wood Framed Loadbearing Acoustical Performance Fire Performance Reference Construction Detail Description STC Test Number Rating Test Number ARL Index wt. 7 5/8 SHEETROCK Brand FIRECODE Core 34 USG-30-FT-G&H 1 hour UL Des U305, SA920 A-25 Gypsum Panels or FIBEROCK Brand Panels Based on 16 stud spacing and U " 2x4 wood stud 16 or 24 o.c. screws 6 o.c. joints finished optional veneer plaster 37 USG Based on 24 stud spacing 46 BBN Based on 24 stud spacing and 3 mineral wool batt wt. 7 5/8 SHEETROCK Brand FIRECODE C Core 50 BBN hour UL Des U327 A " Gypsum Panels 2x4 wood stud 16 or 24 o.c. 3 THERMAFIBER SAFB RC-1 channel or equivalent one side joints finished wt. 12 5/8 SHEETROCK Brand FIRECODE Core 52 USG hour UL Des U301 SA920 A-27 6" Gypsum Panels or SHEETROCK Brand Water-Resistant FIRECODE Core Gypsum Panels or FIBEROCK Brand Panels 2x4 wood studs 16 o.c. Based on same assembly (non-fire rated) with RC-1 channel and without mineral wool batt joints finished optional veneer plaster 58 USG Based on same assembly with RC-1 channel and 2 mineral wool batt Chase Walls 1/2 SHEETROCK Brand FIRECODE C Core 57 RAL-TL hour GA-WP-3810 A-28 Gypsum Panels, both outside both walls 3-1/2 glass fiber double layer and inside single layer " " 5/8 SHEETROCK Brand FIRECODE Core 51 RAL-TL hour GA-WP-3820 A-29 Gypsum Panels, or FIBEROCK Brand Panels 2 rows 2x4 wood studs 16 o.c. on separate plates 1 apart joints finished 56 USG Based on 3-1/2 thick insulation in one cavity 58 GA-NGC " 5/8 SHEETROCK Brand FIRECODE C Core 47 RAL-TL hour GA-WP-3910 A-30 Gypsum Panels or FIBEROCK Brand Panels 2x4 wood studs 16 o.c. on 2x6 common 51 GA-NGC-2377 plate joints finished 20 USG Acoustical Assemblies

23 KINETICS NOISE CONTROL TEST REPORT #AT KINETICS NOISE CONTROL PRODUCTS: o SOUNDMATT ACOUSTICAL RATINGS: o STC 58 o IIC 54 TESTING AGENCY & REPORT NUMBER: o NATIONAL RESEARCH COUNCIL OF CANADA o B KINETICS DRAWING NUMBER: AT IRELAN PLACE, DUBLIN OH PHONE: FAX: WEB: ARCHSALES@KINETISNOISE.COM

24 KINETICS NOISE CONTROL TEST REPORT #AT KINETICS NOISE CONTROL PRODUCTS: o SOUNDMATT ACOUSTICAL RATINGS: o STC 63 o IIC 54 TESTING AGENCY & REPORT NUMBER: o NATIONAL RESEARCH COUNCIL OF CANADA o B KINETICS DRAWING NUMBER: AT IRELAN PLACE, DUBLIN OH PHONE: FAX: WEB: ARCHSALES@KINETISNOISE.COM