Abstract:
Throughout the world, there are typical site issues/constraints that could be considered a regional issue. Soft, silty soils in alluvially defined areas. Organic soils found in former marshlands and of Pennsylvania. Uncontrolled strip-mine turnover found in the Eastern Coalfields of Pennsylvania. In northeastern Pennsylvania, the propensity of available sites share a handful of the same problematic characteristics – massive grading challenges and the presence of uncontrolled mine fills from historic mining operations. In the case of a speculative warehouse distribution center in Olyphant, Pennsylvania, both of these typical issues were present, the latter of which was exacerbated by a higher-than-average minus 200 fines content to the fill materials, making them more susceptible to changes in moisture content. To further complicate matters, the onset of site construction was set for late fall of 2021, following near historic levels of rainfall in the northeastern United States the previous two to three months, which led to significant quantities of trapped water within the fill material.
This paper will provide a case study on the efforts undertaken to identify and address the issues outlined above, focusing on the several geotechnical construction techniques required in concert to stabilize the site. Specific discussion will focus on the dynamic compaction program implemented for fill stabilization throughout much of the site, the aggregate pier program that became part of the solution in sufficiently loose and saturated areas located in portions of the site, and the implementation of a trench drain network that occurred prior to any ground improvement to facilitate drainage of the excess water within the site to allow equipment to enter the site. A final aspect to be discussed will be the settlement monitoring program that was conducted prior to placement of up to 40 feet of structural fill to establish the proposed site grades following the ground improvement work.
Keywords: ground improvement, soil improvement, dynamic compaction, aggregate piers, subsurface drainage, settlement monitoring