San Antonio Capital Improvement Project, December 2002

By: Jonathan Newman

Two problem areas were holding up the entire project's completion -- URETEK was called to provide the permanent solution.

Location:

The city of San Antonio, Texas, contracted BRH Garver Construction to fulfill a multi-million-dollar capital improvement project in a residential area on the city's southwest side. Within the 2 sq-mile project area, two sections of asphalt road, which had been settling for months, were seriously delaying the project's completion. One was at the intersection of King and Bynum Streets. The second problem involved a manhole two blocks away.

Problem:

Repeated attempts to repair the road using asphalt overlays proved futile. Up to 18 in. of asphalt had been added to level the sinking pavements. The city of San Antonio specified that if any section of road showed signs of failure, the entire block had to be completely reworked. This would add time, traffic disruption and hundreds of thousands of dollars to the total project cost.

Adding to Garver's frustration was the fact that camera surveys of the utilities beneath the roadway found their brand new storm sewer pipes to be in good condition. Nearby culverts also were in good working order and the entire underground infrastructure was intact, thereby ruling out these items as the potential source of the settlement.

After a thorough review of all possibilities, it was finally discovered that a small finger of the Edwards aquifer was flowing through the project area. The engineering teams also found that the water flow and a rising water table, caused by two years of heavy rain, were eroding base soils below the pavement.

Application:

Faced with mounting pressure to provide a long-lasting, cost-effective and fast-acting solution, URETEK was suggested as the way to solve the road settlement quickly, with minimal cost and disruption. Using their patented Deep Injection (DI) process, URETEK densified the soil to halt the settlement without causing distress to the asphalt roadway above.

URETEK's DI process uses 5/8-in. holes in a pre-determined grid pattern to inject a hydro-insensitive expanding polymer into the soil at targeted depths. As the URETEK 486 polymer expands, it fills underground voids, displaces water and densifies loose or weak soils. This is all done in a "No Dig" environment and is carefully monitored at the surface, making it an ideal solution for just this kind of problem.

Furthermore, URETEK 486 maintains its strength in wet environments and is structurally sound in both standing and running water, making it ideal for underground infrastructure applications. The problem manhole was surrounded and encapsulated with the polymer, creating a moisture barrier in addition to densifying the soil.

Each repair location was completed in a single day and traffic lane closures were kept to a minimum throughout the injection process. The total replacement option prescribed by the contract would have taken weeks, with heavy traffic delays and massive disruption to the surrounding neighborhoods.

Results:

The URETEK Deep Injection process created a stable road base and prevented further settlement. Both areas were repaved after the DI process was completed and have remained on grade ever since. Careful monitoring of the previously sunken areas every six months shows that zero movement has taken place since the work was completed.

"The city of San Antonio is very pleased with our decision to take control of this settlement problem by using the URETEK Deep Injection process. We certainly chose the right solution," said Peck Boswell of BRH Garver Construction.

Summary:

When you're ready to control your soil stabilization, pavement lifting and infrastructure rehabilitation problems with a fast, cost-effective, long-term, and environmentally safe solution, go to http://www.uretekusa.com/locations to find your nearest URETEK USA representative or simply call us at 888/287-3835.