75D - PH ZONING ORD AND CUP CALIFORNIA PALMS

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The way in which vibration is transmitted through the earth is called propagation. Propagation of earthbome vibrations is complicated and difficult to predict because of the endless variations in the soil through which waves travel. There are three main types of vitiation propagation; surface, compression, and shear waves. Surface waves, or Rayleigh waves, travel along the ground's surface. These waves carry. most of their energy along an expanding circular wave from, similar to ripples produced by throwing a rock into a pool of water. P-waves, or compression waves, are body waves that carry their energy along an expanding spherical wave front. The particle motion in these waves is longitudinal (i.e., in a "push-puU" fashion). P-waves are analogous to airborne sarnd waves. S-waves, or sheaz waves, are also body waves that carry energy along an expanding spherical wave front. However, unlike P-wanes, the particle motion is transverse or "side-to-side and perpendicular to the dir~tion of Propagator." TABLE I HUMANREACTIONTO TYPT('.dT V7RAe'r'rn~v r rr~~ r irbration Leve[ Peak Particle Velocity rnches/secon Human Reaction E,JJ`ed on Buildings 0.006 - 0.019 Threshold ofpercepton, possibility of Vibrations unlikely to cause damage of intrusion any type 0.08 Vibrations readily perceptible Recommended upper level of vibration to which ruins and ancient monuments should be subjected 0.10 Level at which continuous vibration Virtually no risk of "azchitecturai" begins to armoy people. damage to normal buildings 0.20 Vibrations amroying to people in Threshold at which there is a risk to "architectural" damage to normal buildings. dwelling -houses with plastered walls and ceilings Vibrations considered unpleasant by Vibrations at a greater level than 0.4 - 0.6 People subjected to cominuous normally expected from traffic but vibrations and unacceptable to some , would cause "azclritectural" damage and people walldng by bridges possibly minor structural damage c,. ..•-,~-- vvww. aiGlLLGals LVVL. As vibration waves propagate from a source, the energy is sprrad over anever-increasing area such that the energy level striking a given point is reduced with the distance from the energy source. This geometric spreading loss is inversely proportional to the square of the distance. Wave energy is also reduced with distance as a result of material damping in the form of internal friction, soil layering, and void spaces. The amoum of attenuation provides by material damping varies with soil Lype and condition as well as the frequency of the wave. 2.3 Regulatory Environment 2.3.1 City of Santa Ana Standards The project is located within the City of Santa. Ana. and is therefore subject to the General Plan and noise ordinance incorporated therein. The primary, purpose of the City of Santa Ana Noise Element is to "Prevent significant increases in noise levels in the community and m;nim;ze the adverse effects ofcurrently-existing noise sources." In accordance with the Element, the City has adopted noise standards and guidelines for ]and use planning, These 75D-123