Sinkhole Stabilization and Repair in Virginia


The United States Highway US 15 runs through six states including Virginia. In Leesburg, Virginia, a special route of US 15 called US Route 15 Business (RT 15 Business) cuts through the center of the city’s historic downtown area. A sinkhole formed in RT 15 Business at the location of a previous repair. URETEK was hired to permanently address the sinkhole issue once and for all.


The site of the sinkhole was previously dug out, a large stone was placed 12 feet under the pavement, the area was overlaid with soil and cobles, and the roadway was patched. The patch resettled as much as three inches in two areas. URETEK determined its Deep Injection® (UDI) process would adequately stabilize the subgrade and repair the sinkhole with minimal disruption and no excavation.


The URETEK crew set up a three-dimensional grid pattern for UDI injections in an area 30 feet wide by 24 feet long and 12 feet deep (to the depth of the stone used in the previous repair). First, URETEK pre-drilled holes and inserted tube bundles. Then, they injected URETEK 486 Star® at multiple depths to strengthen the foundation soils and lift the asphalt roadway.


In just four days, URETEK successfully strengthened, stabilized, and lifted RT 15 Business and prevented any future sinkholes from developing. The work was completed without any excavation or heavy construction equipment. Furthermore, because the site of the sinkhole was near three schools, the crew limited their working hours from 9:30AM to 3PM to prevent disruptions to the busy local school bus schedule.

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.

Tape measure on asphalt


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