Soil Densification at Depth

By: Michael Jaques

THE LOCATION

Two westbound lanes of LA 14 collapsed in 2001 over a 22-in. high-pressure gas line near the Erath Bypass in Vermilion Parish, La. The Louisiana Department of Transportation and Development (LADOTD) District 3 closed the two lanes, tore out the failed concrete, excavated the existing soils to a depth of 12 ft, installed and re-compacted new backfill and base material and re-poured the concrete. The westbound lanes were closed for six weeks while this work was done. The project cost was $60,000.

THE PROBLEM

In early 2002, LADOTD discovered that the eastbound side over the same pipeline was showing symptoms similar to the 2001 situation. Unwilling to repeat the expense, time and disruption of 2001, District 3 looked to URETEK USA for a better solution to the problem. They were dealing with a 12-ft-deep high-pressure gas line sitting in Louisiana “gumbo” soils. They needed to stabilize the pipe, densify the base soils, level the highway and avoid further cracking or sinking of the concrete panels.

THE SOLUTION

URETEK USA, based in Tomball, Texas, and represented in Louisiana by Mike Vinton proposed the patented URETEK Deep Injection Process, utilizing URETEK 486, a high-density, hydro-insensitive, expanding polymer. This unique material is environmentally neutral. The expanding material is injected through tubes directly into the weak soil zones and is equally effective in both trapped water and wet soils environments. By measuring and monitoring any surface movement, URETEK is able to demonstrate both proper densification of the zone as well as the precise lifting of pavement sections, where necessary.

THE APPLICATION

The 22-in.-diam. high-pressure gas line was in a sloped trench, 12 ft deep, 16 ft wide (top), 6 ft wide (bottom), which was backfilled using site material. The subsequent voids, water pockets and general settlement in this backfill soil led to surface pavement damage and settlement. URETEK’s Deep Injection solution used two rows of patterned injections on either side of the pipe at 5 ft depth (A, B, C, D) followed by single rows of injections on either side of the pipe at 10 ft depth (A & B). The entire project took three days and involved lane closures only during the polymer injection, with all lanes open during nonworking hours.

RESULTS

The treatment was so effective and the results so complete that when LADOTD detected the same symptoms occurring in the other two eastbound lanes, URETEK USA was called back in early 2004 to repair these as well. The end result--all four eastbound lanes were completed using the URETEK process for half the cost, with total traffic disruption of only six days, instead of six weeks.

SUMMARY

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