3003 W CASINO RD BLDG 40-23 Geotech Report 2025-01-22

r 4. .Subsurface Conditions The existing concrete slab encountered in each of the borings completed forth is study generally measured approximately 14 inches thick. Weathered glacial till soils were encountered in borings B-7 and B-9 along the east side of HBL Positions 5 and 6, respectively. The weathered glacial till, where encountered, extends approximately 7 to 13 feet below existing site grades, and generally consists of dense to very dense silty sand with variable gravel content. Relatively unweathered glacial till soils were encountered below the weathered glacial till in each of the explorations completed at the site. Borings within Position 7 indicate unweathered glacial till soils only. The unweathered glacial till generally consists of very dense silty sand with variable gravel content and extends to the depths explored in each boring completed for this study. Previous borings in the vicinity encountered very dense glacial till to depths greaterthan 50 feet. Occasional fractured rock interpreted as cobbles were observed in the soil cuttings during drilling. Based on our experience in the project vicinity, occasional cobbles and boulders should be anticipated in the glacial till. 4.. Groundwater Conditions Groundwater was not observed in the borings during drilling. We anticipate a seasonally perched groundwater will be present above the unweathered glacial till soils, particularly near the perimeter and outside the factory building. Perched groundwater is common as seepage from precipitation and surface water runoff infiltrates through the upper fill and/or weathered glacial till soils and moves laterally or perches on the underlying very dense glacial till soils. Groundwater levels are anticipated to fluctuate and vary as a function of location, precipitation, season and other factors. 5.1.. Summary of Key Geotechnical Issues Results of numerical modeling for the design loading condition and subsurface soils encountered in the current borings result in a uniform subgrade modulus of 475 pounds per cubic foot (pcf) for the new Positions 5 through 7. A summary of the key geotechnical considerations is provided below. Design level recommendations of each of these items, as well as other important geotechnical recommendations for the proposed project, are contained in subsequent sections of this report. The summary is presented for introductory purposes only and should be used in conjunction with the complete recommendations presented in this report. The site is designated as Site Class C per the 2018 International Building Code (IBC), based on the average blowcounts in borings completed at the site. A uniform modulus of subgrade reaction is appropriate for support of the mat foundation based on the numerical modeling analyses completed and new exploration data. A modulus of subgrade reaction of 475 pounds per cubic inch (pci) is appropriate for HBL Positions 5 through 7 (refer to Appendix D for numerical modeling analyses details). The weathered glacial till and glacial till soils contain a sufficient percentage of fines (silt and clay) and are therefore moisture sensitive. When the moisture content of these soils is more than a few percent above the optimum moisture content, these soils become muddy and unstable, and operation of equipment on these soils is difficult. Re -use of the excavated soils outside the building during periods of wet weather will not be practical. Based on the moisture content of the samples obtained in the GMENGINEERS June 15, 2022 Page 3 File No. 0120-294-02