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L <br />Minnesota Pollution Control Agency r <br />520 Lafayette Road, Saint PauI,^Minnesota 55155 <br />!! <br />Telepfp.OAe ,(612) 296-6300 <br />• L ^ ,'C,; {•[’£! <br />N • <br />MLNSUQIA mo <br />* ♦ <br />................. <br />November 27, 1989 <br />Sergeant Bill Chandler <br />Hennepin County Water Patrol <br />Post Office Box 187 <br />Spring Park, Minnesota 55384 <br />Dear Sergeant Chandler: <br />I appreciate the opportunity to have participated in the personal <br />watercraft noise testing on September 29, 1989, at Lake <br />Minnetonka. It's hard to believe that only 8 weeks ago I was <br />tempted to roll my pants up and wade in the water to cool off! <br />Attached is a copy of your test results to which I added my <br />results. Since my microphone was set up at the corner of the <br />dock platform, the open-throttle pass-bys may not have been at <br />exactly 50 feet. Also, I was not looking for a maximum level <br />during the 50 foot idle pass-by, but rather a minimum range. <br />The following numbers are the result of logarithmically averaging <br />the data on both types of watercraft: <br />(log) average maxlmums: @50', @100', @300', @400', @500' <br />modified: 87 85 71 68 67 <br />stock: 80 77 64 61 62 <br />Modified - vehicle 1,2,3. Stock » vehicle 4,6,7,8,9,10. Vehicle <br />5 didn't fit in either category so I left it out. <br />Two vehicles of each type were monitored at "play” for a few <br />minutes. I was curious to see how close to shore they could <br />operate and be within the State's ambl.tnt noise standards for <br />residents on shore. Two stock vehicles, assuming they stayed in <br />the same area for an hour, woulo appear to be within limits at <br />distances beyond 200 feet. Two modified vehicles, under the same <br />conditions, would need to be beyond 500 feet. <br />Regional Offices: Duluth • Brainerd • Detroit Lakes • Marshall • Rochester <br />Equal Opportunity Employer Prirtled on Recycled Paper <br />•I