Appendix I
Noise Report
NNoisee Technicall Reportt
forr thee
Pacificc Projectt
Prepared for:
Cityy off Sann Marcoss
1 Civic Center Drive
San Marcos, California 92069
Prepared by:
605 Third Street
Encinitas, California 92024
Contacts: Connor Burke, INCE; Mark Storm, INCE Bd. Cert.
NOVEMBER 2022
Printed on 30% post-consumer recycled material.
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Table of Contents
SSECTIONN PAGEE NO..
ACRONYMSS ANDD ABBREVIATIONSS .............................................................................................................................. III 1 INTRODUCTIONN ANDD BACKGROUNDD .............................................................................................................. 1 2 REGULATORYY SETTINGG .................................................................................................................................. 7 3 EXISTINGG CONDITIONSS ................................................................................................................................. 11 4 THRESHOLDSS OFF SIGNIFICANCEE ................................................................................................................. 15 5 IMPACTT DISCUSSIONN ................................................................................................................................... 18 6 MITIGATIONN MEASURESS ............................................................................................................................... 28 7 SUMMARYY OFF FINDINGSS .............................................................................................................................. 30 8 REFERENCESS CITEDD ..................................................................................................................................... 32
APPENDICES
A Baseline Noise Measurement Field Data
B Construction Noise Modeling Input and Output
C Traffic Noise Modeling Input and Output
D Transmission Loss Predictions
E Residential HVAC Noise Prediction
FIGURESS
1 Project Location .............................................................................................................. .....................................3 2 Conceptual Site Plan........................................................................................................... .................................5 3 Noise Measurement and Modeled Receptor Locations .............................................................................. ... 13
TABLESS
1 Exterior Noise Standards by Zone.............................................................................................. .........................8 2 Permitted Increase in Noise Levels ............................................................................................ ........................9 3 Permitted Increase in Interior Noise Levels ................................................................................... ....................9 4 Measured Baseline Outdoor Ambient Noise Levels................................................................................ ........ 11 5 Typical Construction Equipment Maximum Noise Levels........................................................................... .... 18 6 Estimated Distances between Construction Activities and the Nearest Noise- Sensitive Receptors.......... 19 7 Predicted Construction Noise Levels per Activity Phase ........................................................................ ........ 20 8 Roadway Traffic Noise Modeling Results ........................................................................................ ................ 21 9 Predicted Net Sound Transmission Class of Occupied Room façade ........................................................... 23
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Acronyms and Abbreviations
AAcronym/Abbreviation DDefinition
a.k.a. Also known as
APN Assessor parcel number
Caltrans California Department of Transportation
CEQA California Environmental Quality Act
City City of San Marco
CNEL Community Noise Equivalent Level
dB decibel
dBA A-weighted decibel
DOT Department of Transportation
Pacific General Plan Amendment/Rezone Project proposed project FHWA Federal Highway Administration
FTA Federal Transit Administration
ips inches per second
Ldn day–night average noise level
Leq equivalent noise level
Lmax maximum sound level
Lmin minimum sound level
OPR Office of Planning and Research
PPV peak particle velocity
RCNM Roadway Construction Noise Model
SLM Sound level meter
SPL Sound pressure level
ST Short-term
STC Sound transmission class
TL Transmission loss
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1 Introduction and Background
This technical noise report evaluates the potential noise impacts during construction and operation of the Pacific General Plan Amendment/Rezone Project (project). This assessment utilizes City of San Marcos (City) significance thresholds that are comparable to those relating to noise and vibration assessment in Appendix G of the California Environmental Quality Act Guidelines (14 CCR 15000 et seq.).
PProjectt Descriptionn
The approximately 33.2-acre project site is located in the western portion of the City, at the northwest corner of Las Posas Road and Linda Vista Drive. The project location and project site boundary are shown in Figure 1 (Project Location) and Figure 2 (Conceptual Site Plan).
The Pacific Project (project) proposes a General Plan Amendment and Rezone (GPA/Rezone) to change the land use from Industrial (I) to Specific Plan Area (SPA). The project would allow for the development of 449 residential units, including a mix of five-story podium apartments, three-story rowhomes, three-story villas, and four-story affordable flats on approximately 15.09 acres within the 33.2-acre project site. The project would consist of 101 rowhomes, 108 villas, 172 apartments, and 68 affordable flats. 68 of the 449 total units (15 percent of the total) would be designated as deed-restricted affordable units.
The project would also include a total of 927 parking spaces and an 134,985 square feet of common open space area. The proposed project also includes landscaping, bio-retention areas and circulation improvements. The remaining 17.94 acres of the 33.2-acre project site would be preserved and restored open space and habitat area.
Noisee Characteristicss
Sound is mechanical energy transmitted by pressure waves in a compressible medium, such as air. Noise is defined as sound that is loud, unpleasant, unexpected, or undesired. The sound pressure level (SPL) has become the most common descriptor used to characterize the loudness of an ambient sound level. The unit of measurement of sound pressure is a decibel (dB). Under controlled conditions in an acoustics laboratory, the trained, healthy human ear is able to discern changes in sound levels of 1 dB when exposed to steady, single-frequency signals in the mid- frequency range. Outside such controlled conditions, the trained ear can detect changes of 2 dB in normal environmental noise. It is widely accepted that the average healthy ear, however, can barely perceive noise level changes of 3 dB. A change of 5 dB is readily perceptible, and a change of 10 dB is perceived as twice or half as loud (Caltrans 2013). A doubling of sound energy results in a 3 dB increase in sound, which means that a doubling of sound energy (e.g., doubling the number of daily trip s along a given road) would result in a barely perceptible change in sound level.
Sound may be described in terms of level or amplitude (measured in dB), frequency or pitch (measured in hertz or cycles per second), and duration (measured in seconds or minutes). Because the human ear is not equally sensitive to sound at all frequencies, a special frequency-dependent rating scale is used to relate noise to human sensitivity.
The A-weighted decibel (dBA) scale performs this compen sation by discriminating against low and very high frequencies in a manner approximating the sensitivity of the human ear.
Several descriptors of noise (a.k.a., noise metrics) exist to help predict average community reactions to the adverse effects of environmental noise, including traffic-generated noise. These descriptors include the equivalent noise
TECHNICAL NOISE REPORT FOR THE PACIFIC GENERAL PLAN AMENDMENT/REZONE PROJECT 13170
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level over a given period (L eq), the day–night average noise level (L dn), and the community noise equivalent level (CNEL). Each of these descriptors uses units of dBA.
Leq is a decibel quantity that represents the constant or energy-averaged value equivalent to the amount of variable sound energy received by a receptor during a time interval. For example, a 1-hour L eq measurement of 60 dBA would represent the average amount of energy contained in all the noise that occurred in that hour. L eq is an effective noise descriptor because of its ability to assess the total time-varying effects of noise on sensitive receptors, which can then be compared to an established L eq standard or threshold of the same duration. Another
descriptor is maximum sound level (L max), which is the greatest sound level measured during a designated time interval or event. The minimum sound level (Lmin) is often called the floor of a measurement period.
Unlike the Leq, Lmax, and Lmin metrics, Ldn and CNEL descriptors always represent 24-hour periods and differ from a 24-hour Leq value because they apply a time-weighted factor designed to emphasize noise events that occur during the non-daytime hours (when speech and sleep disturbance is of more concern). Time weighted refers to the fact that Ldn and CNEL penalize noise that occurs during certain sensitive periods. In the case of CNEL, noise occurring during the daytime (7:00 a.m. to 7:00 p.m.) receives no penalty. Noise during the evening (7:00 p.m. to 10:00 p.m.) is penalized by adding 5 dB to the actual levels, and n ighttime (10:00 p.m. to 7:00 a.m.) noise is penalized by adding 10 dB to the actual levels. L dn differs from CNEL in that the daytime period is longer (defined instead as 7:00 a.m. to 10:00 p.m.), thus eliminating the dB adjustment for the evening period. L dn and CNEL are the predominant criteria used to measure roadway noise affe cting residential receptors. These two metrics generally differ from one another by no more than 0.5–1 dB, and are often considered or actually defined as being essentially equivalent by many jurisdictions.
V
Vibrationn Fundamentalss
Vibration is oscillatory movement of ma ss (typically a solid) over time. It is described in terms of frequency and amplitude and, unlike sound, can be expressed as displacement, velocity, or acceleration. For environmental studies, vibration is often studied as a velocity that, akin to the discussion of sound pressure levels, can also be expressed in dB as a way to cast a large range of quantiti es into a more convenient scale and with respect to a reference quantity. Vibration impacts to buildings are generally discussed in terms of inches per second (ips) peak particle velocity (PPV), which will be used herein to discuss vibration levels for ease of reading and comparison with relevant standards. Vibration can also be annoying and thereby impact occupants of structures, and vibration of sufficient amplitude can disrupt sensitive equipment and processes (Caltrans 2020), such as those involving the use of electron microscopes and lithography equipment. Common sources of vibration within communities include construction activities and railroads. Groundborne vibration generated by construction projects is usually highest during pile driving, rock blasting, soil compacting, jack hammering, and demolition-related activities where sudden releases of subterranean energy or powerful impacts of tools on hard materials occur. Depending on their distances to a sensitive receptor, operation of large bulldozers, graders, loaded dump trucks, or other heavy construction equipment and vehicles on a construction site also have the potential to cause high vibration amplitudes. 78 RICHMARAVE
DESCANSO AVE
ALTURA
DR
CRAVEN
RD
BUSINESS PARKDR
LAKERIDGEDR
ACACIADR
POINSETTIA AVE
WHITESANDSDR
LA SOMBRA DR
W SAN MARCOS BLVD
ECHO LN
W
MISSION
RD
SANT ABARBARADR
SMILAX RD
LAFLORA
DR
SANMARINO
DR
OLEANDER AVE
SSANTAFEAVE
SYCAMOREAVE
NLASPOSASRD
VIA PORTOLA
KNOLL RD
GREEN
OAKRD
PALOMARCOSAVE
TESOROAVE
PLUMOSAAVE
SANDYLN
VIA LAVENTA
MCMAHR RD
DISCOVERY ST
NAVAJO ST
MIMOSAAVE
GLENDALEAVE
RUSH DR
SRANCHOSANTAFERD
01ST ST
QUAIL
HILLDR
AVENIDAAGUILA
GRANDON AVE
SPECIALTYDR
PAWNEE ST
SANPABLODR
S PACIFIC ST
PRIVATERD
LAS FLORES DR
W
BORDEN
RD
POPPY
RD
VIEWPOINTDR
SHENAN
DOAHAVE
LA TIERRA DR
LAN
OCHEDR
CAPALINA RD
CAMINODELSOL
BINGHAM DR
N PACIFIC ST
APPLE
WILDEDR
HILLHAVENDR
GRAND AVE
HOLLENCREST RD
KIRKW
ALLDR
VIOLETAVE
BLUESAGE DR
LA MIRADA DR
AUTUMN DR
CORT
ELOREN
HONEYSUCKLEDR
PRIVATERD
PARKW
O
ODAVE
CASITALN
AVENIDAAZUL
WINDRIDGECIR
PROGRESSST
VIA VERA CRUZ
ARBORVIEW
DR
CREEK ST
LA MIRADA DR
LINDA VISTA DR09TH ST
ALLEY
BIRCHST
COMMERCE WAYG
RANDAVE
CADESWAY
HAPPY HILL LN
HELMSDALERD
JOYCT
LOSVALLECITOSBLVD
DOGWOODWAY
SCOTTST
LA COLUSA DR
COMETCIR
CURRY COM BDR
S BENT AVE
WESTLAKEDR
DECISION
ST
ARMORLITE DR
ASHST
TOYONTER
TILLEY LN
PRIVATERD
TI G ER WAY
VIRGINIA PL
LACASITADR
JUNIPER LN
ACTIVITYDR
SEQUOIAS
T
PIONEERAVE
LOMAALTADR
DELEONERD
FIRELN
PRIVATE
RD
PRIVATE
RD
Project Location
Pacific GPA/Rezone EIR
SOURCE: SANGIS 2020
Date: 3/25/2021 - Last saved by: agreis - Path: Z:\Projects\j1317001\MAPDOC\DOCUMENT\Noise\Figure1-ProjectLocation.mxd 02 , 0 0 0 1,000
Feet
Project Boundary
FIGURE 1
Chula Vista
Solana Beach
Encinitas
San Diego
Carlsbad
Oceanside
La Mesa
Santee
Poway
San Marcos
Escondido
Vista
Imperial
Beach
Del Mar
Coronado
Riverside
County
Mexico
905
209
75 52
94 125
241
9854
73 274
195
56 86
111
67 74
74 76 79
78 805
215
15 5
8 Project Site
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RECREC
24.0 24.0
24.0 24.0
24.0 24.0
24.0 24.0
19.0 19.9
19.2 24.0
24.0 24.0
24.0 24.0
24.0 24.0
16.0 7.210.0
8.8 10.2
16.2 16.0 14.0
24.0 24.0
24.0 24.0
24.0 24.0
24.0 10.0
10.2 15.1
17.9 20.1
47.8 22.0
17.4 24.0
24.0 24.0
8.2 16.3
24.0 24.0
24.0 24.0
24.0 24.0
AC UNITS TYP.
USPS PARKING LOCATION
AVAILBLE FROM 9AM TO 5PM
USPS PARKING
LOCATION AVAILABLE
FROM 9AM TO 5PM
TRASH PICK UP LOCATION
LOADING/TRASH
PICK UP
LOCATION
TRASH PICK UP
LOCATION
LOADING/TRASH
PICK UP
LOCATION
RECLSG
MIN. PRIVATE
GROUND FLOOR
OPEN SPACE
250 SF TYPICAL
24.0 24.0
24.0 APARTMENTS - LOT 3
86 1B/1BA 740 SF
62 2BD/2.5BA 1,256 SF
24 3BD/2.5BA 1,579 SF
172 4.308 AC = 39.93 DU/AC
PARKING SUMMARY PER CA 65915
1BD 86 X 1.0 = 86 SPACES
2&3BD 86 X 1.5 = 129 SPACES
TOTAL REQUIRED 215 SPACES
PROVIDED COVERED (1:1) 172 GARAGES
PROVIDED OPEN 187 SPACES
TOTAL PROVIDED 359 SPACES
FUTURE EV REQUIRED 36 SPACES (10%X359)
PRIVATE OPEN SPACE REQUIRED PROVIDED
172 X 50 SF 8,600 SF 11,180 SF
COMMON OPEN SPACE REQUIRED PROVIDED
GROUND FLOOR SF X 30% 15,606 SF
TOT LOT (1:25 DU) 6X400 SF 2,400 SF
PLAYGROUND 800 SF
TOTAL 18,806 SF 47,870 SF
AFFORDABLE - LOT 4
UNIT MIX
8 STUDIO/1BA 512 SF
42 1BD/1BA 625 SF
18 2BD/2BA 924 SF
68 1.781 AC = 38.18 DU/AC
PARKING PROVIDED PER CA 65915
50 X 1.0 SP/DU = 50 SPACES
18 X 1.5 SP/DU = 27 SPACES
TOTAL REQUIRED 77 SPACES
TOTAL PROVIDED 80 SPACES
FUTURE EV INCLUDED 8 SPACES (10%X80)
PRIVATE OPEN SPACE REQUIRED PROVIDED
68 X 50 SF 3,400 SF 3,111 SF
COMMON OPEN SPACE REQUIRED PROVIDED
GROUND FLOOR SF X 30% 2,828 SF
TOT LOT (1:25 DU) 3X400 SF 1,200 SF
TOTAL 4,028 SF 16,340 SF
VILLAS - LOT 2
60 2BD/2BA 1,272 SF
24 3BD/2.5BA 1,486 SF
24 3BD/3BA 1,832 SF
108 4.583 AC = 23.57 DU/AC
PARKING SUMMARY PER CA 65915
2&3 BD 108 X 1.5 = 162 SPACES
TOTAL REQUIRED 162 SPACES
TOTAL PROVIDED 254 SPACES* (38 OPEN/216 GARAGES)
FUTURE EV REQUIRED 25 SPACES (10%X254)
*NOTE: RECIPROCAL ACCESS & PARKING AGREEMENT BETWEEN LOT 1 & 2
PRIVATE OPEN SPACE REQUIRED PROVIDED
108 X 50 SF 5,400 SF 6,180 SF
COMMON OPEN SPACE REQUIRED PROVIDED
GROUND FLOOR SF X 30% 16,204 SF
TOT LOT (1:25 DU) 5X400 SF 2,000 SF
PLAYGROUND 800 SF
TOTAL 19,004 SF 29,899 SF
RESIDENCES 449 HOMES
GROSS SITE AREA 33.229 ACRES (15.091 ACRES NET)
GROSS DENSITY 13.51 DU/AC (29.75 DU/AC NET)
ROWHOMES - LOT 1
23 2BD/2BA 1,200 SF
23 3BD/3BA 1,310 SF
28 3BD/3.5BA 1,736 SF
27 4BD/3.5BA 1,890 SF
101 4.419 AC = 22.86 DU/AC
PARKING SUMMARY PER CA 65915
2&3 BD 74 X 1.5 = 111 SPACES
4 BD 27 X 2.5 = 68 SPACES
TOTAL REQUIRED 179 SPACES
TOTAL PROVIDED 234 SPACES* (32 OPEN/202 GARAGES)
FUTURE EV REQUIRED 23 SPACES (10%X234)
*NOTE: RECIPROCAL ACCESS & PARKING AGREEMENT BETWEEN LOT 1 & 2
PRIVATE OPEN SPACE REQUIRED PROVIDED
101 X 50 SF 5,050 SF 6,959 SF
COMMON OPEN SPACE REQUIRED PROVIDED
GROUND FLOOR SF X 30% 12,945 SF
TOT LOT (1:25 DU) 4X400 SF 1,600 SF
PLAYGROUND 800 SF
TOTAL 15,345 SF 40,876 SF
Conceptual Site Plan
Pacific Project EIR
FIGURE 2SOURCE: Summa Architecture, 2022
Z:\Projects\j1317001\MAPDOC\DOCUMENT\EIR
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2 Regulatory Setting
RRegulatoryy Settingg
Federall
Federall Transitt Administrationn
In its Transit Noise and Vibration Impact Assessment guid ance manual, the Federal Transit Administration (FTA) recommends a daytime construction noise level threshold of 80 dBA L eq over an 8-hour period (FTA 2018) when detailed construction noise assessments are performed to evaluate potential impacts to community residences surrounding a project. Although this FTA guidance is not a regulation, it can serve as a quantified standard in the absence of such limits at the state and local jurisdictional levels.
Statee
Californiaa Codee off Regulations,, Titlee 244
Title 24 of the California Code of Regulations sets standards that new development in California must meet.
According to Title 24, interior noise levels are not to exceed 45 dBA CNEL in any habitable room (International Construction Code 2019).
Californiaa Departmentt off Healthh Servicess Guideliness The California Department of Health Services has developed guidelines of community noise acceptability for use by local agencies (OPR 2003). Selected relevant levels are listed here:
x Below 60 dBA CNEL: normally acceptable for low-density residential use x 50 to 70 dBA: conditionally acceptable for low-density residential use x Below 65 dBA CNEL: normally acceptable for high-density residential use and transient lodging x 60 to 70 dBA CNEL: conditionally acceptable for hi gh-density residential, transient lodging, churches, educational, and medical facilities
Californiaa Departmentt off Transportation
In its Transportation and Construction Vibration Guidance Manual (Caltrans 2020), the California Department of Transportation (Caltrans) recommends 0.5 inches per second (ips) peak particle velocity (PPV) as a threshold for the avoidance of structural damage risk to typical newer residential buildings exposed to continuous or frequent intermittent sources of groundborne vibration. For transient vibration events, such as blasting, the damage risk threshold would be
1.0 ips PPV (Caltrans 2020) at the same type of newer residential structures. For older structures, these guidance thresholds would be more stringent: 0.3 ips PPV for continuous/intermittent vibration sources, and 0.5 ips PPV for transient vibration events. With respect to human annoyance, Caltrans guidance indicates that building occupants exposed to groundborne vibration of 0.10 ips PPV from continuous or frequently intermittent sources may find it “strongly perceptible” (Caltrans 2020) and on such basis would thus be considered a significant groundborne vibration impact for purposes of this assessment. Although these Caltrans guidance thresholds are not regulations, they can serve as quantified standards in the absence of such limits at the local jurisdictional level.
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LLocall
The following are summarized or reproduced portions of relevant City regulations and General Plan policies.
Sann Marcoss
Cityy off Sann Marcoss Municipall Codee
The City of San Marcos Municipal Code Chapter 10.24: Noise (San Marcos 2017) addresses construction noise.
Erection and demolition of buildings is exempt between 7:00 a.m. and 6:00 p.m. Monday through Friday and on Saturdays from 8:00 a.m. to 5:00 p.m. The Municipal Code s does not set noise limits on construction activities.
Commonly, the City has utilized the County of San Diego’s Noise Ordinance noise limit of 75 dBA (8-hour average) for construction activities.
Chapter 20.300 (Site Planning and General Development St andards) of the City’s Municipal Code includes noise regulations in the form of noise standards by zone (Section 20.300.070, Performance Standards). It should be noted that Municipal Code noise standards typically pertain to stationary (i.e., non-transportation-related) noise sources. The relevant portions of these noise standards are provided below:
1. Noise shall be measured with a sound-level meter that meets the standards of the American National Standards Institute (ANSI) (Section S1.4-1979, Type 1 or Type 2). Noise levels shall be measured in decibels at the property line of the receptor property, and at least five (5) feet above the ground and ten (10) feet from the nearest structure or wall. The unit of measure shall be designated as an A-weighted decibel (dBA) Leq standard. A calibration check shall be made of the instrument at the time any noise measurement is made (Ord. No. 2017-1446, 7-25-2017)
2. No person shall create or allow the creation of exterior noise that causes the noise level to exceed the noise standards established by Table 20.300-4 [shown in this report as Table 1]. Increases in allowable noise levels listed in Table 20.300-4 may be permitted in accordance with th e standards outlined in Table 20.300-5 [shown in this report as Table 2].
Tablee 11.. EExteriorr Noisee Standardss byy Zonee
Zone
Allowablee Noisee Level
(dBAA Leq)) Measuredd
fromm thee Propertyy Line
Single--Familyy Residentiall (A,, R--1,, R--2) 1,, 22
7 a.m. to 10 p.m. (daytime) 60
10 p.m. to 7 a.m. (overnight) 50
Multifamilyy Residentiall (R--3)) 1,, 2
7 a.m. to 10 p.m. (daytime) 65
10 p.m. to 7 a.m. (overnight) 55
Commerciall (C,, O--P,, SR) 3
7 a.m. to 10 p.m. (daytime) 65
10 p.m. to 7 a.m. (overnight) 55
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TTablee 11.. EExteriorr Noisee Standardss byy Zonee
ZZone
AAllowablee Noisee Level
((dBAA Leeq)) Measuredd
fromm thee Propertyy Line
Industrial
7 a.m. to 10 p.m. (daytime) 65
10 p.m. to 7 a.m. (overnight) 60
Source: City of San Marcos 2017 (Table 20.300-4)
Notes::
1 For single-family detached dwelling units, the "exterior noise level" is defined as the noise level measured at an outdoor living area which adjoins and is on the same lot as the dwelling, and which contains at least the following minimum net lot area: (i) for l ots less than 4,000 square feet in area, the exterior area shall include 400 square feet, (ii) for lots between 4,000 square feet to 10 acres in area, the exterior area shall include 10 percent of th e lot area; (iii) for lots over 10 acres in area, the exterior a rea shall include 1 acre.
2 For all other residential land uses, "exterior noise level" is de fined as noise measured at exterior areas which are provided fo r private or group usable open space purposes. "Private Usable Open Space" is defined as usable open space intended for use of occupants of one dwelling unit, normally including yards, decks, and balconies. When the noise limit for Private Usable Open Space cannot be met, then a Group Usable Open Space that meet s the exterior noise level standa rd shall be provided. "Group Usable Open Space" is defined as usable open space intended for common use by occupants of a development, either privately owned and maintained or dedicated to a pu blic agency, normally including swimming pools, recreation co urts, patios, open landscaped areas, and greenbelts with pedestrian walkways and equestrian and bicycle trails, but not including off-street parking and loading areas or driveways.
3 For non-residential noise sensitive land uses, exterior noise leve l is defined as noise measured at the exterior area provided for public use.
3. No person shall create nor allow the creation of noise that causes the interior noise level when measured within a dwelling unit to exceed forty-five (45) dBA at any time, except as permitted by Table 20.300-6 [shown in this report as Table 3].
4. Use of compressors or other equipment, including vents, ducts, and conduits, but excluding window or wall-mounted air conditioners, that are located outside of the exterior walls of any building, shall be enclosed within a permanent, non-combustible, view-obscuring enclosure to ensure that the equipment does not emit noise in excess of the ANSI standards.
Table 2.. Permittedd Increasee inn Noisee Levels
Permitted Increasee (dBA) Durationn (cumulative minutess perr hour) 5 15
10 5
15 1
20 Less than 1 minute
Source: City of San Marcos 2017 (Table 20.300-5)
Tablee 33.. PPermittedd Increasee inn Interiorr Noisee Levelss Permitted Increasee (dBA) Durationn (cumulative minutess perr hour) 5 1
10 Less than 1 minute
Source: City of San Marcos 2017 (Table 20.300-6)
TECHNICAL NOISE REPORT FOR THE PACIFIC GENERAL PLAN AMENDMENT/REZONE PROJECT 13170
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CCityy off Sann Marcoss Generall Plann
To control transportation related noise sources such as arterial roads, freeways, airports, and railroads, the City of San Marcos has established guidelines for acce ptable community noise levels in the Noise Element of the General Plan (City of San Marcos 2012). For noise-sensitive rural and single-family residential uses, schools, libraries, parks, and recreational areas the City Noise Element requires an exterior noise levels of less than 60 dBA CNEL for outdoor usable area. For multi-family developments the standard is 65 dBA CNEL and a standard of 70 dBA CNEL is typically applied to commercial uses. The City has also established an interior noise limit of 45 dBA CNEL for all residential uses.
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3 Existing Conditions
Sound pressure level (SPL) measurements were conducted near the proposed project site on March 10, 2021, to quantify and characterize the existing outdoor ambient sound levels. Table 4 provides the location, date, and time period at which these baseline noise level measurements were performed by an attending Dudek field investigator using a Rion-branded Model NL-52 sound level meter (SLM) equipped with a 0.5-inch, pre-polarized condenser microphone with pre-amplifier. The SLM meets the current American National Standards Institute standard for a Type 1 (Precision Grade) sound level meter. The accuracy of the SLM was verified using a field calibrator before and after the measurements, and the measurements were conducted with the microphone positioned approximately five feet above the ground.
Four (4) short-term (ST) noise level measurement locations (ST1 – ST4) intended to be representative of the outdoor ambient sound environment for existing or potential future noise-sensitive receivers in the vicinity of the proposed project were selected near the proposed project site. These locations are depicted as receivers ST1 – ST4 on Figure 3, Noise Measurement and Modeled Receptor Locations. The measured L eq and Lmax noise levels at these surveyed
locations are provided in Table 4. The primary noise sources at the sites identified in Table 4 consisted of traffic along adjacent roadways, the sounds of leaves rustling , and birdsong. As shown in Table 4, the measured SPL ranged from 66.9 dBA Leq at ST1 to 60.5 dBA Leq at ST3. Beyond the summarized information presented in Table 4, detailed noise measurement data is included in Appendix A, Baseline Noise Measurement Field Data.
TTablee 44.. Measuredd Baselinee Outdoorr Ambientt Noisee Levels SSite LLocation/Address DDate/Time LLeeq Lmax
ST1 Perpendicular to project site, East of S Las
Posas Rd.
2021-03-10, 11:50
AM to 12:00 PM 66.9 75.9
ST2 Perpendicular to project site, North of La
Mirada Dr.
2021-03-10, 12:10
PM to 12:20 PM 61.0 71.8
ST3 Perpendicular to project site, West of S
Pacific St.
2021-03-10, 12:30
PM to 12:40 PM 60.5 71.1
ST4 Perpendicular to project site, South of Linda
Vista Dr,
2021-03-10, 12:45
PM to 12:55 PM 64.7 74.9
Source: Dudek 2022 (Appendix A)
Notes: Leq = equivalent continuous sound level (time-averaged sound level); L max = maximum sound level during the measurement interval; dBA = A-weighted decibels; ST = short-term noise measurement locations.
Generally, the measured samples of daytime Leq agree with expectations: ST1 is near 67 dBA Leq due largely to its proximity to Las Posas Road, a major roadway and thus a fairly continuous acoustical contributor to the measured outdoor ambient sound environment. Surrounding land uses include industrial to the north and west, light industrial to the south, and commercial to the east. Although the nearest single-family home is located approximately 1,420 feet away, due to the City of San Marcos adopting the County of San Diego’s Noise Ordinance, a distance of 150 feet to nearest occupied building was used for noise analysis and modeling.
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LA MIRADA DR
S LAS POSAS RD
S PACIFIC ST
ALPINEPL
RYAN DR
LINDA VISTA DR
PRIVATE RD
TA ULB EES LN
William Bradley
Park
ST2
ST1
ST3
ST4
Noise Measurement Locations
Pacific GPA/Rezone EIR
SOURCE: SANGIS 2020
Date: 3/25/2021 - Last saved by: agreis - Path: Z:\Projects\j1317001\MAPDOC\DOCUMENT\Noise\Figure3-NoiseMeasurementLocations.mxd 0 300 150
Feet
Project Boundary
Noise Measurement Locations
Short-term Measurement Location
FIGURE 3
Grand Plaza
Shopping Mall
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4 Thresholds of Significance
The following significance criteria are based on Appendix G of the California Environmental Quality Act Guidelines (14 CCR 15000 et seq.) and will be used to determine the significance of potential noise impacts. Impacts to noise would be significant if the proposed project would result in the following:
a. Generation of a substantial temporary or permanent increase in ambient noise levels in the vicinity of the project in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies;
b. Generation of excessive groundborne vibration or groundborne noise levels; and c. Expose people residing or working in the project area to excessive noise levels (for a project located within the vicinity of a private airstrip or an airport land use plan, or where such a plan has not been adopted, within 2 miles of a public airport or public use airport).
In light of these above significance criteria, this analysis uses the following standards to evaluate potential noise and vibration impacts.
x Construction noise – The City of San Marcos Municipal Code Chapter 10.24: Noise (San Marcos 2017) addresses construction noise. Erection and demolition of buildings is exempt between 7:00 a.m. and 6:00 p.m. Monday through Friday and on Saturdays from 8:00 a.m. to 5:00 p.m. The Municipal Code does not set noise limits on construction activities. Through adherence to the limitation of allowable construction times provided in the City of San Marcos Municipal Code, the construction-related noise levels would not exceed local standards. However, were the City to consider adoption of the County of San Diego’s Noise Ordinance noise limit of 75 dBA (8-hour L
eq) for construction activities, then for information purposes this assessment will compare predicted construction noise against the County’s 75 dBA 8-hour Leq threshold. The analysis assumes that the 8-hour period over which the County’s 75 dBA Leq could apply would be within the aforementioned exempt hours as allowed by the City of San Marcos. x Off-site project-attributed transportation noise – For purposes for this analysis, a direct roadway noise impact would be considered significant if increases in roadway traffic noise levels attributed to future residential development as a result of the proposed project were greater than 3 dBA CNEL at an existing noise-sensitive land use.
x Off-site project-attributed stationary noise – For purposes for this analysis, a noise impact would be considered significant if noise from typical operation of heating, ventilation, and air conditioning and other electro-mechanical systems associated with future residential development as a result of the proposed project exceeded 65 dBA hourly Leq for multi-family homes and 60 dBA hourly L eq for single-family homes at the property line from 7:00 a.m. to 9:59 p.m., and 55 dBA hourly Leq for multi-family homes and 50 dBA hourly Leq for single-family homes from 10:00 p.m. to 6:59 a.m. x Construction vibration – Guidance from Caltrans indicates that a vibration velocity level of 0.2 ips PPV received at a structure would be considered annoying by occupants within (Caltrans 2013b). As for the receiving structure itself, aforementioned Caltrans guidance from Section 2 recommends that a vibration level of 0.3 ips PPV would represent the threshold for building damage risk.
For purposes of disclosure, since current CEQA noise criter ia listed above do not consider it, this analysis also evaluates compatibility of on-site traffic noise exposure levels with the City of San Marcos exterior and interior noise
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standards of 65 dBA CNEL for multi-family homes, 60 dBA CNEL for single-family homes and 45 dBA CNEL, respectively.
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5 Impact Discussion
aa)) Wouldd thee projectt resultt inn generationn off aa substantiall temporaryy orr permanentt increasee inn ambientt noisee levelss inn thee vicinityy off thee projectt inn excesss off standardss establishedd inn thee locall generall plann orr noisee ordinance,, orr applicablee standardd off otherr agencies?? Short-Termm Constructionn
Construction noise and vibration are temporary phenomena. Construction noise and vibration levels vary from hour to hour and day to day, depending on the equipment in use, the operations performed, and the distance between the source and receptor.
Construction assumptions, including timing, phasing, and equipment type and quantity, as well as worker and vendor truck trips, were based on information provided by the applicant. Default values provided by the California Emissions Estimator Model (CalEEMod) were used since detailed project site-specific information is not currently available. Equipment that could be in use during construction would include, in part, graders, backhoes, concrete saws, excavators, dump trucks, loaders, cranes, manlifts, cement mixers, pavers, rollers, welders, and air compressors. The typical maximum noise levels for various pieces of construction equipment at a distance of 50 feet are presented in Table 5. Usually, construction equipment operates in alternating cycles of full power and low power, producing average noise levels over time that are less than the listed maximum noise level. The average sound level of construction activity also depends on the amount of time that the equipment operates and the intensity of construction activities during that time.
Tablee 55.. TTypicall Constructionn Equipmentt Maximumm Noisee Levels Equipmentt Type Typicall Equipmentt (LLmax,, ddBAA att 500 Feet)) Air compressor 78
Backhoe 78
Concrete pump truck 81
Grader 85
Crane 81
Roller 80
Manlift 75
Generator 72
Front End Loader 79
Paver 77
Scraper 84
Welder 74
Source:: DOT 2006.
Note: Lmax = maximum sound level; dBA = A-weighted decibels.
Aggregate noise emission from assumed construction activities, broken down by sequential phase, was predicted at two distances to the nearest apparent existing noise-sensitive receptor: 1) from the nearest position of the construction site boundary and 2) from the geographic center of the construction site, which serves as the time-averaged location or geographic acoustical centroid of active construction equipment
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for the phase under study. The intent of the former distance is to help evaluate anticipated construction noise from a limited quantity of equipment or vehicle activity expected to be at the boundary for some period of time, which would be most appropriate for phases such as site preparation, grading, and paving.
The latter distance is used in a manner similar to the general assessment technique as described in Federal Transit Administration (FTA) guidance for construction noise assessment (FTA 2018), when the location of individual equipment for a given construction phase is uncertain over some extent of (or the entirety of) the construction site area. Because of this uncertainty, all the equipment for a construction phase is assumed to operate—on average—from the acoustical centroid. Table 6 summarizes these two distances to the apparent closest noise-sensitive receptor for each of the five sequential construction phases. Adoption of the County’s noise ordinance threshold would mean that an “occupied property”, which could be a residence or any occupied building, would be the nearest noise-sensitive receptor in this context. At the site boundary, this analysis assumes that the equipment may be operating up to all of eight (8) hours per day (i.e., comparable to a typical on-site work shift).
TTablee 66.. Estimatedd Distancess betweenn Constructionn Activitiess andd thee Nearest NNoise-- SSennsitivee Receptorss
CConstructionn Phasee (andd Equipmentt Typess Involved) DDistancee fromm
NNearestt Noise--
Sensitivee Receptorr too
Constructionn Sitee
Boundaryy (Feet)
Distancee fromm Nearestt
Noise-Sensitivee Receptorr
too Acousticall Centroidd off
Sitee (Feet)
Site Preparation (Backhoe, Dozer) 150 520
Grading (Excavator, Grader, Dozer, Scraper, Backhoe) 150 520 Building Construction (Crane, Forklift, Backhoe, Welder, Generator)
150 520
Architectural Finishes (Air Compressor) 150 520
Paving (Roller, Paver, Mixer Truck) 150 520
A Microsoft Excel–based noise prediction model emulating and using reference data from the Federal Highway Administration Roadway Construction Noise Model (RCNM) (FHWA 2008) was used to estimate construction noise levels at the nearest occupied noise-sensitive land use. (Although the RCNM was funded and promulgated by the Federal Highway Administration, it is often used for non-roadway projects, because the same types of construction equipment used for roadway projects are often used for other types of construction.) Input variables for the predictive modeling consist of the equipment type and number of each (e.g., two graders, a loader, a tractor), the duty cycle for each piece of equipment (e.g., percentage of time within a specific time period, such as an hour, when the equipment is expected to operate at full power or capacity and thus make noise at a level comparable to what is presented in Table 5, Typical Construction Equipment Maximum Noise Levels), and the distance from the noise-sensitive receiver. The predictive model also considers how many hours that equipment may be on site and operating (or idling) within an established work shift. Conservatively, no topographical or structural shielding was assumed in the modeling. The RCNM has default duty-cycle values for the various pieces of equipment, which were derived from an extensive study of typical construction activity patterns. Those default duty-cycle values were used for this noise analysis, which is detailed in Appendix B, Construction Noise Modeling Input and Output, and produce the predicted results displayed in Table 7.
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TTablee 77.. Predictedd Constructionn Noisee Levelss perr Activityy Phase CConstructionn Phasee (andd Equipmentt Typess
IInvolved)
88--HHourr Leeq att Nearestt Noise--
Sensitivee Receptorr too
Constructionn Sitee Boundaryy
(dBA)
8--Hourr Leq att Nearestt Noise--
Sensitivee Receptorr too
Acousticall Centroidd off Sitee
(dBA)
Site Preparation (Backhoe, Dozer) 70.5 59.7
Grading (Excavator, Grader, Dozer, Scraper,
Backhoe)
70.5 59.7
Building Construction (Crane, Forklift, Backhoe,
Welder, Generator)
71.2 60.4
Architectural Finishes (Air Compressor) 63.2 52.1
Paving (Roller, Paver, Mixer Truck) 72.3 61.5
Notes:: Leq = equivalent noise level; dBA = A-weighted decibels.
As presented in Table 7, the estimated construction noise levels are predicted to be less than 75 dBA Leq over an 8-hour period when activities take place near the north-western project boundaries. Note that these estimated noise levels at a source-to-receiver dist a n c e o f 1 5 0 f e e t o c c u r w h e n n o t e d p i e c e s o f h e a v y equipment would each operate for a cumulative period of 8 hours a day. Under these conditions, predicted operation of construction equipment and processes do not exceed noise levels of 75 dBA Leq.
Compared to measurements of the daytime outdoor ambient sound level at representative sample locations as shown in Table 4, predicted construction noise levels ranging in the lower to middle seventies of A-weighted decibels as appearing in Table 7 are considerably higher and would be clearly perceptible to an average listener having healthy human hearing. However, at nearby off-site residences exposed to such construction-related noise, the increased noise levels would typically be relatively short term and temporary—lasting only as long as construction occurs during allowable hours. And because it is anticipated that construction activities associated with future development as a result of the proposed project would take place within the hours of 7:00 a.m. and 6:00 p.m. Monday through Friday and on Saturdays from 8:00 a.m. to 5:00 p.m., the noise-producing activity would thus be in compliance with the City’s Municipal Code with respect to allowable hours, and less than the County’s 75 dBA 8-hour Leq limit; thus, construction noise impacts would be considered llesss thann significant.
Long-Termm Operationall
Roadwayy Trafficc Noisee
Potential future development as a result of the proposed project would result in the creation of additional vehicle trips on local arterial roadways (i.e., Las Po sas Road, La Mirada Drive, Linda Vista Drive, and S Pacific Street), which could result in increased traffic noise levels at adjacent offsite existing noise-sensitive land uses. Appendix C, Traffic Noise Modeling Input and Output, contains a spreadsheet with traffic volume data (average daily traffic) for su rrounding arterial roadways. In particular, potential future residential development as a result of the proposed project is estimated to add 2,694 average daily trips to local roadways.
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Potential noise effects from vehicular traffic were assessed using the Federal Highway Administration’s Traffic Noise Model version 2.5 (FHWA 2004). Information used in the model included the roadway geometry, posted traffic speeds, and traffic volumes for the following scenarios: existing (year 2021), existing plus project, near-term (2025), near-term plus project, horizon year (2050) and horizon year plus project. Noise levels were modeled at representative noise-sensitive receivers ST1 -ST4, as shown in Figure 3, and modeled to be 5 feet above the local ground elevation. The traffic noise prediction model results for the existing (year 2021), existing plus project, near-term (2025), near-term plus project, horizon year (2050) and horizon year plus project scenarios at these four assessment positions, and the arithmetic dB differences, are summarized in Table 8.
The predicted traffic noise levels, expressed as CNEL values, for the Existing (2021) scenario appearing in Table 8 are within 2 dB (an imperceptible difference) of the measured daytime sample L eq values appearing
in Table 4 for the same studied positions. While the metrics are dissimilar, the good agreement is consistent with what would be anticipated between daytime L eq and day-night level (L dn) per Federal Transit Administration (FTA) guidance (FTA 2018) and help s validate the Traffic Noise Model (TNM) prediction technique to evaluate the plus-Project and additional studied future scenarios appearing in Table 8. In particular, outdoor ambient sound level estimation techniques appearing in the afore-cited FTA’s Transit Noise and Vibration Impact Assessment Manual include guidance indicating that in proximity to dominant roadway or rail traffic noise, a daytime L
eq can be considered comparable to the Ldn value.
The City’s Noise Element establishes a policy for exterior sensitive areas to be protected from high noise levels.
The Noise Element sets 65 dBA CNEL for the outdoor areas and 45 dBA CNEL for interior areas as the normally acceptable levels. For the purposes of this noise analysis, such impacts are considered significant when they cause an increase of 3 dB from existing noise levels. An increase or decrease in noise level of at least 3 dB is required before any noticeable change in community response would be expected (Caltrans 2013a).
TTablee 88.. Roadwayy Trafficc Noisee Modelingg Results MModeledd
RReceiverr ## ––
Description
Existingg
(2021))
Noisee
Levell
(dBAA CNEL)
Existingg
(2021))
Pluss
Projectt
Noisee
Levell
(dBAA CNEL)
Near-termm
(2025))
Noisee level
(dBAA CNEL)
Near-termm
(2025))
Pluss
Projectt
Noisee levell
(dBAA CNEL)
Horizonn
yearr
(2050))
Noisee
Level
(dBAA CNEL)
Horizonn
yearr
(2050))
pluss
Projectt
Noisee
Level
(dBAA CNEL
Maximumm
Project-
Related
Noisee Levell
Increasee
(dB))
ST1 67.7 68.1 67.8 68.2 68.6 69 0.4
ST2 61.2 63.6 61.2 63.6 61.6 63.9 2.4
ST3 61.7 62.1 62.4 62.6 63.9 64.1 0.4
ST4 66.2 66.3 66.3 66.5 67 67 0.2
Notes: dBA = A-weighted decibel; CNEL = Community Noise Equivalent Level; dB = decibel; ST = short-term; Table 8 shows that at all four listed representative receivers, the addition of traffic to the roadway network as a result of potential future residential development would result in a CNEL increase of less than 3 dB at sensitive receptors, which is below the discernible level of change for the average healthy human ear. Thus,
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a lless-than-significantt impact is expected for proposed project-related off-site traffic noise increases affecting existing residences in the vicinity.
Trafficc Noisee Exposuree too Futuree Projectt Occupantss Aside from exposure to aviation traffic noise, current CEQA noise-related guidelines at the state level do not require an assessment of exterior-to-interior noise intrusion, environmental noise exposure to occupants of newly-created project residences, or environmental noise exposure to exterior non-residential uses attributed to the potential future development at the proposed project site. Nevertheless, the City’s CEQA guidelines and the California Building Code requires that interior background noise levels not exceed a CNEL of 45 dB within habitable rooms. Hence, the following predictive analysis of traffic noise exposure at the exteriors of occupied residences and outdoor living areas is provided below.
The ambient noise levels found in Table 8 were used to predict the existing-plus-project scenario traffic noise levels at multiple on-site exterior areas. Exterior sound levels presented in Table 8 that are higher than 65 dBA CNEL indicate potential locations where an exterior-to-interior noise analysis should be performed for the approximate future occupied residential unit on the project site.
The results from Table 8 indicate that ambient traffic noise levels could reach as high as 67.7 dBA CNEL in acoustically equivalent locations to ST1 along Las Posas Road. With the 45 dBA CNEL interior background sound level limit, this means the minimum composite sound transmission class (STC) rating for the exterior shell separating the habitable interior space from the outdoor sound level should be at least 22. The composite STC rating for the portion of a building shell that separates an interior space from the outdoors is calculated from the area-dependent contributions of its elements: windows, wall assemblies, and doors.
There is a potential for newly built residential units o n the project site to feature balconies as part of the design, for which access would likely be provided by single-panel, out-swing fiberglass French doors (comparable to a Milgard Essence series model or similar from another manufacturer) or alternately sliding- type doors. For purposes of this analysis, either of these patio/balcony door design styles are assumed to feature a dual-pane glazing system similar to a standard residential window assembly (i.e., two 1/8”-thick glass panes separated by a 3/8” wide airgap) in narrow-perimeter frames compatible with modern thermal insulation (and thus energy conserving) design. The analysis also assumes that these door products feature good seals and related hardware, so that when closed, the effective sound insulating performance is represented by the glass. Viracon data indicates that such glazing should demonstrate an STC rating of 31 (Viracon 2019).
This study further assumes an exterior wall assembly that includes and is typical of modern residential building construction: one layer of 5/8” gypsum wallboard (GWB) on the interior-facing side, 2”x4” wood studs, glass fiber batt insulation in the stud cavities, and a dual-layer of 5/8” GWB on the exterior-facing side. Acoustical transmission loss (TL) data is available on this representative assembly (Halliwell 1998), and is used as part of estimating the composite STC ratings reported herein. For purposes of this analysis, the dual-layer GWB on the exterior surface approxim ates the mass and solidity of what may be other approved material options as determined by the Project architect, such as cement fiber siding panels, brick masonry veneer, or cement plaster attached to layers of fiberglass mat sheathing and plywood sheathing.
Table 9 summarizes the calculated net STC ratings for a set of hypothetical example occupied room facades that, if so designed and built, would be anticipated to be exposed to predicted exterior noise levels greater
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than 60 dBA CNEL. Details of these calculations that account for the façade surface area and its composite areas of exterior wall assembly and windows appear in Appendix D.
Clearly, an open window or open door to an adjoining patio or balcony greatly compromises the sound insulation performance of the façade wall assembly, as presented for the sample units appearing in Table
9. However, when such windows and doors are closed, all facades are anticipated to exhibit a predicted STC rating of at least 36, and thus would provide sufficient exterior-to-interior sound insulation from outdoor traffic noise to yield interior background sound levels that are less than 45 dBA CNEL and thus compliant with the City and state standards. Recall that none of the predicted exterior traffic noise levels at the studied receptor locations exceeded 67.7 dBA CNEL; thus, the STC rating value (for closed windows and doors) subtracted from these exterior noise values must result in interior noise levels of less than 45 dBA CNEL (e.g., 67 – 36 = 31 dBA CNEL, which is less than 45). This apparent requirement for closed windows and doors means that the design of these habitable room s should feature mechanical ventilation or an air- conditioning system to provide interior comfort of the occupants. Detailed transmission loss data is included in Appendix D, Transmission Loss Predictions. Thus, the City’s threshold of 45 dB CNEL within habitable rooms would not be exceeded and considered l
lesss thann significant.
Tablee 99.. Predictedd Nett Soundd Transmissionn Classs off Occupiedd Roomm façade Occupiedd Roomm Facade
Predictedd Nett Soundd TTransmissionn Classs (STC)) forr Scenarioo Closedd Window(s)) andd Doorr *
Openn Window(s)) && Closedd Frenchh
Door*
1st floor Bedroom, eastern façade 37 8
2nd floor Bedroom w/ balcony,
eastern façade 36 11
3rd floor Bedroom, eastern façade 38 11
Source: Dudek 2022
Notes:: n/a = not applicable
* Doors are only modeled for scenarios that contain the balcony door.
Stationaryy Operationss Noisee
Future residential development on the project site will add a variety of noise-producing mechanical equipment that include those presented and discussed in the fo llowing paragraphs. Most of these noise-producing equipment or sound sources would be considered stationary, or limited in mobility to a defined area.
Facilityy Unitt Heating,, Ventilation,, andd Airr Conditioningg Noisee According to the site plan future residential development would likely include cooling by rooftop-mounted air-cooled condensing [ACC] units, could expose nearby industrial-zoned land uses to aggregate stationary electro-mechanical noise emission representing the following scenario: for potential new residential buildings onsite, a cooling load of up to 40 tons of refrigeration, based on oft-used industry reference data for interior occupied building spaces of similar usage, with each potential future residential unit needing approximately two tons of refrigeration (Loren Cook Company, 2015).
For purposes of this analysis, each of the potential new occupied residential units in the first bulleted scenario would be expected to feature its own 2-ton ACC unit. Each of these ACC units would have an SPL of 68 dBA at 3 feet based on available data from a likely manufacturer (Carrier 2012). At the closest existing
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offsite noise-sensitive residential receptor to the west of the project site’s northwestern-most potential structure in the residential-emphasizing project scenario, the predicted sound emission level from the combination of 20 operating ACC would be lower than 41 dBA L eq and thus be compliant with the City’s nighttime threshold of 60 dBA hourly L eq for industrial-zoned land uses. Under such conditions, the operation of residential air-conditioning units would result in a less-than-significant noise impact. Details for this hypothetical stationary noise prediction scenario appear in Appendix E.
Because the measured samples of existing outdoor ambient sound levels are already in excess of 60 dBA Leq during the daytime, as shown in Table 4, then FTA guidance suggests that average nighttime ambient noise levels would be at least 50 dBA Leq. This is because Table 4-17 (Estimating Existing Noise Exposure for General Noise Assessment) from the aforementioned FTA guidance document shows a 10-dB difference between daytime and nighttime noise levels regardless of the type of “dominant existing noise source.” On this basis, and because the predicted stationary operations noise received by the closest offsite residential receptor would be less than 50 dBA as presented in the preceding paragraphs, the potential increase in outdoor ambient noise level due to the introduction of new stationary sound sources would be no greater than a barely-perceptible three decibels and consequently considered a lless-than-significantt noisee impact.
Cumulativee Noisee Assessmentt
Transportationn Sourcess
Table 8 and its contextual discussion already addresses cumulative acoustical contribution to the outdoor sound environment that is attributed to ongoing development (and corresponding changes to proximate roadway traffic) in the project area through the near-term and horizon timeframes. With predicted changes in roadway traffic noise attributed to the proposed project shown to be less than significant in the cumulative analysis scenarios, the proposed projec t would not be expected to have a cumulatively considerable effect..
Constructionn Activitiess
Temporary changes to the outdoor sound environment could also occur not only due to project construction noise that has already been presented herein, but as a cumulative result of potential concurrent project construction activity noise and the noise emission from construction of other projects in the vicinity.
Due to the decrease in noise levels with distance and the presence of physical barriers (i.e., intervening buildings and topography), noise due to construction of other projects would not meaningfully combine with that of the proposed project and produce a cumulative noise effect during construction. By way of illustration, if there are two concurrent construction projects of comparable sound emission intensity, and the activity nearest to a common studied noise-sensitive receptor is compliant with the aforementioned 75 dBA 8-hour Leq, then the other activity could be no closer than three times the distance of the receptor to the nearest activity and not make a cumulatively measurable contribution to the total noise exposure level.
If, on the other hand, two concurrent projects were comparably close to a receptor, the cumulative noise would be one of the following:
x The louder (in dBA) of the two concurrent activities; or
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x a logarithmic sum of the two activity noise levels that, per acoustic principles, cannot be more than 3 dBA greater than the louder of the two individual noise-producing activities.
In sum, cumulative construction noise is likely to be dominated by the closest or loudest activity to the receptor, and the combination will be no more than a barely perceptible difference (i.e., up to a 3 dBA change). On the basis of such a barely perceptible cumulative construction noise level occurring due to the proposed project and what may be a nearby concurrent construction activity, the impact would be considered less than significant.
S
Stationaryy Operationall Sourcess
Akin to the preceding discussion of cumulative construction noise, operation noise from stationary equipment attributed to the proposed project (as already presented herein) and any others potentially operating in the future and in the vicinity of a common offsite noise-sensitive receptor would need to be compliant with the City’s applicable standards. Cumulative contribution of the proposed project to this future aggregate noise level from multiple established projects or facilities assumed to have comparable individual noise emission from stationary sources would be bounded by the same potential outcomes as follows:
x The louder (in dBA) of the two concurrently operating projects or facilities; or x a logarithmic sum of the two operation noise levels that, per acoustic principles, cannot be more than 3 dBA greater than the louder of the two individual levels.
In sum, cumulative operation noise is likely to be dominated by the closest or loudest project to the receptor, and the combination will be no more than a barely perceptible difference (i.e., up to a 3 dBA change). On the basis of such a barely perceptible cumulative operation noise level occurring due to the proposed project and what may be nearby and concurrent operation of offsite stationary noise sources, the impact would be considered less than significant.
b)) Wouldd thee projectt resultt inn generationn off excessivee groundbornee vibrationn orr groundbornee noisee levels?? Conventionall Constructionn Activityy Vibrationn
Construction activities may expose persons to excessive groundborne vibration or groundborne noise, causing a potentially significant impact. Caltrans has collected groundborne vibration information related to construction activities (Caltrans 2020). Informatio n from Caltrans indicates that continuous vibrations with a PPV of approximately 0.1 inch per second (ips) could be considered annoying on the basis of it being “strongly perceptible” by building occupants. For context, heavier pieces of construction equipment, such as a bulldozer that may be expected on the project site, have peak particle velocities of approximately
0.089 ips PPV or less at a reference distance of 25 feet (FTA 2018).
Groundborne vibration attenuates rapidly, even over short distances. The attenuation of groundborne vibration as it propagates from source to receptor through intervening soils and rock strata can be estimated with expressions found in FTA and Caltrans guidance. By way of example, for a bulldozer operating on site and as close as the northern project boundary (i.e., 150 feet from the nearest occupied property) the estimated vibration velocity level would be 0.006 ips PPV per the equation as follows (FTA 2018):
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PPVrcvr = PPVref * (25/D)^1.5 = 0.006 = 0.089 * (25/150)^1.5 In the above equation, PPV rcvr is the predicted vibration velocity at the receiver position, PPV ref is the reference value at 25 feet from the vibration source (the bulldozer), and D is the actual horizontal distance to the receiver. Therefore, at this predicted PPV, th e impact of vibration-induced annoyance to occupants of nearby existing homes would be less than 0.1 ips PPV and therefore less than significant.
Construction vibration, at sufficiently high levels, can also present a building damage risk. However, anticipated construction vibration associated with future development on-site would yield levels of 0.006 ips, which do not surpass the guidance limit of 0.2 to 0.3 ips PPV for preventing damage to residential structures (Caltrans 2020). Because the predicted vibration level at 150 feet is less than this guidance limit, the risk of vibration damage to nearby structures is considered l lesss thann significant.
c)) Forr aa projectt locatedd withinn thee vicinityy off aa privatee airstripp orr ann airportt landd usee plann or,, wheree suchh aa plann hass nott beenn adopted,, withinn twoo miless off aa publicc airportt orr publicc usee airport,, wouldd thee projectt exposee peoplee residingg orr workingg inn thee projectt areaa too excessivee noisee levels?? There are no private airstrips within the vicinity of the project site. The closest airport to the project site is the McClellan Palomar Airport approximately 4.4 miles west of the site; the project site is not located within the boundaries of the land use plan adopted for this airport. Impacts from aviation overflight noise exposure would be considered l
lesss thann significant.
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6 Mitigation Measures
The results indicate that potential impacts during construction and operation would be less than significant. No mitigation is required.
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7 Summary of Findings
This noise report was conducted for potential future deve lopment associated with the approval of the proposed project. The results indicate that potential impacts during construction would be less than significant. Noise impacts due to operation of the proposed project (including traffic noise) would be less than significant. No mitigation is required.
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8 References Cited
Caltrans (California Department of Transportation). 2013. Technical Noise Supplement to the Traffic Noise Analysis Protocol. September.
Caltrans. 2020. Transportation and Construction Vibration Guidance Manual. Division of Environmental Analysis, Environmental Engineering, Hazardous Waste, Air, Noise, Paleontology Office. Sacramento, California. April.
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TECHNICAL NOISE REPORT FOR THE PACIFIC GENERAL PLAN AMENDMENT/REZONE PROJECT 13170
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Appendix A
Baseline Noise Measurement Field Data
Appendix B
Construction Noise Modeling Input and Output
Appendix C
Traffic Noise Modeling Input and Output
Appendix D
Transmission Loss Prediction
Appendix E
Residential HVAC Noise Prediction