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<br /> <br /> <br />Geotechnical Report <br />2021 Street Improvements <br />Hugo, Minnesota <br />WSB Project No. 015887-000 Page 3 <br />3. EXPLORATION RESULTS <br /> <br />3.1 Site and Geology <br />The borings were completed through the existing pavement section, with the exception of Boring B-1 and <br />B-3 which were completed in planned future roadway areas. Based on a review of MnTOPO contours, <br />boring elevations ranged from about 930 to 933 feet with the exception of Boring B-1 which was at an <br />elevation of about 910 feet. <br /> <br />Geologic origins can be difficult to determine solely from boring samples. We referenced online geologic <br />data of the area and used our experience to help determine geologic origin of the soils, however only a <br />detailed geologic exploration would accurately determine the geologic history of the site. <br /> <br />The Washington County Geologic Atlas indicates the surficial geology of the area is mostly glacial <br />stratified deposits consisting of sand, silty and clayey sand, and gravels. These soils are locally <br />interbedded with silt and glacial till deposits. <br /> 3.2 Subsurface Soil and Groundwater Conditions <br />The boring profile generally consisted of the pavement section or topsoil materials overlying fills and <br />glacial outwash soils. <br /> <br />Pavement Section <br />The bituminous sections encountered in the borings ranged from 2 to 4 inches in thickness. The <br />aggregate base section encountered in the borings ranged from 4 to 8 inches in thickness. Borings B-1 <br />and B-3 were not completed within a pavement area, and no discernable aggregate base section was <br />observed at Boring B-4 below the bituminous pavement. <br /> <br />Organics <br />At Boring B-1, we encountered organic clays at the surface that extended to a depth of about 2 feet below <br />grade. These topsoil deposits were black in color and generally moist. <br /> <br />Fills <br />At Borings B-2, B-4, B-6, B-7, and B-8 we noted fill materials below the pavement section. These fills <br />consisted of sands that were generally moist. <br /> <br />Glacial Outwash <br />Below the pavement section, fills, and organic clays, we encountered glacial outwash soils that consisted <br />mostly of sands that were light brown to dark brown in color and moist to wet to waterbearing. At Boring <br />B-1 we noted silts with sand at a depth of about 12 ½ feet to termination depth that were gray in color and <br />saturated. <br /> <br />Table 1 below presents the existing roadway pavement section and subgrade prof iles. <br /> <br />Table 1: Pavement Section and Subgrade Soils <br />Boring No. <br />Bituminous <br />Thickness <br />(inches) <br />Aggregate <br />Base <br />Thickness <br />(inches) <br />Subgrade Soils <br />(Upper 4 feet) <br />B-1 n/a n/a Organic Clay, Sand <br />B-2 4 2 Fill (Sand), Sand <br />B-3 n/a n/a Sand <br />B-4 4 n/a Fill (Sand) <br />B-5 3 8 Sand