From: Healey, William
To: Mary Jeyaprakash
Cc: Schmidt, Melinda; Smithson, Dawn; Noren Caliva-Lepe; Gonzalez, Salvador Subject: RE: Additional Items from Planning Commission Hearing Date: Friday, May 8, 2026 10:25:21 AM
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Hello,
I believe the last outstanding item is a response clarifying why Cal Water needs to drill a new well at the LAS Sta. 20 property. Here is the response:
The issue is not whether another existing Cal Water station could physically be used for a new well.
The issue is that Cal Water has multiple aging wells that will need to be replaced over time and only a limited number of existing stations available for replacement well construction.
There are five active wells in the City and only seven Cal Water stations total. LAS Sta. 20 is not currently supplying water, which makes it better suited for well construction because the work can be completed without disrupting Cal Water’s ability to reliably supply water. Cal Water’s other stations are currently operating, and drilling a new well at those sites could require taking active facilities out of service.
For these reasons, LAS Sta. 20 is an important site for maintaining long-term supply reliability and fire protection. Removing LAS Sta. 20 from consideration would further limit the number of viable station sites available for future well replacement work and could make it more difficult to replace aging wells while maintaining reliable service.
Thanks,
William Healey, P.E.
P-3 Project Engineer
California WatEr SErviCE
+1 (213) 5769867
Quality. Service. value.
calwater.com
from: Mary Jeyaprakash <[email protected]>
Sent: Thursday, May 7, 2026 11:58 AM
Applicant Memo: Feasibility for Alternate Site
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Introduction 0
800 Carlisle Way Well & Water
Tank Project Preliminary Noise and
Vibration Monitoring Plan
Prepared for:
California Water Service Company
2632 W. 237th Street
Torrance, CA 90505
Prepared by:
Behrens and Associates, Inc.
2320 Alaska Avenue
El Segundo, California 90245
Carol Colby
Acoustical Engineer Jason Peetz
Engineering Manager
June 12, 2026
Corporate Office: El Segundo, California
Carson, California ~ Aledo, Texas ~ Longmont, Colorado ~ Smithton, Pennsylvania ~ Red Deer, Alberta Oakland, California ~ Johnson City, Tennessee
Phone 800-679-8633 ~ Fax 310-331-1538
www.environmental-noise-control.com ~ www.drillingnoisecontrol.com Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Introduction 1
1. Introduction
The following Noise and Vibration Monitoring Plan was developed to outline the noise and vibration monitoring procedure for the 800 Carlisle Way Well & Water Tank Project (Project). This plan is for monitoring the water well drilling operations at the 800 Carlisle Way Well & Water Tank Project in Sunnyvale, California. The location of the Project site is shown in Figure 1-1
Figure 1-1 Project Site Location
800 Carlisle Way
Well & Water Tank
Project Site
Location
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Introduction 2
1.1 Noise Fundamentals
Sound is most commonly experienced by people as pressure waves passing through air. These rapid fluctuations in air pressure are processed by the human auditory system to produce the sensation of sound. The rate at which sound pressure changes occur is called the frequency . Frequency is usually measured as the number of oscillations per second or Hertz (Hz). Frequencies that can be heard by a healthy human ear range from approximately 20 Hz to 20,000 Hz. Toward the lower end of this range are low-pitched sounds, including those that might be described as a “rumble” or “boom”. At the higher end of the range are high -pitched sounds that might be described as a “screech” or “hiss”.
Environmental noise generally derives, in part, from a combination of distant noise sources. Such sources may include common experiences such as distant traffic, wind in trees, and distant industrial or farming activities. These distant sources create a low-level "background noise" in which no particular individual source is identifiable. Background noise is often relatively constant from moment to moment, but varies slowly from hour to hour as natural forces change or as human activity follows its daily cycle.
Superimposed on this low -level, slowly varying background noise is a succession of identifiable noisy events of relatively brief duration. These events may include the passing of single-vehicles, aircraft flyovers, screeching of brakes, and other short-term events. The presence of these short-term events causes the noise level to fluctuate. Figure 1-2 presents typical indoor and outdoor sound levels.
Figure 1-2 Typical Indoor and Outdoor Sound Levels
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Introduction 3
1.2 Ground-Borne Vibration Fundamentals
Vibration is acoustic energy transmitted as waves through a solid medium, such as soil or concrete. Like noise, the rate at which pressure changes occur is called the frequency of the vibration, measured in Hz. Vibration may be the form of a single pulse of acoustical energy, a series of pulses, or a continuous oscillating motion.
Ground-borne vibration is the ground motion about some equilibrium position that can be described in terms of displacement, velocity, and acceleration. It can be generated by transportation systems, construction activities, and other large mechanical systems. Vibration motion moves in the X, Y and Z axes.
The way that vibration is transmitted through the ground depends on the soil type, the presence of rock formations or man-made features and the topography between the vibration source and the r eceptor location. As a general rule, vibration waves tend to dissipate and reduce in magnitude with distance from the source. Also, the high frequency vibrations are generally attenuated rapidly as they travel through the ground, so that the vibration received at locations distant from the source tends to be dominated by low-frequency vibration. The frequencies of ground-borne vibration most perceptible to humans are in the range from less than 1 Hz to 100 Hz.
When ground-borne vibration arrives at a building, a portion of the energy will be reflected or refracted away from the building, and a portion of the energy will typically continue to penetrate through the ground -building interface.
However, once the vibration energy is in the building structure, it can be amplified by the resonance of the walls and floors. Occupants can perceive vibration as motion of the building elements (particularly floors) and also rattling of lightweight components, such as windows , shutters or items on shelves. At very high amplitudes (energy levels) , low-frequency vibration can cause damage to buildings.
1.3 Vibration Descriptors
The following section describes the vibration descriptors that will be used in this study.
Peak Particle Velocity
The peak particle velocity (PPV) is defined as the maximum instantaneous velocity of a particle as it transmits a vibration wave. The accepted unit for measuring PPV is inches per second (ips). PPV is appropriate for evaluating the potential for building d amage and for evaluating human response to ground -borne vibration. When reporting measured PPV values, a time interval is generally specified over which the PPV values were recorded during the measurement process
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Project Noise Thresholds and Sound Monitoring Locations 4
2. Project Noise Thresholds and Sound Monitoring Locations The Project noise thresholds are provided in the City of Sunnyvale Municipal Code Noise Standards along with agreed upon thresholds established with the City of Sunnyvale on August 4, 2023.
2.1 Water Well Drilling Project Noise Thresholds and Sound Monitoring Locations • Per CEQA documentation, w ater well drilling operations shall not exceed 80 dBA during daytime hours (7am-6pm), 60 dBA during the evening hours (6pm-10pm) and 50 dBA during nighttime hours (10pm-7am) at residential property boundaries. Sound level trigger thresholds of 78 dBA (Daytime), 58 dBA (Evening) and 48 dBA (Nighttime) will be established to notify the field operator or designated representative that noise levels are approaching the applicable limits. Upon notification, the party responsible will assess whether the elevated noise levels are attributed to project related activities. Cal Water Services has designated a 24-hour noise coordinator to contact if any noise concerns arise during the water well drilling operations . If project operations are determined to be the source, appropriate corrective measures will be implemented to reduce noise levels and prevent exceedance of the established thresholds. The corrective measures are detailed in Section 4.6 Figure 2-1 presents the proposed sound level meter monitoring locations during water well drilling operations.
• Daily summary reports will be generated to document the sound levels that were captured during the continuous monitoring period. If applicable, brief notes describing any exceedances will be provided. If noise reduction mitigation efforts are implemented, notes describing the measures taken will be provided.
The proposed sound level monitoring locations are positioned at the residential property boundary closest to the most sensitive locations to the project activities.
Figure 2-1 Sound Monitoring Locations During Water Well Drilling Operations Sound
Monitoring
Location 1
Sound
Monitoring
Location 2
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Project Vibration Thresholds and Vibration Monitoring Locations 5
3. Project Vibration Thresholds and Vibration Monitoring Locations The following details the vibration velocity level thresholds that will be utilized to determine if the vibration levels are approaching the threshold limit.
3.1 Water Well Drilling Operations Project Vibration Thresholds and Vibration Monitoring Locations
• Per CEQA documentation, w ater well drilling operations shall not exceed a vibration level of 0.25 in/sec (PPV) during daytime hours (7am-10pm) and 0.04 in/sec during nighttime hours (10pm-7am) at residential property boundaries. A vibration trigger level of 0.20 in/sec PPV (Daytime) and 0.03 in/sec PPV (Nighttime) will be established to notify the field operator or designated representative that vibration levels are approaching the allowable limit. Upon notification, the party responsible will evaluate whether the elevated vibration level is attributed to project related activities. If project operations are determined to be the source, appropriate corrective measures will be implemented to reduce vibration levels and prevent exceedance of the established threshold. The corrective measures are detailed in Section 4.6. Figure 3-1 presents the proposed vibration monitoring location during water well drilling operations. • Daily summary reports will be generated to document the vibration velocity levels that were captured during the continuous monitoring period. If applicable, brief notes describing any exceedances will be provided. If vibration mitigation efforts are implemented, notes describing the measures taken will be provided.
The proposed vibration level monitoring locations are positioned at the residential property boundary closest to the most sensitive locations to the project activities.
Figure 3-1 Vibration Monitoring Location During Water Well Drilling Operations Vibration Meter
Location 1
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Noise and Vibration Instrumentation, Installation, and Operational Procedures 6
4. Noise and Vibration Instrumentation, Installation, and Operational Procedures
4.1 Instrumentation
Table 4-1 provides equipment manufacturers and model numbers of the noise and vibration meters that will be used during the continuous noise and vibration monitoring at the Project site. Instrumentation specifications are provided in Appendix B.
Table 4-1 Continuous Noise and Vibration Monitoring Instrumentation Item Quantity Equipment
Sound Level Meter 2 Type I sound level meter capable of remote continuous monitoring
Vibration Level Meter 2 Vibration meter capable of remote continuous monitoring
During the sound level monitoring process, the sound level meter(s) will be installed in a metal enclosure box as shown in Figure 4-1 with the microphone positioned outside of the box . The boxes provide security and weather shelter for the sound level meters.
Figure 4-1 Sample Deployed Sound Level Meter Photographs Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Noise and Vibration Instrumentation, Installation, and Operational Procedures 7 During the vibration monitoring process, the vibration meter(s) will be installed in an irrigation box as shown in Figure 4-2. The box provides security and weather shelter for the vibration meters.
Figure 4-2 Sample Vibration Meter Deployment Photographs Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Noise and Vibration Instrumentation, Installation, and Operational Procedures 8
4.2 Continuous Noise Monitoring Alarms and Notifications During the continuous noise monitoring, the instantaneous alert system will send an email and/or SMS text notification if measured noise level s exceed the applicable threshold limits . The measured noise levels will be conducted in terms of 15-minute A-weighted equivalent sound levels (15-min Leq, dBA). The notifications will be triggered if the 15-minute Leq sound levels exceed the below thresholds.
The proposed noise threshold trigger levels are shown in Table 4-2. Separate notifications will be sent for the “warning” and “exceedance” levels.
Table 4-2 Water Well Drilling Phases Noise Threshold Notification Levels (dBA) Alert Type
Notification Level
Daytime (7am-
6pm)
Notification
Level Evening
(6pm-10pm)
Notification Level
Nighttime (10pm-
7am)
Recipients
Noise Level 1
(Warning) 78 dBA 58 dBA 48 dBA California Water
Services
Noise Level 2
(Exceedance) 80 dBA 60 dBA 50 dBA California Water
Services
4.3 Continuous Vibration Monitoring Alarms and Notifications During the continuous vibration monitoring, the instantaneous alert system will send an email and/or SMS text notification if measured vibration velocity levels exceeds the (PPV) established threshold limits in the vertical direction. The measured vibration velocity levels will be conducted in terms of maximum peak-particle-velocity (ppv) reported in inches per second (ips) in the vertical axis over 5-minute intervals.
The proposed noise threshold trigger levels are shown in Table 4-3. Separate notifications will be sent for the “warning” and “exceedance” levels.
Table 4-3 Water Well Drilling Vibration Threshold Notification Levels (PPV) Alert Type Notification Level Notification Recipients
Vibration Level 1 (Warning) 0.20 inch/sec California Water Services Vibration Level 2 (Exceedance) 0.25 inch/sec California Water Services
4.4 Examples of Continuous Noise and Vibration Notification and Alarm Messages Figure 4-3 and Figure 4-4 present sample notification/alarm message from the noise and vibration meters after a trigger level has been exceeded.
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Noise and Vibration Instrumentation, Installation, and Operational Procedures 9 Figure 4-3 Sample Sound Level Meter Notification/Alarm Figure 4-4 Sample Vibration Level Meter Notification/Alarm
4.5 Monitoring and Reporting Methodology
The measured sound data will be recorded continuously using professional grade equipment (ex. Svantek SV307A) that meets international “Class 1” precision standards. The sound level meters will be powered by solar panels.
Measured data will be sent to a secure website via cellular connection. Sound data from each monitoring location will be downloaded and used to generate daily reports displaying 15-min Leq, dBA values. The measurement results will be reported in a format similar to that exhibited in Appendix A.
The measured vibration data will be recorded continuously using professional grade equipment (ex. Svantek SV803) in line with current industry standards. The vibration meter will be battery powered. Measured data will be sent to a secure website via cellular connection. Vibration data from each monitoring location will be downloaded and used to generate daily reports displaying ppv values in inches per second (ips) in the vetical direction over 5-min intervals.
The measurement results will be reported in a format similar to that exhibited in Appendix A.
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Noise and Vibration Instrumentation, Installation, and Operational Procedures 10
4.6 Noise Exceedance and Complaint Response
Examples of noise notification responses by trigger level are shown in Table 4-4.
Table 4-4 Noise Response Notification Water Well Drilling Operations Alert Type
Notification
Level Daytime
(7am-6pm)
Notification
Level Evening
(6pm-10pm)
Notification Level
Nighttime (10pm-
7am)
Response
Noise Level 1
(Warning) 78 dBA 58 dBA 48 dBA
The Project onsite superintendent
identifies offending equipment or
activity
Noise Level 2
(Exceedance) 80 dBA 60 dBA 50 dBA
The Project onsite superintendent
identifies offending equipment or
activity and modifies activity to
reduce the noise level;
Superintendent communicates
with 24-hour noise coordinator
Melinda Schmtt and documents a
description of the offending
equipment or activity; Mitigation
measures are proposed and
implemented as needed
If a notification of a noise exceedance is received, The Project onsite superintendent will identify the offending activity and take the necessary measures to reduce that impact to remain within the thresholds. If necessary, triggered audio recordings can be reviewed to determine if the cause of the exceedance was due to The Project activity or unrelated offsite sources. If it is determined that The Project caused the noise exceedance, noise mitigation measures will be pursued.
Cal Water Services has designated Melinda Schmi dt to be a 24 -hour noise coordinator to be contacted about any noise concerns that may arise during the water well drilling operations. She can be contacted at (650) 280-6033.
Potential noise mitigation measures include:
• Substitute lower powered equipment for offending equipment • Substitute or alter offending activity
• Increase distance between offending equipment and sensitive location being monitored • Install additional noise barriers, shrouds, or enclosures at the site for noise issues
4.7 Vibration Exceedance and Complaint Response
In the event that the levels do approach and reach the threshold limits , Table 4-5 describe the measures to be taken by California Water Services designated representative on site.
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
Noise and Vibration Instrumentation, Installation, and Operational Procedures 11 Table 4-5 Vibration Response Notification Response Water Well Drilling Operations Notification Level Response
Vibration
Level 1
(Warning)
0.20 inch/sec The Project onsite superintendent identifies offending equipment or activity
Vibration
Level 2
(Exceedance)
0.25 inch/sec
The Project onsite superintendent identifies offending equipment or activity and modifies activity to reduce vibration level; Superintendent communicates with management and documents a description of the offending equipment or activity; Mitigation measures are proposed and implemented as needed
If a notification of a vibration exceedance is received, The Project onsite superintendent will identify the offending activity and take the necessary measures to reduce that impact to remain within the thresholds. If it is determined that the Project caused the vibration exceedance, vibration mitigation measures will be pursued.
Potential noise and vibration mitigation measures include:
• Substitute lower powered equipment for offending equipment • Increase distance between offending equipment and sensitive location being monitored • Substitute or alter offending activity
Attachment 15
2022-7041
800 Carlisle Way
Behrens and Associates, Inc.
Environmental Noise Control
12 Appendix A - Sample Noise and Vibration Monitoring Report Attachment 15
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Environmental Noise Control
13 Figure A-1 Sample Daily Noise Monitoring Report
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Environmental Noise Control
14 Figure A-2 Sample Daily Vibration Monitoring Report
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Behrens and Associates, Inc.
Environmental Noise Control
15 Appendix B - Instrumentation Specifications
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Environmental Noise Control
16 Figure B-1 SVANTEK SV307A Sound Level Meter Product Sheet Page 1 Attachment 15
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17 Figure B-2 SVANTEK SV307 Sound Level Meter Product Sheet Page 2 Attachment 15
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18 Figure B-3 SVANTEK SV307 Sound Level Meter Product Sheet Page 3 Attachment 15
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Environmental Noise Control
19 Figure B-4 SVANTEK SV307 Sound Level Meter Product Sheet Page 4 Attachment 15
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Environmental Noise Control
20 Figure B-4 SVANTEK SV803 Vibration Level Meter Product Sheet Page 1 Attachment 15
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Environmental Noise Control
21 Figure B-5 SVANTEK SV803 Vibration Level Meter Product Sheet Page 2 Attachment 15
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Environmental Noise Control
22 Figure B-6 SVANTEK SV803 Vibration Level Meter Production Sheet Page 3 Attachment 15
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Environmental Noise Control
23 Figure B-7 SVANTEK SV803 Vibration Level Meter Product Sheet Page 4 Attachment 15
2022-7041
800 Carlisle Way
From: Healey, William
To: Mary Jeyaprakash
Cc: Schmidt, Melinda; Smithson, Dawn; Noren Caliva-Lepe; Gonzalez, Salvador Subject: RE: Additional Items from Planning Commission Hearing Date: Tuesday, May 5, 2026 3:49:27 PM
Attachments: image001.png
image002.png
image003.png
image004.png
LAS 20 Noise & Vibration Monitoring Plan - 5-5-2026.pdf WARNING - This email came from an EXTERNAL source. Confirm the sender and its contents are safe before responding, opening attachment or links.
Hello,
Per the Planning Commission hearing, please see the attached Noise & Vibration Monitoring & Reporting Plan for LAS Sta. 20. The plan includes a sample report so residents can see what future reports will look like.
Here is the language from our well consultant in regards to the use of an electric drill:
“An electric-powered drill rig is not a practical or feasible option for construction of a deep, large diameter municipal supply well of the type proposed. Wells of this scale, approximately 800 feet in depth with a borehole diameter exceeding 28 inches, require high torque, sustained rotary power, and substantial hoisting capacity. Through research, it is LSCE’s understanding that delivering the power required for a project of this magnitude to an electrified drill rig would necessitate the use of a large diesel generator to supply sufficient energy to the rig. This approach would effectively negate any potential benefits of electrification, as the generator would produce comparable noise levels and diesel exhaust emissions to a conventional diesel-powered drill rig.
Furthermore, the pool of qualified drilling contractors with experience in Northern California capable of executing a project of this complexity is limited. Based on LSCE’s experience and industry knowledge, none of these contractors operate electric drill rigs, and such equipment is not used in this region for municipal supply well construction. Accordingly, specifying or requiring an electric drill rig would not only be impractical from a technical standpoint, but would also unduly restrict the already limited number of qualified bidders, potentially affecting project feasibility, cost, and schedule.”
Please let me know if you need anything else from our team to support the City Council hearing.
Thanks,
William Healey, P.E.
P-3 Project Engineer
California WatEr SErviCE
+1 (213) 5769867
Applicant Memo: Alternate Drilling
Attachment 15
2022-7041
800 Carlisle Way