09-22-2004 Council Agenda - Laserfiche WebLink

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Aug 26 04 07:53a ,Ion Whitcomb AUG 25 '04 OE 35PM BRAUN INTERTEC P.3/23 651 -430 -0029 P.3 BRAUN INTERTEC Braun Inienee Ca,poratan 3d5 tog Ro:eiown A.envc Si. ?cu, MN 86 117 May 2I, 2004 Project SP-04-03734 Mr. Jon Whitcomb Wesley investment, Inc. 275 South 3'a Street , Suite 302 Stillwater, MN 55082 Dear Mr. Whitcomb: .Phone 651.687 32a.I Fux: 651.487.1 812 Web- UmunlnMneemm Re: Geotechnical Evaluation, Proposed Residential Development, Properties at 692 and 696 County Road B2, tide Canada, Minnesota. The geotechnical evaluation for the above- referenced project has been completed. This letter summarizes otur results and recommendations. Summary of Results Three of our four borings encountered about 9 feet of swamp and lacustrine (lake) deposits over clayey glacial till that extended to the termination depths of the borings, The remaining boring, drilled in topographically higher ground towards the south end of the site, encountered glacial till beneath about 1 -foot of topsoil. The swamp deposits consisted of slightly organic clay, organic silt and peat. The lake deposits cnncieted of sEzhtly org �ic zi3ty sane,' and clayey sand that were . . ._._.__ _. _.. _.. -.r ... �.,....- w., : o..!.m .�.<.., clayey oovu that vGi f loose to iveuC, 'The giaciai rill consisted of sandy lean clay and clayey sand that was locally rather soft, but mostly rather stiff to stiff Groundwater was observed in two of the four borings at depths of' about 4 % to 5 feet, corresponding to elevations of approximately 857 to 859 1/2. Standing water was observed in the ditch located within the northwest portion of the site at about elevation 861, and the normal water elevation of nearby Gervais Lake is 353. Summary of Recommendations The swamp and lake deposits are considered compressible and unsuitable for support of residential foundations. Where present below proposed building areas, we recommend that they be excavated and replaced with compacted engineered backfill. Removal and replacement of these organic soils with compacted mineral soils is also recommended for utility support. Although consideration could be given to leaving the organic soils in -place (at- depth) below the proposed street, given that corrective excavations will be needed for utilities placed, presumably, within the street, we recommend removing, organic soils from below the proposed street as well. Based on our water level observations and nearby ditch and lake levels, we estimate that groundwater elevations range from about 857 to 86L At these elevations, groundwater will impact construction, as excavations to remove organic materials will extend below groundwater. We recommend that lowest floor elevations be placed at least 4 feet above groundwater, and at least two feet above the I00 -year flood elevation of nearby ponds and lakes. _ _ .. ....... _......._..- _.. Prn.,,dnl" u.4ineerin= mid :n. n�,nmenrat .nlunnit <mre 1057