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Subsurface Exploration and Foundation Evaluation Proposed Golden Oil Refueling Station • Stoughton, Wisconsin PSI Project No. 0092822 Page 5 The foregoing discussion of soil conditions on this site represents a generalized soil profile as determined at the test boring locations. A more detailed description and supporting data for each test location can be found on the individual Soil Boring Logs. Groundwater Observations Groundwater observations were made during auger advancement and in the open boreholes at completion. Groundwater was encountered in all borings except B-6, at depths ranging from about 6 to 13 feet (EL. 866.1 to EL. 861.5) below the ground surface. All of the holes caved to varying depths upon withdrawal of the auger; therefore, observations could not be made below the caved depth. Upon completion and removal of the augers, groundwater was present at SW-1 and SW-2, respectively. The groundwater observations reported herein are considered approximate. It must be recognized that groundwater levels fluctuate with time due to variations in seasonal precipitation, lateral drainage conditions, and soil permeability characteristics. Longer term monitoring would be required to better evaluate groundwater levels on this site. EVALUATION AND RECOMMENDATIONS General Development Considerations Fill soils with somewhat variable support characteristics were present to a depth of 6 feet (EL. 868.5 to EL. 869.1) below existing grade at B-1, B-2, and B-3, which were performed in the area of the building. Fill soils are not recommended for foundation support due to potential excessive total and differential settlements. The proposed structure can be supported by means of conventional spread footings extended through the existing fill and any buried topsoil, to bear on suitable natural soils, or upon newly placed compacted structural fill (or lean concrete slurry) used to replace the existing materials. About 2 to 3 feet of overexcavation below frost depth footings (with deeper undercuts within interior footings) is estimated to be necessary in the planned building area to reach suitable materials. However, some variation should be expected. The existing fill soils can be utilized for support of the floor slab after proper subgrade preparation. However, some overexcavation of unsuitable soils may be necessary. Conventional asphalt pavement can be used in the parking lot and driveway areas. However, some increased maintenance and more frequent repairs may be necessary due to the presence of variable strength existing fill and possible buried topsoil. A discussion of the building foundation and pavement design parameters, as well as the support conditions for the floor slab and pavement are included in later sections. Site Preparation The presence of organic topsoil and vegetation in the subgrade can adversely affect the serviceability of structural fills, foundations, floor slabs, pavements, and other structures placed upon them. Approximately 2 to 8 inches of topsoil or topsoil fill were present on the surface of most of the boring locations. However, some variation should be anticipated. All