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.., Jeffry S. Rice, AICP City of Santa Ana February 7, 200 I Page 2 URS and recommended expanding the discussion of why sound insulation was not considered for "moderately" noise-impacted buildings. 3. The original noise analysis assumed that the CenterLine project would use LRVs with noise characteristics similar to the Tri-Met system in Portland. The SIR DEIS/R has additionally evaluated an alternative technology using the Ansaldo Breda STREAM vehicles. These are also steel-wheel-on-steel-rail technology LRVs that may eliminate the need for catenary masts and wires. The SIR DEIS/R noise analysis assumed that the Breda STREAM vehicle noise emissions would be equivalent to those of the Tri-Met LRVs. While this assumption is reasonable, no data was presented to support the assumption/assertion that the Breda LRVs would produce comparable noise levels. 4. Implementation of the revised Elevated Alternative (EA-2) results in zero residual noise impact to sensitive uses in Santa Ana, assuming inclusion of noise abatement design or mitigation measures. Thus, the EA-2 Alternative would be the environmentally preferred alternative from a noise impact perspective. 5. Vibration impacts for all project alternatives in Santa Ana are mitigable. Reasonable and feasible vibration mitigation methods and actions were described in the DEISIR. However, there was no clear commitment in the DEIS/R to specifically incorporate vibration reduction measures into the project design or adopt them as separate vibration impact mitigation measures. The SIR DEIS/R remains cloudy on this issue of vibration mitigation. 6. With respect to vibration effects, the authors of the SIR DEIS/R based their analysis of impact on what we believe to be an incorrect and unsupportable assertion regarding the FT A's impaci criterion. The authors have arbitrarily used a vibration level two velocity decibels (+2 VdB) above the established FTA impact criterion of 72 VdB for Category 2 uses (primarily residences) exposed to "Frequent Events" (70+ vibration events per day). The author's rationale is that FT A specifies two classes of impact for noise effects. While this is true for noise, thc FT A has adopted criteria levels for various land use types and frequency of events that result in only one specific vibration impact criterion for each set of vibration circumstances. The FT A guidelines do not provide for arbitrary modification of their impact critcria into subclasses. There is no ambiguity regarding vibration impact in our opinion. If the project vibration levels will be below the FT A-specified impact critcrion there will be no impact; if vibration levels are expected to be above the FT A criterion there would be impact and it should be mitigated. Thus, we recommend that the City require I) a clarification of Section 4.10.7 regarding vibration impacts, and 2) a commitment to providing vibration reducing design features or incorporation of mitigation measures as necessary to avoid vibration impact from any selected Alternative. 7. The Rail Systems Specifications, Task 5.], Section]], NOISE AND VIBRATION, contained in Volume II of the SIR DEIS/R (page 89 et. seq.) provide design criteria to avoid adverse effects and significant impacts from noise and vibration arising out of operation of the system including 1':\200 ]\57-0996] 035.02 CcnterLinl.'\rcporLdoc