a. Exposure of persons to or generation of noise levels in excess of standards established in the local general plan or noise
ordinance, or applicable standards of other agencies? b. Exposure of persons to or generation of excessive ground borne
vibration or ground borne noise levels?
c. A substantial permanent increase in ambient noise levels in the
project vicinity above levels existing without the project d. A substantial temporary or periodic increase in ambient noise
levels in the project vicinity above levels existing without the
project?
e. For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels?
f. For a project within the vicinity of a private airstrip, would the project expose people residing or working in the project area to
excessive noise levels?
Sources: St Helena 1993 General Plan: Public Health and Safety Element (8-3); Culinary Institute of America Vineyard Lodge Noise Study, Prepared by ICF International, June 15, 2016.
Setting:
Noise is generally defined as unwanted sound. It is characterized by various parameters that include the rate of oscillation of sound waves (frequency), the speed of propagation, and the pressure level or energy content (amplitude). The sound pressure level is the most common descriptor used to characterize the loudness of an ambient (existing) sound level. The decibel (dB) scale is used to quantify sound intensity, but given that the human ear is not equally sensitive to all frequencies in the entire spectrum, noise measurements are weighted more heavily for frequencies to which humans are sensitive in a process called “A-weighting,” written as “dBA” and referred to as “A-weighted decibels”. In general, human sound perception is such that a change in sound level of 1 dB cannot typically be perceived by the human ear, a change of 3 dB is just noticeable, a change of 5 dB is clearly noticeable, and a change of 10 dB is perceived as doubling or halving the sound level.
The primary noise sources within the St. Helena City limits include vehicular traffic, the Napa Valley Wine Train, and agricultural activities (e.g. Vineyard frost fans, pumps in isolated areas, fixed machinery, and heavy vehicle traffic during harvest). Noise sources also include hot air balloon flyovers and limited industrial activities, particularly the Sulphur Springs gravel mining operation on Sulphur Springs Creek. The Napa Valley Wine train tracks are located southwest of the Vineyard Lodge Project site, with passages occurring twice a day, seven days per week, at approximately 1pm and 2pm.The slow speed of the train and the short duration are such that the train is not considered a significant noise source.
The City of St. Helena Municipal Code Section 8.24.010 (C), limits Construction activities which generate noise that can be heard at the property line of any parcel of real property within the city limits to between the hours of eight a.m. to five p.m. and delivery of materials/equipment and cleaning and servicing of machines/equipment shall be limited to seven a.m. to six p.m. Exceptions to these time restrictions may be granted by the public works director. No construction activities which generate noise that can be heard at the property line of any parcel of real property within the city limits are allowed on Sundays or Holidays. Operational noise levels are addressed by the General Plan’s Noise Element according to land use type. For example, residential land uses are considered completely compatible with noise exposures of up to 55dBA and tentatively compatible in noise exposure areas of up to 60dBA.
Traffic is the primary noise generator in the vicinity of the project sites. The Vineyard Lodge site is also subject to noise generated by agricultural activities on adjacent properties. To characterize noise levels at the Vineyard Lodge Housing Site, a Noise Study was prepared by consultants, ICF International, on June 15, 2016. Noise monitoring was conducted on the Vineyard Lodge project site to characterize existing noise levels in the project area. The Napa Wine Train was not operating during this time and the existing housing facilities were not occupied as students were on break. The measured noise levels therefore represent the lowest noise levels likely to be encountered in the area. Overall, the noise measurements indicate that the noise environment in the project area is generally quiet and consistent with the rural setting.
Impact Analysis:
a.(Exposure to Excessive Noise Levels) Less than Significant: Traffic serves as the primary noise generator in the vicinity of the
Vineyard Lodge Housing Site. Measurements taken on the project site indicate that existing traffic noise levels at the project site are in the range of 57 to 63 Ldn. The project is expected to add less than 8 trips to Pratt Avenue during the a.m. and p.m. peak hours .This would constitute a negligible increase in traffic noise of less than 0.5 dB which falls well below the threshold of a perceptible change of 3 dB. As such implementation of the proposed project will not substantially increase traffic noise in the area. Further, conventional building construction with windows closed is expected to reduce exterior noise by at least 20 dB at interior locations. Accordingly interior noise levels at the new facility are expected to be 45 Ldn or less which is in compliance with the City standard for interior noise. Activities at the Greystone Campus will not generate or expose receptors to excessive noise levels. Impacts would be less than significant.
and other impacts devices such as pavement breakers create seismic waves that radiate along the surface of the earth and downward into the earth. These surface waves can be felt as ground vibration. Vibration from operation of this equipment can result in effects ranging from annoyance of people to damage of structures. Varying geology and distance will result in different vibration levels containing different frequencies and displacements. In all cases, vibration amplitudes will decrease with increasing distance.
Perceptible ground-borne vibration is generally limited to areas within a few hundred feet of construction activities. As seismic waves travel outward from a vibration source, they excite the particles of rock and soil through which they pass and cause them to oscillate. The rate or velocity (in inches per second) at which these particles move is the commonly accepted descriptor of the vibration amplitude, referred to as the peak particle velocity (PPV).
Construction at the Vineyard Lodge Housing site would occur approximately 75 feet from nearby residences. According to the Noise Study, construction activity would generate vibration that is barely to distinctly perceptible at the nearest residence but is not at a level that could cause damage to nearby structures. Because periods of perceptible vibration would be brief and temporary, the project is not expected to expose people to excessive groundborne vibration. Likewise, construction activity at the Greystone Campus would occur proximate to the onsite student housing. Cave construction would consist of excavating the tunnels using mechanical means (backhoe, milling head, and/or roadheader) and may result in ground borne vibration; however periods of perceptible vibration would be brief and temporary, the project is not expected to expose people to excessive ground borne vibration and impacts would be less than significant.
c.(Permanent Increase in Ambient Noise Levels) Less than Significant: As mentioned above, the City of St. Helena regulates
the noise environment through Chapter 8.25 of the Municipal Code, which identifies noise levels of 55 CNEL as completely compatible and provides that noise levels up to 60 CNEL are tentatively compatible for residential land uses.
At project operation, the onsite land use at the Vineyard Lodge Housing Site and associated noise environment will continue to be typical of a multi-unit development (dormitories) and subject to the City’ noise exposure standards. The expansion of the Vineyard Lodge Housing site is not expected to introduce a substantial permanent increase in the ambient noise environment due to activities onsite or as a result of stationary or mobile sources. The noise generating elements of the proposed project such as outdoor conversations, mechanical equipment, the operation of landscaping equipment, car engines and car doors would be similar to the existing noise environmental present on-site. The project is expected to introduce noise elements at levels that are generally consistent with the ambient noise conditions.
New mechanical systems associated with heating, ventilation, and air conditioning may generate noise. The specific details on the design and location of these systems has not yet been determined. However, per Municipal Code Section 8.24.10(b), no commercial or other activity may create noise that can be heard at the property line of any private property between the hours of 10:00 p.m. and 7:00 a.m. As such, the project must shield/ attenuate noise generated by mechanical systems to comply with the Standard City requirements. With the requisite adherence to City Code provisions, there is no expectation that the proposed mechanical systems would generate a level of noise that would adversely impact adjacent properties.
The facility will have a central quad area that may be used as a gathering place for students. Events such as barbeques and other social events could be held in the quad. Gatherings could include up to 120 students who would live on the site which would equate to a cumulative sound level of approximately 54 dBA at 50 feet. The nearest residence is about 260 feet from the center of the quad. A sound level of 54 dBA at 50 feet would drop to about 47 dBA at 260 feet assuming attenuation of 6 dB per doubling of distance. In addition the new buildings will surround the quad providing acoustical shielding of at least 5 dB between the quad and the nearest residence. The resultant sound level at the nearest residence would therefore be approximately 42 dBA. This is well below the measured daytime ambient sound levels that are in the range of 50 to 64 dBA. In addition, the CIA regulates activities at the Vineyard Lodge Housing Site to prohibit amplified music outside, enforces a 9:30pm n noise curfew, and prohibits non-residents from attending events in the quad.
Given the presence of this acoustical shielding and the rules that will be in place and required under the Use Permit, student activities are not expected to result in noise that can be heard at the property line between the hours of 10:00 p.m. and 7:00 a.m. Accordingly, the proposed Vineyard Lodge Housing project is not expected to result in noise that exceeds applicable local noise standards. This impact is therefore considered to be less than significant.
Following implementation of the proposed changes at the Greystone Campus, interior and exterior noise levels would be similar to existing conditions. In other words, operational noises are not expected to generate additional sources of noise at the Greystone Campus and no impacts are expected.
d.) (Temporary Increase in Ambient Noise) Less than Significant with Mitigation: The City’s Noise Ordinance establishes
standards to minimize the temporary noise impacts associated with construction, such as limitations on the time of day and week when construction activities are acceptable. Construction activities associated with the CIA Campus Master Plan would result in temporary noise disturbances that could potentially impact nearby sensitive receptors due to the site’s proximity to surrounding residential development. Noise generated during construction would vary depending on the construction phase and the type and amount of equipment used at the construction site. Construction activities that would generate noise include site grading, excavation, hauling and deliveries, foundation work, and to a lesser extent framing, and exterior and interior finishing. The highest noise levels would be generated during grading of the site, with lower noise levels occurring during building construction and finishing. No pile driving, jack hammering, or extensive work that would generate substantial groundborne vibration is anticipated.
Construction activities associated with the proposed project have the potential to result in temporary noise levels that would impact nearby noise sensitive land uses periodically over the course of the construction period. Construction related noise impacts are typically only occasionally intrusive and cease once construction is complete. Nonetheless, in order to ensure that noise levels due to onsite construction are minimized Mitigation Measure NOI-1, set forth below shall be implemented. NOI-1 below, which goes beyond the requirements of the City’s Noise Ordinance, will ensure that potential noise impacts due to the temporary exposure of sensitive receptors to excessive noise during construction are reduced to less than significant levels.
(e-f) No Impact
The proposed project is not located within two miles of a public airport or public use airport, nor is it located near a private airstrip and does not expose people residing or working in the project area to excessive noise levels. Residents or visitors onsite would not be exposed to excessive noise levels generated by the airport and no impacts due to excessive noise exposure would occur.
Mitigation Measures:
NOI-1. Due to the proximity of sensitive receptors to the project sites, all construction activities shall be required to comply with the following and be noted accordingly on construction contracts:
1. Construction Equipment Mufflers and Maintenance: All construction equipment powered by internal combustion engines shall be properly muffled and maintained.
2. Idling Prohibitions: All equipment and vehicles shall be turned off when not in use. 3. Unnecessary idling of internal combustion engines is prohibited.
4. Equipment Location and Shielding: All stationary noise-generating construction equipment, such as air compressors, shall be located as far as practical from the adjacent homes.
5. Acoustically shield such equipment when it must be located near adjacent residences.
6. Quiet Equipment Selection: Select quiet equipment, particularly air compressors, whenever possible. Motorized equipment shall be outfitted with proper mufflers in good working order.
7. Staging and Equipment Storage: The equipment storage location shall be sited as far as possible from nearby sensitive receptors.
8. Noise Disturbance Coordinator: Applicant shall designate a "noise disturbance coordinator" who will be responsible for responding to any local complaints about construction noise. This individual would most likely be the contractor or a contractor’s representative. The disturbance coordinator would determine the cause of the noise complaint (e.g., starting too early, bad muffler, etc.) and would require that reasonable measures warranted to correct the problem be implemented. The telephone number for the disturbance coordinator shall be conspicuously posted at the construction site.