25C - AGMT - OCWD CENTENNIAL PARK

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Section 5 Alternative 2: Less than significant adverse impact Alternative 3: Less, than significant adverse impact Alternative 4: Less than significant adverse impact IMPACT N-4: Would the project expose persons to or generation of excessive groundborne vibration or groundborne noise levels? California Administrate Code 15000, Title 14 requires that all state and local agencies implement the California Environmental Quality Act (CEQA) Guideline, which requires an exposure analysis of persons to excessive groundborne vibration. Presently, the state or the City of Santa Ana has yet to quantify the level at which excessive groundborne vibration occurs, either any statute or other means. Several different methods are used to quantify vibration amplitude Such as the maximum instantaneous peak in the vibrations velocity, which is known as the peak particle velocity (PPV) or the root mean, square (rms) amplitude of the vibration velocity. Because of the typically small amplitudes of vibrations, vibration velocity is often expressed in decibels and is denoted as L, and is based on the rms velocity amplitude. A commonly used abbreviation is VdB, which in this text, is when L, is based on the reference quantity of one micro-inch persecond, Caltrans issued the Transportation and Construction Induced Vibration Guidance Manual in 2004. The manual provides practical guidance to Caltrans engineers, neers, planners, and consultants who must address vibration issues associate with the construction, operation and maintenance of Caltrans projects, The Guidance Manual establishes numeric thresholds for construction related and transportation related vibration impacts. The Guidance Manual determines that human response becomes distinctly perceptible at 0,04 inch per second PPV for continuous sources and 0.25 inch per second PPV for transient sources. Construction activity can result in varying degrees of ground vibration, depending on the equipment used on the site. Operation of construction equipment causes ground vibrations that spread through the ground and diminish in strength with distance. Buildings in the vicinity of the construction site respond to these vibrations with varying results ranging from no perceptible effects at the low levels to slight damage at the highest levels. Table 81 gives approximate vibration levels for particular construction activities for a wide range of sail conditions. As vibration waves propagate from a Source, the vibration energy decreases in a logarithmic nature and the vibration levels typically decrease by 6 LV per doubling of the distance from the vibration source. Mid Basin Centennial Park Injection Well Project Final EIR 5-214 25C-315