07/15/2004 Env Bd Packet - Laserfiche WebLink

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• ]' STS Consultants, Ltd. voice 763 - 315 -6300 `� 10900 73rd Avenue North, Suite 150 fax 763 -315 -1836 r STS C p N S U L.TANTS Maple Grove, Minnesota 55369 -5547 web www.stsconsultants.com January 20, 2003 Mr. Ed Vaughan 1432 Pheasant Hills Drive Lino Lakes, MN 55038 Re. Environmental Assessment Worksheet (EAW) for Bridge and Road Construction at Pheasant Hills Preserve 12th Addition in Lino Lakes, Minnesota; STS Project 98623 -A Dear Mr. Vaughan: The site of the proposed Pheasant Hills Preserve 12th Addition is a ridge of higher land or "island" totally encircled by a wetland. In order to construct this project, it will be necessary to build a bridge across the wetland. Because of the depths of compressible organic soils at the bridge site, we have recommended that the bridge should be supported on driven piles. Your consulting engineer for this project, Loucks and Associates, Inc., has asked us to provide comments and recommendations regarding noise and vibration associated with the pile driving, for inclusion in an Environmental Assessment Worksheet. Noise For this specific project, we have recommended the use of steel pipe piles. We recommend that these should be driven with a relatively small hammer, to reduce noise and vibration effects. The pile driving hammer should have a rated energy no more than 30,000 foot pounds per blow. Typically, such a hammer operates a frequency of about 50 to 60 blows per minute, which relatively speaking is considered to be a low frequency. The hammer creates impulsive noise (series of repeated sounds) which would slightly exceed the noise standards for a Noise 1 classification area, namely 60 to 65 decibels. Thus the pile driving should be restricted to no earlier than 8 AM, and no later than 4 PM, with no pile driving on Saturdays and Sundays. Vibration With respect to vibration effects from pile driving, we have reviewed actual seismograph data taken adjacent to pile driving operations. This material was provided to us courtesy of LH Bolduc Company and Carl Bolander and Sons Company. The seismograph tests indicate that the frequency of the vibrations is less than 2 cycles per second and the maximum particle velocity recorded, even as close as 15 to 20 feet from the pile driver, is generally less than 1 inch per second. On this basis, there should be no damage to the nearest house, which is 70 feet from one end of the bridge. It should be noted that the human body is quite sensitive, and thus occupants of the house might feel some small vibrations, or some crockery may rattle during the pile driving, but the effects on the structure should be none or negligible. A figure showing safe vibration levels for residential structures is appended. We trust that this provides the information necessary for inclusion in the EAW. If we can be of further service, please call us. Sincerely, STS • SULTANTS T Mervyn Mindes . P.E. Senior Project Engineer MM /cb Encs: Figure 6 -2 "Safe Vibration Levels for Residential Structures" cc: Mr. Jared Andrews — Loucks and Associates, Inc. C623A001.doc Reviewed By: James H. Overtoom, P.E. Principal EngineerNice President t00 -LH-8 )4/02)