Irrigation Head Gate Void Fill Erosion Control Soil Stabilization


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.


  • Create a permanent solution to undermining and channeling caused by water.
  • Fill voids without having to excavate the structure.
  • Consolidate the soil and rock material into an effective support system for the structure.


  • ZERO EXCAVATION in situ repair process.
  • Hydro-Insensitive material.
  • Easily reach areas where large equipment would cause damage, or unable to access.
  • Effective rehabilitation of existing infrastructure eliminates cost of rip out and replace.

Drain Pan Void Fill Structural Support CDOT Region 1

A drain pan structure running adjacent to US-287 near Broomfield Colorado had experienced significant voids of varying severity beneath the structure. The drain pan was designed to move water away from the roadway during water events and run off; however, due to issues with the design of this particular structure, water was running beneath the concrete and eroding areas beneath the pan. The integrity of the structure was compro-mised due to the weakened and eroded supporting soil.

CDOT needed an effective solution to treat and repair the almost 800 foot long problem section of drain pan that would not only fill the voided areas, but also protect it against additional damage and structural failure that may also effect the safety of the adjacent highway.

A thorough evaluation of the site was conducted prior to design of the repair plan for the drain pan. It was determined that the more severe voids were located on the uphill slope area of the structure. Alternate solutions, including a flowable fill, were taken into account while determining the most effective way to treat the area. However, due to the advanced features of CST’s proprie-tary injection process, and the unique characteristics of the specialized expanding structural polymer, it was determined that filling the voided areas using this process would most effectively and most efficiently solve the problem. Injections were made directly through the drain pan, filling voids, and strengthening the supporting soils.

The entire stretch of affected drain pan was void filled and stabilized in four days without any disruption to traffic flow along the adjacent highway.

The treatment method allowed CDOT to extend the use life of the structure and avoid the expense of tearing out and replacing the structure.

The specifically designed repair not only eliminated the void space beneath the pan and strengthened the soils, but also provided protection to the structure against future erosion.

Repair costs came in under budget for this project.

Layland Canyon Mine Reclamation – Lincoln County, WY

Concrete Stabilization Technologies, Inc. (CST) completed a high profile in-situ compaction and water control project at the Layland Canyon Phosphate Mine in western Wyoming. The Layland Canyon Mine area is an abandoned mountainside phosphate mine located in Lincoln County, near Cokeville, Wyoming. The mass grading and reconstruction of the slope area of the mine was being completed as part of the State of Wyoming’s reclamation of abandoned mine land. Concrete Stabilization Technologies, Inc. sub-contracted with Oftedal Construction, Inc. to perform the injection of Expanding Structural Polymer into areas of the high wall face area of the mine, in order to help steer water off the zone next to the face by compacting the soils and mitigating the settlement and water inflow into the backfill and rock interface. With topsoil being placed over this area, a desired shingle effect was created beneath to divert water, and help stabilize and control future erosion of the reconstructed area.

Concrete Stabilization Technologies, Inc. Regional Engineer Roy Mathis worked with Chris Walla, P.E., of RESPEC Consulting to develop the procedure and specification for injection of Expanding Structural Polymer (ESP) that was successfully used on this project. Crews joined Oftedal Construction, Inc. for a site-specific safety meeting, and then drove to the injection location to begin placing probes and prepping the CST injection equipment. After a field adjustment by AVI’s Field Engineer the first set of injections were placed on the north end of the high wall, 11 feet south of Station 17+70, 59 feet north of the original plan. Due to wider top bench, injection points were moved 30 to 40 feet north of the original injection plan. ESP design was adjusted from three injection rows, to two rows. The second row was adjusted with increased material per injection location in order to ensure good compaction and the material spread between injections into the backfill and against the high wall. Injections were made at three foot and 10 foot depths.

CST crews were highly efficient in completing the project and devising the best solution based on actual field conditions once the work began. In consideration of water runoff, adjustments were made to meet the goal of shedding water away from the high wall. Slope changes were taken into account and injection points altered from the original 2 foot area to 4 foot along the slope and wall in order to provide maximum effect from the stabilization of the soil. Adjustments to compensate for blowout were also made at the 10 foot level.

The CST ESP was injected into the high wall area of the mine site, successfully compacting, stabilizing and providing erosion protection for the abandoned area. Even as inclement weather rolled in, the work was completed in three days. A total of 1100 lineal feet of compaction and water control was completed at the interface of the high wall and fill material to assure stabilization of the soils and provide excellent results for the successfully reclaimed mining site.

Team Members:

  • State of WY DEQ Abandoned Mine Lands Division, Owner
  • Jim Murphy, P.E. AVI Engineering, Inc.
  • Chris Walla, P.E., Environmental Manager, RESPEC Consulting & Services
  • Roy Mathis, CST Consultant & CST Project Manager, Concrete Stabilization Technologies, Inc.
  • Matt Otterby, Project Manager, Oftedal Construction, Inc.
  • Tomas Ramos, Project Superintendent, Concrete Stabilization Technologies, Inc.

Slope Stabilization – Buffalo, WY

The Problem

A torrential late spring rainfall that dropped a deluge of water in upwards of 10 inches over a short period of 36 hours caused a dirt retaining wall below the deck area of this residence that is built on a steep incline area, to slough off. The heavy down rush of water and resulting landslide, ripped out a portion of the home’s deck and board walk area. Water and rock chunks that broke loose carried soil away, leaving voids and unstable areas on the steep slope directly below the home and creating an unstable situation.

The homeowner was not only concerned about the stability of the area, but planned on rebuilding the deck and boardwalk that had been destroyed during the slide. In order to do so, the retaining wall and slope would need to be re-compacted and any void areas filled and stabilized in order to make the area safe and strong enough to hold up during future water events and to support the reconstructed deck and walkway.

Factors for Consideration

The homeowner planned to rebuild the deck and boardwalk area that was washed out during the heavy rain. The steep slope would need to be reinforced to ensure a safe, stable area to rebuild on and that would withstand additional water flow and remain stable for years to come. The safety of CST’s crews who would perform the void fill and stabilization of this steep incline was a major factor. Technicians used extra fall protection and tie off methods to ensure their safety during the project.

Method/Process Applied

The CST technologies were used to stabilize the weakened and loose soils on the entire length and width of the slope.

The CST deep injection process which involves injecting expanding structural polymer at different depths directly into the soil was used to fill voids, encapsulate loose rock and dirt, and build the stability back into the soils. The injection plan was designed and safety equipment put in place to protect crew members on the steep incline. Injections were made in increments as the crew worked across the area, recompacting the soil, filling voids, and improving the stability of the slope. Final injections were made in the area of the hillside where the deck and boardwalk would be reconstructed.


The entire retaining wall area and hillside were stabilized, re-compacted and void filled in less than 5 hours. Bearing capacity of the soil was increased and areas void filled to ensure strength and durability of the slope.


The quick, non-destructive nature of the CST technologies makes an ideal solution for slope stabilization and areas where events such as heavy rain, flooding, and erosion have caused unstable soils. The no-dig repair method allows for very little disruption to landscaping features and families.

The CST processes provide fast results that protect from property loss, minimize costs and provide a safe, and durable repair alternative to costly and disruptive underpinning methods. State-of-the-Art equipment and highly trained technicians easily perform repairs in tight or steep areas where large equipment required for traditional repair methods have a difficult time accessing. Areas are able to be used immediately following completion of injections.