> Appendix-P-Noise — San Marcos City Council, June 24, 2025

Project: 22-124 Armorlite Lofts 225 Noise

NOISE ASSESSMENT

Armorlite Lofts Residential Development
GPA23-0002, R23-0001
SDP23-0003, CUP23-0002
City of San Marcos, CA

Prepared for:

City of San Marcos
1 Civic Center Drive
San Marcos, CA 92069

Prepared By:

23811 Washington Ave, C110-333
Murrieta, California 92562
760-473-1253

November 4, 2024

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TABLE OF CONTENTS

TABLE OF CONTENTS ............................................................................................................. ............................. II LIST OF FIGURES ................................................................................................................................................ III LIST OF TABLES .................................................................................................................................................. III ATTACHMENTS ................................................................................................................... .............................. III GLOSSARY OF COMMON TERMS ...................................................................................................... ................. IV EXECUTIVE SUMMARY ............................................................................................................. .......................... V

1.0 PROJECT INTRODUCTION .......................................................................................................... ................. 1

1.1 PURPOSE OF THIS STUDY ........................................................................................................................................ 1

1.2 PROJECT LOCATION .............................................................................................................................................. 1

1.3 PROJECT DESCRIPTION AND PURPOSE ....................................................................................................................... 1

2.0 FUNDAMENTALS................................................................................................................... ..................... 4

2.1 ACOUSTICAL FUNDAMENTALS ................................................................................................................................. 4

2.2 VIBRATION FUNDAMENTALS ................................................................................................................................... 5

3.0 SIGNIFICANCE THRESHOLDS AND STANDARDS ......................................................................................... .. 7

3.1 CONSTRUCTION NOISE .......................................................................................................................................... 7

3.2 BLASTING AND VIBRATION STANDARDS .................................................................................................................... 7

3.3 TRANSPORTATION NOISE STANDARDS ...................................................................................................................... 9

3.4 OPERATIONAL NOISE STANDARDS.......................................................................................................................... 12

4.0 CONSTRUCTION NOISE ............................................................................................................ ................. 14

4.1 CONSTRUCTION NOISE PREDICTION METHODOLOGY ................................................................................................ 14

4.2 GRADING ACTIVITIES NOISE FINDINGS .................................................................................................................... 14

4.3 ROCK DRILL NOISE FINDINGS AND MITIGATION ........................................................................................................ 16

4.4 ROCK CRUSHING NOISE FINDINGS AND MITIGATION ................................................................................................. 17

4.5 CONSTRUCTION VIBRATION FINDINGS AND MITIGATION ............................................................................................ 18

4.6 BLASTING VIBRATION FINDINGS AND MITIGATION .................................................................................................... 19

4.7 CONSTRUCTION NOISE AND VIBRATION CONCLUSIONS .............................................................................................. 20

5.0 TRANSPORTATION NOISE .......................................................................................................... ............... 22

5.1 EXISTING NOISE ENVIRONMENT ONSITE ................................................................................................................. 22

5.2 FUTURE ONSITE ROADWAY NOISE ......................................................................................................................... 24

5.3 ONSITE RAIL LINE NOISE ...................................................................................................................................... 26

5.4 CUMULATIVE NOISE LEVELS .................................................................................................................................. 26

5.5 PROJECT RELATED OFFSITE TRANSPORTATION NOISE ................................................................................................ 29

5.6 TRANSPORTATION NOISE CONCLUSIONS ................................................................................................................. 30

6.0 OPERATIONAL NOISE ............................................................................................................. ................... 31

7.0 SUMMARY OF PROJECT IMPACTS, MITIGATION & CONCLUSION................................................................ 33

8.0 REFERENCES .................................................................................................................... ......................... 36

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LIST OF FIGURES

FIGURE 1-A: PROJECT VICINITY MAP ................................................................................................................... 2 FIGURE 1-B: RESIDENTIAL DEVELOPMENT DETAILS ............................................................................................. 3 FIGURE 5-A: AMBIENT MONITORING LOCATION ................................................................................................ 23 FIGURE 5-B: MODELED RECEPTOR LOCATIONS ................................................................................................... 25 FIGURE 5-C: FUTURE UNMITIGATED EXTERIOR NOISE LEVELS .......................................................................... .. 27 FIGURE 5-D: NOISE CONTROL RECOMMENDATIONS ..................................................................................... ..... 28

LIST OF TABLES

TABLE 2-1: HUMAN REACTION TO TYPICAL VIBRATION LEVELS ......................................................................... .. 6 TABLE 3-1: GROUNDBORNE VIBRATION AND NOISE IMPACT CRITERIA (HUMAN ANNOYANCE) ........................... 8 TABLE 3-2: GROUNDBORNE VIBRATION IMPACT CRITERIA (STRUCTURAL DAMAGE) ........................................... 9 TABLE 3-3: NOISE COMPATIBILITY GUIDELINES .................................................................................................. 10 TABLE 3-4: NOISE STANDARDS .................................................................................................... ...................... 11 TABLE 3-5: SOUND LEVEL LIMITS ................................................................................................. ...................... 13 TABLE 4-1: CONSTRUCTION NOISE LEVELS .......................................................................................... ............... 15 TABLE 4-2: CONSTRUCTION NOISE LEVELS FROM ROCK DRILL ............................................................................ 16 TABLE 4-3: ROCK CRUSHING NOISE LEVELS (RESIDENTIAL RECEPTORS)............................................................... 18 TABLE 4-4: ROCK CRUSHING NOISE LEVELS (COMMERCIAL RECEPTORS) ............................................................. 18 TABLE 4-5: VIBRATION LEVELS FROM CONSTRUCTION ACTIVITIES (RESIDENTIAL RECEPTORS) ............................ 19 TABLE 5-1: LONG-TERM NOISE LEVEL SUMMARY ............................................................................................... 22 TABLE 5-2: FUTURE TRAFFIC PARAMETERS .......................................................................................... .............. 24 TABLE 5-3: EXTERIOR NOISE LEVELS WITH BALCONY DESIGN FEATURES ............................................................. 29 TABLE 6-1: PROJECT HVAC NOISE LEVELS (EASTERN RESIDENTIAL PROPERTY LINE) ............................................ 32

ATTACHMENTS

FRESNEL BARRIER CALCULATIONS .................................................................................................. ................... 37

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GLOSSARY OF COMMON TERMS
Sound Pressure Level (SPL): a ratio of one sound pressure to a reference pressure (Lref) of 20 μPa. Because of the dynamic range of the human ear, the ratio is calculated logarithmically by 20 log (L/Lref).

A-weighted Sound Pressure Level (dBA): Some frequencies of noise are more noticeable than others. To compensate for this fact, different sound frequencies are weighted more.

Minimum Sound Level (Lmin): Minimum SPL or the lowest SPL measured over the time interval using the A-weighted network and slow time weighting.

Maximum Sound Level (L max): Maximum SPL or the highest SPL measured over the time interval the A-weighted network and slow time weighting.

Equivalent sound level (Leq): the true equivalent sound level measured over the run time. Leq is the A-weighted steady sound level that contains the same total acoustical energy as the actual fluctuating sound level.

Day Night Sound Level (Ldn): Representing the Day/Night sound level, this measurement is a 24 –hour average sound level where 10 dB is added to all the readings that occur between 10 pm and 7 am. This is primarily used in communi ty noise regulations where there is a 10 dB “Penalty” for nighttime noise. Typically, Ldn’s are measured using A weighting.

Community Noise Exposure Level (CNEL) : The accumulated exposure to sound measured in a 24-hour sampling interval and artificially boosted during certain hours. For CNEL, samples taken between 7 pm and 10 pm are boosted by 5 dB; samples taken between 10 pm and 7 am are boosted by 10 dB.

Octave Band: An octave band is defined as a frequency band whose upper band-edge frequency is twice the lower band frequency.

Third-Octave Band: A third-octave band is defined as a frequency band whose upper band- edge frequency is 1.26 times the lower band frequency.

Response Time (F,S,I): The response time is a standardized exponential time weighting of the input signal according to fast (F ), slow (S) or impulse (I) time response relationships. Time response can be described with a time constant. The time constants for fast, slow and impulse responses are 1.0 seconds, 0.125 seconds and 0.35 milliseconds, respectively. v
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EXECUTIVE SUMMARY

This noise study has been comple ted to determine the noise impacts to and from the proposed residential project. The project is located north of State Route 78 (SR-78) and east of Las Posas Road between W. Mission Road and Armorlite Drive in the City of San Marcos CA. The project is located adjacent to the San Diego Northern Ra ilroad (SDNR) consisting of Sprinter service operated by the NCTD.

Construction Noise

The grading equipment will be spread out over the project site from distances near the occupied property lines to distances of 200 feet or more away. Based upon the site plan the majority of the grading operations, on average from the center of the construction activities, will occur more than 100 feet from the property lines. At an averag e distance of 100 feet fr om the center of the construction activities to the nearest property line, noise levels will comply with the 75 dBA Leq standard over 8 hours at the property lines. The material haulage is also anticipated to comply with the City’s thresholds. Therefore, no impacts are anticipated and no mitigation is required during construction of the proposed Project. Additionally, all equipment should be properly fitted with mufflers and all staging and maintenance should be conducted as far away from the existing residence as possible.

Additionally, the project may require blasting whic h would also require the need for a rock drill.

Rock drilling and blasting will occur on an as-needed basis on site. In the event that the rock drill is staged within 160 feet of any occupied noise sensitive land use, it is recommended that a specific noise mitigation plan based upon the location of the construction equipment, topography and construction schedule be identified by an acoustical engineer. A mitigation plan should be developed that may include a temporary noise barrier along any property line where the impacts could occur.

Based on previous projects, a barrier ranging from 8 to 12 feet in height may be needed. The proposed noise barrier will need to be of solid non-gapping material to adequately reduce construction noise levels below the noise threshold. The mitigation plan can also incorporate the usage of the equipment (amount of time used and/or the location in respect to the property line).

The mitigation plan would determine the final height and location of a temporary barrier if one is necessary.

The rock crushing equipment will be located in the northwest portion of the site at the proposed parking area, and more than 200 feet from the nearest residential property line. The noise levels are anticipated to be below the City’s 60 dBA Leq standard at the property lines without mitigation.

Noise measurements of the rock crusher should be conducted once the final crusher type and location are determined to ensure compliance with the City’s thresholds. If noise levels are found to be above the established thresholds of 60 dBA at any existing single-family residential use, 65 vi
Ldn Consulting, Inc. 11/4/24 22-124 Armorlite Lofts 225 Noise dBA for any multi-family use, or 70 dBA at a co mmercial use, then additional mitigation in the form of higher barriers, sound absorbing materials or operational limits on the crushers usage will need to be incorporated.

Construction Vibration

Project construction activities would result in PPV levels below the FTA’s criteria for vibration induced structural damage. Therefore, Project construction activities would not result in vibration induced structural damage to residential buildings near the construction areas. The FTA criterion for infrequent vibration induced annoyance is 80 Vibration Velocity (VdB) for residential uses.

Construction activities would generate levels of vibration that would not exceed the FTA criteria for nuisance for nearby reside ntial uses. Therefore, vibratio n impacts would be less than significant.

Blasting Vibration

Blasting for construction projects typically results in a root mean square (RMS) vibration velocity of about 100 VdB at 50 feet from the blast based on FTA findings. This is equivalent to a peak particle velocity of about 0.4 inch per second. Given attenuation of vibration velocities with distance, the RMS vibration velocity and peak part icle velocity at the ne arest existing residence would be about 82 VdB and 0.05 inch per second, respectively. Based on the construction vibration damage criteria published by the FTA, the threshold vibration levels for damage to "Non- engineered timber and masonry buildings" are 94 VdB and 0.20 inch per second.

Therefore, the effect of the blasting activity on nearby residential structures will not be significant.

On the other hand, the human annoyance criterion of 80 VdB would be s lightly exceeded when blasting occurred within about 250 feet of existing residences. If blasting is required within 250 feet of existing residences, the potential annoyance may not be completely avoided it can be minimized by following the City’s blasting procedures.

Onsite Transportation Noise

The results of this analysis indicate that futu re vehicle noise from Las Posas Road, W. Mission Road, Armorlite Drive, State Route 78 (SR-78), and the Sprinter commuter rail are the principal sources of noise that would impact the site. Due to the combined roadway and train activities, the outdoor use areas were found to exceed the City’s 65 dBA CNEL threshold without noise control measures. Noise control recommend ations in the form of 3.5-fo ot barriers installed at the balconies/decks for the units having direct line of sight to W. Mission Road and Las Posas Road is needed to comply with the City of San Marcos Noise standards for multi-family uses based on transportation related noise sources (i.e., vehicle).

vii
Ldn Consulting, Inc. 11/4/24 22-124 Armorlite Lofts 225 Noise It should be noted that the ground floor flex units along Armorlite Drive to the south could potentially be converted to residential units and would be required to comply with the City’s 65 dBA CNEL noise standard. The units would comply with the City’s 65 dBA CNEL noise standard without additional noise mitigation measures.

Additionally, a final noise assessment is required prior to the issuance of the first building permit since the building facades are above 60 dBA CNEL. This final report would identify the interior noise requirements based upon architectural and building plans. It should be noted; interior noise levels of 45 dBA CNEL can be obtained with convention al building construction methods and providing a closed window condition requiring a means of mechanical ventilation (e.g., air conditioning) and upgraded windows for all sensitive rooms (e.g., bedrooms and living spaces).

Offsite Transportation Noise

The Project does not create a noise increase of more than 3 dBA CNEL on any of the analyzed roadway segments. Therefore, the Project’s contributions to off-site roadway noise increases will not cause any significant impacts to any existing or future noise sensitive land uses.

Operational Noise

Based on noise levels, the distances to the property lines and the proposed parapet walls, the noise levels from the proposed roof-mounted HVAC would be considered less than significant at the residential property lines to the east and south, and the commercial property lines to the west. Therefore, the operational noise levels are in compliance with the City of San Marcos Municipal Code Sections 10.24 and 20.300.

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1.0 PROJECT INTRODUCTION

1.1 Purpose of this Study

The purpose of this Noise study is to determine potential noise impacts (if any) created from the proposed construction operations and to determine potential noise impacts (if any) to the site generated from offsite sources. Should impacts be determined, the intent of this study would be to recommend suitable measures to bring those impacts to a level that would meet local requirements.

1.2 Project Location

The vacant 2.4-acre project site having an Assessor Parcel Number (APN) of 219-612-62-00 is located along Armorlite Drive in the City of San Marcos. Specifically, the project site is located north of State Route 78 (SR-78) and east of Las Posas Road between W. Mission Road and Armorlite Drive. A project vicinity map and locati on map are shown in Figure 1-A. The existing site is currently vacant. The project is bounded by existing commercial and retail uses to the west, existing multi-family residential units to the ea st, W. Mission Road and the San Diego Northern Railroad (SDNR) to the north, and Armorlite Drive to the south. Existing multi-family residential units are located across Armorlite Drive to the south.

1.3 Project Description and Purpose

The project proposes up to 165 multi-family residential units within a five-story building situated on approximately 2.4 gross acres. The project woul d also include up to 5,600 square foot (s.f.) of retail/flex use. Additionally, the Project proposes as many as 254 parking spaces which includes 13 Level 2 electric vehicle (EV) spaces, 62 EV ready spaces, and 25 EV capable spaces. The project seeks a General Plan Amendment (GPA) and to rezone the property from Public- Institutional (P-I) Specific Plan Area (SPA). The project development plan is shown on Figure 1- B of this report.

2 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Figure 1-A: Project Vicinity Map

Project
Location
Source: (Google, 2023)

3 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Figure 1-B: Residential Development Details

Source: (Summa Architecture, 2024)

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2.0 FUNDAMENTALS

2.1 Acoustical Fundamentals

Noise is defined as unwanted or annoying sound which interferes with or disrupts normal activities. Exposure to high noise levels has been demonstrated to cause hearing loss. The individual human response to environmental noise is based on the sensitivity of that individual, the type of noise that occurs and when the noise occurs. Sound is measured on a logarithmic scale consisting of sound pressure levels known as a decibel (dB). The sounds heard by humans typically do not consist of a single frequency but of a broadband of frequencies having different sound pressure levels. The method for evaluating all the frequencies of the sound is to apply an A-weighting to reflect how the human ear responds to the different sound levels at different frequencies. The A-weighted sound level adequa tely describes the instantaneous noise whereas the equivalent sound level depicted as Leq repr esents a steady sound level containing the same total acoustical energy as the actual fluctuating sound level over a given time interval.

The Community Noise Equivalent Level (CNEL) is the 24 hour A-weighted average for sound, with corrections or penalties for evening and nighttime hours. The corrections require an addition of 5 decibels to sound levels in the evening hours between 7 p.m. and 10 p.m. and an addition of 10 decibels to sound levels at nighttime hours between 10 p.m. and 7 a.m. These additions are made to account for the increa sed sensitivity during the evening and nighttime hours when sounds appear louder.

A vehicle’s noise level is from a combination of the noise produced by the engine, exhaust and tires. The cumulative traffic noise levels along a roadway segment are based on three primary factors: the amount of traffic, the travel speed of the traffic, and the vehicle mix ratio or number of medium and heavy trucks. The intensity of traffic noise is increased by higher traffic volumes, greater speeds and increased number of trucks.

Because mobile/traffic noise levels are calculated on a logarithmic scale, a doubling of the traffic noise or acoustical energy results in a noise leve l increase of 3 dBA. Therefore, the doubling of the traffic volume, without changing the vehicle sp eeds or mix ratio, results in a noise increase of 3 dBA. Mobile noise levels radiant in an almo st oblique fashion from the source and drop off at a rate of 3 dBA for each doubling of distance under hard site conditions and at a rate of 4.5 dBA for soft site conditions. Hard site conditions consist of concrete, asphalt and hard pack dirt while soft site conditions exis t in areas having slight grade changes, landscaped areas and vegetation. On the other hand, fixed/point sources radiate outward uniformly as it travels away from the source. Their sound levels attenuate or drop off at a rate of 6 dBA for each doubling of distance.

5 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise The most effective noise reduction methods consist of controlling the noise at the source, blocking the noise transmission with barriers or relocating the receiver. Any or all of these methods may be required to reduce noise levels to an acceptable level.

2.2 Vibration Fundamentals

Vibration is a trembling or oscillating motion of the ground. Like noise, vibration is transmitted in waves, but in this case through the ground or solid objects. Unlike noise, vibration is typically felt rather than heard. Vibration can be either natural as in the form of earthquakes, volcanic eruptions, or manmade as from explosions, heavy machinery, or trains. Both natural and manmade vibration may be continuous, such as from operating machinery; or infrequent, as from an explosion.

As with noise, vibration can be described by both its amplitude and frequency. Amplitude may be characterized in three ways: displacement, velocity , and acceleration. Particle displacement is a measure of the distance that a vibrated particle travels from its original position and for the purposes of soil displacement is typically measured in inches or millimeters. Particle velocity is the rate of speed at which soil particles move in inches per second or millimeters per second.

Particle acceleration is the rate of change in velocity with respect to time and is measured in inches per second or millimeters per second. Typically, particle velocity (m easured in inches or millimeters per second) and/or acceleration (measured in gravities) are used to describe vibration.

Table 2-1 shows the human reaction to various levels of peak particle velocity.

Vibrations also vary in frequency and this affect s perception. Typical construction vibrations fall in the 10 to 30 Hz range and usually occurring ar ound 15 Hz. Traffic vibrations exhibit a similar range of frequencies; however, due to their susp ension systems, it is less common, to measure traffic frequencies above 30 Hz.

Propagation of ground-borne vibrations is comp licated and difficult to predict because of the endless variations in the soil through which the waves travel. There are three main types of vibration propagation: surface, compression, and shear waves. Surface waves, or Rayleigh waves, travel along the ground’s surface. These waves carry most of their energy along an expanding circular wave front, similar to ripples produced by dropping an object into water. P-waves, or compression waves, are waves that carry their energy along an expanding spherical wave front.

The particle motion in these waves is longitudinal. S-waves, or shear waves, are also body waves that carry energy along an expanding spherical wave front. However, unlike P-waves, the particle motion is transverse, or side-to-side and perpendicular to the direction of propagation.

As vibration waves propagate from a source, the energy is spread over an ever-increasing area such that the energy level is reduced with the distance from the energy source. This geometric spreading loss is inversely proportional to the square of the distance. Wave energy is also reduced

6 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise with distance as a result of material damping in the form of internal fr iction, soil layering, and special voids. The amount of attenuation provided by material damping varies with soil type and condition as well as the frequency of the wave.

Table 2-1: Human Reaction to Typical Vibration Levels
Vibration Level
Peak Particle Velocity
(in/sec)
Human Reaction Effect on Buildings

0.006–0.019 Threshold of perception, possibility of
intrusion
Vibrations unlikely to cause damage of any
type

0.08 Vibrations readily perceptible
Recommended upper level of vibration to
which ruins and ancient monuments should
be subjected

0.10 Level at which continuous vibration
begins to annoy people
Virtually no risk of “architectural” (i.e., not
structural) damage to normal buildings

0.20 Vibrations annoying to people in
buildings
Threshold at which there is a risk to
“architectural” damage to normal dwelling –
houses with plastered walls and ceilings

0.4–0.6
Vibrations considered unpleasant by
people subjected to continuous
vibrations and unacceptable to some
people walking on bridges
Vibrations at a greater level than normally
expected from traffic, but would cause
“architectural” damage and possibly minor
structural damage
Source: Caltrans, Division of Environmental Analysis, Transportation Related Earthborne Vibration, Caltrans Experiences, Technical Advisory, Vibration, TAV-02-01-R9601, 2020 (Caltrans, 2020).

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3.0 SIGNIFICANCE THRESHOLDS AND STANDARDS

3.1 Construction Noise

The City of San Marcos Municipal Code (Section 17.08.080) addresses the limits of grading, extraction and construction activities between 7:00 a.m. and 6:00 p.m. Monday through Friday, 8:00 a.m. and 5:00 p.m Saturdays, and no gradin g, extraction or construction is allowed on Sundays or City holidays. The Municipal code does not set noise limits on construction activities.

Commonly, the City has utilized Section 36.409 of the County of San Diego’s Noise Ordinance noise limit of 75 dBA Leq (8-hour) for other projects.

3.2 Blasting and Vibration Standards

The City of San Marcos Section 17.60.06 of the City’s Municipal Code states that all blasting operations within the City of San Marcos are prohibited unless a Certificate of Authorization is first obtained from the San Marcos Building Director and an Operations Permit issued by the Fire Chief. Additional relevant sections of the City’s Code for Blasting are provided below:

• The general contractor or property owner/developer shall give reasonable notice in writing at the time of issuance of a building permit, grading permit or encroachment license to all residences or businesses within 600 feet of any potential blast location. The notice shall be in a form approved by the Building Director. Any resident or business receiving such notice may request of the Building Director that a notice of impending blasting be given by the blaster at the time of the 12 hour advance notice given to the Building Director. The general contractor or property owner/developer shall make all reasonable efforts to contact any and all parties requesting the second notice.

• The blaster shall file a written certification with the Building Director certifying that the general notice required by Section 17.60.060(b) has been given. The certificate shall include addresses and date(s) of notification. A copy shall be retained on file at the Building Division.

• Inspections of all structures within 300 feet of the blast site shall be made before blasting operations. The persons inspecting shall obtain the permission of the building owner to conduct an inspection. The inspections shall be done by a registered structural engineer employed by the blaster or project contractor. The inspection shall be only for the purpose of determining the existence of any visible or reasonably recognizable pre-existing defects or damages in any structure. Inspection refusal shall be at the discretion of the property owner.

• Blasting shall only be permitted between the hours of 9:00 a.m. and 4:00 p.m. during any weekday, Monday through Friday, exclusive of City recognized holidays unless special circumstances warrant another time or day and special approval is granted by the Building Director and Fire Chief.

8 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise The City of San Marcos has not yet adopted vibration criteria for construction. The United States Department of Transportation Federal Transit Administration (FTA) provides criteria for acceptable levels of groundborne vibration for various types of special buildings that are sensitive to vibration. For purposes of identifying pote ntial project-related vibration impacts, the FTA criteria will be used. The human reac tion to various levels of vibr ation is highly subjective. The upper end of the range shown for the threshold of perception, or roughly 65 VdB, may be considered annoying by some people. Vibration below 65 VdB may also cause secondary audible effects, such as a slight rattling of doors, suspended ceilings/fix tures, windows, and dishes, any of which may result in additional annoyance. Table 3-1 shows the FTA groundborne vibration and noise impact criteria for human annoyance.

Table 3-1: Groundborne Vibration and Noise Impact Criteria (Human Annoyance)

Groundborne Vibration
Impact Levels
(VdB re 1 microinch/second)
Groundborne Noise Impact Levels
(dB re 20 micropascals)
Frequent
Events1
Occasional
Events2
Infrequent
Events3
Frequent
Events1
Occasional
Events2
Infrequent
Events3
Category 1: Buildings where low
ambient vibration is essential for interior
operations.
65 VdB4 65 VdB 4 65 VdB 4 N/A 4 N/A 4 N/A 4
Category 2: Residences and buildings
where people normally sleep. 72 VdB 75 VdB 80 VdB 35 dBA 38 dBA 43 dBA Category 3: Institutional land uses with
primarily daytime use. 75 VdB 78 VdB 83 VdB 40 dBA 43 dBA 48 dBA Source: United States Department of Transportation Federal Transit Administration (FTA), Transit Noise and Vibration Impact Assessment, 2018 (FTA, 2018).
1 “Frequent Events” are defined as more than 70 vibration events per day. Most rapid transit projects fall into this category. 2 “Occasional Events” are defined as between 30 and 70 vibration events of the same source per day. Most commuter truck lines have this many operations.
3 “Infrequent Events” are defined as fewer than 30 vibration events of the same kind per day. This category includes most commuter rail branch lines.
4 This criterion limit is based on levels that are acceptable for most moderately sensitive equipment such as optical microscopes.

Vibration-sensitive manufacturing or research will require detailed evaluation to define the acceptable vibration levels. Ensuring lower vibration levels in a building often requires special design of the HVAC systems and stiffened floors. 5 Vibration-sensitive equipment is not sensitive to groundborne noise.

In addition to the vibration annoyance standards presented above, the FTA also applies the following standards for construction vibration damage. Table 3-2 on the following page, structural damage is possible for typical residential construction when the peak particle velocity (PPV) exceeds 0.2 inch per second (in/sec). This criterio n is the threshold at which there is a risk of damage to normal dwellings.

9 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise In the context of this analysis, the noise and vi bration impacts associated with the construction operations and blasting operations will be conditioned to comply with the thresholds stated above.

The potential noise and vibration impacts are analyzed separately below.

Table 3-2: Groundborne Vibration Impact Criteria (Structural Damage) Building Category PPV (in/sec) VdB
I. Reinforced-concrete, steel, or timber (no plaster) 0.5 102 II. Engineered concrete and masonry (no plaster) 0.3 98 III. Non-engineered timber and masonry buildings 0.2 94 IV. Buildings extremely susceptible to vibration damage 0.12 90 Source: United States Department of Transportation Federal Transit Administration (FTA), Transit Noise and Vibration Impact Assessment, 2018 (FTA, 2018).

Notes: RMS velocity calculated from vibration level (VdB) using the reference of one microinch/second.

3.3 Transportation Noise Standards

The City’s General Plan Chapter 7 Noise Element uses the Noise Compatibility Guidelines listed in Table 7-3 of the General Plan Noise Element (provided below as Table 3-3) to determine the compatibility of land use when evaluating proposed deve lopment projects. The Noise Compatibility Guidelines indicate ranges of compat ibility and are intended to be flexible enough to apply to a range of projects and environments (City of San Marcos General Plan, 2012). For example, a commercial project would be evaluated differently than a residential project.

A land use located in an area identified as “acceptable” indicates that standard construction methods would attenuate exterior noise to an acce ptable indoor noise level and that people can carry out outdoor activities with minimal noise interference. Land uses that fall into the “conditionally acceptable” noise environment should have an acoustical study that considers the type of noise source, the sensitivity of the noise receptor, and the degree to which the noise source may interfere with sleep, speech, or other activities characteristic of the land use. For land uses indicated as “conditionally acceptable,” structures must be able to attenuate the exterior noise to the indoor noise level as indicated in the Noise Standards listed in Table 7-4 of the General Plan Noise Element (provided below as Table 3-4). For land uses where the exterior noise levels fall within the “unacceptable” range, new construction generally should not be undertaken.

10 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Table 3-3: Noise Compatibility Guidelines

11 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Table 3-4: Noise Standards

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3.4 Operational Noise Standards

The City noise regulations that apply to the Pr oject are found in Chapter 20.300 Site Planning and General Development Standards of the City Municipal Code. These regulations aim to prohibit unnecessary, excessive, and annoying noises from all sources, as certain noise levels are detrimental to the health and welfare of individuals. The standards of this section and of Chapter

10.24 Noise of the Municipal Code apply to all land uses in all Zones unless otherwise specified.

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 (provided in Table 3-5 on the following page).

The City Ordinance limits noise generation in commercial/and multi-family zones to 65 dB Leq (one-hour average) between the hours of 7 am and 10 pm and 55 dB Leq between the hours of 10 pm and 7 am as measured at the project property line as shown above in Table 3-5. Per the City of San Marcos General Plan Noise Element (GPNE), noise standards for commercial, multi- family, and mixed-use land uses are the same, and are higher than single-family residential areas because they reflect a more urban environmen t (GPNE, pg. 7-10). Higher thresholds are permitted due to the integrated mix of residential and commercial activity and their usual location near major arterials (GPNE, pg. 7-9).

Retail uses are located adjacent to the projec t to the west and are zoned Commercial. The existing AT&T lot located adjacent to the project to the west is zoned Public-Institutional (P-I).

The nearest residential uses are the multi-family units located adjacent to the project to the east and to the south across Armorlite Drive and are zoned under the Palomar Station Specific Plan Area for Mixed-Use. Therefore, the City Ordinance limits of 65 dBA hourly noise standard during the daytime hours between 7 a.m. and 10 p.m., a 55 dBA standard during the nighttime hours between 10 p.m. and 7 a.m. would apply at all property lines.

13 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Table 3-5: Sound Level Limits
Zone Allowable Noise Level (dBA Leq) Measured
from the Property Line
Single-Family Residential (A, R-1, R-2) 1, 2
7 a.m. to 10 p.m. (daytime) 60
10 p.m. to 7 a.m. (overnight) 50
Multifamily Residential (R-3) 1, 2
7 a.m. to 10 p.m. (daytime) 65
10 p.m. to 7 a.m. (overnight) 55
Commercial (C, O-P, SR) 3
7 a.m. to 10 p.m. (daytime) 65
10 p.m. to 7 a.m. (overnight) 55
Industrial
7 a.m. to 10 p.m. (daytime) 65
10 p.m. to 7 a.m. (overnight) 60

1. For single-family detached dwelling units, the “exterior nois e level” is defined as the noise level measured at an outdoor living area which adjoins and is on the same lot as the dwe lling, and which contains at least the following minimum net lot area: (i) for lots 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 the lot area ; (iii) for lots over 10 acres in area, the exterior area shall include 1 acre.

2. For all other residential land uses, “ext erior noise level” is defined as noise measured at exterior areas which are provide d for private or group usable open space purposes. “Private Usab le 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 meets the exterior noise level standard 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 public agency, normally including swimming pools, recreation courts, patios, open landscap ed areas, and greenbelts with pedestrian walkways and eque strian and bicycle trails, but not including off-street parking and loading areas or driveways.

3. For non-residential noise sensitive land uses, exterior noise level is defined as noise measured at the exterior area provided for public use.

14 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise

4.0 CONSTRUCTION NOISE

4.1 Construction Noise Prediction Methodology

Construction noise represents a short-term impact on the ambient noise levels. Noise generated by construction equipment includes haul trucks, water trucks, graders, dozers, loaders and scrapers can reach relatively high levels. Grading activities typically represent one of the highest potential sources for noise impacts. The most effective method of controlling construction noise is through local control of construction hours and by limiting the hours of construction to normal weekday working hours.

The U.S. Environmental Protection Agency (U.S . EPA) has compiled da ta regarding the noise generating characteristics of specific types of construction equipment. Noise levels generated by heavy construction equipment can range from 60 dBA to in excess of 100 dBA when measured at 50 feet. However, these noise levels diminish rapidly with distance from the construction site at a rate of approximately 6 dBA per doubling of distance. For example, a noise level of 75 dBA measured at 50 feet from the noise source to the receptor would be reduced to 69 dBA at 100 feet from the source to the receptor and reduced to 63 dBA at 200 feet from the source.

Using a point-source noise prediction model, calculations of the expected construction noise impacts were completed. The essential model input data for these performance equations include the source levels of each type of equipment, relative source to receiver horizontal and vertical separations, the amount of time the equipment is operating in a given day, also referred to as the duty-cycle and any transmission loss from topography or barriers. The equipment needed for the most intensive grading activities would consist of a medium sized rubber tire tractor/backhoe, a large bulldozer, a medium sized front loader, a water truck, and a small to medium sized paver/blade. Based on the EPA noise emissions, empirical data and the amount of equipment needed, worst case noise levels from the construction equipment for site preparation would occur during the grading operations.

The potential noise sensitive uses are located adjacent or near the property lines. The affected land uses include the existing retail uses adjacent to the project to the west, and the existing multi-family residential uses to the east and south across Armorlite Drive. These uses would be, on average, over 100-feet from the center of the proposed construction activities. W. Mission Road and the railroad line are located to the north and are not consider ed sensitive uses. Existing ambient noise levels were determined to be 61 dBA Leq and 67.6 CNEL without construction noise as identified in Section

5.1 of this report.

4.2 Grading Activities Noise Findings

The grading activities would consist of the preparation of internal roadways, parking, the finished

15 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise pads, and retaining walls. The equipment would be spread out over the project site from distances near the occupied property lines to distances of 200 feet or more away at the western property line.

Based upon the site plan the majority of the grading operations, on average from the center of the construction activities, would occur more than 100 feet from the property lines. This means that most of the time the average distance from all the equipment to the nearest property line is 100 feet.

As can be seen in Table 4-1, at an average distance of 100 feet from the center of the construction activities to the nearest property line would re sult in a noise attenuati on of 6.0 dBA without shielding. This results in a property line noise le vel of 74.1 dBA. Given this, the noise levels will comply with the 75 dBA Leq standard at the property lines. Therefore, the construction noise impacts would be considered less than significant and no mitigation is required during construction of the proposed Project. Additionally, all equipment should be properly fitted with mufflers and all staging and maintenance should be conducted as far away from the existing residences as possible. Because the rock drill and rock crusher will work independently of the construction equipment, additional analysis for each or them is provided below.

Table 4-1: Construction Noise Levels
Equipment Type Quantity Used Source @ 50 Feet
(dBA)
Cumulative Noise Level
@ 50 Feet (dBA)
Tractor/Backhoe 1 72 72.0
Dozer D9 Cat 1 74 74.0
Loader/Grader 1 73 73.0
Water Trucks 1 70 70.0
Paver/Blade 1 75 75.0
Cumulative Level 80.1
Distance to Sensitive Use 100
Noise Reduction due to Distance -6.0
Property Line Noise Level 74.1

Haulage

Grading would consist of approximately 6,950 cubi c yards (CY) of cut material and 4,400 CY of fill material. Based on discussions with the engi neer, shrinkage would be expected and the total export expected would be approximately 2,250 CY of material. Assuming the use of 15 CY trucks and 15 work days, this equates to approximately 10 truck trips per day. Community noise level changes greater than 3 dBA are often identified as audible and considered potentially significant,

16 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise while changes less than 1 dBA will not be discernible to local residents. In the range of 1 to 3 dBA, residents who are very sensitive to noise may perceive a slight change. There is no scientific evidence available to support the use of 3 dBA as the significance threshold. Community noise exposures are typically over a long time period rather than the immediate comparison made in a laboratory situation. Therefore, the level at which changes in community noise levels become discernible is likely greater than 1 dBA and 3 dBA appears to be appropriate for most people. For the purposes of this analysis a direct and cumulative roadway noise impacts would be considered significant if the project increases noise levels for a noise sensitive land use by 3 dBA CNEL and if the project increases noise levels above an unacceptable noise level per the City’s General Plan in the area adjacent to the roadway segment.

Typically, it requires a project to double (or add 100%) to the traffic volumes to result in a 3 dBA CNEL which is considered a potential impact. Based on a current traffic volume of approximately 5,000 ADT or more on the roadwa ys along the site and along th e anticipated haul route, the additional trucks would add less than 0.5 dBA to the overall noise level. This is well below a 3 dBA increase that is considered a potential im pact. No noise impacts are anticipated at the residential uses that are located along the roadway due to the low volume of trucks.

4.3 Rock Drill Noise Findings and Mitigation

Areas of the project site that require deeper cuts and where the native material is not easily rippable (graded) may require blasting and the use of a rock drill. The rock drill would be moved around the site on an as needed basis dependent upon the site characteristics. The use of a rock drill would occur independently of all other proposed equipment. The drilling and blasting activities would occur in one area then the grading eq uipment would relocate or remove the debris. To determine the worst-case noise levels from the drilling operations the noise level from the rock drill would be 85.0 dBA at 50 feet (Federal Highway Administration, 2006)
; (Ontario Ministry of Labour, 2016). Utilizing
a 6 dBA reduction per doubling of distance, at an average distance of 160 feet from any property line, the noise levels will comply with the 75 dBA standard as shown in Table 4-2.

Table 4-2: Construction Noise Levels from Rock Drill
Construction
Equipment Quantity
Source Level
@ 50 Feet
(dBA)
Duty Cycle
(Hours/Day)
Noise Level @ 50 Feet
(dBA)
Rock Drill 1 85 8 85.0
Noise Reduction Needed to Comply -10.0
Distance Required to Reduce Noise Levels 160
NEAREST PROPERTY LINE NOISE LEVEL 74.9

17 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Rock drilling and blasting will occur on an as-needed basis on site. In the event that the rock drill is staged within 160 feet of any occupied noise sensitive land use, it is recommended that a specific noise mitigation plan based upon the location of the construction equipment, topography and construction schedule be identified by an acoustical engineer. A mitigation plan should be developed that may include a temporary noise barrier along any property line where the impacts could occur.

The mitigation plan would determine the final height and location of a temporary barrier if one is necessary. The project’s requested approvals include a Conditional Use Permit, which would allow for the use of the temporary rock crusher.

Blasting may be required during the project grading and site preparation activities. The project would comply with all provisions identified in the City’s Municipal Code Section 17.60.06 as it relates to blasting and blasting shall only be permitted between the hours of 9:00 AM and 4:00 PM during any weekday.

4.4 Rock Crushing Noise Findings and Mitigation

This section examines the potential noise source impacts associated with the operation of the proposed temporary rock crushing facility. Rock crushing will oc cur between the hours of 7:00 AM and 4:00 PM. The rock crushing equipment will be located in the northwest corner of the site in the proposed parking area, over 200 feet from the nearest residences to the east, over 500 feet from the residences to the south, and over 200 feet from the nearest commercial use to the southwest. Based on empirical data collected at the existing Mission 316 residential development from a similar rock crusher, noise levels rang ed between 70-72 dBA at 100 feet (Ldn, 2021). A worst-case noise level of 72 dBA at 100 feet will be utilized for the analysis.

As can be seen in Tables 4-3 and 4-4, the anticipated noise levels at the eastern multi-family residential property line and commercial property line to the southwest would be below the City’s 75 dBA Leq construction noise standard without mitigation. In the past, the City of San Marcos has applied the operational noise standards to rock crushing activities when operating on a longer- term basis. The rock crushing equipment woul d be in compliance with the City’s 65 dBA Leq operational noise standard at the nearest multi-family residences and and the City’s 70 dBA Leq operational standard without mitigation. The prop erty directly to the west is zoned Public- Institutional (P-I) with minimal usage and would not be considered a sensitive use. Therefore, no impacts are anticipated and no mitigation is required.

Additionally, if the City applies the operational noise threshold of 65 dBA Leq and the rock crusher

18 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise is located within 210 feet of multi-family residential uses or within 160 feet of the commercial use without shielding, noise levels may exceed the applied threshold. If noise levels are found to be above the applied thresholds of 65 dBA for any multi-family residential use or 70 dBA at a commercial use then additional mitigation in the form of higher barriers, sound absorbing materials or operational limits on the crusher’s usage will need to be incorporated.

Table 4-3: Rock Crushing Noise Levels (Residential Receptors) Equipment Type Quantity
Used
Source @ 100
Feet (dBA)
Duty Cycle
(hrs/day)
Cumulative Noise Level @
100 Feet (dBA)
Thunderbird Hazemag
#CP300 1 72 8 72.0
Distance to Sensitive Use 220
Noise Reduction due to Distance -6.8
Property Line Noise Level 65

Table 4-4: Rock Crushing Noise Levels (Commercial Receptors) Equipment Type Quantity
Used
Source @ 100
Feet (dBA)
Duty Cycle
(hrs/day)
Cumulative Noise Level @
100 Feet (dBA)
Thunderbird Hazemag
#CP300 1 72 8 72.0
Distance to Sensitive Use 220
Noise Reduction due to Distance -6.8
Property Line Noise Level 65

4.5 Construction Vibration Findings and Mitigation

The nearest vibration-sensitive uses are the existi ng multi-family homes to the east located 100 feet or more from the center of the proposed construction. Table 4-5 lists the average vibration levels that would be experienced at the nearest vibration sensitive land uses from the temporary construction activities.

The FTA has determined vibration levels that would cause annoyance to a substantial number of people and potential da mage to building structures. The FT A criterion for vibration induced structural damage is 0.20 in/sec for the peak particle velocity (PPV). Project construction activities would result in PPV levels below the FTA’s criter ia for vibration induced structural damage, as

19 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise shown in Table 4-5 Therefore, project construction activities would not result in vibration induced structural damage to residentia l buildings near the construction areas. The FTA criterion for infrequent vibration induced annoyance is 80 Vibration Velocity (VdB) for residential uses.

Table 4-5: Vibration Levels from Construction Activities (Residential Receptors) Equipment
Approximate
Velocity Level
at 25 Feet
(VdB)
Approximate
PPV Level
at 25 Feet
(in/sec)
Approximate
Velocity Level
at 100 Feet
(VdB)
Approximate
PPV Level
at 100 Feet
(in/sec)
Small bulldozer 58 0.003 40.0 0.0004
Jackhammer 79 0.035 61.0 0.0044
Loaded trucks 86 0.076 68.0 0.0095
Large bulldozer 87 0.089 69.0 0.0111
FTA Criteria 80 0.2
Significant Impact? No No
1 PPV at Distance D = PPVref x (25/D)1.5

4.6 Blasting Vibration Findings and Mitigation

Blasting for construction projects typically results in an RMS vibration velocity of about 100 VdB at 50 feet from the blast based on FTA findings. Th is is equivalent to a pe ak particle velocity of about 0.4 inch per second. As discussed above, the nearest distance between an existing residential building and the blasting activity wa s assumed to be 200 feet. Given attenuation of vibration velocities with distance, the RMS vibration velocity and peak particle velocity at the nearest existing residences would be about 82 VdB and 0.05 inch per second, respectively. Based on the construction vibration damage criteria published by the FTA, the threshold vibration levels for damage to "Non-engineered timber and masonry buildings" are 94 VdB and 0.20 inch per second. Therefore, the effect of the blasting activity on nearby residential structures will not be significant. On the other hand, the human annoyance criterion of 80 VdB would be slightly exceeded when blasting occurred within about 250 feet of existi ng residences. If blasting is required within 250 feet of existing residences , the potential annoyance may not be completely avoided. However, it can be minimized by following the City’s blasting procedures as stated above in Section 3.2 by providing proper notice.

20 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise

4.7 Construction Noise and Vibration Conclusions

Additionally, the project may require blasting whic h would also require the need for a rock drill.

Based on previous projects, a barrier ranging fr om 8 to 12 feet in height maybe needed. The proposed noise barrier will need to be of solid non-gapping material to adequately reduce construction noise levels below the noise threshold. The mitigation plan can also incorporate the usage of the equipment (amount of time used and/or the location in respect to the property line).

The mitigation plan would determine the final height and location of a temporary barrier if one is necessary.

The rock crushing equipment will be located in the northwest portion of the site at the proposed parking area, and more than 200 feet from the nearest residential property line. The noise levels are anticipated to be below the City’s 65 dBA Leq standard at the property lines without mitigation.

Noise measurements of the rock crusher should be conducted once the final crusher type and location are determined to ensure compliance with the City’s thresholds. If noise levels are found to be above the established thresholds of 60 dBA at any existing single-family residential use, 65 dBA for any multi-family use, or 70 dBA at a co mmercial use, then additional mitigation in the form of higher barriers, sound absorbing materials or operational limits on the crushers usage will need to be incorporated.

21 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise for infrequent vibration induced annoyance is 80 VdB for residential uses. Construction activities would generate levels of vibration that would not exceed the FTA criteria for nuisance for nearby residential uses. Therefore, vibration impacts would be less than significant.

22 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise

5.0 TRANSPORTATION NOISE

5.1 Existing Noise Environment Onsite

A long-term 24-hour measurement was taken at the project site having a relatively flat terrain and no obstruction from trees or structures. The noise measurement was recorded from Thursday December 7th to Friday December 8th, 2023 by Ldn Consulting between approximately 1:00 p.m. and 1:00 p.m. the following day. The noise measurement was taken using a Larson-Davis Spark Model 706 Type 2 precision sound level meter, programmed, in "slow" mode, to record noise levels in "A" weighted form. The sound level meter and microphone were mounted on a tripod, five feet above the ground and equipped with a windscreen during all measurements. The sound level meter was calibrated before and after the monitoring using a Larson-Davis calibrator, Model CAL 200.

Table 5-1 provides the hourly noise levels alon g with the average and CNEL values. The noise measurement location was determined based on site access and noise impact potential to the proposed sensitive uses. Long-term monitoring location 1 (LT-1) was located at the northern portion of the project site. The noise monitoring location is provided graphically in Figure 5-1.

Table 5-1: Long-Term Noise Level Summary
Time
LT-1
(Leq)
LT-1
(CNEL)
2:00 PM 60.0 60.0
3:00 PM 62.5 62.5
4:00 PM 62.6 62.6
5:00 PM 64.9 64.9
6:00 PM 63.4 63.4
7:00 PM 63.6 63.6
8:00 PM 62.9 67.9
9:00 PM 63.6 68.6
10:00 PM 57.1 62.1
11:00 PM 60.4 70.4
12:00 AM 51.7 61.7
1:00 AM 50.6 60.6
2:00 AM 49.4 59.4
3:00 AM 49.7 59.7
4:00 AM 49.5 59.5
5:00 AM 62.4 72.4
6:00 AM 65.1 75.1
7:00 AM 65.3 75.3
8:00 AM 62.9 62.9
9:00 AM 64.4 64.4
10:00 AM 61.7 61.7
11:00 AM 58.4 58.4
12:00 PM 60.6 60.6
1:00 PM 60.4 60.4
Overall 61.8 67.6

23 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Figure 5-A: Ambient Monitoring Location

LT-1

24 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise

5.2 Future Onsite Roadway Noise

To determine the future noise environment, the projected roadway segment noise levels were calculated using the methods in the Highway Noise Model published by the Federal Highway Administration (Source: (FHWA, 1978)). The FHWA Model uses the traffic volume, vehicle mix, speed, and roadway geometry to compute the equi valent noise level. The peak hour traffic volumes range between 6-12% of the average daily traffic (ADT) and 10% is generally acceptable for noise modeling.

Table 5-2 presents the roadway parameters used in the analysis including the peak traffic volumes, vehicle speeds and the hourly traffic flow distribution (vehicle mix). The vehicle mix provides the hourly distribution percentages of automobiles, medium trucks and heavy trucks for input into the FHWA Model. The Buildout conditions for W. Mission Road, Las Posas Road, and Armorlite Drive include the future year 2050 traffic volume forecasts provided by the project traffic study by Linscott, Law, & Greenspan, (Linscott, Law, and Greenspan, 2023). In addition, the Project is located over 1,000 feet north of SR-78. According to the City of San Marcos’ General Plan Noise Element, background noise levels from future traffic along SR-78 is 60 dBA CNEL at approximately 800 feet. The noise contours for this area would also include traffic noise from W. Mission Road and Las Posas Road. Sprinter noise may also contri bute to that contour. The modeled observer locations for the potential outdoor use areas for are presented in Figure 5-B.

Table 5-2: Future Traffic Parameters
Roadway
Average
Daily Traffic
(ADT)1
Peak Hour
Volumes1
Modeled
Speeds
(MPH)
Vehicle Mix %2
Auto Medium
Trucks
Heavy
Trucks
W. Mission Road 22,450 2,245 45 96 2 2
Las Posas Road 36,290 3,629 45 96 2 2
Armorlite Drive 6,704 670 25 96 2 2
1 Source: Linscott Law and Greenspan, Armorlite Apartments Draft Local Transportation Analysis, Year 2050 2 Typical City vehicle mix

25 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Figure 5-B: Modeled Receptor Locations

1 Modeled Receptors
5 5
2 4
3 26
Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise

5.3 Onsite Rail Line Noise

The proposed Project property line is located a pproximately 42 feet from the centerline of the San Diego Northern Railroad (SDNR) consisting of Sprinter service operated by the NCTD.

According to the City of San Marcos General Plan Noise Element, the 65 dBA CNEL noise contour from the rail activity, with no shielding, is located 130 feet from the centerline of the railroad.

5.4 Cumulative Noise Levels

The noise levels determined for the roadway and train activities were combined to determine the overall cumulative noise levels at the proposed receptors. Sound levels are logarithmic and so cannot be manipulated without being converted back to a linear scale. You must first antilog each number, add or subtract and then log them again in the following way.

𝐿 =1 0 ∗𝐿 𝑜 𝑔 ∑ 10
ಽ೔
భబ௡
௜ 𝑜𝑟 𝐿 = 1 0 ∗ 𝐿𝑜𝑔 [10
ఱర
భబ + 1 0
ఱవ
భబ
] =60 dBA CNEL

A spreadsheet calculation was used which computes equivalent noise levels for each of the time periods used in the calculation of CNEL. Weighting these equivalent noise levels and summing them gives the CNEL for the traffic projections. The modeling results for the adjacent roadways and the cumulative noise levels with the background noise from Las Posas Road, SR-78, and train noise are provided in Figure 5-C, on the following page. Additionally, three decibels of attenuation is allowed for the first row of buildings when they block 40 to 65% of the line of sight to the noise source, and five decibels of attenuation is allowed when the buildings obstruct more than 65% of the line of sight (Source: (Caltrans, 2006)). The line of sight to the roadways are blocked by the existing and proposed structures, therefore, a factor of 3 or 5 dBA was taken into account as shown in Figure 5- C.

Based upon these findings, noise control recommendations are necessary at the balconies/decks along W. Mission Road and Las Posas Road to comply with the City Noise Standard of 65 dBA CNEL.

To determine the required barrier heights at the balconies along W. Mission Road and Las Posas Road, the Fresnel Barrier Reduction Calculations, used to determine barrier attenuation based on distance, source height, receiver elevation and the top of barrier, were modeled. The Fresnel calculations are provided as an
Attachment A.

It was determined that 3.5-foot noise barriers located at the balconies would provide a 6.1 dBA noise reduction along the northern façade an d a 5.3 dBA noise reduction along the western façade. Based upon these findings the future noise levels at the balconies were found to comply with the City’s 65 dBA CNEL noise standard. These recommendations are shown in Figure 5-D for the balconies/decks. The barriers must be constr ucted of a non-gapping material consisting of masonry, ¼ inch thick glass, earthen berm or any combination of these materials.

27 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Figure 5-C: Future Unmitigated Exterior Noise Levels

28 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Figure 5-D: Noise Control Recommendations

Balconies Requiring

3.5-Foot Barriers

29 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise It was determined that noise levels at the comm on outdoor areas would comply with the City’s 65 dBA CNEL noise standard with no mitigation. Additionally, the project is proposing minimum

3.5-foot barriers at the pool area which would further reduce noise levels. The overall reduced noise levels are shown in Table 5-3.

Table 5-3: Exterior Noise Levels with Balcony Design Features Receptor
Number Receptor Location
Noise Level
@ Receptor
(dBA CNEL) 1
Reduction Due
to Barriers
(dBA CNEL)
Resultant
Noise Level
(dBA CNEL)
1 Building Facades along W. Mission Road 70.4 -6.1 64.3 2 Building Facades facing Las Posas Road 69.1 -5.3 63.8 3 Internal Courtyard 59.6 - 59.6
4 Pool Area 64.9 -5.0 59.9
5 Building Facades along Armorlite Drive 65.4 - 65.4
1 FHWA Highway Traffic Noise Prediction Model, FHWA-RD-77-108

It should be noted that the ground floor flex units along Armorlite Drive to the south could potentially be converted to residential units and would be required to comply with the City’s 65 dBA CNEL noise standard. The units would comply with the City’s 65 dBA CNEL noise standard without additional noise mitigation measures.

Additionally, a final interior noise assessment is required prior to the issuance of the first building permit since the exterior noise levels at the building facades are above 60 dBA CNEL. This final report would identify the interior noise requirements based upon architectural and building plans to meet the City’s established interior noise limit of 45 dBA CNEL. It should be noted; interior noise levels of 45 dBA CNEL can easily be obtained with conventional bu ilding construction methods and providing a closed window condition requiring a means of mechanical ventilation (e.g., air conditioning) for each building and upgraded windows for all sensitiv e rooms (e.g., bedrooms and living spaces).

5.5 Project Related Offsite Transportation Noise

To determine if direct or cumulative off-site noise level increases associated with proposed project development would create noise impacts, the tra ffic volumes for the existing conditions were compared with the traffic volume increase of exis ting plus the proposed project. The project is estimated to only generate 1,214 daily trips with a peak hour volume of 109 trips according to the project traffic study (Linscott, Law, and Greenspan, 2023)). The existing average daily traffic (ADT) volumes on the adjacent roadways is several thousand ADT according to the traffic study.

Typically, it requires a project to double (or add 100%) the traffic volumes to have a direct impact

30 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise of 3 dBA CNEL or be a major contributor to the cumulative traffic volumes. The project would not double the traffic volumes to any adjacent roadway volumes. Therefore, no direct or cumulative impacts are anticipated.

5.6 Transportation Noise Conclusions

The results of this analysis indicate that futu re vehicle noise from Las Posas Road, W. Mission Road, Armorlite Drive, SR-78, and the Sprinter commuter rail are the prin cipal sources of noise that will impact the site. Due to the combined roadway and train activities, the outdoor use areas were found to exceed the City’s 65 dBA CNEL threshold without noise control measures. Noise control recommendations in the form of 3.5-foot barriers installed at the balconies/decks for the units having direct line of sight to W. Mission Road and Las Posas Road is needed to comply with the City of San Marcos Noise standards for multi-family uses based on transportation related noise sources (i.e., vehicle).

31 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise

6.0 OPERATIONAL NOISE

This section examines the potential operational noise source levels associated with the development and operation of the proposed project. Noise from a fixed or point source drops off at a rate of 6 dBA for each doubling of distance. Which means a noise level of 70 dBA at 5 feet would be 64 dBA at 10 feet and 58 dBA at 20 feet. A review of the proposed project indicates that noise sources such as the roof mounted mechanical ventilation system (HVAC) are the primary source of stationary noise.

The project is adjacent to existing multi-family residential uses to the east. Therefore, the City Ordinance limits of 65 dBA hourly noise standard during the daytime hours between 7 a.m. and 10 p.m., a 55 dBA standard during the nighttime hours between 10 p.m. and 7 a.m. would apply at all property lines.

Roof-top mechanical ventilation units (HVAC) will be installed at the proposed residential units.

The project anticipates installing Carrier CA15NA (Series, 24-A) or equivalent HVAC units with a reference noise level of 71 dBA at 3-feet (Source: Carrier). The manufacturer’s specifications and noise levels are provided in Attachment B. Th e HVAC units will cycle on and off throughout the day. Typically, HVAC units run for approximately 20 minutes each operating cycle to provide the necessary heating or cooling. It is anticipated that the HVAC units will operate twice in any given hour or run for 40 minutes in any given hour. Noise levels drop 3 decibels each time the duration of the source is reduced in half.

Therefore, hourly HVAC noise level over a 40-minute period would be reduced approximately 2 decibels to 69 dBA based on operational time. To predict the property line noise level, a reference noise level of 69 dBA at 3-feet was used to represent the HVAC units.

The HVAC units are located a minimum of 46 feet from the eastern residential property line and will be shielded by the parapet walls that will brea k the line of sight to the HVAC units and will provide a minimum 5 dBA reduction (Federal Highway Administration, 2017). Up to 20 units will be clustered together closest to the nearest residential property line to the east. At any point along the property line, the receiver would be exposed to more than the 20-unit cluster. However, the additional clusters are separated by at least 80 feet and this separation would result in a 20 dBA difference between other HVAC clusters. This 20 dBA difference would not cumulatively increase the noise levels at the point of the receiver. Therefore, the worst-case combined noise from the HVAC would occur from 20 units.

32 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Utilizing a 6 dBA decrease per doubling of distance, noise levels at the nearest residential property line as described above were calculated for the HVAC. The HVAC units are located a minimum of 46 feet from the nearest residential property line to the east. The noise level reductions due to distance and the building for the nearest property line is provided in Table 6-1.

Table 6-1: Project HVAC Noise Levels (Eastern Residential Property Line) Distance to
Nearest
Observer
Location
(Feet)
Hourly
Reference
Noise
Level
(dBA)
Noise
Source
Reference
Distance
(Feet)
Noise
Reduction
Due to
Distance
(dBA)
Reduction
Due to
Buildings
(dBA)
Noise
Level at
Property
Line
(dBA)
Quantity
Property
Line
Cumulative
Noise Level
(dBA)*
46 69.0 3.0 -23.7 -5.0 40.3 20 53.3
*Complies with the nighttime Noise Standard of 55 dBA.

Additionally, the noise levels at the nearest retail uses adjacent to the project to the west were analyzed using the same methodology described ab ove. Up to 20 units w ill be clustered closest to the western property line and would be separated by the remaining HVAC units by parapet walls and distance. Based on the distance to the property line to the west, noise associated with the operation of the HVAC units are expected to be up to 48.0 dBA, which is below the 55 dBA nighttime threshold for commercial uses. The mult i-family residential property line to the south is located further than the property line to the east, therefore, would also comply.

The noise levels from the proposed roof-mounted HVAC would be considered less than significant at the residential property line to the east an d south and the commercial lines to the west with the proposed parapet walls and are in compliance with the City of San Marcos Municipal Code Sections 10.24.

33 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise

7.0 SUMMARY OF PROJECT IMPACT S, MITIGATION & CONCLUSION

Construction Noise

Additionally, the project may require blasting whic h would also require the need for a rock drill.

The mitigation plan would determine the final height and location of a temporary barrier if one is necessary.

Rock Crusher Noise
The rock crushing equipment will be located in the northwest portion of the site at the proposed parking area, and more than 200 feet from the nearest residential property line. The noise levels are anticipated to be below the City’s 60 dBA Leq standard at the property lines without mitigation.

Noise measurements of the rock crusher should be conducted once the final crusher type and location are determined to ensure compliance with the City’s thresholds. If noise levels are found to be above the established thresholds of 60 dBA at any existing single-family residential use, 65 dBA for any multi-family use, or 70 dBA at a co mmercial use, then additional mitigation in the form of higher barriers, sound absorbing materials or operational limits on the crushers usage will need to be incorporated.

34 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise Construction Vibration

Blasting Vibration

Blasting for construction projects typically results in an RMS vibration velocity of about 100 VdB at 50 feet from the blast based on FTA findings. Th is is equivalent to a pe ak particle velocity of about 0.4 inch per second. Given attenuation of vibration velocities with distance, the RMS vibration velocity and peak particle velocity at the nearest existing residence would be about 82 VdB and 0.05 inch per second, respectively. Based on the construction vibration damage criteria published by the FTA, the threshold vibration levels for damage to "Non-engineered timber and masonry buildings" are 94 VdB and 0.20 inch per second.

Therefore, the vibration effect of the blasting activity on nearby residential structures will not be significant. On the other hand, the human annoyance criterion of 80 VdB would be slightly exceeded when blasting occurred within about 250 feet of existing residences. If blasting is required within 250 feet of existing residences , the potential annoyance may not be completely avoided, however, it can be minimized by following the City’s blasting procedures.

Onsite Transportation Noise

The results of this analysis indicate that futu re vehicle noise from Las Posas Road, W. Mission Road, Armorlite Drive, State Route 78 (SR-78), and the Sprinter commuter rail are the principal sources of noise that will impact the site. Due to the combined roadway and train activities, the outdoor use areas were found to exceed the City’s 65 dBA CNEL threshold without noise control measures. Noise control recommend ations in the form of 3.5-fo ot barriers installed at the balconies/decks for the units having direct line of sight to W. Mission Road and Las Posas Road is needed to comply with the City of San Marcos Noise standards for multi-family uses based on transportation related noise sources (i.e., vehicle).

35 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise a closed window condition requiring a means of mechanical ventilation (e.g., air conditioning) and upgraded windows for all sensitive rooms (e.g., bedrooms and living spaces).

Offsite Transportation Noise

Operational Noise

Based on noise levels, the distances to the property lines and the proposed parapet walls shielding the HVAC units, the noise levels from the proposed roof-mounted HVAC would be considered less than significant at the residential property lin es to the east and south, and the commercial property lines to the west, and are in complianc e with the City of San Marcos Municipal Code Sections 10.24.

36 Ldn Consulting, Inc. 12/11/23 22-124 Armorlite Lofts 225 Noise

8.0 REFERENCES

Caltrans2020Transportation Related Earthborne Vibration, Caltrans Experiences City of San Marcos General Plan2012Noise Element of the General Plan City of San Marcos Municipal Code2019City of San Marcos Municipal Code Federal Highway Administration1978Highway Traffic Noise Prediction ModelFHWA-RD-77-108 Federal Highway Administration2006Highway Construction Noise Handbook Federal Highway Administration2017Noise Barrier Design Handbook FTA2018Transit Noise and Vibration Impact Assessment
Google2023
Linscott, Law, and Greenspan2023Armorlite Apartments Local Transportation Analysis Ontario Ministry of Labour2016Training, and Skills Development Summa Architecture2024Conceptual Site Plan

ATTACHMENT A

FRESNEL BARRIER CALCULATIONS

W. Mission Road

Source to Receiver Horizontal Distance (ft) = 203.00
Source to Barrier Horizontal Distance (ft) = 200.00
Barrier to Receiver Horizontal Distance (ft) = 3.00
Source Height (ft) = 0.00
Receiver Height (ft) = 18.00
Barrier Height (ft) = 18.50
Distance Source to Receptor (ft) d = 203.80
Distance Source to Barrier top (ft) d1 = 200.85
Distance Barrier top to Receiver (ft) d2 = 3.04

Frequency (Hz) = 500 Attenuation (db) = 5.9 Fresnel N = 0.088

Sprinter

Source to Receiver Horizontal Distance (ft) = 103.00
Source to Barrier Horizontal Distance (ft) = 100.00
Barrier to Receiver Horizontal Distance (ft) = 3.00
Source Height (ft) = 0.00
Receiver Height (ft) = 18.00
Barrier Height (ft) = 18.50
Distance Source to Receptor (ft) d = 104.56
Distance Source to Barrier top (ft) d1 = 101.70
Distance Barrier top to Receiver (ft) d2 = 3.04

Frequency (Hz) = 500 Attenuation (db) = 6.8 Fresnel N = 0.157

Las Posas Road

Source to Receiver Horizontal Distance (ft) = 291.00
Source to Barrier Horizontal Distance (ft) = 288.00
Barrier to Receiver Horizontal Distance (ft) = 3.00
Source Height (ft) = 0.00
Receiver Height (ft) = 18.00
Barrier Height (ft) = 18.50
Distance Source to Receptor (ft) d = 291.56
Distance Source to Barrier top (ft) d1 = 288.59
Distance Barrier top to Receiver (ft) d2 = 3.04

Frequency (Hz) = 500 Attenuation (db) = 5.5 Fresnel N = 0.070

San Marcos City CouncilJune 24, 2025

San Marcos City Council
June 24, 2025