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f M AWOinSOW. V#C# PfM Opf^ttom <br />C G KRUSir Vice ing$m9nn§ <br />§ PERCOLATION <br />1, Richard Dohert; <br />d <br />Ota <br />itly taken <br />> assist <br />ground- <br />tary <br />the above <br />s were <br />ind as <br />It the <br />3rth Arm <br />5 with <br />ruary 17, <br />soil <br />logs were <br />the con- <br />strata <br />ncoun- <br />ssified <br />fication <br />ual and <br />^ is <br />‘d to our <br />itions by <br />lin in <br />! for your <br />77-045 <br />Braucr ^ Assoc., Inc.-2-February 24, 1977 <br />The borings were probed immediately after their completion <br />to check for the presence of groundwater. The borings were <br />also rechecked prior to leaving the site on February 17. <br />Absence of groundwater was noted in both probings of the <br />borings to their respective 15-foot termination depths, A <br />recheck of the boring 1 week later also encountered no <br />groundwater to the 15-foot depth. <br />The percolation tests were run in 6-inch diameter holes <br />drilled to an approximate depth of 36 inches, in accordance <br />with procedures recommended by the Minnesota Department of <br />Health (MHD) and with the procedures recommended by the City <br />of Orono. In accordance with these procedures, the bottom <br />and sides of the holes were scratched with a knife blade to <br />remove any smeared soil surfaces and to nrovide a natural <br />soil interface into which the water may percolate. Two <br />inches of coarse sand was then placed in the bottom of the <br />holes to prevent scouring. The holes were then carefully <br />filled with clear water to a minimum depth of 12 inches over <br />the top of the sand layer and allowed to soak overnight with <br />the percolation tests being conducted the following day. An <br />insulation material was placed over the holes prior to <br />leaving the site to prevent freezing of the water and soils <br />overnight. <br />RESULTS: <br />The log of the soils encountered in the borings and the <br />water level observations are shown on the attached Log of <br />Boring sheets. <br />Boring B-1, taken in Lot 5, encountered a coarse alluvium <br />silty sand, brown in color, with a trace of gravel, from <br />the surface to the 7-foot depth. Clayev sand glacial till <br />was then encountered from the 7-foot depth to the 15-foot <br />termination depth in the boring. <br />Boring B-2, taken in Lot 4, encountered a dark brown silty <br />sand topsoil layer from the surface to approximately the 4- <br />foot depth and was immediately underlain by coarse alluvium <br />silty sand between the 4 and the 7-foot depth. A clayey <br />sand glacial till was then encountered from the 7-foot depth <br />lo approximately the 12-foot depth and was in turn underlain <br />by a sandy clay glacial till to its 15-foot termination <br />depth.