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Minnesota Pollution Control Agency <br />612-296-7282 <br />February 7, 1978 <br />Hon. Don Valento <br />Mayor of Little Canada <br />515 E. Little Canada Road <br />Little Canada, MN 55117 <br />Dear Mr. Valenta: <br />I met with you and Roger Runyan Thursday, February 2, 1978 to <br />determine carbon monoxide levels in and around a proposed <br />snowmobile underpass under Interstate 35E in Little Canada. <br />An Ecolyzer model 2600 calibrated with 46 parts per million <br />by volume (ppm) reference gas was used to monitor CO levels. <br />The monitor was spanned before and after the sample period. <br />Wind speed in the underpass was low at approximately 1 meter <br />per second. <br />~'r The first sample was taken approximately 20 feet down wind of <br />two idling snowmobiles. Levels constantly in excess of 100 <br />ppm were encountered (100 ppm is the highest level indicated <br />on the monitor). After one snowmobile which was apparently <br />mistuned was turned off, CO levels dropped to about 30 ppm. <br />The two snowmobiles were then run through the underpass twice. <br />The airmass issuing from the underpass contained an average of <br />50 ppm and persisted for several minutes under the existing <br />wind conditions. <br />The national ambient air standard for carbon monoxide which <br />is designed to protect the health of the general population <br />is 35 ppm, one hour average. The hazard to drivers or pass- <br />engers from driving through the underpass would be minimal <br />due to the short duration of the exposure. If snowmobiles <br />were stopped and idled however, hazardous and possible lethal <br />concentrations could develop under low wind conditions. <br />If the underpass is used for snowmobile traffic, measures <br />should be undertaken to insure no stopping or idling in the <br />tunnel. If you judge this measure non -enforceable, I would <br />Pechnical <br />nd Lainst opening the underpass to traffic. <br />�ely, !% <br />... <br />Se <br />Clerk's Exhibit no. 00`13 <br />Services Section Meeting-2-8-78 Original on file under <br />Division of AiJ9_V @(gstl;�,iunty Road B2, Roseville, Minnesota 55113 Snow moble trails <br />Regional Offices • Duluth / Brainerd / Fergus Falls / Marshall / Rochester/ Roseville <br />Equal Opportunity Employer <br />