Using Uretek technologies, it was possible to restore the emergency spillways protecting the city of Houston, Texas. The Addicks and Barker reservoirs are designed to protect Houston and its surroundings from floods. They feed Buffalo Bayou, which flows through downtown Houston and into the Gulf of Mexico.

If one of the reservoirs fails in its task of controlling water flow, a significant part of Houston will be flooded, with water possibly rising to the level of the third floor. It has been estimated that Addicks and Barker prevent an average of $16 million in flood damage annually.

Both reservoirs were built in the 1940s. A tubular spillway located within the concrete dam is used to control floodwater levels. Over the long period of operation, growth and development of the city, the tubular spillway has been modified to withstand greater water flow. Continuous water outflow from the reservoir, increased pressure, a spillway designed for previous water volumes, soil erosion, and hidden voids are the main enemies of the technical condition and operational purpose of the Houston reservoir system.

On April 30, 2009, a record water level rise was recorded at the reservoir, prompting the US Army Corps of Engineers to act quickly to strengthen and stabilise the spillway. Previous inspections of the system revealed huge voids and water flows under the culvert pipes. The enormous size and volume of the voids, combined with the recent record water level rise, convinced the US Army Corps of Engineers of the need for urgent repair of the Addicks and Barker reservoir spillway systems. Soil erosion was undermining the integrity of the tubular spillway, so the risk of hydraulic structure failure was extremely high.

The US Army Corps of Engineers specialists considered various repair options, but the continuous flow of water passing through and under the system did not favour traditional methods, which involve high impact loads and vibrations. The high water level in the reservoir did not allow the spillway to be shut down for a long time to enable a complete replacement of the culvert pipes. Most importantly, all measures to eliminate voids and water leakage under the spillway were intended to protect the residents of Houston.

“We are pleased with the work of URETEK specialists. In adverse conditions, they were able to achieve solutions to all the set tasks, and the risks to the city are now minimal” – US Army Corps of Engineers.

In water‑saturated soils, cementation would be unproductive and, given the flow rate of water into the reservoir, would not stabilise the system. Also, heavy cement masses would increase the threat of erosion and unpredictable loads on already weakened soil. The US Army Corps of Engineers specialists chose URETEK as a company that uses geopolymers that can be injected into water‑saturated soils to stabilise weak soils beneath heavy structures and increase their bearing capacity.

URETEK completed both spillway stabilisation projects at the Addicks and Barker reservoirs as required by the US Army Corps in less than three weeks. Tests carried out after completion revealed significant improvements in soil characteristics. It was also noted that the voids were now filled with compacted soil, high‑density polymer, or a combination of both. This indicates that the soil layers are performing an excellent support function for the structure. After URETEK completed its injection processes, the “emergency” status was lifted because the spillway systems became stable, safe and suitable for further operation by the city of Houston and its surroundings.