22 January 2025
Caroline Layden
Quarterra
429 9th Street, Suite 300
Oakland, CA 94607
[email protected]
Subject: Willow Apartments
Preliminary Environmental Noise Study
Salter Project 24 -0542
Dear Caroline:
We have conducted a preliminary environmental noise study for the project. The purpose of the study is to determine the noise environment at the project site, compare the measured data with applicable standards, and propose initial mitigation measures as necessary. This report summarizes the results of our study.
PROJECT CRITERIA
California Building Code (Title 24)
Section 1206.4 of the California Building Code (CBC) requires that the indoor noise level in residential units of multi-family dwellings not exceed DNL 1 45 dB.
City of Hercules
Zoning Ordinance Chapter 13-31.300.11 states 2:
● Indoor noise levels for new housing units are not to exceed DNL 45 dB, which is in agreement with Title 24.
1 DNL (Day-Night Average Sound Level) – A descriptor for a 24-hour A-weighted average noise level. DNL accounts for the increased acoustical sensitivity of people to noise during the nighttime hours. DNL penalizes sound levels by 10 dB during the hours from 10 PM to 7 AM. DNL is sometimes written as Ldn. 2 https://www.codepublishing.com/CA/Hercules/#!/Hercu les13/Hercules1331.html Willow Apartments
22 January 2025
Preliminary Environmental Noise Study
● Single-event noise (e.g., train passbys) should not exceed Lmax 3 50 dB in bedrooms and 55 dB in other habitable rooms.
● Outdoor noise levels should not exceed DNL 60 dB for residential areas (larger areas like courtyards, but not small decks). DNL 65 dB might apply at the decks, at the City’s discretion. ● The outdoor noise goal is DNL 70 dB when the noise source is a railroad.
CALGreen
CALGreen Code Section 5.507.4 addresses acoustical issues for non-residential spaces. If a building is exposed to an exterior Leq (h) 4 of 65 dB during any hour of operation, the building envelope must reduce the interior noise environment to L eq (h) of 50 dB in occupied areas. We have assumed this will apply at the clubhouse.
NOISE ENVIRONMENT
The project site is along Willow Avenue, east of Interstate 80 (I-80), south of State Route 4 (CA-4), and north of the Burlington Northern Santa Fe (BNSF) railway. The noise environment at the site is predominantly controlled by traffic on Willow Avenue, the freeways, and the railway.
To quantify the existing noise environment, we conducted three long-term noise measurements between 6 and 8 January 2025 (see Figure 1 for the measurement locations and measured noise levels). The noise monitors were at a height of 12 feet above grade, except for the on-site monitor, which was about 7-feet above grade.
A traffic analysis has not been provided for this project. We have added 1 dB to our measured noise levels to account for future traffic increases
5. 3 L max30 (Typical Maximum Sound Level) – There is no standardized metric to quantify “typical” maximum sound levels in an environment (instead of the absolute maximum sound level for a measurement period). The metric L max30 comes from a paper by Rob Greene (“Max Level Intrusive Noise Limit: 1982 National Conference on Environmental and Occupational Noise”). It is based on the logarithmic average of the noisiest 30 percent of single events (e.g., train passbys, aircraft flyovers).
4 L eq (h) – The equivalent steady-state A-weighted sound level that in an hour would contain the same acoustic energy as the time-varying sound level during that hour.
5 The California Department of Transportation (DOT) ass umes a traffic volume increase of three-percent per year, which corresponds to a 1 dB increase in DNL over a ten-year period.
Willow Apartments
22 January 2025
Preliminary Environmental Noise Study
RECOMMENDATIONS
Interior Noise (Code)
Using site plan drawings dated 18 October 2024, we calculated the window and exterior door STC 6 ratings needed to meet the project criteria, as shown in Figure 2. For our calculations, we have assumed the following:
● All spaces will have hard-surfaced (non-carpeted) flooring ● Bedrooms will be 12 feet by 10 feet and living rooms will be 15 feet by 12 feet ● Ceilings will be 9-feet high
● Windows will account for 50% of the facade
● The exterior wall achieves minimum STC 45 (equivalent to 7/8-inch-thick stucco over wood sheathing) At some locations, an upgraded exterior wall (achieving STC 50) will be necessary to meet Code. These locations are indicated in Figure 2.
The recommended STC ratings are for full window and door assemblies (glass and frame) rather than just the glass itself. Tested sound-rated assemblies should be used. For reference, typical one-inch glazing assemblies (two 1/4-inch-thick panes with 1/2-inch airspace) typically achieve an STC rating of 32. STC ratings above 32 should include laminated glass. STC ratings above 38 might require an IGU greater than one-inch thick. This will vary depending on the window manufacturer.
Where windows need to be closed to achieve an indoor DNL of 45 dB, an alternative method of supplying fresh air (e.g., mechanical ventilation) should be considered. This applies to all locations. This issue should be discussed with the project mechanical engineer.
Interior Noise (Single-Event Noise)
To meet the single-event criteria, it will be necessary to provide upgraded exterior wall assemblies at the southern facades of Buildings 5 and 6. With these upgrades, windows and exterior doors in these facades would need STC ratings up to STC 46. When the project design is more developed, we can provide more detailed STC ratings in the final environmental noise study.
6 STC (Sound Transmission Class) – A single-number rat ing defined in ASTM E90 that quantifies the airborne sound insulating performance of a partition under laboratory conditions. Increasing STC ratings correspond to improved airborne sound insulation.
Willow Apartments
22 January 2025
Preliminary Environmental Noise Study
Exterior Noise
There are no common outdoor-use areas shown in the plans. If that changes, we can provide recommendations as part of the later final environmental noise study. * * * This concludes our preliminary environmental noise study for the project. Please feel free to reach out with any questions you may have.
Best,
SALTER
Zamar Bravo Tapia
Consultant
Eric Mori, PE
Executive Vice President
MEMORANDUM
DATE: 18 November 2025
NAME: COMPANY: EMAIL:
Jason Winterboer Quarterra [email protected] FROM: Brian Wourms and Eric Mori, PE
SUBJECT: Emblem Hercules
Review of Project Exterior HVAC Noise
PROJECT: 24-0542
As requested, we have reviewed the project-generated HVAC noise and compared it with the City of Hercules Municipal Code. This memo presents our findings.
CRITERIA
The City of Hercules Zoning Ordinance Chapter 13.31.11.A.5 states that for non-transportation related noise sources, outdoor noise levels within a residential property should not exceed the limits in Table 7 of the Noise Element.
The Hercules Noise Element Table 7 requires noise at a receiving residential land-use property line to not exceed an hourly Leq of 50 dBA during the day and 45 dBA at night. Also, Table 7 Note 5 provides a provision that allowable levels shall be raised to ambient noise levels where the ambient levels exceed the allowable levels.
The project is not directly adjacent to any other properties. The closest residential receiver is approximately 600 feet to the northeast of the site, across Highway 4.
EXPECTED NOISE LEVELS
The project will use interior fan-coils with outdoor heat pumps at each residence. Quarterra provided cutsheets for the heat pumps (attached) indicating the maximum noise level is 60 dBA at 1 meter for the loudest unit. At the closest residential receiver 600 feet away, heat pump noise would be approximately 15 dBA. This is well below the 45 dBA nighttime limit, and the expected ambient noise level near a highway. Therefore, the project will meet the stationary noise requirements of the Zoning Ordinance.
This concludes our comments on this issue. Let us know if you have any questions.
EFFICIENCY
SEER2 EER2 HSPF2 COP
Non-Ducted:21.00 12.00 10.00
Ducted:
Mixed: 10.50 6.00 5.00 0
PERFORMANCE
COOLING: HEATING:
Rated (Btu/hr): 17,200 Rated (Btu/hr): 18,500
Operating
Range: 14°F - 115°F Operating
Range: 5°F - 60°F
Rated Cooling Conditions: Rated Heating Conditions:
Indoor (°F DB/DB): 80 / 67
Ambient (°F DB/WB): 95 / 75
Indoor (°F DB/WB): 70 / 60
Ambient (°F DB/WB): 47 / 43
ELECTRICAL
Power Supply (V/Hz/Ph):
*See Engineering Manuals for other voltages.*208-230 / 60 / 1 System MCA:
(Min.circuit amps) 15.6
System MFA:
(Max.fuse amps) 20.0
Compressor RLA:
(Rated load amps) 14.0
Outdoor fan motor FLA:
(Full load amps) 0.3
Outdoor fan motor W:
(Rated output watts) 150.0
PIPING
Max. System Piping Length:
(feet): 164 Gas Conn.
(inch): 3/8
Max. Interunit Piping
Length: (feet): 164 Liquid Conn.
(inch): 1/4
Max. Height Difference
IDU to ODU (feet): 49.25 Drain Conn.
(inch): 5/8
Max. Height Difference
IDU to IDU (feet):
Refrigerant Pre-Charged
Pipe Length (ft): 98.4
Submittal Data Sheet
R-32 1.5-Ton, 2-Port Heat Pump, Ductless ODU
2MXM18AVJU9
SPECIFICATIONS
Compressor Type: Swing Compressor Stage: Inverter
Refrigerant Type: Refrigerant Oil: PVE (FVC50K)
Factory Charge (Lbs): 3.3 Additional Refrigerant Charge (Ozs/ft): .22
COOLING - Airflow Rate (cfm): HEATING - Airflow Rate (cfm):
High: 2,112 High: 2,140
Med: 2,112 Med: 2,140
Low: 1,911 Low: 1,561
Sound Level (dBA): 52 Sound Level (dBA): 54
Dimensions (HxWxD) (in): 29-1/2 x 34-1/4 x 12-5/8 Net Weight (lb): 127 www.daikinac.com www.daikincomfort.comDaikin City Generated Submittal Data Submittal Date: 4/18/2025 11:18:09 AM Page 2 of 4
Daikin North America LLC, 19001 Kermier Rd, Waller, TX 77484 (Daikin's products are subject to continuous improvements. Daikin reserves the right to modify product design, specifications and information in this data sheet without notice and without incurring any obligations)
EFFICIENCY
SEER2 EER2 HSPF2 COP
Non-Ducted:21.00 12.00 10.00
Ducted:
Mixed: 10.50 6.00 5.00 0
PERFORMANCE
COOLING: HEATING:
Rated (Btu/hr): 23,000 Rated (Btu/hr): 24,000
Operating
Range: 14°F - 115°F Operating
Range: 5°F - 60°F
Rated Cooling Conditions: Rated Heating Conditions:
Indoor (°F DB/DB): 80 / 67
Ambient (°F DB/WB): 95 / 75
Indoor (°F DB/WB): 70 / 60
Ambient (°F DB/WB): 47 / 43
ELECTRICAL
Power Supply (V/Hz/Ph):
*See Engineering Manuals for other voltages.*208-230 / 60 / 1 System MCA:
(Min.circuit amps) 19.9
System MFA:
(Max.fuse amps) 25.0
Compressor RLA:
(Rated load amps) 17.0
Outdoor fan motor FLA:
(Full load amps)
Outdoor fan motor W:
(Rated output watts) 150.0
PIPING
Max. System Piping Length:
(feet): 230 Gas Conn.
(inch): 3/8
Max. Interunit Piping
Length: (feet): 230 Liquid Conn.
(inch): 1/4
Max. Height Difference
IDU to ODU (feet): 49.25 Drain Conn.
(inch): 5/8
Max. Height Difference
IDU to IDU (feet):
Refrigerant Pre-Charged
Pipe Length (ft): 131.25
Submittal Data Sheet
2.0-Ton R-32, 3-Port Heat Pump, Ductless ODU
3MXM24AVJU9
SPECIFICATIONS
Compressor Type: Swing Compressor Stage: Inverter
Refrigerant Type: Refrigerant Oil: PVE (FVC50K)
Factory Charge (Lbs): 4.9 Additional Refrigerant Charge (Ozs/ft): 0.22
COOLING - Airflow Rate (cfm): HEATING - Airflow Rate (cfm):
High: 2,462 High: 2,140
Med: 2,055 Med: 2,140
Low: 1,939 Low: 1,070
Sound Level (dBA): 52 Sound Level (dBA): 54
Dimensions (HxWxD) (in): 29-1/2 x 34-1/4 x 12-5/8 Net Weight (lb): 140 www.daikinac.com www.daikincomfort.comDaikin City Generated Submittal Data Submittal Date: 4/18/2025 11:18:33 AM Page 2 of 4
Daikin North America LLC, 19001 Kermier Rd, Waller, TX 77484 (Daikin's products are subject to continuous improvements. Daikin reserves the right to modify product design, specifications and information in this data sheet without notice and without incurring any obligations)
EFFICIENCY
SEER2 EER2 HSPF2 COP
Non-Ducted:20.00 10.00 9.50
Ducted:
Mixed: 10.00 5.00 4.75 0
PERFORMANCE
COOLING: HEATING:
Rated (Btu/hr): 34,200 Rated (Btu/hr): 34,600
Operating
Range: 14°F - 115°F Operating
Range: 5°F - 60°F
Rated Cooling Conditions: Rated Heating Conditions:
Indoor (°F DB/DB): 80 / 67
Ambient (°F DB/WB): 95 / 75
Indoor (°F DB/WB): 70 / 60
Ambient (°F DB/WB): 47 / 43
ELECTRICAL
Power Supply (V/Hz/Ph):
*See Engineering Manuals for other voltages.*208-230 / 60 / 1 System MCA:
(Min.circuit amps) 24.1
System MFA:
(Max.fuse amps) 25.0
Compressor RLA:
(Rated load amps) 18.5
Outdoor fan motor FLA:
(Full load amps)
Outdoor fan motor W:
(Rated output watts) 150.0
PIPING
Max. System Piping Length:
(feet): 230 Gas Conn.
(inch): 3/8
Max. Interunit Piping
Length: (feet): 230 Liquid Conn.
(inch): 1/4
Max. Height Difference
IDU to ODU (feet): 49.25 Drain Conn.
(inch): 5/8
Max. Height Difference
IDU to IDU (feet):
Refrigerant Pre-Charged
Pipe Length (ft): 131.25
Submittal Data Sheet
3.0-Ton R-32, 4-Port Heat Pump, Ductless ODU
4MXM36AVJU9
SPECIFICATIONS
Compressor Type: Swing Compressor Stage: Inverter
Refrigerant Type: Refrigerant Oil: PVE (FVC50K)
Factory Charge (Lbs): 4.9 Additional Refrigerant Charge (Ozs/ft): 0.22
COOLING - Airflow Rate (cfm): HEATING - Airflow Rate (cfm):
High: 2,896 High: 2,518
Med: 2,402 Med: 2,518
Low: 2,055 Low: 1,070
Sound Level (dBA): 56 Sound Level (dBA): 60
Dimensions (HxWxD) (in): 29-1/2 x 34-1/4 x 12-5/8 Net Weight (lb): 142 www.daikinac.com www.daikincomfort.comDaikin City Generated Submittal Data Submittal Date: 4/18/2025 11:19:14 AM Page 2 of 4
Daikin North America LLC, 19001 Kermier Rd, Waller, TX 77484 (Daikin's products are subject to continuous improvements. Daikin reserves the right to modify product design, specifications and information in this data sheet without notice and without incurring any obligations)