Emergency Sinkhole Stabilization and Repair in Utah

Problem

When a sinkhole approximately 30 feet in diameter appeared on I-15 near Scipio, Utah, the Utah Department of Transportation (UDOT) had an emergency on their hands. The sinkhole caused roadway settlement of 10 inches in just one week. This rapid settlement posed an immediate danger to traffic on the busy interstate and needed to be leveled as soon as possible. As a temporary measure, UDOT applied asphalt patching to level the roadway, but UDOT needed a more permanent solution without shutting down the interstate. UDOT contacted URETEK because of their work on previous successful sinkhole stabilization projects.

Analysis

URETEK offered to provide a preliminary plan for stabilization contingent on future soil testing. The preliminary injection plan assumed that the first 12 feet of subgrade would require stabilization. The plan was delivered to UDOT for review within a few hours of its request. UDOT discussed the potential solution and gave approval to commence work the following week. Upon arrival, URETEK performed two Dynamic Cone Penetrometer (DCP) tests to provide subsurface soil data. The data revealed that the soils needed deeper stabilization than initially assumed. As shown by DCP results, there was insufficient support in the subgrade zone between 12 and 30 feet. URETEK quickly provided a revised injection plan for review; UDOT approved the plan, and work resumed.

Solution

URETEK performed an emergency mobilization and began work 11 days before Thanksgiving. The weak zone identified from DCP tests was targeted and treated with the URETEK Deep Injection® (UDI) process. The subgrade support was so poor that the roadway continued to settle even during the injection process. The URETEK crew demobilized from the jobsite over Thanksgiving to allow both lanes to be open during heavy holiday traffic. Despite especially poor subgrade, stabilization was successfully completed within a few days after work resumed.

Result

URETEK re-aligned and stabilized the 30-foot diameter section of settled pavement on I-15. Because URETEK’s expanding, strong, lightweight, water-resistant polymer was injected into the underlying soils, no further settlement is to be expected. URETEK provided an immediate, permanent, and guaranteed solution to UDOT’s sinkhole problem on I-15. At least one lane remained open to traffic flow for the duration of the project, and the URETEK crew stepped back during peak holiday traffic flow to allow for use of both lanes. URETEK provided a two-year warranty against further settlement. UDOT was able to avoid the expense and prolonged timeline of a deep excavation and backfill solution by choosing the cost-effective and expedient UDI repair method.

URETEK Deep Injection® (UDI)

Widely referenced throughout our industry, UDI involves the injection of structural polymer into base and subgrade soils to increase the load bearing capacity. This is achieved by injecting the polymer through small holes drilled directly through the pavement structure to depths determined by site-specific analysis. Our URETEK 486 Star® material flows easily into voids and weak zones within the soil mass below. Through a controlled chemical reaction, the expanding polymer compacts surrounding soils and applies a controlled pressure on targeted areas of the affected pavement above. If needed, a multi-injection design plan is utilized to gently return the pavement to its original grade. The composite material quickly cures into a strong, dimensionally stable, and water-resistant geo-material, providing years of reliable service.

URETEK 486 Star®

URETEK 486 Star® polymer is a two-component, high-density, expanding thermoset polyurethane system. It was developed to be the ideal solution for under-sealing, void filling, lifting of settled pavement, stabilization and stiffening of weak soils, and for encapsulating and sealing buried infrastructure. URETEK 486 Star® is environmentally inert, non-toxic, and resists underground water erosion or weakening due to its industry-leading hydrophobic properties.

URETEK technicians inject a grid of URETEK 486 Star® polymer into the settled Utah Highway