~ Noise ~

3.2.5-1 INTRODUCTION
This section of the EIR provides an overview of local ambient noise levels and the degree to which Township growth could affect those levels. Issues addressed include construction and cumulative traffic impacts on ambient noise levels.

3.2.5-2 SETTING

The human response to environmental noise is subjective and varies considerably from individual to individual. The effects of noise can range from interference with sleep, concentration and communication to causation of physiological and psychological stress and, at the highest intensity levels, to hearing loss. Listed below are several examples of the noise levels associated with common situations, given in A-weighted decibels (dBA).

Jet Takeoff at 200 feet	125 dBA
Discotheque	115 dBA
Motorcycle at 20 feet	110 dBA
Freight Train at 50 feet	95 dBA
Freeway Traffic at 50 feet	95 dBA
Vacuum Cleaner	70 dBA
Average Office	50 dBA
Library	40 dBA
Recording Studio	20 dBA
Leaves Rustling	10 dBA

Environmental noise fluctuates in intensity over time, and several descriptors of time averaged noise level are in use. The three most commonly used are Leq, Ldn, and CNEL. Leq, the energy equivalent noise level, is a measure of the average energy content (intensity) of noise over any given period of time. Ldn, the day-night average noise level, is the 24-hour average of the noise intensity, with a 10-dBA "penalty" added for nighttime noise (10 p.m. to 7 a.m.) to account for the greater sensitivity to noise during this period. CNEL, the community equivalent noise level, is similar to Ldn, but adds a 5-dBA penalty to evening noise (7 p.m. to 10 p.m.).

Regulatory Background
The California Department of Health Services (DHS) Office of Noise Control has studied the correlation of noise levels and their effect on different land uses. A summary of DHS findings is contained in Table 3.2.5-1. The table shows the noise levels (in this case Ldn) below which the land use would be compatible with the exterior noise environment, with no special noise insulation requirements (e.g. for residential uses, this "normally acceptable" level would be an Ldn less than 60 dBA). It also shows the noise levels above which the land use would be considered unacceptable due to the difficulty of providing the needed noise insulation (e.g., for residential uses, this "clearly unacceptable" level would be an Ldn greater than 75 dBA). Finally, the table indicates that there is often a large range of exterior noise levels for which a land use could be made compatible if the necessary noise reduction features are included in the design of a proposed project (e.g., for residential uses, noise ranging from 60 dBA to 75 dBA, levels considered "conditionally acceptable" to "normally acceptable," could be accommodated by installing adequate insulation).

Turning to applicable State standards governing interior noise levels, Title 24 of the California Code of Regulations establishes standards that apply to all new, multifamily residential units in California. These standards require that buildings to be located in areas where the existing Ldn exceeds 60 dBA must have an acoustical study performed before construction to establish mitigations that will limit maximum noise levels to 45 dBA in any inhabitable room. There are no generally applicable interior noise standards pertinent to all residential uses in California, but many communities in California have adopted the 45-dBA interior standard for single family homes as well.

According to the Mendocino County General Plan, the County Division of Environmental Health has established "preferred levels or goals for the more sensitive uses and differentiated between day and night levels." For residential receptors the preferred levels are 40 dBA Leq at night and 50 dBA Leq during the day. The County's preferred levels are more restrictive than the State of California's "normally acceptable" residential outdoor noise level of 60 dBA Ldn, as shown in Table 3.2.5-1 below.

KEY:
a. Normally Acceptable - land use is satisfactory; buildings need no special noise insulation.

b. Conditionally Acceptable - new construction should be undertaken only after acoustic analysis and installation of noise insulation. Conventional construction but with closed windows and fresh air supply systems or air conditioning will normally suffice.

c. Normally Unacceptable - new construction should be discouraged. If construction does proceed, acoustic analysis to determine the insulation needed is required.

d. Clearly Unacceptable - new construction should not be undertaken.

Source: Office of Noise Control, California Department of Health Services.

Existing Noise Environment
Major sources of noise in Mendocino County include traffic, industry, railroads, and aircraft. Brooktrails Township lies in the central part of the County, approximately three miles northwest of the City of Willits. The Brooktrails Township is accessed via U.S. 101 to Sherwood Road. The Willits Creek basin is primarily heavily forested, and ambient noise levels are dominated by natural background noise such as wind in trees, wildlife and water flow. However, due to the "canyon" nature of the area, noise echoes. Nearby sensitive receptors would also include trail users, wildlife, and a golf course. Although no noise measurements have been made at the Township, typical noise levels are estimated in the range of 30 to 50 dBA. Noise levels will vary, especially in areas least affected by traffic noise and the sounds of the creeks.

The Noise Element of the Mendocino County General Plan, revised in 1986, indicates that the predicted distance in 1995 to the 65-dBA noise contour along the section of U.S. 101 nearest to the Humboldt County line extends from 185 feet to 288 feet from the center of the highway. Traffic volumes on Sherwood Road are estimated at 509 average daily vehicular trips during peak traffic hours. Traffic volumes on the Brooktrails roads are low.

3.2.5-2 IMPACTS AND MITIGATION MEASURES
Brooktrails Township Specific Plan Policies

The Plan goal specifically related to noise in the Plan area appears in the Environmental Resources Chapter of the Plan as GOAL ER-6.6-2. The Policies for implementing the Goal are central to the issue of maintaining acceptable noise levels within the Township and are reiterated here to allow the reader easy reference to the actual language in the Plan.

NOISE GOAL ER-6.6-2A: Minimize potential noise pollution within the Township to maintain the tranquility that currently characterizes Brooktrails Township.

POLICY ER-6.6-2A: Ensure community consistency with the Mendocino County General Plan Noise Element, Land Use Compatibility for Community Noise Environments.

POLICY ER-6.6-2B: Evaluate the noise implications of the U.S. 101 Willits bypass if the western route is selected.

Standards of Significance
CEQA Guidelines indicate that a project will normally result in a significant adverse impact if it causes a substantial increase in the ambient noise level within areas sensitive to noise adjacent to the project site. The potential for significant impacts also exists where land use compatibility standards for community noise as defined by the State of California and the County of Mendocino, are exceeded.

Impact 3.2.5-1
Construction activities would generate high noise levels on and around the locations of activity over the entire period of construction, potentially disturbing area residents. (PS)

Table 3.2.5-2 shows outdoor noise levels likely to be experienced near a site during the various project construction phases. Because noise from localized sources typically diminishes by about six dBA with each doubling of distance from source to receptor, outdoor receptors within 1,600 feet of construction sites that have an uninterrupted view of the construction site would experience noise greater than 60 dBA when noise on the construction site exceeds 90 dBA.

TABLE 3.2.5-2
TYPICAL CONSTRUCTION NOISE LEVELS AT 50 FEET (dBA)1

Noise from construction activities would significantly impact the vicinity of a proposed project, exceeding the California State residential noise standard of 60 dBA and the preferred residential noise level of 50 dBA specified by the Mendocino County Division of Environmental Health.

During construction, noise would also be generated from increased traffic volumes and equipment moving on roads leading to the construction sites. The areas along Sherwood Road and other Brooktrails roads would be affected to the greatest degree.

Mitigation Measure 3.2.5-1
Construction should be limited to between 7 A.M. and 6 P.M., Monday through Friday, to minimize disruption due to noise. (I)

Construction specifications should include a provision requiring adequate mufflers on trucks and other construction equipment.

Construction crews should be transported to the construction site by a shuttle bus from a parking area in the community to reduce traffic movements and noise on Sherwood Road.

Impact 3.2.5-2
At Township build-out, traffic noise levels at the homes closest to Sherwood Road would exceed County preferred levels and State normally acceptable levels. (PS)

According to the Brooktrails Specific Plan, a setback of 20 feet would be provided between homes and roadways. At this distance, the daytime maximum hourly Leq and the Ldn would be 66 dBA and 64 dBA, respectively, under build-out traffic conditions on Sherwood Road. This would exceed the 50 dBA County daytime preferred Leq and the 60 dBA State normally acceptable Ldn. Increasing the minimum setback to 60 feet would meet the State standard, but a minimum setback of over 200 feet would be required to meet the County standard.

Mitigation Measure 3.2.5-2
Install sufficient acoustic insulation in the proposed Brooktrails residences along Sherwood Road to assure that maximum noise levels in any inhabitable room will not exceed 45 dBA Ldn. (1)