Road Settlement Solution in Middletown, Delaware


In Middletown, Delaware, DelDOT officials were faced with a systemic issue with many of their CMP (corrugated metal pipe) culverts where oxidation holes had formed at the crown of the pipe, causing fine loss through the holes. This, in turn, caused the road to settle. The tri-culvert located at Brick Mill Road was beginning to show signs of settlement at the shoulder and guardrails. Something needed to be done quickly to prevent the road from settling further. DelDOT was looking for a long-term solution to the settlement problem that would provide a smooth and safe ride for drivers with as little construction impact on traffic flow as possible.


DelDOT approached URETEK about stabilizing and densifying the soils around the CMPs from the roadway-down to prevent the soils from migrating through the holes in the pipe, causing further damage to the road. URETEK Deep Injection® (UDI) was proposed for the project as a quick and effective way to stabilize the underlying soils while providing a lift to the settled asphalt pavement system.


For the Brick Mill Road project in Middletown, UDI was the perfect solution to stabilize the soils and lock them up to prevent further damage to the road. During the repairs, the crew worked in the evening from 7PM to 5AM with the road closed during the time they were working. Crewmembers injected URETEK’s 486 Star® polymer into the soils at elevations of -3’, -7’, and -11’ after determining the pipes’ integrity was still sufficient enough in shape to perform UDI.


UDI stabilized the road, increased the compressive strength of the soils below, and restored a safe and comfortable ride for area drivers. All work was completed within three work shifts, and the URETEK crew consistently monitored the area of the pipes below the road to make sure no material entered the water that flowed downstream. After a systemic roadway settlement issue at Brick Mill Road, DelDOT officials were pleased to finally have a long-term repair in place without dealing with the steep costs and long project timelines associated with traditional rip and replace repair methods.

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.

Roadway in Middleton
Road settlement
URETEK technicians preparing tubing on roadway at night


See All Case Studies