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Date Palm Drive over Whitewater River

Cathedral City, California

Bridge Scour Countermeasure


June 2018

Technical Description:

• 82,800 sf of ArmorFlex®
Class 85-L Mats

According to data from the National Bridge Inventory (NBI) database, the Date Palm Drive bridge over Whitewater River in Cathedral City, California (originally constructed in 1981) had an average daily traffic rate of 22,000 vehicles by 2008 and a future average estimated at 46,000 by 2037. In November 2008, inspection reports of the bridge indicated it was “structurally deficient” and “functionally obsolete.” In order to remediate the bridge, the following was required: seismic strengthening, scour protection, deck repairs and improving the traffic flow by widening the bridge to accommodate two additional lanes, bicycle lanes, sidewalks, barriers and railings. Additionally, since the piers were located in the river, scour protection was needed. 

Under the Standard Project Flood (SPF) conditions, pier scour in the channel was calculated at 30 feet deep resulting in the need for countermeasures to protect the existing pile foundations for the piers. The existing piers were too short to handle the calculated pier scour as well as erosion around the foundation from severe flood events. 

The preferred alternative approved by the United States Army Corps of Engineers (USACE) was Articulated Concrete Block (ACB) placed at the top of pier wall footings buried below the channel surface so that the improvements were not visible. An additional benefit included a reduction in permanent environmental impacts in the channel because the ACB system allows water to flow through it as compared with the alternative which consists of a solid impervious concrete channel section. This resulted in early USACE approvals.

For these reasons, 82,800 sf of ArmorFlex® Class 85-L Mats from Contech Engineered Solutions were selected as the best solution to provide scour protection in the channel while also avoiding permanent impacts to the environment and meeting regulations. 

Partially funded by the Highway Bridge Program (HBP), there also was significant involvement with Caltrans Local Assistance while preparing the documentation necessary to secure funding for the design, the right-of-way acquisition and the construction. The funding was as follows: 88.53% Federal Funds and 11.47% local funds from Cathedral City and Coachella Valley Association of Governments (CVAG).

In the end, the ArmorFlex product was a great solution for the site, and Cathedral City and Michael Baker International were pleased with the outcome. The project also was awarded a 2020 Project of Merit Honorable Mention Award in the Transportation category from American Public Works Association (APWA).

Technical Description:

• 82,800 sf of ArmorFlex®
Class 85-L Mats

800-338-1122 |
Project #: 506327

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