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• <br />• <br />Company <br />STS Project # <br />Date <br />Page 2 <br />With respect to vibration effects from pile driving, we have reviewed actual seismograph data taken <br />adjacent to pile driving operations. This material was provided to us courtesy of LH Bolduc Company and <br />Carl Bolander and Sons Company. The seismograph tests indicate that the frequency of the vibrations is <br />less than 2 cycles per second and the maximum particle velocity recorded, even as close as 15 to 20 feet <br />from the pile driver, is generally Tess than 1 inch per second. On this basis, there should be no damage <br />to the nearest house, which is 70 feet from one end of the bridge. It should be noted that the human body <br />is quite sensitive, and thus occupants of the house might feel some small vibrations, or some crockery <br />may rattle during the pile driving, but the effects on the structure should be none or negligible. <br />STS will provide a continuously recording seismograph to the site during all pile driving operations. We <br />will also establish pre - existing vibration levels in the neighborhood resulting from street traffic such as <br />garbage or delivery trucks. During construction, vibration levels (amplitude and frequency will be <br />recorded at the closest house to the pile driving operations and at any nearby home where a complaint is <br />made. If vibration levels exceed 1 inch /sec particle velocity, modifications to the pile driving will be <br />necessary. Records of vibration events will be submitted to the City upon completion of the piling <br />operations, or as any issues or complaints arise. <br />The pre- condition survey, and pre - construction noise and vibration studies can be initiated upon your <br />request The results of these surveys can be forwarded to the City if you desire. If we can be of further <br />service, please call us. <br />Sincerely, <br />STS CONSULTANTS, LTD. <br />James H. Overtoom, P.E. <br />Principal EngineerNice President <br />JHO/ <br />cc: Mr. Jeff Shopek — Loucks and Associates, Inc. <br />C623B001.doc <br />