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EIR Amendment - Appendix B - Supplemental Noise and Vibration AssessmentILUNGWORTH&RODKINJACm 111l1Acoustics • Air Quality 1111! I Willowbrook Court, Suite 120 Petaluma, California 94954 Tel: 707-794-0400 Fax: 707-794-0405 www.illingworthrodkin.com illro@illingworthrodkin.com June 28, 2018 Ms. Kristy Weis David J. Powers & Associates 1871 The Alameda, Suite 200 San Jose, California 95126 Subject: Vallco Special Area Specific Plan Project, Cupertino, CA Addendum Letter to the Environmental Noise Assessment Dear Ms. Weis: In addition to the proposed project and the three previously studied project alternatives, a new Housing Rich Alternative has been proposed as part of the Vallco Special Area Specific Plan Project in Cupertino, California. This addendum letter focuses on the impacts of this new alternative and how it compares to the impacts discussed in the May 2018 Noise and Vibration Assessment. Details pertaining to the Housing Rich Alternative are included in Table 1. Additionally, a supplemental traffic study completed for the Housing Rich Alternative. TABLE 1 Summary of Project and Project Alternative Development Land uses Commercial Office Hotel Residential Green Roof Civic Space (square (square (units) (units) (acres) (square footage) foota a footage) 1,500,000 65,000 600,000 (includes (includes (includes 40,000 sf 50,000 sf Housing Rich 60,000 sf as school 339 3,250 30 City Hall and Alternative performing administration 15,000 sf arts center) building and Adult 10,000 sf Education STEM Lab) Space) Ms. Kristy Weis, David J. Powers & Associates Vallco Special Area Specific Plan Project, Cupertino, California June 28, 2018 GENERAL PLAN CONSISTENCY ANALYSIS Future Exterior Noise Environment The traffic volumes for the Housing Rich Alternative were inputted into the SoundPLAN Version V8.0 model developed for the proposed project, and Table 2 presents the community noise equivalent levels for each cumulative plus project design scenario and the cumulative (no project) scenario, calculated at a reference distance of 75 feet from the center of the near travel lane for the major roadways surrounding the site. As indicated in Table 2, there is a 1 to 2 dBA CNEL difference between the cumulative and cumulative plus project scenarios under any proposed alternative. Figure 1 shows the cumulative plus project noise level contours for the Housing Rich Alternative, which would be within 1 dBA of the proposed project and other project alternatives, as discussed in the May 2018 assessment. 2 Ms. Kristy Weis, David J. Powers & Associates Vallco Special Area Specific Plan Project, Cupertino, California June 28, 2018 TABLE 2 Cumulative No Project and Cumulative Plus Project Modeled Noise Levels Along Surrounding Roadways Future Noise Level 75 feet from the Centerline of the Roadway, dBA CNEL General Plan Roadway Cumulative Occupied/ Proposed Buildout with Retail & No Project Re -Tenanted Specific Plan Max. Residential Housing Rich Mall Residential I-280 85 85 85 85 85 85 Perimeter Road, north of 65 66 67 66 66 67 Stevens Creek Boulevard Perimeter Road, near 62 62 63 63 62 63 Amherst Drive Perimeter Road, west of 68 69 69 69 69 69 North Wolfe Road Perimeter Road, east of 76 76 76 76 76 76 North Wolfe Road Perimeter Road, north of 66 67 67 67 67 67 Vallco Parkway Stevens Creek Boulevard 71 71 71 71 71 71 Vallco Parkway 68 69 70 70 69 70 North Wolfe Road, north of 71 71 71 71 71 71 Stevens Creek Boulevard North Wolfe Road, at Vallco 71 71 72 72 71 72 Parkway North Wolfe Road, south of 72 73 73 73 73 73 Perimeter Road North Wolfe Road, north of 74 75 75 75 75 75 Perimeter Road Ms. Kristy Weis, David J. Powers & Associates Vallco Special Area Specific Plan Project, Cupertino, California June 28, 2018 uniumE 1 future iNolse contours for Cumulative Flus dousing tticn Alternative lranic scenario Future Noise Contours - Cumulative Plus Housing Rich Alternative Noise level Ldn in dB(A) = 55 =60 =65 =70 =75 =80 = 85 Signs and symbols W.11 0 300 600 1200 feet t ,s 4 t -x - '4r o- 1. ' r''"''' � � •��� c i• ,•, -4 . r TAir ,c r — Ms. Kristy Weis, David J. Powers & Associates Vallco Special Area Specific Plan Project, Cupertino, California June 28, 2018 Proposed Multi -Family Residential Land Uses The noise levels from Table 2 for the alternative representing the worst-case scenario, which was the Housing Rich Alternative scenario as it generates more daily trips than the proposed project and other project alternatives evaluated in the May 2018 assessment, were used to estimate the distances at which common outdoor use areas with direct line -of -sight to the roadways would need to be set back from area roadways to meet the 65 dBA CNEL threshold for multi -family residential land uses. Table 3 summarizes the setbacks required to meet 65 dBA CNEL without additional noise control such as barriers. The distances calculated in Table 3 are within 20 feet of the distances described in the EIR. TABLE 3 Cumulative Plus Housing Rich Alternative Setback Distances to Meet the 65 dBA CNEL Threshold of Common Outdoor Use Areas at Residential Land Uses Roadway Distance from Centerline to 65 dBA CNEL I-280 1,035 feet Perimeter Road, north of Stevens Creek Boulevard 105 feet Perimeter Road, near Amherst Drive 45 feet Perimeter Road, west of North Wolfe Road 175 feet Perimeter Road, east of North Wolfe Road 355 feet Perimeter Road, north of Vallco Parkway 115 feet Stevens Creek Boulevard 195 feet Vallco Parkway 165 feet North Wolfe Road, north of Stevens Creek Boulevard 200 feet North Wolfe Road, at Vallco Parkway 215 feet North Wolfe Road, south of Perimeter Road 260 feet North Wolfe Road, north of Perimeter Road 310 feet Proposed Commercial/Office Land Uses The noise levels summarized in Table 2 (i.e., the Housing Rich Alternative) were also used to estimate the distances at which common outdoor use areas with direct line -of -sight to the roadways would need to be set back from area roadways to meet the 70 dBA CNEL threshold for commercial/office land uses. The results for the Housing Rich Alternative are summarized in Table 4. The distances calculated in Table 4 are within 20 feet of the distances described in the May 2018 assessment for the proposed project and other project alternatives. The results for the future exterior noise environment for both residential and commercial uses would be the consistent with the results in the May 2018 assessment. W Ms. Kristy Weis, David J. Powers & Associates Vallco Special Area Specific Plan Project, Cupertino, California June 28, 2018 TABLE 4 Cumulative Plus Housing Rich Alternative Setback Distances to Meet the 70 dBA CNEL Threshold of Common Outdoor Use Areas at Commercial Land Uses Roadway Distance from Centerline to 70 dBA CNEL I-280 580 feet Perimeter Road, north of Stevens Creek Boulevard 35 feet Perimeter Road, near Amherst Drive <15 feet Perimeter Road, west of North Wolfe Road 55 feet Perimeter Road, east of North Wolfe Road 200 feet Perimeter Road, north of Vallco Parkway 40 feet Stevens Creek Boulevard 90 feet Vallco Parkway 65 feet North Wolfe Road, north of Stevens Creek Boulevard 100 feet North Wolfe Road, at Vallco Parkway 115 feet North Wolfe Road, south of Perimeter Road 130 feet North Wolfe Road, north of Perimeter Road 170 feet Future Interior Noise Environment Proposed Multi -Family Residential Land Uses For residential building setbacks from the centerline of the nearby roadway equivalent to those distances shown in Table 3, the exterior -facing units would be exposed to future exterior noise levels of 65 dBA CNEL, and the future interior noise levels at these units would be 50 dBA CNEL, which would exceed 45 dBA CNEL. Proposed residential buildings with standard construction materials would not meet the City's interior noise level threshold and would require noise insulation features to be compatible with the noise environment at the site. Proposed Commercial Land Uses Assuming a minimum of 20 dBA of exterior -to -interior noise reduction, the future interior noise levels would be 50 dBA Leq(1-hr) or less at the setback distances shown in Table 4. Commercial buildings proposed nearer to area roadways than the minimum screening distances shown in Table 4 would potentially be exposed to interior noise levels above 50 dBA Leq(1-hr) and would require noise insulation features to be compatible with the noise environment at the site. Recommendations to Reduce Future Exterior and Interior Noise Levels The same recommendations discussed in the May 2018 assessment would be consistent for the proposed project, the Housing Rich Alternative, and each of the other proposed alternatives. Gol Ms. Kristy Weis, David J. Powers & Associates Vallco Special Area Specific Plan Project, Cupertino, California June 28, 2018 NOISE IMPACTS AND MITIGATION MEASURES The results in the May 2018 assessment for Impacts 1 (Noise Levels in Excess of Standards), 2 (Exposure to Excessive Groundborne Vibration due to Construction), and 5 (Temporary Construction Noise) would be consistent for the Housing Rich Alternative. Mitigation Measures 1 and 2 in the May 2018 assessment would be recommended for the proposed project, the Housing Rich Alternative, and each of the other proposed alternatives. A total of 67 intersections were included in the supplemental traffic study completed in June 2018. With the exception of Perimeter Road, receptors along Vallco Parkway and all other roadway segments in the project vicinity would experience noise level increases of 2 dBA CNEL or less under the project and project alternatives, including the Housing Rich Alternative. Perimeter Road receptors north of Stevens Creek Boulevard and north of Vallco Parkway would experience a 6 to 8 dBA increase in noise levels above existing conditions under the project and project alternative traffic scenarios. However, only the receptors located north of Stevens Creek Boulevard would be considered noise -sensitive. Therefore, the results for Impact 3 (Permanent Noise Level Increase) in the May 2018 assessment would be consistent with the results of the Housing Rich Alternative, and Mitigation Measure 3 in the May 2018 assessment would be recommended for the proposed project, the Housing Rich Alternative, and each of the other proposed alternatives. For Impact 4 (Cumulative Noise Increase), traffic noise levels along Vallco Parkway, between Perimeter Road and North Wolfe Road, are projected to increase by 3 dBA CNEL under cumulative plus project (and each alternative) conditions, while cumulative (no project) conditions resulted in an increase of 2 dBA CNEL. Additionally, along Vallco Parkway, east of Perimeter Road, a 3 dBA CNEL increase would occur under the cumulative plus project scenario and under the Housing Rich Alterative only, while the other proposed alternatives and the cumulative (no project) scenarios would result in a 2 dBA CNEL increase. Since each scenario involving project and alternative conditions would be substantially increased between Perimeter Road and North Wolfe Road and east of Perimeter Road under the proposed project and the Housing Rich Alternative scenarios, and the project's contribution would be 1 dBA CNEL, the project would cause a significant cumulative traffic noise impact. Additionally, along Perimeter Road north of Stevens Creek Boulevard and north of Vallco Parkway, an increase of 6 to 8 dBA was calculated under the cumulative plus project scenario and each alternative, while the cumulative (no project) scenario resulted in an increase of 1 dBA CNEL or less. However, as in Impact 3, only the segment along Perimeter Road north of Stevens Creek Boulevard would impact existing noise -sensitive receptors. As determined in the May 2018 assessment, a cumulatively considerable contribution to the overall traffic noise increase at the adjacent existing residential land uses would occur under the proposed project and each alternative, including the Housing Rich Alternative. Impact 4 is a significant impact, and Mitigation Measure 4 from the May 2018 assessment would also be recommended to reduce the Cumulative plus Housing Rich Alternative Noise Increase impact. fd Ms. Kristy Weis, David J. Powers & Associates Vallco Special Area Specific Plan Project, Cupertino, California June 28, 2018 TABLE 5 Calculated Cumulative Noise Level Increases Above Existing Conditions The calculated increases shown in the table are for the roadway segments in the immediate vicinity of the project site. All other intersections included in the traffic study resulted in the same noise level increases for all cumulative conditions (no project, plus project, and each project alternative). The Housing Rich Alternative and the traffic volumes for the four additional intersections did not change the results of the impact analysis in the Vallco Special Area Specific Plan Project EIR. 8 Cumulative Plus Project (and General Plan Buildout with Cumulative Plus Cumulative Maximum Roadway Segment (No Project) Residential Housing Rich Alternative Noise Noise Increase Alternative and Retail and Increase Residential Alternative) Noise Increase Perimeter Road, north of Stevens Creek Boulevard < 1 dBA 7 to 8 dBA 8 dBA Perimeter Road, north of Vallco 1 dBA 6 dBA 7 dBA Parkway North Wolfe Road, north of 1 dBA 2 to 3 dBA 3 dBA Vallco Parkway North Wolfe Road, between Vallco Parkway and Stevens 1 dBA 2 dBA 2 dBA Creek Boulevard Miller Avenue, south of Stevens 1 dBA 1 dBA 1 dBA Creek Boulevard Stevens Creek Boulevard, east 1 dBA 1 to 2 dBA 2 dBA of North Wolfe Road Stevens Creek Boulevard, between North Wolfe Road and 1 dBA 1 dBA 1 dBA Perimeter Road Stevens Creek Boulevard, west of Perimeter Road 1 dBA 2 dBA 2 dBA Vallco Parkway, east of 2 dBA 2 to 3 dBA 3 dBA Perimeter Road Vallco Parkway, Perimeter 2 dBA 3 dBA 3 dBA Road to North Wolfe Road The calculated increases shown in the table are for the roadway segments in the immediate vicinity of the project site. All other intersections included in the traffic study resulted in the same noise level increases for all cumulative conditions (no project, plus project, and each project alternative). The Housing Rich Alternative and the traffic volumes for the four additional intersections did not change the results of the impact analysis in the Vallco Special Area Specific Plan Project EIR. 8 Ms. Kristy Weis, David J. Powers & Associates Vallco Special Area Specific Plan Project, Cupertino, California June 28, 2018 Sincerely, lk*i Carrie J. Janello Senior Consultant Illingworth & Rodkin, Inc.