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Minutes - San Leandro City Council Meeting - April 6, 1992 Page - 19 - PUBLIC HEARINGS (continued) In response to questions from the City Council , Mr. Springer said the build-out would occur in 7-10 years, but it was noted that the Conditions of Approval required the Wicks/Lewelling mitigation be completed before occupancy. Jeff Pack, from Edward Pack Acoustical Consultants, said he was a noise consultant on the project. He noted there were several concerns related to noise. He said ground vibration from railroad pass-bys is a concern. He said trains do not create a significant amount of ground vibration, rather, it is mostly airborne sound. He said the primary noise source will be the railroad. He said the development is 75 feet away from the railroad tracks so soundwalls and acoustical windows will be used as mitigation. He discussed fly-bys by aircraft. He said the noise contours have regressed from the site since 1986 because air- traffic patterns are centered away from the site. He said the difference in noise levels from 1986 to 1991 is about 3-4 decibels. He said peak noise levels may not exceed 40-45 decibels dba interior so his firm recommended acoustical windows and other construction techniques to mitigate noise. He said traffic on Lewelling Boulevard will create noise impact and a soundwall has been proposed as well as other construction techniques. Council Member Perry asked how possible expansion of the airport would affect the project. Mr. Pack said if the airport expands to the east there would only be a few decibels increase which could be mitigated. He also noted that aircraft technique has increased and aircraft are much quieter than they used to be. Council Member Santos asked if testing of general aviation aircraft versus jets had been done because the general aviation aircraft are very loud. He asked if noise levels would be kept to 40-45 dba. Mr. Pack said yes they would. Council Member Santos requested that they check on the general aviation flight patterns in the early mornings. Mr. Pack said his study includes that information. Council Member Glaze asked if it would be better to build a soundwall near Mission Bay Mobilehome Park out of sound-deadening material rather than masonry because masonry reflects sound. Mr. Pack said there is only 1.5 decibel increase with masonry, and it is not really noticeable. Council Member Glaze asked if they had done any studies elsewhere in San Leandro, such as on Halcyon Drive. Mr. Pack said they have done studies on freeways such as 680 at Alcosta. He said, actually, wood. is a better absorber than masonry.