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Pam Hazdy Apri19, 2008 Page 7 The Pleasanton Noise Element strongly discourages residential development in areas exposed to excessive aircraft noise. The project site is located well outside the 60 dBA DNL contour for the airport. The noise exposure is estimated to be less than 55 dBA DNL. Aircraft noise is, therefore, less than significant at the project site. The site, however, is exposed to intermittent noise from the OSC. Of particular concern is the noise from the police firing range. The sound of the firing range would be clearly audible at the homes along the southern azeas of the site adjacent to the OSC. The 1996 study stated that gunshot noise is significantly more annoying than road traffic noise at the same level. The annoyance of the two sources can be compared by adding 13 dBA to the Ley of the gunshot noise. We concur with this opinion. Special noise control treatments are, therefore, warranted in residential buildings along the south property boundary (Lots 3, 4 and Lots 91 through 96). Recommended Mitigation for Lots 3 and 4 and Lots 91 through 96 The existing sound wall is sufficient to attenuate noise in outdoor activity areas. If the wall is to be demolished and replaced, it should be of at least equal height to the existing wall along the common property line between the OSC and the project site. It is recommended that I,,,,e,~ levels from the gunshots be reduced to no more than 40 dBA inside the residences with windows closed. The exterior-to-interior noise reduction provided by these buildings on facades located on the east, south, and west sides of the buildings should provide at least 25 dBA of noise reduction when going from outside to inside at the Bound floor and 35 dBA of noise reduction at upper floors. This can be accomplished with a combination of sound rated windows and doors. Units should be provided with forced air mechanical ventilation so that windows may be kept closed at the discretion of the occupants to control noise transmission. At the time for the final design for the buildings, detailed recommendations shall be made to specify the sound transmission class ratings for the various building elements. As noted in the 1996 study, there should be a full disclosure to future residents of the various noise sources at the City OSC and the more distant industrial land uses. These include the use of the police firing range, the weekly engine generator testing, the occasional movement of materials and the associated sound of backup beepers at the OSC and at distant industrial sites. This concludes our analysis of environmental noise levels at the proposed project. If you have any questions or if we maybe of further assistance, please do not hesitate to call. Sincerely yours, ~~~- ~~~ Richazd B. Rodkin, PE Illingworth &Rodkin, Inc. RBR:gfl (08-012)