California Culvert Rehab - City of Vista

September 2016

Vista, California Turns to High Strength Fiber-Reinforced Polymer Concrete to Rehab Culvert

In 2002, the corrosion of a culvert pipe structure within the 80-acre business park became known within the City of Vista. The City of Vista, located in the heart of Southern California's industrial and commercial hub, began seeking recommendations on the repair of the 15-ft diameter aluminum arch culvert. Any solution with minimal construction footprint was highly needed from the city. The city wanted to minimize impacts to the sensitive areas surrounding the project sites, including coastal sage scrub and wetland habitats.

Rehabilitation Requirments

The primary design criterion was to support the earthen embankment and any live vehicular loading. Another requirement was that the exposed culvert material be non-flammable and resistant to heat, as City staff had observed campfire remnants within the culvert. Due to the oval shape of the pipe and its use as a roadway underpass for both sewer and fire trucks, rehabilitation needed to follow the same profile of the existing CMP.
These design requirements eliminated some options such as high-density polyethylene spiral lining and epoxy lining systems. Consequently, concrete or steel rehabilitation systems were recommended to meet the design criteria.

The Rehabilitation Solution

The City of Vista has considered several rehabilitation methods for jobs. Sliplining was rejected as a potential option due to the limitations and size of the repair pipe. The City of Vista seeks out Inland Pipe Rehabilitation or IPR South Central for recommendations. EcoCast and it's geopolymer solution by Milliken Infrastructure Solutions (MIS) came into the plan. EcoCast would work well to coat out the large diameter structures. The GeoSpray mortar can be customized based on the type of project involved.

Project Challenges

During the rehabilitation project, the IPR crew encountered movement in the pipe after removal of the asphalt roadway, which had previously locked the structure in place. Replacing the roadway with a structural slab that would be traffic rated and strong enough for large sewer and fire trucks to pass through presented a major challenge. It needed to be thick enough — and consist of enough rebar — to withstand the anticipated loads of large trucks.

However, remaining within the rehabilitation envelope meant constructing a slab that could be no more than 5 in. thick, a full 4 in. less than most conventional traffic-rated concrete slabs. EcoCast’s high strength characteristics made it the perfect material for the new slab construction. IPR imported 5 in. of gravel, fixed #2 rebar and poured a 5-inch thick layer of geopolymer.

With a crew of only five installers and one project manager, IPR completed the project within budget, and within the estimated two-month time frame with no overtime or weekend work required.

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