Project: City of Lufkin
Location: Lufkin, TX
Asset: Triple Barrel Box (TBB) culvert, approximately 110 LF, running through a retention-pond levee on a former riverbed
CHALLENGE
A Triple Barrel Box Culvert approximately 110 LF was constructed on the west end of a retention pond on the east side of Lufkin. The culvert ran through the levee at an area of the retention pond that had previously been a riverbed. About 90 days after construction was complete, following some heavy rains, 70 to 80 LF of the culvert settled as much as 12 inches at the lowest point.
SOLUTION
The City of Lufkin contacted Superior for a repair method, with the city engineer's biggest concern being to stabilize the box culvert against any further settlement. Soil testing determined that the soils beneath the culvert were loose to a depth of 5 ft. Superior proposed injecting expanding polyurethane to fill the loose soil and stabilize the culvert in place, using High-Density Polyurethane injection. Crews drilled 5/8-inch holes through the 12-inch-thick concrete culvert and an additional 5 ft into the soils, on a grid pattern 6 ft on center. HD polyurethane was injected at each location until refusal, indicated by polyurethane emerging from an adjacent drilled hole or moisture appearing through the stress cracks the settlement had created. The culvert's elevation was monitored throughout the process, and pre-job and post-job elevation readings were documented.
Results
Stabilized the triple barrel box culvert and the soils beneath it to a 5 ft depth.
Injected approximately 28,000 pounds of High-Density Polyurethane.
The City of Lufkin monitored the culvert for the following year, and no movement was detected.
