Malibu Municipal Code § 6.3 Existing Noise Environment

The City includes a wide variety of land use and development types that are noise sensitive. Noise sensitive land uses include, single and multiple family residences, schools, libraries, medical facilities, retirement/rest homes, and places of religious worship. The predominant land uses in the City are noise sensitive residential uses.

The existing measurable noise environment was documented through both a community noise survey and computer generated noise contours. The noise survey identified existing noise levels generated by various sources at specific locations within the City while the computer analysis predicted existing and future roadway noise levels.

A community noise survey was conducted on July 16, 1992 to document the existing noise environment within the City of Malibu. Noise measurements were conducted at 10 sites between 9:28 a.m. and 3:03 p.m. The locations were representative of residential, commercial and public use areas. Noise measurement survey data forms for each location are provided in Appendix A of the Background Report to this Element. The approximate locations of the noise measurements are illustrated in Figure N-3 and the results are presented in Table 6-1. Each site was measured for 15 minutes. The quantities measured are in Leg, Lmin, and Lmax. The noise measurement results summarized in Table 6-1 should be used as a guide or indication of noise levels throughout the community.

The land uses in the locations surveyed included predominantly noise sensitive land uses such as residential neighborhoods. Commercial uses also exist at three of the measurement sites and one location contains only commercial uses. Public open space such as the Malibu Bluffs Park were also surveyed for noise levels. The noise sources in most of the locations surveyed included vehicular traffic, street maintenance, animals, helicopter and other aircraft; and lawn equipment. The noise survey recorded Leg noise levels throughout the City of 74 dBA and below. Most of the noise levels in these areas are compatible with the land uses, there are however, a few areas identified on Table 6-1 in which the noise levels exceed the normally acceptable levels for the existing land uses.

Table 6-1 NOISE MEASUREMENT SURVEY RESULTS

Source: Harland Bartholomew & Associates, July 1992

The dominant noise source in Malibu is roadway traffic from Pacific Coast Highway which runs east/west throughout the City. Additional roadway traffic noise arises from some of the canyon roads including, Malibu Canyon Road and Kanan Dume Road which run north/south.

The noise contours represent lines of equal noise exposure, just as the lines on a weather map indicate equal temperature or atmospheric pressure. The contours provide a visualization of estimates of sound level. Land forms and man-made structures have very complex effects on sound transmission and on noise contours. Generally, barriers between a source and receiver absorb or reflect noise resulting in a quieter environment. Where barriers or land forms do not interrupt the noise transmission path from source to receiver, the contours prove to be good estimates of the average noise level. In areas where barriers or land forms interrupt the sound transmission, the noise contours overestimate the extent to which a source intrudes into the community. The noise contour distances describe worst-case conditions because they do not account for any obstructions to the noise path, such as walls, berms, or buildings. There were 16 roadway segments that were analyzed; Table 6-2 provides the results of the analysis along Pacific Coast Highway during the summer months which are the peak traffic months.

A graphic display of the 55, 60, 65, 70 and 75 dB CNEL noise contours for the existing major roadway noise sources is provided in Figures 6-4(A-D) and 6-5(A-D). Figure 6-4(A-D) presents an overall picture and several detailed maps of the contours for annual roadway noise. Figure 6-5(A-D) presents an overall picture and several detailed maps of the contours for the summer months/peak season roadway noise along Pacific Coast Highway. The noise contours represent unmitigated conditions. Therefore, on roadways where walls, berms or structures block the noise path, the contours overestimate the noise impact.

It is not possible for a general plan noise element to analyze each roadway segment of the City for barrier noise attenuation. Therefore, where specific projects are proposed within noise impacted areas, an acoustical analysis should be completed to evaluate the noise reduction provided by any barriers to the noise path. A description of the study methodology and data sources is included in the Background Report to this Element.

Table 6-2 EXISTING ROADWAY NOISE LEVELS

Table 6-3 EXISTING ROADWAY NOISE LEVELS DURING SUMMER MONTHS

Figures N-4 and N-5 display the 75, 70, 65, 60 and 55 dB CNEL noise contours that were generated using the FHWA noise model for existing roadway noise sources in the City of Malibu. The contours portray areas of equal noise level within an equivalent distance from the roadway centerline.

The eastern segment of Pacific Coast Highway which runs from the eastern City limits to Serra Road, is characterized by the highest noise levels. This area generates a 75 dB CNEL contour which extends 55 feet from the roadway centerline, a 70 dB CNEL contour which extends approximately 140 feet from the roadway centerline, and a 65 dB CNEL contour which extends approximately 400 feet from the roadway centerline. The average half-width of Pacific Coast Highway is 25 feet. Therefore, the 75 dB CNEL extends 30 feet beyond the outer boundary of the roadway. A significant number of the residential dwelling units are located along Pacific Coast Highway with no setbacks. Many of these homes are exposed to noise levels as high as 75 dB CNEL depending on the type of landscaping or other noise-attenuating barriers located at each structure. The 65 db CNEL extends as far as the Pacific Ocean, encompassing all of the beach side residential units along this segment of Pacific Coast Highway. Noise levels of 65, 70 and 75 dB CNEL are considered incompatible with single-family residential dwelling units.

Along Pacific Coast Highway east of the Civic Center area, Serra Road to Cross Creek Road, noise contours of up to 75 dB CNEL are generated approximately 52 feet from the roadway centerline. Undeveloped/open space areas dominate the land adjacent to the street along this segment of Pacific Coast Highway. Noise levels of 75 dB are acceptable with this type of land use. There are noise contours of 70 dB CNEL generated approximately 87 feet from the roadway centerline along the segment of Pacific Coast Highway running through the Civic Center area, Cross Creek Road to Civic Center Road. The land uses along this segment of Pacific Coast Highway are primarily commercial. Noise levels of 70 dB CNEL and lower are compatible with commercial uses. However, most uses such as the Hughes Market are set back from the roadway and/or have large parking lots adjacent to Pacific Coast Highway and therefore the actual use is exposed to even lower noise levels.

The segment of Pacific Coast Highway which runs from Civic Center Way to Ramirez Canyon Road generates noise contours of 70 dB CNEL approximately 74 feet from the roadway centerline. Much of the land along this segment of the road is undeveloped/open space, however there is some commercial and a significant amount of residential land uses along there as well. The undeveloped/open space areas and commercial land uses are compatible with noise levels of 70 dB CNEL and below and are therefore not incompatible with the noise levels. The 65 dB CNEL contour extends 143 feet from the roadway centerline. Therefore residents along Pacific Coast Highway are exposed to noise levels of 65 dB CNEL and to some extent 70 dB CNEL which is incompatible with the state guidelines. Along Cross Creek Road, the noise levels are lower, with the 65 dB CNEL contour extending approximately 51 feet from the roadway centerline. The primary land use along Cross Creek Road is commercial and therefore the noise levels are compatible with the land uses.

Noise contours of up to 65 db CNEL are generated along Malibu Canyon Road between Pacific Coast Highway and Civic Center Way and extend approximately 51 feet from the roadway centerline. The area to the east of the roadway is undeveloped/open space and the area to the west is not within the City limits. North of Civic Center Way, contours of up to 65 dB CNEL extend approximately 82 feet from the roadway centerline. The land uses along this segment of Malibu Canyon Road include the Hughes Aircraft Research Facility, religious facilities and residential uses. Most of the structures are set back from the roadway and are not exposed to this noise level. Noise levels of 60 dB CNEL and below are compatible with all land uses.

There are similar noise contours generated along Pacific Coast Highway running west of Ramirez Canyon Road to Morning View Drive. The noise levels of up to 70 dB CNEL are compatible with the commercial uses in the area, however these noise levels are incompatible with both the multifamily and single-family residential land uses located in the area. The 70 dB CNEL contours extend approximately 70 feet from the roadway centerline and many of the residential uses may be set back farther than 45 feet from the edge of the roadway and would not be exposed to these noise levels. Noise contours of 65 dB CNEL extend approximately 133 feet from the roadway centerline. Multifamily residential uses are compatible with this noise level but 65 dB CNEL noise levels are incompatible with the existing single-family residential land uses.

Along Kanan Dume Drive north of Pacific Coast Highway the highest noise contours are 60 dB CNEL which extend approximately 63 feet from the roadway centerline. This noise level is compatible with all land uses.

The segment of Pacific Coast Highway that runs from Morning View Drive to the western City limits is dominated by undeveloped/open space areas, single-family residential uses, and a limited number of commercial uses. The 70 dB CNEL noise contours extend approximately 56 feet from the roadway centerline or approximately 30 feet from the edge of the roadway. The undeveloped/open spaces areas and commercial uses are not incompatible with this noise level. Many of the single-family residential land uses are set back farther than 30 feet from the edge of the roadway and are not exposed to this noise level. The 65 dB CNEL noise contour extends approximately 100 feet from the roadway centerline, or 75 feet from the edge of the roadway. Many of the single-family residential units may have setbacks of greater than 75 feet or have landscaping or some other form of sound barrier and therefore may not be within the 65 dB CNEL contour. The single-family land uses that are within 65 dB CNEL are exposed to noise levels incompatible with the land uses.

Figure N-5 represents noise contours generated by vehicular traffic along Pacific Coast Highway during the peak traffic months, typically June through September. The noise contours generated by peak vehicular traffic extend slightly farther than the noise contours generated during the non-peak months. There are few differences in the distances of the contours, the higher contours extend approximately two to three feet (75 dB CNEL) farther, three to 11 feet longer (70 dB CNEL), and nine to 30 feet longer (65 dB CNEL) during the peak season. The same land uses which are affected by high noise levels during the off-peak season are affected during the peak season, with no additional uses affected. The exception occurs on the segment of Pacific Coast Highway which runs from Cross Creek Road to Civic Center Way. The 75 dB CNEL contour extends approximately 52 feet from the roadway centerline during the peak season and there is no 75 dB CNEL contour during the off-peak season. The commercial uses along this segment of the road are set back from the highway and would not be exposed to the higher noise levels.

The noise measurements described above indicate that noise levels in the majority of the areas surveyed in the City are compatible with the surrounding land uses according to State guidelines. The noise contours in Malibu indicate that the eastern portion of the City experiences greater noise levels than the western portion and that, according to State guidelines, homes not located along Pacific Coast Highway are generally not exposed to unacceptable levels of noise. However, comments made during all phases of the citizen participation process indicate that City residents have found the level of noise, particularly during peak visitor days, to be unacceptable.

Table 6-4 MAXIMUM EXTERIOR NOISE LIMITS NON-TRANSPORTATION SOURCES

Table 6-5 MAXIMUM ALLOWABLE NOISE EXPOSURE TRANSPORTATION NOISE SOURCES