3003 W CASINO RD BLDG 40-58 Geotech Report 2022-10-25

onsite, except for lower and more variable density. The fill soil encountered in the borings was typically medium dense,but ranged from loose to dense. The fill contains fragments and pieces of wood. In some borings more wood was present and one boring may have been drilled through a tree stump that could have been left in place at the time of original grading. The native glacial till soils encountered in our explorations were observed to generally consist of dense to very dense, silty to very silty, fine sand with gravel. When encountered in a boring, glacial till extended to the maximum depth of that boring; underlying soil units such as advance outwash were not encountered. Several borings intended primarily for pavement or floor slab design did not extend into the glacial till but instead were terminated in fill. Previous geotechnical investigations in the area generally confirm observations made during the geotechnical explorations accomplished for this project. However, in some borings, soil strata were reported on logs as "fill," although consistently high standard penetration test (SPT) results suggested either glacial till instead,or unusually dense and well-compacted fill. Previous borings reviewed for this preliminary draft report include 10 borings advanced by Earth Consultants Incorporated(ECI) in February and March 1994, plus 20 borings advanced by Dames & Moore in 1967, as reported by ECI. Logs and subsurface profiles prepared for these previous explorations are included in Appendix C. 2.4 GROUNDWATER At the time of our subsurface investigation in April 2014, isolated zones of perched groundwater were observed in a few of our soil borings. Monitoring wells were not installed in any of the current borings. Some of the previous borings advanced by ECI encountered groundwater seepage between 11 and 33 feet below the existing grades; elsewhere, groundwater was not encountered. We located several of these monitoring wells during field exploration and measured recent groundwater levels as follows: Previous Boring ID Completed Well Depth* Depth to Groundwater* B-105-94 36.7 32.65 B-106-94 50 34.8 B-107-94 24 11.83 * depths reported are in feet below the existing ground surface at the well location These groundwater measurements likely represent a perched groundwater condition atop the glacial till surface. Perched groundwater can occur in situations where infiltrating water can collect above very dense, low-permeability soils or within sandy zones within the low-permeability soils. Perched 5/16/14 P:\1423\002\010\FileRm\R\Draft Bldg 40-58 Report\Bldg 40-58_draft rpt.docx INTERIM D RA F T 2-3