Erosion of support soils beneath this concrete head gate had happened over time caused by turbulent water eroding soils beneath the inlet floors and undermining the structure. The voids created beneath the inlet had grown large enough that the foundation of the structure was compromised. In high water events, the undercut of the water could potentially wash out the entire head gate.
FC Excavation, the general contractor responsible for repair of the head gate was hired to provide a permanent solution to stop water from undercutting and carrying soil away from beneath the floor of the structure. An in situ solution, that would not require excavation or ripping out and replacing the concrete was preferred. They were also looking to make the repair during the fall when water was not being diverted through the head gate and have it solid before irrigation started in the Spring.
Concrete Stabilization Technologies partnered with Josh Frappart of FC Excavation in designing a permanent solution to fill voids and create an impermeable curtain wall beneath the head gate to support the structure and prevent future erosion.
Upon investigation of the site, it was discovered that voids as large as 2 cubic yards exist-ed beneath the head gate. To create a stronger base, the FC Excavation crew first added rock and soil into the large voids. Injections were then made into the soil, creating support pressure and filling the voids.
The hydro-insensitive expanding structural polymer (ESP) consolidates and strengthens the weak base soil and lenses out to fill voids, reinforces and densifies the soil, and creates a permanent barrier against water erosion.
Once the crew had finished injections, the contractor brought in rip rap to be placed on top of the repaired area.
The entire repair of this undermined head gate was completed in 6 hours.
The expanding structural polymer installed by CST’s technicians efficiently and effectively rehabilitated this irrigation head gate with ZERO EXCAVATION.
The ESP used to repair the head gate will effectively mitigate against future erosion. The impervious barrier created beneath the structure will divert water from forming a channel beneath the head gate.
CST’s expanding structural polymer repair process is highly effective for preventing seepage and controlling erosion caused by water. Because of its hydro-insensitive characteristics, the ESP can be installed in wet environments and does not degrade in water. This in situ repair process saves irrigation districts and land owners the high cost and downtime of rip out and replace while providing a permanent solution.