Sinkhole Mechanism Determination and Rehabilitation Associated with Near-Surface Stormwater System Along a Major Interstate Highway in the Twin Cities

Sinkholes can be detrimental to infrastructure and pose a potential hazard to civilians. The underlying mechanisms for sinkhole formation include loss of material which creates a void and sets in motion continued loss of material and degradation of existing infrastructure. A sinkhole developed in close proximity to a near-surface storm sewer system along a major trunk highway in the Twin Cities of Minnesota. The surficial expression of the sinkhole required ongoing maintenance for many years. This paper presents the evaluation and desktop study of historical data and field investigations performed (geotechnical soil borings, laboratory testing of soil samples, and a tracer study) to evaluate and establish existing site conditions. The findings were used to determine the sinkhole mechanisms and identify the specific section of the nearby storm sewer system associated with the loss of material, allowing for the development of an appropriate design for remediation of the sinkhole.