The Lumpkin Road Reconstruction Project should have been relatively routine, but the deeper Houston’s Memorial City Redevelopment Authority dug, the more problems they encountered.
With design parameters stacking up on each other, meeting the tight budget and even tighter schedule proved challenging. The project’s goals of improving traffic flow, providing pedestrian accessibility to Houston Community College and upgrading stormwater systems, collided at the Lumpkin Road and Westview Drive intersection.
The detention basin at that corner would need to be expanded to align with the city’s drainage master plans. The L-shaped detention area had to be deepened to 19 ft, and all six retaining walls had to be pushed back 5 ft.
The engineering firm Lockwood, Andrews & Newnam Inc. (LAN) realized the narrow right of way made reinforcing the walls as tall as 20 ft an impossibility. Gravity walls would be complicated due to poor soil issues, which were compounded when test-boring samples went as deep as 40 ft without hitting bedrock.
LAN engineers attended a Lunch & Learn about the Redi-Rock system presented by Browne Baker of Wilbert Vaults of Houston. Redi-Rock is an engineered retaining wall system that uses patented knob-and-groove, one-ton precast concrete blocks that stack together like giant Lego blocks to create strong, durable walls.
“At the end of the presentation, LAN engineers mentioned a large project they were working on, that they thought might be a good application for Redi-Rock,” said Baker.
Brian Whitney, P.E., project manager at LAN, sent design parameters to Baker, who consulted with Redi-Rock International and local installer Matt Airhart from Gulf Coast Pavers. They put together a preliminary wall design, and Clint Hines, P.E., managing principal at JC Hines & Associates LLC, provided backup calculations.
Hines prepared drawings for six interconnected retaining wall segments using the Redi-Rock gravity wall system with 9-in. setback blocks. To solve the foundation issues, the project’s geotechnical consultants Aviles Engineering Corp. proposed an innovative recycled concrete aggregate.
Hines used Redi-Rock Wall Freeware to design and analyze the wall, particularly for the cement-stabilized soil concept.
“We were able to compare [Aviles] proposed limits to the results from the Redi-Rock software,” said Hines. He modeled the proposed foundation solution with enough confidence to sign off on the project’s structural integrity.
The cost concerns and timing constraints to hit the dry season were also addressed with the Redi-Rock system, which is stacked by machinery for a quick and simple installation.
Gulf Coast Pavers was the crew awarded the job, and they installed 4,000 Redi-Rock gravity blocks in four months to complete the detention pond improvements. More than 22,000 sq ft of retaining wall surface increased the capacity by 20 acre-ft, and the rest of the Lumpkin Road Reconstruction Project goals could come to fruition.