Appendix I-2
Noise Technical Memorandum for the
Pacific Specific Plan Project Alternative
MEMORANDUM
To: City of San Marcos
From: Connor Burke, INCE.
Subject: Reduced Pacific Specific Plan Project Alternative Date: January 4, 2024
Attachment(s): A: Noise Technical Report for the Pacific Project, November 2022
This memorandum summarizes potential noise and vibration impacts associated with the Reduced Pacific Specific Plan Project Alternative, the revised 299-unit residential development project plan for the Pacific Project , in comparison to the previous 449 -unit 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.).
The following analysis refers to the Noise Technical Report we prepared for the Pacific Project dated November 2022 (Attachment A) and compares the anticipated noise and vibration impacts from the revised 299-unit project to the previous 449-unit project.
1 Impact Discussion
1.1 Short-Term Construction
The revised project would eliminate the apartment units previously proposed in the northeastern portion of the site, reducing the overall residential unit count from 449 to 299 units. This reduction in the development footprint and scale of construction would likewise proportionally reduce demolition, grading, and building construction noise generated on-site. The technical analysis of the previous 449 -unit project concluded con struction noise impacts would be less than significant with construction occurri ng during allowable daytime hours. The revised 299-unit project confined to the remaining portions of the site would likewise generate construction noise within acceptable levels. Construction noise impacts would be reduced compared to the previous project and remain less than significant without need for additional mitigation.
1.2 Roadway Traffic Noise
The reduction in project units from 449 to 299 would proportionally decrease the amount of traffic added to nearby roadways. With 1 50 fewer units, the project vehicle trip generation would be reduced by approximately 33% (assuming consistent trip generation rates per unit). Traffic noise levels increase logarithmically in relation to the actual traffic volume. Therefore, a 33% reduction in project traffic volumes would correspond to approximately a 1
MEMORANDUM
SUBJECT: REDUCED PACIFIC SPECIFIC PLAN PROJECT ALTERNATIVE
13170 2 JANUARY 2024
dB decrease in traffic noise levels generated by the project. The traffic noise analysis for the 449 -unit project did not identify any significant impacts at sensitive receptors. The incremental 1 dB reduction in traffic noise for the smaller 299-unit project reaffirms that this impact would remain less than significant and marginally improved compared to the prior project site plan.
1.3 Stationary Operations Noise
With fewer residential units proposed, stationary noise sources associated with building operations, such as HVAC systems, would likewise be reduced compared to the previous project. Stationary noise impacts associated with the 449 -unit project were found to be less than significant. The smaller 299-unit project would further reduce stationary noise levels and this impact would remain less than significant.
1.4 Conventional Construction Activity Vibration
The overall reduction in project scale and concentration of construction activities within the remaining project site areas would result in similar vibration levels compared to the previous project. Construction vibration impacts associated with the 449-unit project were found to be less than significant at nearby sensitive receptors. The 299- unit project would generate similar vibration levels that would remain below thresholds for human annoyance and building damage. Vibration impacts would be similar to the previous project and less than significant without mitigation needed.
2 Conclusion
In summary, the reduction in project units from 449 to 299 would proportionally decrease construction and operational noise levels, as well as groundborne vibration generated by the project. The noise and vibration analyses conducted for the previous 449-unit project did not identify any significant impacts. The revised 299-unit project would further reduce the projected noise and vibration levels. Impacts would remain less than significant and no additional mitigation measures are necessary beyond what was identified for the previous project.
This technical memorandum appends the previous Noise Technical Report dated November 2022 prepared for the original 449-unit project. The memorandum demonstrates the revised 299-unit project would have reduced noise and vibration impacts compared to the previous project.
Should you have any questions, comments, or suggestions on how this memo could better suit your needs, please do not hesitate to contact me at [email protected].
Sincerely,
Connor Burke, INCE
Environmental Noise Specialist
78 SOURCE: USGS 7.5-Minute Serues San Marcos Quadrangle Date: 3/23/2021 - Last saved by: agreis - Path: Z:\Projects\j1317001\MAPDOC\DOCUMENT\Cultural\Figure1-ProjectLocation.mxd 02 , 0 0 0 1,000
Feet
Project Boundary
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
78 580
215
15 5
8 Project Site
FIGURE 1
Project Location
Pacific Specific Plan
SOURC
E: Summ
a Architecture,
2024
Z:\Projects\j1317001\MAPDOC\DOCUMENT\EIR
FIGURE 2
Reduced Pacific Specific Plan Project Alternative
Pacific Project EIR