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SH20 over Spavinaw Creek

Mayes County, Oklahoma

Emergency Abutment Protection

Technical Description:

• 5,293 sf of ArmorFlex® Class 85L Mats
• 15,041 sf of ArmorFlex® Class 45s Mats

After a fluke storm event caused an eddy current at the abutment of a conventional bridge, emergency abutment protection was necessary. Even though the bridge was less than a year old, the riprap protection around the east abutment was completely washed out forcing the Oklahoma Department of Transportation (ODOT) to close the bridge due to the danger associated with the scour. 

“With this project located in a rural area with many lakes and rivers, closing this bridge was a huge inconvenience to the surrounding communities," stated Jennifer Bullard, Resident Engineer at ODOT. "Given the severity of the scour, Contech Engineered Solutions helped determine the best product to use that could be installed quickly and be very resilient in case any other weather events would occur in the area." 

In October 2019, ODOT contacted Contech Engineered Solutions for help finding a cost-effective solution that would sustain future large storm events. By using the site parameters and stream hydraulics, Contech's engineering team determined that a combination of 5,293 sf of  ArmorFlex® Class 85L mats under the bridge and 15,041 sf of ArmorFlex® Class 45s mats along the approaches of the bridge would provide a sufficient and cost effective solution. ArmorFlex is a flexible, interlocking matrix of cellular concrete blocks of uniform size, shape, and weight used for hard armor erosion control. ArmorFlex blocks have specific, tested, hydraulic capacities and are laced longitudinally with revetment cables to provide ease-of-handling and rapid installation.

The job bid in late October 2019 with the end of November set as the deadline for completion. The contractor, Manhattan Road and Bridge (MRB) out of Tulsa, won the bid and in order to ensure a successful installation, Contech worked closely with the company to help with best practices, mat sizing and pick weights.  The existing abutments and deck created a very tight installation space, so MRB was very ingenious in their approach to installing the mats. Contech created a variation of mat sizes, manufacturing smaller mats for installation adjacent to the abutment, and then larger mats for faster installation in other areas.

“This product has not been widely used in our area, so it was much appreciated that Contech's representative was available for guidance and advice the entire duration of the project,” added Bullard.

MRB used the Contech-provided spreader bar in a unique configuration to slide the smaller mats under the bridge adjacent to the existing abutment. A combination of pushing and pulling with cranes and other equipment was utilized to place the ArmorFlex mats in the specified locations. In the end, a great emergency solution was provided for this abutment replacement project, and ODOT and MRB were pleased with the outcome.

“Contech's representatives were on site working hand in hand with our contractor," concluded Leslie Lewis PE, CFM, ODOT's State Bridge Hydraulic Engineer. "Together they came up with this innovative solution to get the top toes in without harming the beams of the relatively new bridge. I have had the pleasure of working with the Contech team on several projects, and they are there for you from project initiation through design and construction.“

Technical Description:

• 5,293 sf of ArmorFlex® Class 85L Mats
• 15,041 sf of ArmorFlex® Class 45s Mats

800-338-1122 |
Project #: 631697


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